Skip to main content
NCBI home page
Saudi Pharmaceutical Journal : SPJ logoLink to Saudi Pharmaceutical Journal : SPJ
. 2023 Feb 2;31(3):433–443. doi: 10.1016/j.jsps.2023.01.010

Berberine ameliorates the neurological dysfunction of the gastric fundus by promoting calcium channels dependent release of ACh in STZ-induced diabetic rats

Congcong Hou a,1, Hongyu Liang a,b,1, Zhangsen Hao a, Ding Zhao a,⁎
PMCID: PMC10071329  PMID: 37026044

Graphical abstract

graphic file with name ga1.jpg

Open in a new tab

Keywords: Berberine, Contractile function, Gastric fundus, ACh, NO, Calcium channel

Highlights

  • •

    In diabetic rats, the neurogenic contractile response of gastric fundus is disordered.

  • •

    BBR enhances the EFS-induced neurogenic contractile response of diabetic rats’ gastric fundus.

  • •

    BBR promotes the release of Ach through calcium channels to correct contraction disorder.

Abstract

Background

It has been reported diabetic gastroparesis is related to diabetic autonomic neuropathy of the gastrointestinal tract, and berberine (BBR) could ameliorate diabetic central and peripheral neuropathy. However, the influence of BBR on the function and motility of the gastric fundus nerve is unclear.

Methods

A diabetic rat model was constructed, and HE staining was used to observe the morphological changes in the gastric fundus. The changes in cholinergic and nitrogen-related neurochemical indexes and the effects of BBR on them were measured using Elisa. The effects of BBR on the neural function and motility of gastric fundus were investigated by electric field stimulation (EFS) induced neurogenic response in vitro.

Results

In the early stage of STZ-induced diabetic rats, the contractile response of gastric fundus induced by EFS was disorder, disturbance of contraction amplitude, and the cell bodies of neurons in the myenteric plexus of gastric fundus presented vacuolar lesions. Administration with BBR could improve the above symptoms. BBR further enhanced the contraction response in the presence of a NOS inhibitor or the case of inhibitory neurotransmitters removal. Interestingly, the activity of ACh could affect NO release directly and the enhancement of BBR on contractile response was canceled by calcium channel blockers completely.

Conclusions

In the early stage of STZ-induced diabetic rats, the neurogenic contractile response disorder of the gastric fundus is mainly related to cholinergic and nitrergic nerve dysfunction. BBR promotes the release of ACh mainly by affecting the calcium channel to improve the neurological dysfunction of the gastric fundus.

1. Introduction

Gastrointestinal autonomic neuropathy in diabetes may be defined as dysfunction of the autonomic nervous system innervating gastrointestinal motility, which usually causes gastrointestinal dysfunction. Diabetic gastroparesis or abnormally delayed gastric emptying is the best-characterized manifestation of gastrointestinal autonomic neuropathy and occurs frequently (Bharucha et al., 2019, Marathe et al., 2020). Under normal circumstances, gastric emptying is precisely tuned to react to various intrinsic and extrinsic signals, including intrinsic neural plexuses, extrinsic autonomic factors, and neurohormonal mechanisms (Mussa, Sood, & Verberne, 2018). The extrinsic control of the parasympathetic and sympathetic pathways are still the predominant players that modulate various gastric processes along with the output of the intrinsic plexuses (Browning and Travagli, 2014, McMenamin et al., 2016). In particular, the regulation of gastric motility depends on excitatory (cholinergic) inputs and inhibitory (nitrogenous)inputs to a great extent(Mussa et al., 2018).

A large number of studies on diabetic gastroparesis have shown the content and activity of neurotransmitters are various in different stages and parts (He et al., 2014, Wang et al., 2009). Studies have confirmed that the injury or loss of nitrogenous neurons is an important reason for various stomach upsets and dysfunction (Gangula et al., 2018). Significantly, insulin therapy can efficiently delay the development of diabetic gastroparesis by protecting the myenteric cholinergic neurons and interstitial cells of Cajal (Yang et al., 2017). Previous studies in our laboratory have also found that the first lesion in diabetic gastroparesis may occur in the gastric fundus, and the damage of nitrergic and cholinergic nerves is the direct cause of diabetic gastric dysfunction (Hao et al., 2015).

Suboptimal glycemic control and insulin resistance are associated with high risk of macrovascular and microvascular complications. Silymarin is a herbal medicine with an antioxidant and anti-inflammatory properties when given in a dose of 140 mg thrice daily for 3 months as an adjuvant for glycemic control, lipid profile and insulin resistance proved to have a beneficial efficacy (Elgarf, Mahdy, & Sabri, 2015). Additionally, Daflon 500 mg (micronized purified flavonoid fraction of Rutaceae aurantiae, consisting of 90 % diosmin and 10 % hesperidin), twice daily for 45 days is helpful in reducing glucose level and the risk of cardiovascular disease (Rizk & Sabri, 2009), Beneficial nutrients and antioxidants including coenzyme Q10 and alpha-tocopherol proved to have a neuroprotective effect (Nagib et al., 2018). Moreover, estrogenic compounds as genistein proved to exhibit a neuroprotective effect attributed to its estrogenic, antioxidant, and/or anti-apoptotic properties (Elsayed et al., 2018). Additionally, Diabetic Polyneuropathy (DPN) represents a major health problem as it increases morbidity affecting patients' quality of life. Vitamin B frequently is used for treating DPN. ALPHA Lipoic Acid (ALA) seems to delay or reverse DPN. Combined therapy of DPN with ALA and Vitamin B complex, improves the symptoms of neuropathy (MNSI) with a similar trend in NCS (Boghdadi, Afify, Nagwa, & Makboul, 2017).

Traditional Chinese medicine is getting more and more attention in clinical research due to its definite curative effect in treating gastrointestinal motility disorders (Lee et al., 2010, Shin et al., 2018, Zeng et al., 2019). It may also be a valuable tool for treating gastrointestinal dysfunction in diabetes (Tian et al., 2017). Having been used for thousands of years to treat gastrointestinal diseases, the main active ingredient of Coptidis Rhizoma, berberine (BBR), has exhibited a wide spectrum of biochemical and pharmacological effects in studies in recent years including its antidiabetic, anticancer, neuroprotective, anti-inflammatory, and anti-atherosclerotic actions (Hou et al., 2020). Notably, BBR possesses anti-diabetic effects, which is related to the property of stimulating insulin secretion and modulating lipids (Leng, Lu, & Xu, 2004). It is precisely because of it upregulates liver low-density lipoprotein receptor (LDLR) expression to improve hypercholesterolemia that BBR was suggested to be a promising new hypolipidemic drug(Kong et al., 2004). The vast majority of BBR dosage forms in the population are mainly oral. Therefore, BBR is a promising drug for further development. Some studies have also shown that BBR may play a neuroprotective role by exerting cholinergic, anti-oxidative, and anti-inflammatory effects (Akbar et al., 2021, Wang and Zhang, 2018, Zhao et al., 2021). Moreover, it has been reported that BBR can improve the central and peripheral neuropathy of diabetes (Zan, Kuai, Qiu, & Huang, 2017). Our previous studies also confirmed that BBR improves the neurogenic contractions of bladder detrusor (Ren et al., 2013) and mesenteric and iliac arteries (L. Zhao et al., 2019) in streptozotocin-induced diabetic rats. In addition, it has also been reported that BBR has a protective effect on the gastric injury of alcoholic mice (Pan et al., 2005), and may play a role in inhibiting the contraction of the circular smooth muscle of the guinea pigs' gastric antrum (Yuan, Zhang, Yu, & Wu, 2009). However, the gastric fundus is a sensitive area in diabetic gastroparesis, and there is no report on the effect of BBR on the function of the gastric fundus.

Therefore, this experiment adopts the STZ-induced early diabetes rat model and explores the regulation effects of BBR on the cholinergic and nitrergic nerves in the contraction of the circular muscles of the stomach fundus induced by electric field stimulation (EFS). It may develop a new perspective to use BBR in the prevention and treatment of diabetic gastroparesis drugs.

2. Materials and methods

2.1. Animals

One hundred and four male Sprague-Dawley rats (200–220 g) were purchased from the Experimental Animal Center of Hebei Medical University (China). Rats were fed with normal rat chow and water ad libitum and housed under 12 h (light)-12 h (dark) cycles in the animal care facility. Animals were randomized into 4 groups: normal (control) rats, diabetic rats, and diabetic rats treated with high or low dose BBR. Among them, fifty-six normal rats were used for isometric tension recording in EFS-induced contractile and relaxation responses, molecular detecting of gastric fundus tissues and histomorphological examination. Thirty-two diabetic rats were used for isometric tension recording in EFS-induced contractile responses, molecular detecting of gastric fundus tissues and histomorphological examination. There were eight rats in the high dose BBR gavage group and eight in low dose BBR gavage group respectively, that were used to isometric tension recording in EFS-induced contractile and histomorphological examination. Diabetes was induced in rats by intraperitoneal injection of 65 mg·kg−1 streptozotocin (STZ, in 0.1 mol·L−1 citrate buffer) after 12 h fasting. After 72 h, STZ-treated rats with random blood glucose concentrations consistently greater than 16.7 mmol/L (greater than300 mg/dL) were used as successfully established diabetic rats (Zhu, Han, Yuan, Xue, & Pang, 2018). After two weeks of the STZ administration, the rats in the high/low dose gavage group were given 200/100 mg·kg−1 BBR (Wang et al., 2011, Zhao et al., 2019) by intragastric administration, once a day for two weeks. All animals were used in accordance with our institutional guidelines for animal care and the guidelines laid down by the NIH in the US regarding the care and use of animals for experimental procedures, and the present study was approved by the Hebei Medical University Ethics Committee for Animals.

2.2. Reagents

Berberine was obtained from Sichuan Xieli Pharmaceutical Company (Batch Number: 061002, SFDA approval number: H51020007). STZ was obtained from ALEXIS Biochemicals Company. Atropine sulfate (Atr), Nω-Nitro-l-arginine methyl ester (l-NAME), α-chymotrypsin (α-chy), suramin hexasodium salt (Sur), and tetrodotoxin (TTX) were obtained from Sigma Chemical Company. Carbachol hydrochloride (CCh) was obtained from ABCR GmbH & Co KG. l-arginine (l-arg) was obtained from Beijing Bailingwei Science and Technology Company. Neostigmine Methylsulfate was obtained from Henan Hongrun Pharmaceutical Company. Amlodipine Besylate (AML) and Cilnidipine were obtained from TCI Company. Nitric Oxide Synthase 1 (NOS1) Rat SimpleStep ELISATM Kit was obtained from Abcam Company. Nitric Oxide Synthase (NOS) Kit, Acetylcholine Kit, Acetylcholine esterase Kit, and Choline acetyltransferase Kit were obtained from Nanjing Jiancheng Biology Engineering Institute. All drugs were dissolved in distilled water except STZ, which that STZ was dissolved in 0.1 mol·L−1 citrate buffer (pH 4.5).

2.3. Specimen preparations for measuring smooth muscle tension

Rats were fasted overnight and killed by exsanguinations, followed by removal of the stomach through an abdominal incision. The circular muscle strips of the gastric fundus (approximately 8 mm in length and 2 mm in width) were made, and the mucosal layers were gently removed.

Isometric tension transducer coupled to a MedLab data acquisition system (MedLab-U/4cs, Meiyi Technology Company, Nanjing, China) to record the responses of the preparations. The strips were mounted in 10 mL organ baths containing Krebs-Henseleit (K-H) solution (composition (mmol·L−1): NaCl, 133; KCl, 4.7; NaH2PO4·2H2O, 1.35; NaHCO3, 16.3; MgSO4·7H2O, 0.61; glucose, 7.8; CaCl2, 2.52; pH 7.2), maintained at 37 ± 0.5 °C, and constantly aerated with a mixture of 95 % O2 − 5 % CO2 v/v.

A resting tension of 1.0 g was applied to the strips. EFS was performed via two parallel platinum wire electrodes. Electrical impulses were provided by a modified stimulator (Grass S48, USA). Neurogenic contractile and relaxant responses induced by EFS were confirmed by blocking action potentials in nerves with 0.1 μmol·L−1 TTX added before the end of the experiments. The method used for isometric tension recording has been described in full elsewhere (Ren et al., 2013).

2.4. Effects of BBR on EFS-induced contractile responses in the gastric fundus

The contractile responses induced by EFS (50 V, 20 Hz, 1 ms for 10 s, train duration with 100 s intervals between the trains) in circular muscle strips of the gastric fundus were observed (Lu et al., 2014). To investigate the mechanism of BBR, the contractile responses were performed in presence of 100 µmol·L−1 l-NAME, or 1 and 10 µmol·L−1 BBR, or 1.0 µmol·L−1 Atr.

2.5. Effects of neostigmine on EFS-induced relaxation responses in the gastric fundus

All specimens received a 1 h equilibration period with heating to 37 °C and repeated washing every 10–15 min. After the equilibration period, the segments were pre-contracted with carbachol (0.3 µmol·L−1). When the contractile response formed a plateau, EFS (1–10 Hz) was given (Gibson, Cotter, & Cameron, 2006). After the stimulation, the specimens were washed several times.

The effect of neostigmine on the diastolic response by EFS was investigated in gastric fundus circular muscles in rats by cumulative application. The results of the first two rounds of stimulation served as the control group. After the second round of stimulation, the bath solution was then replaced and added neostigmine (0.01 µmol·L−1) and incubated for 20 min (Cellini, DiNovo, Harlow, & LePard, 2011).

2.6. Detecting the related molecular of gastric fundus tissues

Gastric fundus from all experimental groups was homogenized in a low-temperature environment, and homogenates were centrifuged at 3500 rpm for 10 min at 4 °C to obtain the supernatant. The contents of nNOS, tNOS, acetylcholine (ACh), Choline acetyltransferase (ChAT) and ACh esterase (AChE) in the gastric fundus tissues were detected by using ELISA kit. According to the kits, instructions were to operate strictly until the reaction was complete, and the OD values were measured using a microplate reader (L. C. Li, Li, & Du, 2021).

2.7. Histomorphological examination

The gastric fundus strips were fixed with formaldehyde and paraffin sections were made according to the standardized process. 5 µm thick paraffin sections were prepared and stained with hematoxylin and eosin to observe the morphological changes in gastric fundus tissues.

2.8. Statistical analysis

Two-group comparisons were made using a two-tailed unpaired Student's t-test. One-way ANOVA was used to compare multiple groups, with a least significant difference or Dunnett's test as post-hoc evaluation for P < 0.05. The measured values are presented as means ± standard error. Data analysis and creation of graphics were performed using SPSS version 21.0 (IBM Corp., Armonk, NY, USA) and GraphPad Prism version 8.0 (GraphPad Software, Inc., San Diego, CA, USA), respectively.

3. Results

3.1. Effects of BBR on gastric fundus tissue morphology and function in diabetic rats

In the sections, the nuclei and basophilic granules were stained blue-purple. The neuronal cell body is rounded, elliptic or irregular, concentrated in the intramuscular nerve plexus, the nucleus is visible, and the nucleoli are obvious. Basophilic fine particles, namely Nissl bodies, are scattered in the cytoplasm. The cell bodies of neurons in the diabetes model group presented vacuolar lesions. And after treatment with BBR, the vacuolar lesions were improved (Fig. 1A).

Fig. 1.

Fig. 1

Open in a new tab

Effects of berberine on tissue morphology and function in the gastric fundus of diabetic rats. (A) The influence of berberine on the pathological morphology by HE staining in gastric fundus smooth muscle of diabetic rats (×400). In the normal rats’ group, Nissl body is clear; in the diabetic rats’ group, the neurons have vesicular degeneration; berberine o.p.h rats’ group, the number of vesicular degenerations in neurons has decreased. (B) Original traces showing the contractile responses to EFS in isolated gastric fundus strips from those normal, diabetic, o.p.h group rats. (C) Contractile responses to EFS in the isolated gastric fundus strip of normal rats, diabetic rats, berberine o.p.h rats, and berberine o.p.L rats. n = 8, 7, 7, 7. (D) Effects of berberine (1, 10 μM), TTX (0.1 μM), and Atr (1 μM) on the contractile responses to EFS in the isolated gastric fundus strip of normal and diabetic rats. The data are presented as the mean ± SEM. *P < 0.05 vs normal rats and #P < 0.05, ##P < 0.01 vs diabetic rats in solvent respectively by Dunnett’s test；※P < 0.05 vs normal rats by Student t-test. n = 8.

To investigate the effects of BBR on the function of gastric fundus smooth muscle, we analyzed the contraction response of smooth muscle to EFS. In contrast to the diabetic rats, administration with 200 mg·kg−1 BBR could correct the disturbance of contraction amplitude and enhance the contractile response of gastric fundus smooth muscle induced by EFS (Fig. 1B and C). Unfortunately, administration with 100 mg·kg−1 BBR failed to improve the contraction response (Fig. 1C). Therefore, administration with 200 mg·kg−1 BBR was selected for intragastric administration in subsequent experiments. The contractile responses of gastric smooth muscle induced by EFS could be completely blocked by TTX or atropine. It suggested that all the responses observed were neurogenic and mainly caused by cholinergic nerve activity. Moreover, 1 and 10 µmol·L−1 BBR increased the contraction response of gastric fundus smooth muscle induced by EFS in a concentration dependence (Fig. 1D). Interestingly, in the presence of l-NAME, a NOS inhibitor, 10 µmol·L−1 BBR further enhanced the contraction response in normal rat gastric fundus (Fig. 2AB). Additionally, when the interference of neurogenic diastolic response was removed by inhibitory neurotransmitters, including nitric oxide (NO), vasoactive intestinal peptide (VIP), and adenosine triphosphate (ATP) blockers (l-NAME, α-chymotrypsin, and suramin), BBR could still further promote the EFS induced contraction response (Fig. 2C). Collectively, these data suggested that BBR could directly regulate the dysfunction of the excitatory neurotransmitter ACh thereby correcting decreased neurogenic systolic responses and disorders in diabetic rats.

Fig. 2.

Fig. 2

Open in a new tab

Berberine could further promote the EFS-induced contraction response when the interference of neurogenic diastolic response was removed. (A, B) Effect of l-NAME (10,100 μM) and berberine (10 μM) on EFS induced contractile responses in gastric fundus circular muscle of normal rats. (C) Effects of berberine (10 μM) in the presence of l-NAME (100 μM), α-Chymotrypsin (10 μM), and suramin (100 μM) on the contractile responses to EFS in the isolated gastric fundus strip of normal and diabetic rats. The data are presented as the mean ± SEM. **P < 0.01, ***P < 0.001, ****P < 0.0001 vs normal rats and #P < 0.05 vs l-NAME, ###P < 0.001, ####P < 0.0001vs diabetic rats in solvent respectively by Dunnett’s test；※※P < 0.01 vs normal rats by Student t-test. n = 8.

3.2. Effects of BBR on NOS and ACh content or their related enzyme activity in vivo

Is the effect of BBR on cholinergic nerves in diabetic rats achieved by affecting NO and Ach-related synthesis or decomposition enzymes? Further studies showed that tNOS activity was not changed significantly while nNOS content was decreased significantly in the gastric fundus of diabetic rats (Fig. 3A-B). BBR administration had no significant effect on tNOS activity and nNOS content (Fig. 3A-B), that is, BBR did not improve the reduction of neurogenic NO. The ChAT activity was significantly up-regulated, and AChE activity was significantly decreased in the gastric fundus of diabetic rats (Fig. 3C-D), suggesting that the cholinergic nerve function in the gastric fundus was enhanced by diabetes. BBR significantly reduced the up-regulation of ChAT but did not affect the decrease of AChE activity (Fig. 3C-D). BBR administration also had no significant effect on ACh content (Fig. 3E).

Fig. 3.

Fig. 3

Open in a new tab

The changes in the enzyme’s activity in gastric fundus tissue. The changes of (A) n NOS, (E) ACh content and (B) t NOS, (C) ChAT, and (D) AChE activity in the gastric fundus of normal, diabetic, and o.p.h rats. The data are presented as the mean ± SEM. *P < 0.05, **P < 0.01 vs normal rats and ##P < 0.01 vs diabetic rats, n = 8,8,6,6,6.

3.3. Effects of BBR on NOS and AChE activity in gastric fundus tissue in vitro

To further clarify the effects of BBR on ACh, we examined the effects of BBR on NOS and AChE in the gastric fundus of the rat. As shown in Fig. 4A and B, in contrast to the l-NAME-induced activity of tNOS decrease, BBR had no significant effect on tNOS activity even though the concentration went up to 1000 µmol·L−1. Consistently, BBR did not reduce the AChE activity in the gastric fundus, while neostigmine made a significant decline (Fig. 4C, D). It suggested that within the concentration range of this experiment, BBR had no direct effect on the regulation of the neurotransmitter NO and ACh-related enzymes, that is, BBR had no direct effect on the synthesis of NO and the elimination of ACh.

Fig. 4.

Fig. 4

Open in a new tab

Influence of berberine on the enzyme’s activity in vitro in the gastric fundus tissue. The influence of (A) l-NAME (103-105 μM) and (B) berberine (10–103 μM) on the tNOS activity in vitro in the gastric fundus of rats. (C) Effect of Neostigmine (0.01–1 μM) and (D) berberine (10–103 μM) on the AChE activity in vitro in the gastric fundus of the rat. The data are presented as the mean ± SEM. *P < 0.05 vs control, n = 7.

3.4. Interaction between the inhibitory neurotransmitter NO and the excitatory neurotransmitter ACh

Since the key to BBR regulating the ACh is not through the synthesis and elimination of transmitters, it may be related to the release of transmitters in nerve endings. To explore the association of ACh release with NO release, we used donor or inhibitor of NO and ACh to detect changes in contractile responses or relaxation in gastric fundus induced by EFS. l-Arg, a NO donor, reduced the EFS-induced contraction of gastric fundus smooth muscle significantly (Fig. 5A), suggesting that the increasing NO inhibited the contraction reaction induced by ACh. Analogously, the contractile response was significantly increased when administered with l-NAME (an inhibitor of NOS), which was reduced by the l-Arg adding (Fig. 5B, C). The results were also shown that NO directly affects ACh release. Additionally, the cholinesterase inhibitor Neostigmine increased the EFS induced the contraction in a concentration dependence and significantly inhibited the relaxation of gastric fundus smooth muscle induced by EFS at 2 Hz, 4 Hz, and 10 Hz (inhibition rates were 13.8 %, 11.2 %, and 14.2 %, respectively, Fig. 5D, E). The data indicated that the activity of ACh can also affect NO release directly.

Fig. 5.

Fig. 5

Open in a new tab

The interaction between inhibitory neurotransmitter NO and excitatory neurotransmitter ACh. (A) Effects of l-arg (100 μM) on EFS-induced contractile responses in gastric fundus circular muscle. (B) Effects of l-NAME (10, 100 μM) and (C) l-arg (100 μM) on EFS-induced contractile responses in gastric fundus circular muscle. (D) Effects of Neostigmine (0.01 μM) on EFS-induced contractile responses in gastric fundus circular muscle of rats. (E) Effects of Neostigmine (0.01 μM) on EFS-induced relaxation responses in gastric fundus circular muscle of rats. The data are presented as the mean ± SEM. *P < 0.05, **P < 0.01 vs control; #P < 0.05 vs l-NAME group, n = 7, 7, 7, 7, 8.

3.5. Effects of BBR and calcium channel blockers on EFS-induced contraction of the gastric fundus in rats

To further explore the mechanism of BBR in regulating the release of ACh, we applied calcium channel blockers to observe the effects of BBR on EFS-induced contraction of gastric fundus smooth muscle. AML and cilnidipine all significantly inhibited the contractile response, and the enhancement of BBR on contractile response was canceled completely. However, AML showed a significant inhibition but not complete cancellation of the enhancement of contractile response caused by l-NAME or neostigmine (Fig. 6). Taken together, these data indicated that BBR might promote the release of ACh in the intermuscular plexus of the gastric fundus smooth muscle through the opening of calcium ion channels and improve the contraction function.

Fig. 6.

Fig. 6

Open in a new tab

Effects of berberine and calcium channel blockers on EFS induced contraction in gastric fundus smooth muscle. The influence of AML on (A) l-NAME (100 μM) and (B) neostigmine (0.01 μM) enhanced the EFS-induced contractile responses in the gastric fundus circular muscle of rats. The influence of (C) AML (0.1 μM) and (D) cilnidipine (10 μM) on berberine (10 μM) enhanced the EFS-induced contractile responses in the gastric fundus circular muscle of rats. The data are presented as the mean ± SEM. *P < 0.05, **P < 0.01, ****P < 0.0001, n = 8.

4. Discussion

It has been reported that BBR has neuroprotective, anti-inflammatory, and antioxidant effects in various CNS-related diseases in animal models (Wang et al., 2017, Wang et al., 2017). BBR could also enhance the survival and axonal regeneration of motoneurons in rats (Zhang et al., 2019), and ameliorate diabetic central and peripheral neuropathy (Chen et al., 2020, Dong et al., 2019, Zan et al., 2017). Our previous studies have found that BBR restores the balance of neural regulation of vascular tone (L. Zhao et al., 2019) and improves neurogenic contractile response of bladder detrusor muscle in the STZ-induced early diabetic rats (Ren et al., 2013). In this study, it was found that neurons presented slight vacuolar lesions in the gastric fundus smooth muscle of STZ-induced diabetic rats; and BBR treatment could improve the state of neurons in the myenteric plexus of the gastric fundus (Fig. 1A).

In the gastrointestinal system, the excitatory pathway exerts its effect by cholinergic transmission such as ACh; the inhibitory pathway is thought to employ NO, VIP and ATP as its neurotransmitters (Cruz et al., 2019, Curro et al., 2008). ACh, which acts specifically on various choline receptors, is quickly destroyed by cholinesterase in tissues. Studies have shown that the common clinical refractory functional gastrointestinal motility disorders are closely related to the imbalance of the intestinal nervous system and its neurotransmitter release(Chen et al., 2022, Gros et al., 2021, Zheng et al., 2014). Our study showed that EFS-induced contractile response was significantly changed in diabetic rats, including a significantly smaller contractile response than that in normal rats and a disordered contractile amplitude, indicating that the synapses of diabetic rats were changed, and the function of the excitatory neurotransmitter ACh was impaired (Fig. 1B). ACh dysfunction may be caused by several factors: first, decreased synthesis of the neurotransmitter ACh or increased AChE; second, increased inhibitory neurotransmitters that interfere with the role of ACh; third, there is an obstacle to the release of ACh.

As a main active ingredient of Coptidis Rhizoma, the BBR is reported to be an AChE inhibitor, and there are often prescriptions of Chinese medicine containing Coptidis in the treatment of early stages of Alzheimer's disease caused by ACh neurotransmitter abnormalities (Kaufmann et al., 2016, Wang et al., 2018). In the experiment, we found that whether administration in vivo or smooth muscle stimulation experiment in vitro, BBR both showed to correct EFS-induced contractile reaction disorders in the gastric fundus of diabetic rats, which was blocked by atropine, suggesting that BBR can improve the gastric fundus ACh function of diabetic rats (Fig. 1C-D). After removing the interference of neurogenic diastolic response, BBR could further promote the contraction response induced by EFS (Fig. 2C), which indicated that BBR had a direct promoting effect on ACh release. Is the effect of BBR on the cholinergic nerves in diabetic rats affecting inhibitory neurotransmitters (NO) and Ach-related synthesis or decomposition enzymes?

It has been reported that NOS expression in the antrum of streptozotocin-diabetic rats was decreased which might contribute to altered gastric emptying observed in diabetics(Wrzos, Cruz, Polavarapu, Shearer, & Ouyang, 1997). Consistent with the report, we found that nNOS expression decreased in the smooth muscle of the gastric fundus in diabetic rats. But BBR administration had no significant effect on tNOS activity and nNOS content, that is, the reduction of neurogenic NO was not improved by BBR (Fig. 3A-B). However, ChAT activity was significantly up regulated, and AChE activity was significantly decreased in the gastric fundus of diabetic rats, suggesting that the cholinergic nerve function in the gastric fundus was enhanced by diabetes. BBR significantly reduced the up-regulation of ChAT and had no significant effect on the decrease of AChE activity (Fig. 3C-E). This result is different from the results shown in Fig. 1 that the cholinergic nerve function of gastric smooth muscle was weakened in diabetic rats, and BBR significantly enhanced the cholinergic nerve function to improve the contractile response induced by EFS. We hypothesized that the up-regulation of gastric fundus ChAT in early diabetic rats may be compensatory, compensating for the deficiency of cholinergic nerve function. Interestingly, BBR also corrected for compensatory increases of ACh in the diabetic state. However, the key to BBR improving the normal function of ACh is not transmitter synthesis and elimination, which may be related to the transmitter release of nerve endings or may be interfered with by other inhibitory neural activities.

Many studies have shown that in the presence of drugs antagonizing the cholinergic nerve, the effect of NOS inhibitors could not be fully effective, that is, the inhibitory effect of NOS inhibitors depends on the activity of the cholinergic nerve (Baccari, Iacoviello, & Calamai, 1997). At the same time, NOS inhibitors could promote the release of ACh from the intramuscular nerve plexus (Kilbinger & Wolf, 1994) while NO could inhibit smooth muscle responses evoked by cholinergic nerve stimulation in the guinea pig gastric fundus (Yoneda & Suzuki, 2001). There is an interaction between cholinergic and nitrogenous nerves (Leclere & Lefebvre, 1998). In our experiment, we also found that NOS inhibitor l-NAME significantly improved the dysregulation of cholinergic nerve activity in the smooth muscle of the gastric fundus in diabetic rats, similar to the effect of BBR. However, in the presence of l-NAME, BBR can further enhance the contractile reaction (Fig. 2A-B), suggesting that the mechanism of action of BBR and l-NAME is different. Indeed, l-NAME could significantly inhibit tNOS activity and Neostigmine could significantly inhibit AChE activity in the gastric fundus, while BBR had no significant effect on tNOS and AChE activity (Fig. 4). We also confirmed that the function of NO and ACh was closely related to each other and maintained a dynamic balance in the gastrointestinal nervous system. When NO increased, ACh function weakened; when ACh increases, NO function decreases (Fig. 5). As studies have pointed out, endogenous NO significantly inhibited cholinergic neurotransmission by functionally antagonizing ACh level in porcine gastric fundus (Leclere & Lefebvre, 1998) and NOS inhibitors can cause the excitatory nerves to release Ach (Baccari et al., 1997). BBR may just play an important role in regulating the dynamic balance of NO and ACh when an imbalance occurs. Although the results suggested that the regulation of BBR on the contractile response of gastric smooth muscle was probably the result of the combination of nitrogenous nerve and cholinergic nerve, BBR did not regulate the related enzymes of neurotransmitters NO and ACh directly. Hence, we hypothesized that the ACh release process might be precisely regulated by BBR.

The increase of intracellular calcium is the ultimate target of smooth muscle excitation and subsequent contraction. In response to the stimulant, the intracellular calcium concentration increases, this triggers the ACh release and smooth muscle contraction. Studies have shown that BBR might exert a positive inotropic effect on the isolated rat heart by enhancing the Ca(2 + ) influx in left ventricular myocytes (J. Zhao, Wang, Gao, Jing, & Xin, 2020) and restoring the diminished I(to) and I(Ca) current densities to attenuate ischemia-induced arrhythmias in diabetic rats (L. H. Wang et al., 2012). However, in some disease states, BBR has the opposite regulating effect on Ca (2 + ) influx. For example, the abnormal contracted mouse airway smooth muscle could be relaxed by protoberberine alkaloid via altering the intracellular Ca (2 + ) concentration (Wen et al., 2020); BBR showed a good effect on calcium overload in chronic congestive heart failure rats (Y. Li, Chen, Liu, Luo, & Li, 2009); BBR also alleviated the cerebrovascular contractility in STZ-induced diabetic rats through modulation of intracellular Ca(2 + ) handling in smooth muscle cells (Ma et al., 2016). It can be seen that BBR has a multidirectional regulation effect on ion channels in multi-organ smooth muscle. Further studies showed that BBR-induced enhancement of contraction response in gastric fundus was completely canceled by calcium channel inhibitor Amlodipine (AML) and Cilnidipine while l-NAME and neostigmine-induced enhancement of contraction response was only partly inhibited but not be canceled (Fig. 6). Therefore, BBR might promote the release of ACh from the myenteric plexus of gastric fundus smooth muscle and improves the systolic function by opening calcium ion channels in early diabetic gastroparesis rats. It provides important evidence for the study of BBR controlling the calcium channel to regulate the release of peripheral neurotransmitters.

To sum up, the present study shows that in the early stage of STZ-induced diabetic rats, the balance of excitatory and inhibitory nerve function of the gastric fundus was disrupted, and a negative correlation between ACh and NO functions was detected. Given the BBR treatment balanced the excitatory and inhibitory nerve functions in the gastric fundus of early diabetic rats and promoted the release of ACh by affecting calcium ion release, BBR is an attractive pharmacotherapeutic candidate that might potentially prevent diabetic neuropathy.

5. Conclusions

In the early stage of STZ-induced diabetic rats, the neurogenic contractile response of gastric fundus smooth muscle is a disorder, which mainly related to cholinergic and nitrergic nerve disorders. BBR promotes the release of ACh through affecting the calcium channel to correct the neurological dysfunction of the gastric fundus, suggesting a novel effect of BBR on balance of neural regulation of gastric fundus.

6. Authors’ contribution statement

Ding Zhao (the corresponding author): conception and design of the study.

Cong-Cong Hou: establishing animal model, histomorphological examination, and data analysis.

Hong-Yu Liang: gastric fundus reactivity detection, ACh and NO release evaluation, and data analysis.

Zhang-Sen Hao: establishing animal model and gastric fundus reactivity detection.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by grants from The Science and Technology Support programs of Hebei Province, CNo.17967753D, and No. 20327121D, and Hebei Administration of Traditional Chinese Medicine, No. 2023133.

Footnotes

Peer review under responsibility of King Saud University.

Appendix A

Supplementary data to this article can be found online at https://doi.org/10.1016/j.jsps.2023.01.010.

Appendix A. Supplementary material

The following are the Supplementary data to this article:

Supplementary data 1
mmc1.docx (2.3MB, docx)

References

  1. Akbar M., Shabbir A., Rehman K., Akash M.S.H., Shah M.A. Neuroprotective potential of berberine in modulating Alzheimer's disease via multiple signaling pathways. J. Food Biochem. 2021;45(10):e13936. doi: 10.1111/jfbc.13936. [DOI] [PubMed] [Google Scholar]
  2. Baccari M.C., Iacoviello C., Calamai F. Nitric oxide as modulator of cholinergic neurotransmission in gastric muscle of rabbits. Am. J. Physiol. 1997;273(2 Pt 1):G456–G463. doi: 10.1152/ajpgi.1997.273.2.G456. [DOI] [PubMed] [Google Scholar]
  3. Bharucha A.E., Kudva Y.C., Prichard D.O. Diabetic gastroparesis. Endocr. Rev. 2019;40(5):1318–1352. doi: 10.1210/er.2018-00161. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Boghdadi, M. A., Afify, H. E., Nagwa, A. S., & Makboul, K. (2017). Comparative Study of Vitamin B Complex Combined with Alpha Lipoic Acid versus Vitamin B Complex in Treatment of Diabetic Polyneuropathy in Type 2 Diabetic Patients. Clinical and Experimental Pharmacology, 7(4). doi:DOI:10.4172/2161-1459.1000241.
  5. Browning K.N., Travagli R.A. Central nervous system control of gastrointestinal motility and secretion and modulation of gastrointestinal functions. Compr. Physiol. 2014;4(4):1339–1368. doi: 10.1002/cphy.c130055. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Cellini J., DiNovo K., Harlow J., LePard K.J. Regional differences in neostigmine-induced contraction and relaxation of stomach from diabetic guinea pig. Auton. Neurosci. 2011;160(1–2):69–81. doi: 10.1016/j.autneu.2010.10.006. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Chen S., He B., Zhou G., Xu Y., Wu L., Xie Y., Xiao Z. Berberine enhances L1 expression and axonal remyelination in rats after brachial plexus root avulsion. Brain Behav. 2020;10(10):e01792. doi: 10.1002/brb3.1792. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Chen M., Ruan G., Chen L., Ying S., Li G., Xu F., Wei Y. Neurotransmitter and intestinal interactions: focus on the microbiota-gut-brain axis in irritable bowel syndrome. Front. Endocrinol. (Lausanne) 2022;13 doi: 10.3389/fendo.2022.817100. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Cruz M.T., Dezfuli G., Murphy E.C., Vicini S., Sahibzada N., Gillis R.A. GABAB receptor signaling in the dorsal motor nucleus of the vagus stimulates gastric motility via a cholinergic pathway. Front. Neurosci. 2019;13:967. doi: 10.3389/fnins.2019.00967. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Curro, D., Ipavec, V., & Preziosi, P. (2008). Neurotransmitters of the non-adrenergic non-cholinergic relaxation of proximal stomach. European Review for Medical and Pharmacological Sciences, 12, 53-62. Retrieved from <Go to ISI>://WOS:000259182500006. [PubMed]
  11. Dong J., Zuo Z., Yan W., Liu W., Zheng Q., Liu X. Berberine ameliorates diabetic neuropathic pain in a rat model: involvement of oxidative stress, inflammation, and mu-opioid receptors. Naunyn Schmiedebergs Arch. Pharmacol. 2019;392(9):1141–1149. doi: 10.1007/s00210-019-01659-6. [DOI] [PubMed] [Google Scholar]
  12. Elgarf, A. T., Mahdy, M. M., & Sabri, N. A. (2015). Effect of Silymarin Supplementation on Glycemic Control, Lipid Profile and Insulin Resistance in Patients with Type 2 Diabetes Mellitus. International Journal of Advanced Research, 3(12), 812-821. Retrieved from http://www.journalijar.com.
  13. Elsayed A.A., Menze E.T., Tadros M.G., Ibrahim B.M.M., Sabri N.A., Khalifa A.E. Effects of genistein on pentylenetetrazole-induced behavioral and neurochemical deficits in ovariectomized rats. Naunyn Schmiedebergs Arch. Pharmacol. 2018;391(1):27–36. doi: 10.1007/s00210-017-1435-7. [DOI] [PubMed] [Google Scholar]
  14. Gangula P.R., Challagundla K.B., Ravella K., Mukhopadhyay S., Chinnathambi V., Mittal M.K., Sampath C. Sepiapterin alleviates impaired gastric nNOS function in spontaneous diabetic female rodents through NRF2 mRNA turnover and miRNA biogenesis pathway. Am. J. Physiol. Gastrointest. Liver Physiol. 2018;315(6):G980–G990. doi: 10.1152/ajpgi.00152.2018. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Gibson T.M., Cotter M.A., Cameron N.E. Effects of poly(ADP-ribose) polymerase inhibition on dysfunction of non-adrenergic non-cholinergic neurotransmission in gastric fundus in diabetic rats. Nitric Oxide. 2006;15(4):344–350. doi: 10.1016/j.niox.2006.03.003. [DOI] [PubMed] [Google Scholar]
  16. Gros M., Gros B., Mesonero J.E., Latorre E. Neurotransmitter dysfunction in irritable bowel syndrome: emerging approaches for management. J. Clin. Med. 2021;10(15) doi: 10.3390/jcm10153429. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Hao Z.S., Liang H.Y., Hou C.C., Tong M.M., Liu S., Jiang J.D., Zhao D. Alterations in the functions of gastric smooth muscle in type 1 diabetic rats. Chinese J. Compar. Med. 2015;25(11):52–58. [Google Scholar]
  18. He L., Sun Y., Zhu Y., Ren R., Zhang Y., Wang F. Improved gastric emptying in diabetic rats by irbesartan via decreased serum leptin and ameliorated gastric microcirculation. Genet. Mol. Res. 2014;13(3):7163–7172. doi: 10.4238/2014.September.5.2. [DOI] [PubMed] [Google Scholar]
  19. Hou, Q., He, W. J., Wu, Y. S., Hao, H. J., Xie, X. Y., & Fu, X. B. (2020). Berberine: A Traditional Natural Product With Novel Biological Activities. Altern Ther Health Med, 26(S2), 20-27. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/31634873. [PubMed]
  20. Kaufmann D., Kaur Dogra A., Tahrani A., Herrmann F., Wink M. Extracts from traditional Chinese medicinal plants inhibit acetylcholinesterase, a known Alzheimer's disease target. Molecules. 2016;21(9) doi: 10.3390/molecules21091161. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Kilbinger H., Wolf D. Increase by NO synthase inhibitors of acetylcholine release from guinea-pig myenteric plexus. Naunyn Schmiedebergs Arch. Pharmacol. 1994;349(5):543–545. doi: 10.1007/bf00169145. [DOI] [PubMed] [Google Scholar]
  22. Kong W., Wei J., Abidi P., Lin M., Inaba S., Li C., Jiang J.D. Berberine is a novel cholesterol-lowering drug working through a unique mechanism distinct from statins. Nat. Med. 2004;10(12):1344–1351. doi: 10.1038/nm1135. [DOI] [PubMed] [Google Scholar]
  23. Leclere P.G., Lefebvre R.A. Investigation of the interaction between cholinergic and nitrergic neurotransmission in the pig gastric fundus. Br. J. Pharmacol. 1998;125(8):1779–1787. doi: 10.1038/sj.bjp.0702244. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Lee T.H., Son M., Kim S.Y. Effects of corydaline from Corydalis tuber on gastric motor function in an animal model. Biol. Pharm. Bull. 2010;33(6):958–962. doi: 10.1248/bpb.33.958. [DOI] [PubMed] [Google Scholar]
  25. Leng, S. H., Lu, F. E., & Xu, L. J. (2004). Therapeutic effects of berberine in impaired glucose tolerance rats and its influence on insulin secretion. Acta Pharmacol Sin, 25(4), 496-502. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/15066220. [PubMed]
  26. Li, Y., Chen, X., Liu, H., Luo, F., & Li, G. (2009). [Effects of ginseng total saponins with berberine on plasma brain natriuretic peptide and Ca2+ concentration in experimental rats with chronic congestive heart failure]. Zhongguo Zhong Yao Za Zhi, 34(3), 324-327. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/19445159. [PubMed]
  27. Li L.C., Li X.Y., Du X.H. Acupuncture improves cognitive function of vascular dementia rats by regulating PI3K/Akt/mTOR pathway. Zhen Ci Yan Jiu. 2021;46(10):851–856. doi: 10.13702/j.1000-0607.200844. [DOI] [PubMed] [Google Scholar]
  28. Lu H.L., Huang X., Wu Y.S., Zhang C.M., Meng X.M., Liu D.H., Xu W.X. Gastric nNOS reduction accompanied by natriuretic peptides signaling pathway upregulation in diabetic mice. World J. Gastroenterol. 2014;20(16):4626–4635. doi: 10.3748/wjg.v20.i16.4626. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Ma Y.G., Zhang Y.B., Bai Y.G., Dai Z.J., Liang L., Liu M., Guan H.T. Berberine alleviates the cerebrovascular contractility in streptozotocin-induced diabetic rats through modulation of intracellular Ca(2)(+) handling in smooth muscle cells. Cardiovasc. Diabetol. 2016;15:63. doi: 10.1186/s12933-016-0382-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Marathe C.S., Jones K.L., Wu T., Rayner C.K., Horowitz M. Gastrointestinal autonomic neuropathy in diabetes. Auton. Neurosci. 2020;229 doi: 10.1016/j.autneu.2020.102718. [DOI] [PubMed] [Google Scholar]
  31. McMenamin C.A., Travagli R.A., Browning K.N. Inhibitory neurotransmission regulates vagal efferent activity and gastric motility. Exp. Biol. Med. (Maywood) 2016;241(12):1343–1350. doi: 10.1177/1535370216654228. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Mussa B.M., Sood S., Verberne A.J. Implication of neurohormonal-coupled mechanisms of gastric emptying and pancreatic secretory function in diabetic gastroparesis. World J. Gastroenterol. 2018;24(34):3821–3833. doi: 10.3748/wjg.v24.i34.3821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Nagib M.M., Tadros M.G., Al-Khalek H.A.A., Rahmo R.M., Sabri N.A., Khalifa A.E., Masoud S.I. Molecular mechanisms of neuroprotective effect of adjuvant therapy with phenytoin in pentylenetetrazole-induced seizures: impact on Sirt1/NRF2 signaling pathways. Neurotoxicology. 2018;68:47–65. doi: 10.1016/j.neuro.2018.07.006. [DOI] [PubMed] [Google Scholar]
  34. Pan L.R., Tang Q., Fu Q., Hu B.R., Xiang J.Z., Qian J.Q. Roles of nitric oxide in protective effect of berberine in ethanol-induced gastric ulcer mice. Acta Pharmacol. Sin. 2005;26(11):1334–1338. doi: 10.1111/j.1745-7254.2005.00186.x. [DOI] [PubMed] [Google Scholar]
  35. Ren L.M., Zhuo Y.J., Hao Z.S., He H.M., Lu H.G., Zhao D. Berberine improves neurogenic contractile response of bladder detrusor muscle in streptozotocin-induced diabetic rats. J. Ethnopharmacol. 2013;150(3):1128–1136. doi: 10.1016/j.jep.2013.10.039. [DOI] [PubMed] [Google Scholar]
  36. Rizk S.M., Sabri N.A. Evaluation of clinical activity and safety of Daflon 500 mg in type 2 diabetic female patients. Saudi Pharm. J. 2009;17(3):199–207. doi: 10.1016/j.jsps.2009.08.008. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Shin S.J., Kim D., Kim J.S., Kim I., Lee J.R., Kim S.C., Kim B.J. Effects of Gamisoyo-San Decoction, a traditional Chinese medicine, on gastrointestinal motility. Digestion. 2018;98(4):231–237. doi: 10.1159/000489455. [DOI] [PubMed] [Google Scholar]
  38. Tian J., Li M., Zhao J., Li J., Liu G., Zhen Z., Tong X. Research on the traditional Chinese medicine treating gastrointestinal motility in diabetic rats by improving biomechanical remodeling and neuroendocrine regulation. Am. J. Transl. Res. 2017;9(5):2219–2230. https://www.ncbi.nlm.nih.gov/pubmed/28559973 Retrieved from. [PMC free article] [PubMed] [Google Scholar]
  39. Wang Y., Campbell T., Perry B., Beaurepaire C., Qin L. Hypoglycemic and insulin-sensitizing effects of berberine in high-fat diet- and streptozotocin-induced diabetic rats. Metabolism. 2011;60(2):298–305. doi: 10.1016/j.metabol.2010.02.005. [DOI] [PubMed] [Google Scholar]
  40. Wang X.Y., Huizinga J.D., Diamond J., Liu L.W. Loss of intramuscular and submuscular interstitial cells of Cajal and associated enteric nerves is related to decreased gastric emptying in streptozotocin-induced diabetes. Neurogastroenterol. Motil. 2009;21(10):1095–e1092. doi: 10.1111/j.1365-2982.2009.01336.x. [DOI] [PubMed] [Google Scholar]
  41. Wang L.H., Li X.L., Li Q., Fu Y., Yu H.J., Sun Y.Q., Shan H.L. Berberine alleviates ischemic arrhythmias via recovering depressed I(to) and I(Ca) currents in diabetic rats. Phytomedicine. 2012;19(3–4):206–210. doi: 10.1016/j.phymed.2011.11.002. [DOI] [PubMed] [Google Scholar]
  42. Wang H.Y., Liu C., Mei X.F., Cao Y., Guo Z.P., Yuan Y.J., Shen Z.L. Berberine attenuated pro-inflammatory factors and protect against neuronal damage via triggering oligodendrocyte autophagy in spinal cord injury. Oncotarget. 2017;8(58):98312–98321. doi: 10.18632/oncotarget.21203. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Wang X.C., Xu Y.M., Li H.Y., Wu C.Y., Xu T.T., Luo N.C., Quan S.J. Jiao-Tai-Wan improves cognitive dysfunctions through cholinergic pathway in scopolamine-treated mice. Biomed. Res. Int. 2018;2018:3538763. doi: 10.1155/2018/3538763. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Wang J.Q., Zhang M.C., Li H.T., Li G., Jia Z.Q., Sun P., Fan Z.K. Berberine improves motor function recovery by inhibiting endoplasmic reticulum stress-induced neuronal apoptosis via AMPK activation in rats with spinal cord injury. Int. J. Clin. Exp. Pathol. 2017;10(4):4900–4911. Retrieved from <Go to ISI>://WOS:000400550200106. [Google Scholar]
  45. Wang J.P., Zhang Y.M. Neuroprotective effect of berberine agonist against impairment of learning and memory skills in severe traumatic brain injury via Sirt1/p38 MAPK expression. Mol. Med. Rep. 2018;17(5):6881–6886. doi: 10.3892/mmr.2018.8674. [DOI] [PubMed] [Google Scholar]
  46. Wen N., Xue L., Yang Y., Shi S., Liu Q.H., Cai C., Shen J. Coptisine, a protoberberine alkaloid, relaxes mouse airway smooth muscle via blockade of VDLCCs and NSCCs. Biosci. Rep. 2020;40(2) doi: 10.1042/BSR20190534. [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Wrzos H.F., Cruz A., Polavarapu R., Shearer D., Ouyang A. Nitric oxide synthase (NOS) expression in the myenteric plexus of streptozotocin-diabetic rats. Dig. Dis. Sci. 1997;42(10):2106–2110. doi: 10.1023/a:1018830820537. [DOI] [PubMed] [Google Scholar]
  48. Yang S., Wu B., Sun H., Sun T., Han K., Li D., Zhou D. Impaired insulin/IGF-1 is responsible for diabetic gastroparesis by damaging myenteric cholinergic neurones and interstitial cells of Cajal. Biosci. Rep. 2017;37(5) doi: 10.1042/BSR20170776. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Yoneda S., Suzuki H. Nitric oxide inhibits smooth muscle responses evoked by cholinergic nerve stimulation in the guinea pig gastric fundus. Jpn. J. Physiol. 2001;51(6):693–702. doi: 10.2170/jjphysiol.51.693. [DOI] [PubMed] [Google Scholar]
  50. Yuan J.Y., Zhang D.G., Yu X., Wu D.Z. Effects of extracts and active components of Rhizoma Coptidis on contraction of circular smooth muscle isolated from guinea pig gastric antrum. Zhong Xi Yi Jie He Xue Bao. 2009;7(9):831–835. doi: 10.3736/jcim20090907. [DOI] [PubMed] [Google Scholar]
  51. Zan Y., Kuai C.X., Qiu Z.X., Huang F. Berberine ameliorates diabetic neuropathy: TRPV1 modulation by PKC pathway. Am. J. Chin. Med. 2017;45(8):1709–1723. doi: 10.1142/S0192415X17500926. [DOI] [PubMed] [Google Scholar]
  52. Zeng K.Y., Song C., Qu Y.F. Progress in research on Chinese medicine for gastrointestinal motility regulation. Mod. J. Integr. Trad. Chinese Western Med. 2019;28(2):225–228. [Google Scholar]
  53. Zhang X., Liu X.D., Xian Y.F., Zhang F., Huang P.Y., Tang Y., Lin Z.X. Berberine enhances survival and axonal regeneration of motoneurons following spinal root avulsion and re-implantation in rats. Free Radic. Biol. Med. 2019;143:454–470. doi: 10.1016/j.freeradbiomed.2019.08.029. [DOI] [PubMed] [Google Scholar]
  54. Zhao Y.N., Li Z.K., Lu E.R., Sheng Q., Zhao Y. Berberine exerts neuroprotective activities against cerebral ischemia/reperfusion injury through up-regulating PPAR-gamma to suppress NF-kappa B-mediated pyroptosis. Brain Res. Bull. 2021;177:22–30. doi: 10.1016/j.brainresbull.2021.09.005. [DOI] [PubMed] [Google Scholar]
  55. Zhao L., Liu S., Wang M., Zhi M., Geng X., Hou C., Zhao D. Berberine restored nitrergic and adrenergic function in mesenteric and iliac arteries from streptozotocin-induced diabetic rats. J. Ethnopharmacol. 2019;244 doi: 10.1016/j.jep.2019.112140. [DOI] [PubMed] [Google Scholar]
  56. Zhao J., Wang Y., Gao J., Jing Y., Xin W. Berberine mediated positive inotropic effects on rat hearts via a Ca(2+)-dependent mechanism. Front. Pharmacol. 2020;11:821. doi: 10.3389/fphar.2020.00821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Zheng L.F., Song J., Fan R.F., Chen C.L., Ren Q.Z., Zhang X.L., Zhu J.X. The role of the vagal pathway and gastric dopamine in the gastroparesis of rats after a 6-hydroxydopamine microinjection in the substantia nigra. Acta Physiol. (Oxf.) 2014;211(2):434–446. doi: 10.1111/apha.12229. [DOI] [PubMed] [Google Scholar]
  58. Zhu L., Han J., Yuan R., Xue L., Pang W. Berberine ameliorates diabetic nephropathy by inhibiting TLR4/NF-kappaB pathway. Biol. Res. 2018;51(1):9. doi: 10.1186/s40659-018-0157-8. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary data 1
mmc1.docx (2.3MB, docx)

Articles from Saudi Pharmaceutical Journal : SPJ are provided here courtesy of Springer

RESOURCES