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. 2020 Mar 2;72(3):357–366. doi: 10.1007/s10616-020-00382-y

Effect of β-sitosterol on glucose homeostasis by sensitization of insulin resistance via enhanced protein expression of PPRγ and glucose transporter 4 in high fat diet and streptozotocin-induced diabetic rats

Sundaram Ramalingam 1,2,✉, Meenatchi Packirisamy 3, Muthu Karuppiah 4, Ganesh Vasu 1, Rahul Gopalakrishnan 1, Kirubananthan Gothandam 5, Muthusamy Thiruppathi 6
PMCID: PMC7225221  PMID: 32124158

Abstract

Ethnopharmacological relevance

β-Sitosterol is a plant derived compound similar to cholesterol structure and used in the treatment of hypercholesterolemia, prostate cancer, breast cancer and coronary artery disease. But no studies have been reported the effect of β-sitosterol on glucose homeostasis by sensitization of insulin resistance via enhanced protein expression of peroxisome proliferator-activated receptor γ (PPARγ) and glucose transporter 4 (GLUT4) in insulin dependent tissues of high fat diet and streptozotocin-induced diabetic rats.

Materials and methods

Type 2 diabetes was induced in male albino Wistar rats by feeding them with high fat diet comprising of 84.3% standard laboratory chow, 5% lard, 10% yolk powder, 0.2% cholesterol and 0.5% bile salt for 2 weeks. After 2 weeks, the animals were kept in an overnight fast and injected with low dose of streptozotocin (35 mg/kg, dissolved in 0.1 M sodium citrate buffer, pH 4.5). Analysis of blood glucose, insulin, hemoglobin and glycated hemoglobin were done by commercially available diagnostic kits. The PPARγ and GLUT4 were analyzed by western blotting using respective primary and secondary antibodies.

Results

Upon administration of β-sitosterol at a dose of 15 mg/kg body weight per day to high fat diet and streptozotocin induced diabetic rats for 30 days significantly decreased the levels of plasma glucose, homeostatic model assessment of insulin resistance and glycosylated hemoglobin and increased the levels of insulin, hemoglobin and protein expression of PPARγ and GLUT4 in insulin dependent tissues. Furthermore, β-sitosterol administration prevented the body weight loss and excessive intake of food and water.

Conclusion

These finding suggest that β-sitosterol can replace the commercial drugs which could lead to reduction in toxicity and side effect caused by the later as well as reduce the secondary complications.

Keywords: Coccinia grandi, β-Sitosterol, Diabetes, Metabolic enzymes, Insulin resistant, GLUT4

Introduction

Type 2 diabetes mellitus, the frequent form of diabetes, represents more than 90% of all diabetic patients (Tripathi and Srivastava 2006). Insulin resistance and impaired insulin secretion are two main characteristics of type 2 diabetes (Sharma et al. 2011). Insulin resistance in type 2 diabetes mellitus could be provoked by glucotoxicity, oxidative stress, lipotoxicity and inflammation (Weir and Bonner Weir 2004). Recently, the International Diabetes Federation (IDF) reported that the number of diabetic patients was 415 million in 2015 and is expected to rise to 642 million by 2040 (International Diabetes Federation 2015). If ineffectively controlled in diabetic patients, chronic hyperglycemia can cause serious complications in different organs (International Diabetes Federation 2015). Diet, exercise and several pharmacological agents are treatment approaches for type 2 diabetes mellitus. However, the use of currently used pharmacological agents is associated with adverse side effects (Geirch 2003). Therefore, research is focused on medicinal plants which are used in the practices and development of newer drug leads from phytoconstituents with more potential and effective agents with lesser side effects than the existing hypoglycemic agents (Chandramohan et al. 2008). Many medicinal plants are currently used in India for the treatment of diabetes and scientifically its efficacy has been proved earlier (Are et al. 2011).

Coccinia grandis belongs to the family Cucurbitaceae and grows abundantly in India. It is a climbing perennial herb and its fruits are widely used for culinary purposes as a vegetable and traditional treatment of diabetes (Venkateswaran and Pari 2002). Many scientific investigations have been proved that the efficacy of leaf and root extracts of Coccinia grandis reduced the diabetic complications and progression of the disease (Kumar et al. 1993; Venkateswaran and Pari 2003; Akhtar et al. 2007). The present was aimed to isolate and characterize the β-sitosterol from the unripe fruits of Coccinia grandis and investigate its potential on glucose homeostasis by sensitization of insulin resistance via enhanced protein expression of PPARγ and glucose transporter 4 in high fat diet and streptozotocin—induced diabetic rats as there are no scientific reports available on these aspects so far.

Materials and methods

Collection of plant material

The unripe fruits of Coccinia grandis were procured from local place, identified and authentified by Dr. KN. Sunil kumar, Pharmacognosy, Siddha Research Institute (Central council for Research in Siddha, Chennai, Ministry of AYUSH, Government of India) (Voucher no: C17112901G).

Extraction and isolation

Two thousand gram of unripe fruits of Coccinia grandis was purchased from local vegetables market, Chennai. Coccinia grandis was sliced into many pieces and allowed to shade dry for 15 days. After shade drying, the G. grandis was pulverized and soaked in 2.5 L of methanol and kept in refrigerator for 3 days. Then the filtrate was filtered through Whatmann filter paper No 1 and this was repeated three to four times until the filtrate gave no coloration and concentrated using vacuum rotary evaporator at 40 °C. The methanolic concentrate was checked on thin layer chromatography with hexane and ethyl acetate in the ratio of 8:2 which showed four spots (compounds). The methanolic concentrate was chromatographed on silica gel column and eluted with hexane and ethyl acetate (80:20 ratio). Fractions were collected at an interval of 10 mL each and monitored by thin layer chromatography (precoated silica gel merk—60 F254 0.25 mm thick plate). Fractions formed as a pale yellow and showed single spot on TLC and pooled together in a clean vial and evaporated to dryness. This process was repeated until getting satisfactory yield of the compound (500 mg/2 kg of crude extract). The physical nature of the compound was creamish pale yellow. The structure of the compound was confirmed by β-sitosterol on the basis of their 1H & 13C NMR spectral data. The molecular weight of β-sitosterol was m/z: 414.39 and molecular formula was C29H50O. The rest of the three spots (three compounds) are under the isolation process. The physical and spectroscopic data of isolated β-sitosterol are comparable with those reported in literature (Hwang et al. 2008; Gupta et al. 2011). The isolated compound displayed > 90% purity as estimated by the examination of NMR and Mass spectra.

Experimental animals

Adult male albino Wistar rats weighing about 200–220 g were obtained from Sri Muthukumaran Medical College Hospital & Research Institute, Mangadu, Chennai, Tamil Nadu, India. Rats were housed in clean, sterile and polypropylene cages under standard vivarium conditions 12 h light/12 h dark cycle and constant temperature (25 ± 2 °C) with free access to standard commercial rat chow (Pranav Agro Industries Ltd., Pune, Maharashtra, India) and water. The experimental protocol was approved by the Ministry of Social Justices and Empowerment, Government of India and Institutional Animal Ethics Committee Guidelines (IAEC No: No. 32/02/2014).

Induction of type 2 diabetes in rats

The animals were divided into six groups of six animals each. The rats were fed with high fat diet consisting of 84.3% standard laboratory chow, 5% lard, 10% yolk powder, 0.2% cholesterol and 0.5% bile salt for 2 weeks (Xie et al. 2005). After 2 weeks, the animals were kept in an overnight fast and injected with low dose of streptozotocin (35 mg/kg, dissolved in 0.1 M sodium citrate buffer, pH 4.5), (Wu et al. 2012). Fasting blood glucose was measured 3 days after the injection. The rats with fasting blood glucose levels above 250 mg/dL were considered diabetic. The diabetic rats were fed on the high-fat diet for another 4 weeks.

Experimental design

A total of 36 rats (30 diabetic rats and 6 normal rats) were used and experimental animals were divided into six groups, each group consists of a minimum of six rats (n = 6) detailed as given below. β-sitosterol was dissolved in 0.5 mL of olive oil and administered orally at different doses using an intragastric tube for a period of 30 days. Metformin was dissolved in 1 mL of distilled water used as standard drug.

  • Group I: Normal control rats.

  • Group II: Diabetic control rats.

  • Group III: Diabetic + β-sitosterol (5 mg/kg b.wt).

  • Group IV: Diabetic + β-sitosterol (10 mg/kg b.wt).

  • Group V: Diabetic + β-sitosterol (15 mg/kg b.wt).

  • Group VI: Diabetic + Metformin (500 mg/kg b.wt).

Body weight of all the animals was recorded prior to the treatment and sacrifice. Food and water intake of all groups of animals were monitored on a daily basis for 30 days at a fixed time. Fixed amount of rat chow and fluid was given to each rat and replenished the next day. At the end of the treatment period (30 days), the rats were fasted overnight, anaesthetized and killed by cervical decapitation. Blood samples were collected in tubes containing potassium oxalate and sodium fluoride (3:1) mixture for the estimation of plasma glucose and insulin. Hb and HbA1c levels were estimated in whole blood samples. The liver tissues was dissected out, washed in ice-cold saline and weighed. Tissue was minced and homogenized (10%, w/v) with 0.1 M Tris -HCl buffer (pH 7.4) and centrifuged (3000×g for 10 min). The resulting supernatant was used for enzyme assays.

Biochemical analysis

Plasma glucose was estimated by the method of Trinder (1969) using a reagent kit. Haemoglobin (Hb) and glycosyated haemoglobin (HbA1c) were estimated by the method of Drabkin and Austin (1932) and Sudhakar and Pattabiraman (1981), respectively. The plasma insulin was measured by the method of Burgi et al. (1988).

HOMA - IR=fasting insulin×fasting blood sugar/405.

Western blot analysis of PPAR γ and GLUT4

Briefly, 100 mg of adipose tissue and skeletal muscle were taken individually and homogenized in buffer containing 20 mM Tris–HCl (pH 7.8), 300 mM NaCl, 2 mM ethylenediaminetetraacetic acid (EDTA), 2 mM dithiothreitol (DTT), 2% NP-40, 0.2% SDS, 0.2% sodium deoxycholate, 0.5 mM phenylmethylsulfonyl fluoride (PMSF), 50 mM sodium fluoride (NaF), 25 mM sodium pyrophosphate, 40 mM β-glycerophosphate, 2 mM sodium orthovanadate (Na3VO4) and protease inhibitor cocktail (Sigma) using a polytron equipped homogenizer at a precise low setting on ice. The homogenate was centrifuged at 10,000×g for 10 min 4 °C and then the supernatant was collected. The resultant supernatant was sampled as the protein for PPARγ and GLUT4. Protein concentration was estimated by Lowry et al. (1951) using bovine serum albumin (BSA) as a standard. Briefly, each sample (50 µg) was subjected to heat denaturation at 100 °C for 5 min with Laemmli buffer. Proteins were resolved by SDS-PAGE on 10% polyacrylamide gels and then transferred to PVDF membrane (Amersham Biosciences, Little Chalfont Buckinghamshire, UK). The membrane was blocked with 5% blocking buffer (Amersham Biosciences, Little Chalfont Buckinghamshire, UK) in TBS-T (Tris-buffered saline and Tween 20) for 1 h at room temperature followed by incubation with mouse monoclonal primary antibodies to PPARγ (SC-7273, Santa Cruz Biotechnology) and GLUT 4 (SC-53566, Santa Cruz Biotechnology, California, USA) at a dilution of 1:1000. The membrane was subjected for repeated wash for 3 times with TBS-T and then incubated for 1 h in horse radish peroxidase (HRP)-conjugated rabbit mouse secondary antibody by 1:7500 dilutions in TBS-T. The membrane was again subjected for repeated wash for 3 times with TBS and TBS-T. Protein bands were visualized in Chemidoc using Enhanced Chemiluminescence Reagents (ECL; Amersham Biosciences, Little Chalfont Buckinghamshire, UK). The detected bands were quantified by Quantity one software (BioRad). Later, the membranes were incubated in stripping buffer (50 mL, containing 62.5 mM Tris HCl (pH 6.7), 1 g SDS and 0.34 mL β-mercaptoethanol) at 55 °C for 40 min. Following this, the membrane was re-probed using β-actin antibody (1:5000). In the present study, rat β-actin was used as loading control.

Histopathological studies

The pancreas tissues of the experimental rats was fixed in 10% formaldehyde, dehydrated in a graded series of ethanol and embedded in paraffin. Pancreatic sections (5 μm thick) were obtained using a microtome, then dewaxed and rehydrated. Sections were then stained with hematoxylin–eosin and viewed under the light microscope (100×).

Statistical analysis

All the grouped data were statistically evaluated with SPSS 17.0 software. Hypothesis testing methods included one way analysis of variance (ANOVA) followed by least significant difference (LSD) test; P value less than 0.05 were considered to indicate statistical significance. All the results were expressed as the mean ± SD for six animals in each group.

Results

Dose dependent effect of β-sitosterol on blood glucose, plasma insulin levels and HOMA-IR index

There was a significant increase in the level of plasma glucose and decrease in the level of plasma insulin in diabetic rats compared to normal control rats. β-Sitosterol was administered orally to diabetic rats at different doses (5, 10 and 15 mg/kg b.wt.) for 30 days significantly decreased the level of plasma glucose and homeostatic model assessment of insulin resistance whereas the levels of plasma insulin were significantly increased in a dose dependent manner. The effect was more pronounced at a dose of 15 mg/kg b.wt. than 5 and 10 mg/kg b.wt. and it was comparable to that of metformin. Therefore, 15 mg of β-sitosterol was fixed as an effective dose and used for further analysis (Table 1).

Table 1.

Dose dependent of β-sitosterol on the levels of blood glucose, Insulin and Homeostatic model assessment of insulin resistant of control and experimental animals

Group Plasma glucose (mg/dL) Plasma ins ulin (IU/mL) HOMA-IR
Before treatment After treatment Before treatment After treatment Before treatment After treatment
Control 84.10 ± 8.02 92.02 ± 5.09 20.01 ± 2.00 18.51 ± 1.81 4.15 ± 0.55 4.22 ± 0.57
Diabetes induced 260.16 ± 12.91 300.55 ± 11.7a 9.23 ± 0.86 7.53 ± 0.73a 5.93 ± 0.68 5.59 ± 0.49a
Diabetes + β-sitosterol (5 mg/kg b.wt) 254.99 ± 24.35 191.29 ± 9.16b 10.66 ± 0.79 11.59 ± 0.87b 6.71 ± 0.71 5.48 ± 0.54b
Diabetes + β-sitosterol (10 mg/kg b.wt) 246.09 ± 18.06 172.85 ± 8.53c 11.36 ± 0.91 12.58 ± 1.00c 6.90 ± 0.73 5.36 ± 0.43c
Diabetes + β-sitosterol (15 mg/kg b.wt) 235.71 ± 15.59 127.03 ± 9.48d 11.82 ± 0.72 14.98 ± 0.83d 6.90 ± 0.79 4.70 ± 0.42d
Diabetes + Metformin (500 mg/kg b.wt) 240.18 ± 13.65 122.45 ± 9.05 11.71 ± 0.41 16.23 ± 0.74 6.95 ± 0.44 4.91 ± 0.27
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Values are given as mean ± S.D for six animals in each group

Values are considered significantly different at P < 0.05 with post-hoc LSD test *P < 0.05

aControl vs diabetic rats

bDiabetic rats vs. diabetic rats treated with β sitosterol (5 mg/kg b.wt)

cDiabetic rats vs diabetic rats treated with β sitosterol (10 mg/kg b.wt)

dDiabetic rats vs. diabetic rats treated with β sitosterol (15 mg/kg b.wt)

eDiabetic rats treated with β sitosterol (15 mg/kg b.wt) vs Diabetic rats treated with Metformin (500 mg/kg b.wt)

Effect of β-sitosterol on body weight gain

Table 2 depicts the values of the initial and final body weights of the normal and diabetic rats. Body weight significantly decreased in diabetic rats compared to normal control rats. Oral administration of β-sitosterol and metformin to diabetic rats prevented the body weight loss compared to untreated diabetic rats.

Table 2.

Effect of β sitosterol on body weight of control and experimental rats

Group Body weight(g)
Initial Final
Control 186.16 ± 4.87 208.7 ± 7.67
Diabetes induced 188.83 ± 4.09a 147.70 ± 10.64a
Diabetes + β-sitosterol (5 mg/kg b.wt) 185.70 ± 6.24b 187.42 ± 6.18b
Diabetes + β-sitosterol (10 mg/kg b.wt) 181.59 ± 5.59c 191.60 ± 5.16c
Diabetes + β-sitosterol (15 mg/kg b.wt) 185.02 ± 4.22d 197.96 ± 5.59d
Diabetes + Metformin (500 mg/kg b.wt) 182.44 ± 6.010 200.59 ± 8.89
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Values are given as mean ± S.D for six animals in each group

Values are considered significantly different at P < 0.05 with post-hoc LSD test *P < 0.05

aControl vs diabetic rats

bDiabetic rats vs. diabetic rats treated with β sitosterol (5 mg/kg b.wt)

cDiabetic rats vs diabetic rats treated with β sitosterol (10 mg/kg b.wt)

dDiabetic rats.vs diabetic rats treated with β sitosterol (15 mg/kg b.wt)

eDiabetic rats treated with β sitosterol (15 mg/kg b.wt) vs diabetic rats treated with Metformin 500 mg/kg b.wt)

Effect of β-sitosterol on the levels of hemoglobin and glycated hemoglobin

Table 3 represents the levels of Hb and HbA1c in control and experimental rats. The levels of Hb were significantly decreased whereas the levels of HbA1c were significantly increased in high fat diet and streptozotocin induced diabetic rats and when treated with β-sitosterol and metformin, these values were brought toward near normal level.

Table 3.

Effect of β-sitosterol on the levels of hemoglobin and glycated hemoglobin in control and experimental rats

Parameters Control Diabetes Induced Diabetes + β-sitosterol (15 mg/kg b.wt) Diabetes +Metformin (500 mg/kg b.wt)
Haemoglobin (g/dL) 13.12 ± 1.19 8.85 ± 0.83a 11.57 ± 0.65b 12.27 ± 0.72
HbA1c (%) 5.03 ± 0.48 10.90 ± 0.92a 7.10 ± 0.67b 6.72 ± 0.54
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Values are given as mean ± S.D for six animals in each group.Values are considered significantly different at P < 0.05 with post-hoc LSD test *P < 0.05

aControl vs diabetic rats

bDiabetic rats vs Diabetic rats treated with β Sitoterol

cDiabetic rats treated with β sitosterol (15 mg/kg) vs Diabetic rats treated with Metformin (500 mg/kg)

Effect of β-sitosterol on the protein expression of PPARγ in adipose tissue

Figure 1 depicts the protein expression levels of PPARγ in adipose tissue of control and experimental animals. The expression of PPARγ protein was found to be significantly decreased in the adipose tissue of diabetic rats when compared to control rats. However, PPARγ protein expression was significantly increased in the adipose tissue of diabetic rats upon treatment with β-sitosterol and metformin.

Fig. 1.

Fig. 1

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Effect of β sitosterol on PPRγ expression in adipose tissue of control and experimental rats. Values are given as mean ± SD for six animals in each group. Values are considered significantly different at P < 0.05 with post-hoc LSD test *P < 0.05. a Control vs Diabetic rats. b Diabetic rats vs. Diabetic rats treated with β-sitosterol (15 mg/kg b.wt.). c β-sitosterol treated diabetic rats (15 mg/kg b.wt.) vs. Metformin (500 mg/kg b.wt.)

Effect of β-sitosterol on the protein expression of GLUT4 in skeletal muscle

The protein expression levels of GLUT4 in skeletal muscle were significantly decreased in diabetic rats when compared to control rats. However, those proteins levels were elevated in diabetic rats after treatment with β-sitosterol and metformin (Fig. 2).

Fig. 2.

Fig. 2

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Effect of β sitosterol on GLUT 4 expression in skeletal muscle of control and experimental rats. Values are given as mean ± SD for six animals in each group. Values are considered significantly different at P < 0.05 with post-hoc LSD test *P < 0.05. a Control vs Diabetic rats. b Diabetic rats vs. Diabetic rats treated with β-sitosterol (15 mg/kg b.wt.). c β-Sitosterol treated diabetic rats (15 mg/kg b.wt.) vs. Metformin (500 mg/kg b.wt.)

Effect of β-sitosterol on histopathological changes in pancreas

Based on H and E stained pancreatic tissue sections (Fig. 3), normal control rat showing β-cells with displayed granulated cytoplasm and uniform nuclei and there were no notable changes observed in the pancreas of normal rats (A). In contrast, microvesicular, macro vesicular changes and decreased number of the β islets were observed in the pancreas of high fat diet and streptozotocin induced diabetic rats (B). Treatment with β-sitosterol and metformin showed increase in the cellularity of β-cell islets of pancreas when compared to diabetic rats (C and D).

Fig. 3.

Fig. 3

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Histological observations (H&E staining ×100) of pancreatic tissues from control and experimental rats. Control (a), diabetes induced (b), Diabetic + β-sitosterol (c), Diabetic + Metformin (d), Quantification of β cells (e). Values are given as mean ± SD for six animals in each group. Values are considered significantly different at P < 0.05 with post-hoc LSD test *P < 0.05. a Control vs Diabetic rats. b Diabetic rats vs. Diabetic rats treated with β-sitosterol (15 mg/kg b.wt.). c β-sitosterol treated diabetic rats (15 mg/kg b.wt.) vs. Metformin (500 mg/kg b.wt.)

Discussion

High fat diet and low dose streptozotocin are known to induce rapid destruction of pancreatic β-cells leading to impaired glucose stimulated insulin release and insulin resistance, both of which are marked features of type 2 diabetes (Farswan et al. 2009). The elevated blood glucose is a result of reduced glucose uptake in muscle and adipose tissue and increased gluconeogenesis, hepatic glucose production and glycogen breakdown (Sundaram et al. 2013). In the present study, a significant decrease in the levels of blood glucose, HOMA-IR and significant increase in the levels of insulin were observed in diabetic rats treated with β-sitosterol and metformin. β-sitosterol might bring about glucose lowering action by stimulate the surviving β-cells of islets of Langerhans to release more insulin through its antioxidant potential (Gupta et al. 2011).

The decreased body weight observed in diabetic rats compared to control rats indicates the excessive breakdown or loss of structural tissue proteins due to altered carbohydrate metabolic enzymes (Chen and Ianuzzo 1982). Previous study reported that protein synthesis is decreased in all tissues due to decreased production of ATP and absolute or relative deficiency of insulin (Bender 2009). Oral administration of β-sitosterol and metformin improved body weight of diabetic rats which might result from an improvement in glycemic control.

During diabetes the excess of glucose present in blood reacts with hemoglobin to form increased glycosylated hemoglobin (Sheela and Augusti 1992; Sundaram et al. 2013). Estimation of HbA1c has been found to be useful in monitoring the effectiveness of therapy in diabetes and also a vital biochemical marker for the diagnosis and management of ambient glycemia during a period of 3 month (Goldstein et al. 1995). Prolonged administration of β-sitosterol and metformin to diabetic rats significantly reversed the Hb andHbA1c to near normal levels.

PPAR-γ is a member of the nuclear hormone receptor super family of ligand-dependent transcription factors and regulates the expression of genes involved in insulin signaling, carbohydrate and lipid metabolism (Herzig et al. 2003). PPARγ is highly expressed in white adipose tissue and its elevation enhances insulin sensitivity in rodent type 2 diabetes mellitus models (Hevener et al. 2003; Escher et al. 2001, Sharma et al. 2011). Tissue specific PPARγ down regulation in rats causes insulin resistance (Barroso et al. 1999; Rangwala et al. 2003). In our study, the administration of β-sitosterol and metformin decreased insulin resistance by increasing PPAR-γ expression in diabetic rats.

The ability of insulin to reduce blood glucose levels results from the suppression of hepatic glucose production and increased glucose uptake in muscle and adipose tissue via GLUT4 (Singla et al. 2010). Our findings in the present study indicated decreased expression of muscle GLUT4 in high fat diet and streptozotocin induced diabetic rats which could be due the reduced hexokinase activity, decreased glycogen content and elevated plasma glucose levels. However, diabetic rats treated with β-sitosterol and metformin showed significant improvement in muscle GLUT4 expression. The improved expression of muscle GLUT4 and adipose tissue PPARγ are suggested that β-sitosterol is an insulin sensitizing agent and it can be used as an alternative drug for the treatment of type 2 diabetes.

Streptozotocin causes abnormalities on β cells function and it is also documented further that NO and free nitrous radicals (peroxynitrite) may be an aggravating factors in the toxicity of streptozotocin (Elsner et al. 2000). In addition, reactive oxygen species which are generated during ATP degradation by xanthine oxidase from hypoxanthine is also responsible for toxic effect of streptozotocin (Naik et al. 2013). The alkylating potency of streptozotocin known to cause ATP depletion that results in hypoxia and ischemia, a crucial factor for β-cell toxicity, reduced and shrunken of islets. However, diabetic rats showed normal architecture of pancreas with increased number of islets after treatment with β-sitosterol. This result indicates that antidiabetic potential of β-sitosterol which could be mediated through the amelioration of oxidative stress which finally resulted in the prevention of degeneration of pancreatic β-islets and able to preserve its histoarchitecture.

Conclusion

The administration of β-sitosterol significantly reduced blood glucose and increased the protein expression PPARγ and GLUT4 on insulin target tissues which indicate that β-sitosterol improved insulin sensitivity. Decreased blood glucose levels and reduced insulin resistance are key characteristics of treatments for diabetes mellitus; hence, β-sitosterol could be an effective antidiabetic agent and may possibly be used as an alternative to supportive treatment for type 2 diabetes mellitus in old-aged individuals.

Compliance with ethical standards

Conflicts of interest

All authors declare that there are no conflicts of interest.

Footnotes

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