Table 3.

Examples of in vivo studies related to salsolinol. DA dopamine, i.c.v. intracerebroventricular, i.p. intraperitoneal, i.v. intravenous, N/A not available, NAc nucleus accumbens, NE norepinephrine, PRL prolactin, SAL salsolinol, TRH thyrotropin-releasing hormone, VTA ventral tegmental area (a anterior and p posterior part). Salsolinol was applied as a racemic mixture unless otherwise stated

In vivo rodent models
Concentration and source of salsolinol	Route of administration and time course	Model and initial body weight	Results	References
200 mg/kg b.w. (Sigma-Aldrich, USA) in 0.9% NaCl	i.p. osmotic ALZET minipumps for 2 or 4 weeks	male Wistar rats, 230–265 g	The epididymal fat pad weight over final body mass ratio was lower in SAL-treated rats on high fat diet in comparison with the controls. The area, perimeter, short and long axis of the fad pad adipocytes were significantly decreased in SAL-treated rat.	Aleksandrovych et al. (2016)
			The myenteric neuron count, the mean size of the neuron body, the area of ganglia and the diameter of nerve strands were decreased in both of the SAL-treated groups compared with the controls. Exogenous SAL treatment led to enteric neuronal cell death probably via initiation of apoptosis.	Kurnik et al. (2015)
100 mg/kg b.w.(Sigma-Aldrich, USA) in 0.9% NaCl	i.p. injection once or for 14 consecutive days	male Wistar rats, 220–240 g	SAL under physiological conditions could not be an endogenous factor involved in the neurodegenerative processes, it can rather exert a protective action on nerve cells in the brain.	Możdżeń et al. (2015)
30 pmol (Santa Cruz Biotechnology, USA) in aCSF – purified R and S-SAL	slow injection into the left pVTA	female Wistar-derived naïve UChB rats, 200–250 g	Repeated administration of (R)-SAL caused: (1) conditioned place preference; (2) locomotor sensitization; and (3) marked increase in binge-like ethanol intake; while (S)-SAL did not influence any of these parameters.	Quintanilla et al. (2016)
100 mg/kg b.w.(Sigma-Aldrich, USA) in 0.9% NaCl	i.p. injection once or for 14 consecutive days	male Wistar rats, 220–240 g	Chronic administration of SAL significantly impaired the response of dopaminergic neurons to L-DOPA administration.	Wąsik et al. (2015)
30 pmol/0.2 μL in aCSF for VTA injection or 10 mg/kg in 0.9% NaCl for systemic administration (Santa Cruz Biotechnology or Sigma-Aldrich, USA); free of isosalsolinol	single or repeated injection into the left pVTA or i.p.	female Wistar-derived naïve UChB rats, 200–250 g	SAL produced conditioned place preference and increased locomotor activity, whether intracerebrally or intraperitoneally. Results might indicate that systemically administered SAL is able to cross the blood-brain barrier.	Quintanilla et al. (2014)
0.03, 0.3, 1 or 3 μM (Sigma-Aldrich, USA) in aCSF	single injection into the pVTA	male Wistar rats, 350–400 g	Local application of intermediate concentrations of SAL stimulated DA neurons in the pVTA, whereas higher concentrations may be having secondary effects within the pVTA that inhibit DA neuronal activity.	Deehan et al. (2013)
200 mg/kg b.w. (Sigma-Aldrich, USA) in 0.9% NaCl	i.p. osmotic ALZET minipumps for 2 or 4 weeks	male Wistar rats, 243–263 g	SAL increased serum levels of IL-1β and histamine and the total number of mast cells in the gastrointestinal wall.	Kurnik et al. (2013)
			Diminished body weight gain and lower adipose tissue accumulation in SAL-treated animals were due to delayed gastric emptying together with disturbed gut function resulting in absorptive dysfunction.	Kurnik et al. (2012)
50 mg/kg/day b.w. (Sigma-Aldrich, USA) in 0.9% NaCl	i.p. injections for 3 weeks	male Wistar rats, 180–220 g	SAL proved to be destructive on the mast cells in all segments of gastrointestinal tract	Gil et al. (2011)
30 pmol/200 nL/hemisphere (Sigma-Aldrich, USA) in aCSF	single intra-VTA, bilaterally	male Wistar rats, ~300 g	SAL administered into the pVTA produced psychomotor responses and reinforcing effects, probably, through the activation of μ-opioid receptors.	Hipólito et al. (2011)
0.3, 3, 30, 300, and 3,000 pmol (Sigma-Aldrich, USA) in aCSF	single injection or repeatedly during 12 days into the pVTA	male Wistar rats, 220–300 g	Intra-VTA SAL administration induced an increase of the spontaneous motor activity of the rats with the maximal effect at the dose of 30.0 pmol.	Hipólito et al. (2010)
10 μg of SAL (N/A) in 0.9% NaCl or 3 g of banana (corresponding to 75 μg of SAL) homogenized in 0.9% NaCl	single gavage	male Sprague-Dawley rats; adult male alcohol-preferring (P) and alcohol-nonpreferring (NP) rats, N/A	A single administration of SAL resulted in a significant elevation of rat plasma SAL levels, which declined to near basal levels by 14 hours. The mean plasma levels of (S)- and (R)-SAL at 1 hour after administration were 650 ± 46 and 614 ± 42 pg/ml, respectively. The mean basal (S)- and (R)-SAL levels were 11 ± 4 and 10 ± 1 pg/ml, respectively. A single intake banana also increased the plasma SAL level. Despite the increases observed in plasma SAL or DA levels, their levels were not changed in the striatum or NA. The basal SAL levels were markedly lower in the NA of P than NP rats. The SAL levels in the NA of P rats were not changed after 8 weeks of free-choice alcohol drinking and chronic ethanol drinking did not result in changes of SAL enantiomeric distribution, either.	Lee et al. (2010)
0.1, 5 and 25 μmol (Sigma-Aldrich, USA) in aCSF	single 20-min infusion into shell or core subregions of NAc	male Wistar rats, 300–320 g	Application of 5 and 25 μmol SAL into the core increased the dialysate levels of DA. The administration of the same doses of this drug into the shell significantly reduced the DA levels in this subregion.	Hipólito et al. (2009)
0.03, 0.1, 0.3, 1.0 or 3.0 μM (Sigma, St. Louis, MO) in aCSF with ascorbate	self-infusions into the pVTA or aVTA	male Wistar rats, 250–320 g	SAL produced reinforcing effects in the pVTA of Wistar rats, and these effects were mediated by activation of DA neurons and local 5-HT3 receptors.	Rodd et al. (2008)
10, 20, 40 or 80 nmol (Sigma-Aldrich, USA) in 0.9% NaCl – R-SAL	single injection into striatum	male Sprague-Dawley rats, 250–350 g	(R)-SAL led to a concentration-dependent decrease in the activity of acetylocholinesterase. Acetylocholine concentrations in striatum treated with (R)-salsolinol or N-methyl-(R)-SAL were increased to 131.7% and 239.8% in comparison with control, respectively. (R)-SAL reduced the concentrations of DA metabolites in the striatum.	Zhu et al. (2008)
0.2 to 25 mg/kg b.w. (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl	single i.p. injection	male and female Sprague–Dawley rats, 250–350 g; male NE transporter knock out (NET KO) mice, 3-5 months old	SAL did not affect the in vitro release of DA in the median eminence and did not inhibit the L-DOPA induced increase of DA level in the median eminence. Increasing doses of SAL caused a dose dependent decrease of tissue DA concentration and increase of NE to DA ratio in the salivary gland, atrium and spleen.	Székács et al. (2007a)
25 mg/kg b.w. (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl		male Sprague–Dawley rats after medullectomy, adrenalectomy and hypophysectomy, 200–300 g	The presence of the adrenal gland was not required for the changes of PRL secretion, nor for the reduction of peripheral sympathetic activity induced by SAL. The effect of SAL on peripheral sympathetic terminals was not affected by hypophysectomy, consequently the role of pituitary hormones in the effect of SAL on the peripheral catecholamine metabolism might be excluded.	Székács et al. (2007b)
1.8 mg/kg b.w. (Sigma–Aldrich, USA)	single i.p. injection	Male Sprague–Dawley rats, 280–320 g	1,2,3,4-tetrahydroisoquinoline (TIQ), 5,6,7,8-tetrahydroisoquinoline (5-TIQ), 1-benzyl-1,2,3,4-tetrahydroisoquinoline (1-BnTIQ), and SAL were studied. TIQ and 5-TIQ passed through the blood–brain barrier more easily than 1-BnTIQ, while SAL was unable to cross the barrier.	Song et al. (2006b)
50 mg/kg/day b.w. (Sigma-Aldrich, USA) in 0.9% NaCl	i.p. injections for 3 weeks	male Wistar rats, ~200 g	SAL had a direct effect on both interstitial cells of Cajal and neuronal pathways of gastro-duodenal reflexes.	Banach et al. (2006)
			Fasting intestinal myoelectrical activity (IMA) recordings did not reveal differences in frequency of migrating myoelectrical complexes and dominant frequency (DF) of slow waves between SAL and saline group. However in response to gastrointestinal stimulation in the SAL group DF of IMA remained unchanged whereas in the controls increased.	Banach et al. (2005)
10 mg/kg b.w. (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl	single i.v. injection	primiparous lactating Sprague-Dawley-derived rats, N/A	The observed changes in the level of cAMP following the acute treatment of SAL in the median eminence (ME) and the anterior lobe (AL) seems to be related to interacting neuroendocrine signals delivered from the ME to the AL through the long portal vessels to release PRL.	Radnai et al. (2005)
40 mg/kg b.w. (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl		male Sprague-Dawley rats, 350 g or primiparous lactating female rats, N/A	SAL had an important role in the regulation of PRL release induced by physiologic and environmental stimuli; therefore, it could be considered as a candidate for being the PRL releasing factor in the hypothalamo-hypophysial system.	Radnai et al. (2004)
	i.p. injections	male Sprague-Dawley rats, 350 g	SAL could candidate as an endogenous PRL-releasing factor and a potent inhibitor of stress-induced plasma release of epinephrine and NE.	Bodnár et al. (2004)
1.25 nM (Sigma-Aldrich, USA) in 0.1 M of Tris-HCl	single injection into the right substantia nigra	male Sprague-Dawley rats, 180–220 g	DT-diaphorase played a protective role in the nigrostriatal dopaminergic systems.	Díaz-Véliz et al. (2004)
0.3, 1, 3, 12.5 μM (Sigma, St. Louis, MO) in aCSF ⁄ ascorbate	self-infusions into the shell of NAc	female alcohol-preferring (P) rats from the 49th and 50th generations, 250 to 320 g	SAL was reinforcing into the shell of NA of P rats at concentrations that were pharmacologically possible, and these reinforcing actions were mediated in part by D2/D3-like receptors.	Rodd et al. (2003)
5 mg/kg b.w. in 0.9% NaCl (Sigma, St. Louis, MO)	single i.p. injection	naive male C57BL/6 strain mice 8–9 weeks old; randombred CD-1 mice; male Wistar rats, 220–250 g	SAL antagonized the agonistic conformation of DA receptor and that endogenous 1,2,3,4-tetrahydroisoquinolines may play a role of natural feedback regulators of the activity of dopaminergic system.	Vetulani et al. (2001)
		male Wistar rats, 220–240 g	Acute effects of SAL produced small biochemical effects, did not potentiate the action of DA receptor antagonists, counteracted the action of DA receptor agonists and bound to agonistic sites of DA receptors.	Antkiewicz-Michaluk et al. (2000a)
100 mg/kg b.w. (Sigma-Aldrich, USA) in 0.9% NaCl	single i.p. injection or for 18 days	male Wistar rat, 190–220 g	A single dose of SAL did not affect the DA metabolism in the substantia nigra and NAc, but remarkably increased the homovanillic acid concentration in the striatum (by 55%). The effects of chronic treatment were limited to extrapyramidal structures, and resulted in a remarkable depletion of DA (by 62% in the substantia nigra and by 33% in the striatum), concomitant with the decline of DA metabolites.	Antkiewicz-Michaluk et al. (2000b)
1, 3, 10, 30 mg/kg b.w. (Sigma-Aldrich, USA) in 0.9% NaCl	single i.p. injection	male Sprague-Dawley rats, 170–220 g	SAL might have some rewarding effect, potentiated by psychological stress. The rewarding effect of SAL especially under psychological stress might involve the endogenous central opioid system.	Matsuzawa et al. (2000)
1 mmol (synthetized according to Teitel et al, 1972) in Ringer solution – R and S-SAL	40-min infusion into the striatum	male Wistar rats, N/A	The concentration of serotonin in the rat striatum increased from undetectable level to 2.53 +/- 0.12 and 3.69 +/- 0.01 μmol after perfusion of (R)- and (S)-SAL, respectively. SAL increased extracellular dopamine levels but to a much lesser degree than serotonin.	Maruyama et al. (1993)
20 mg/kg b.w. (N/A)	single i.p. injection	male Wistar rats, N/A	SAL should not be able to cross the blood brain barrier since SAL administered intraperitoneally did not result in measurable brain SAL or mono-O-methyl-salsolinol levels.	Origitano et al. (1981)
0.4 mmol/kg b.w. (N/A)	single i.p. injection	rats, N/A	SAL administration resulted in levels of 1-2 nmol/g in striatum and limbic forebrain after 2 h, whereas the corresponding liver values were about 550 nmol/g. Control animals showed SAL values in liver of about 2 nmol/g and in striatum and limbic forebrain 1 nmol/g tissue.	Sjöquist and Magnuson (1980)
250 μg (synthesized by the method of the Pictet- Spengler condensation of dopamine with an aldehyde) in 0.9% NaCl	single i.c.v. injection	male Wistar rat, 180–250 g	SAL induced rise in striatal dopamine was prevented by alpha-methyl-p-tyrosine pretreatment while SAL induced fall in diencephalic noradrenaline was not affected. SAL was found to cause hypothermia.	Awazi and Guldberg (1979)
0.2-3.0 mg/kg (synthetized according to Craig et al, 1952)	single i.v. injection	adult male and female vagotomised cats, N/A	SAL produced agonist effects at cholinoceptors and alpha- and beta-adrenoceptors. In anesthetized cats, SAL (0.2-3.0 mg/kg) produced dose-related falls in mean blood pressure and a fall in heart rate. These effects were antagonized by atropine (1 mg/kg). In atropinized animals, both SAL caused dose-related elevations in mean blood pressure that were blocked by phentolamine (2 mg/kg). SAL produced a reduction in the tension and degree of fusion of the incomplete tetanic contractions of the soleus muscle, an effect antagonized by propranolol (0.4 mg/kg).	Rodger et al. (1979)
10, 20, 40 or 240 μg (Sigma-Aldrich, USA) in Krebs-Ringer with 0.01% ascorbic acid	single intracisternal injection	male and female mice after 18 generations of genetic selection for alcohol sensitivity, N/A	Low doses of SAL produced significantly lower activity levels in the alcohol-sensitive long-sleep (LS) line than in the alcohol-insensitive short-sleep (SS) line. A hypnotic dose of SAL induced significantly longer sleeptimes in the LS line than in the SS line.	Church et al. (1976)
0.038 or 0.38 mM (Sigma-Aldrich, USA) in aCSF	hippocampal perfusion	adult male and female Sprague-Dawley rats, 300–550 g	SAL enhanced the efflux of 45Ca2+ in a concentration-dependent manner during the interval of its perfusion within the hippocampal plane.	Myers et al. (1988)
Other in vivo models
Concentration and source of salsolinol	Route of administration and time course	Model and initial body weight	Results	Authors
1 mg/ml (15 μg/60 μl each infusion) in Ringer–Locke (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary)	a series of five 30-min infusions at 30-min intervals to the third ventricle	mature Polish Longwool sheep (3–4 years old), N/A	SAL stimulated oxytocin secretion during lactation in sheep.	Górski et al. (2016)
5 mg/kg b.w. (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl	single i.v. injection	male Shiba goats, ~25.3 kg	Hypothalamic DA blunted the SAL-induced release of PRL in male goats, regardless of the photoperiod, which suggested that both SAL and DA were involved in regulating the secretion of PRL in goats.	Jin et al. (2014)
		male Shiba goats, ~ 20 kg	DA inhibited the SAL-induced release of PRL in male goats, which suggested that SAL and DA are involved in regulating the secretion of PRL.	Hashizume et al. (2012)
		female Shiba goats, ~27.7 kg	A long photoperiod highly enhanced the PRL-releasing response to SAL in either medium or low ambient temperature in goats.	Yaegashi et al. (2012)
5 μg in total/animal (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in Ringer-Locke	a series of five 30-min i.c.v. infusions at 30-min intervals	mature Longwool sheep, N/A	SAL might play a role as a neuromodulator for the hypothalamic NE and DA systems and as a signal transmitter for the pituitary PRL release.	Misztal et al. (2011)
50 ng oraz 50 μg in total/animal (Sigma-Aldrich, USA) in Ringer-Locke	a series of five 10-min i.c.v. infusions at 20-min intervals	mature ewes during the second month of pregnancy, N/A	SAL infused at the higher dose significantly increased plasma PRL concentration in lactating ewes. SAL in the process of stimulation of PRL release during lactation and that hypothalamic PRL might play an important role in the central mechanisms of adaptation to lactation.	Górski et al. (2010a)
50 ng oraz 50 μg in total/anaimal (Sigma-Aldrich, USA) in Ringer-Locke		nursing Polish Longwool sheep, 50–55 kg	SAL might affect the regulatory process of growth hormone secretion in lactating sheep but its role might not to be major.	Górski et al. (2010b)
5 mg/kg b.w. (for i.v.) or 10 mg/calf (for IIIv) synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl	single i.v. or i.c.v. injection	Japanese male and female calves, ~144 kg and Japanese Black cows, ~418 kg and castrated Holstein calves, ~204 kg	SAL was involved in the regulatory process for the secretion of PRL, not only in male and female calves, but also in cows. The potency of the PRL-releasing response to SAL differed with the physiological status of cattle.	Hashizume et al. (2010)
5 mg/kg b.w. (synthesised at Institute of Pharmaceutical Chemistry, University of Szeged, Hungary) in 0.9% NaCl	three consecutive i.v. injections at 2 h intervals	Shiba goats, ~27 kg	The mechanism(s) by which SAL released PRL were different from the mechanism of action of TRH. The secretion of PRL was under the inhibitory control of DA and SAL did not antagonize the DA receptor’s action.	Hashizume et al. (2009)
	single i.v. injection	female Shiba goats, ~26 kg	SAL was able to stimulate the release of PRL in ruminants. The additive effect of SAL and TRH on the release of PRL detected in vivo might not be mediated at the level of the AP but that DA was able to overcome their releasing activity both in vivo and in vitro.	Hashizume et al. (2008a)
5 or 10 mg/kg b.w. – for i.v. or 1 or 5 mg/calf – for i.c.v. (Sigma-Aldrich, USA) in 0.9% NaCl	single i.v. or i.c.v. injection	female Shiba goats, ~15 kg; castrated Holstein calves, ~172 kg	SAL was present in extract of the PP gland of ruminants and had PRL-releasing activity both in vivo and in vitro.	Hashizume et al. (2008b)