Development of tolerance upon repeated administration with the GABAB receptor positive allosteric modulator, COR659, on alcohol drinking in rodents.

Background: Recent work has demonstrated that acute administration of the novel positive allosteric modulator of the GABAB receptor, COR659, reduces several alcohol-related behaviors in rodents.Objective: To assess whether COR659 continues to lessen alcohol intake after repeated administration, a fundamental feature of drugs with therapeutic potential.Methods: Male C57BL/6J mice (n = 40) were exposed to daily 2-hour drinking sessions (20% (v/v) alcohol) under the 1-bottle "drinking in the dark" protocol and male Sardinian alcohol-preferring rats (n = 40) were exposed to daily 1-hour drinking sessions under the 2-bottle "alcohol (10%, v/v) vs water" choice regimen. COR659 (0, 10, 20, and 40 mg/kg in the mouse experiment; 0, 5, 10, and 20 mg/kg in the rat experiment) was administered intraperitoneally before 7 consecutive drinking sessions.Results: Alcohol intake in vehicle-treated mice and rats averaged 2.5-3.0 and 1.5-1.6 g/kg/session, respectively, indicative of high basal levels. In both experiments, treatment with COR659 resulted in an initial, dose-related suppression of alcohol intake (up to 70-80% compared to vehicle treatment; P < .0005 and P < .0001 in mouse and rat experiments, respectively). The magnitude of the reducing effect of COR659 on alcohol drinking diminished progressively, until vanishing over the subsequent 2-4 drinking sessions.Conclusion: COR659 effectively reduced alcohol intake in two different rodent models of excessive alcohol drinking. However, tolerance to the anti-alcohol effects of COR659 developed rapidly. If theoretically transposed to humans, these data would represent a possible limitation to the clinical use of COR659.

The dopamine ß-hydroxylase inhibitor, nepicastat, reduces different alcohol-related behaviors in rats.

BACKGROUND: Recent experimental data indicate that treatment with the selective dopamine ß-hydroxylase inhibitor, nepicastat, suppressed different reward-related behaviors, including self-administration of chocolate and reinstatement of cocaine and chocolate seeking, in rats. This study was designed to extend to different alcohol-related behaviors the investigation on the "anti-addictive" properties of nepicastat. METHODS: Sardinian alcohol-preferring (sP) rats, selectively bred for excessive alcohol consumption, were exposed to different procedures of alcohol drinking and self-administration. RESULTS: Repeated treatment with nepicastat (0, 25, 50, and 100 mg/kg, intraperitoneally [i.p.], once daily for 10 consecutive days) produced a stable and dose-related reduction in daily alcohol intake in sP rats exposed to the homecage 2-bottle "alcohol (10% v/v) versus water" choice regimen with unlimited access. Acute treatment with nepicastat (0, 25, 50, and 100 mg/kg, i.p.) completely suppressed the "alcohol deprivation effect" (i.e., the temporary increase in alcohol intake occurring after a period of abstinence; model of alcohol relapse episodes) in sP rats exposed to the 2-bottle choice regimen. Acute treatment with nepicastat (0, 25, 50, and 100 mg/kg, i.p.) dose dependently and selectively reduced oral alcohol self-administration in sP rats trained to lever respond for alcohol (15% v/v) on a fixed ratio 4 schedule of reinforcement. Finally, combination of nepicastat (0, 50, and 100 mg/kg, i.p.) and alcohol (2 g/kg, intragastrically) did not alter spontaneous locomotor activity in sP rats. CONCLUSIONS: Together, these data extend to alcohol the capacity of nepicastat to suppress different behaviors motivated by natural stimuli and drugs of abuse.

Protective effect of Panax ginseng in cisplatin-induced cachexia in rats.

AIM: This study investigated the protective effect of a standardized extract of Panax ginseng on multiple cisplatin-induced 'sickness behaviors' (model of cancer-induced cachexia) in rats. MATERIALS & METHODS: Cisplatin was administered twice weekly (1-2 mg/kg, intraperitoneal) for 5 consecutive weeks. Panax ginseng extract (0, 25 and 50 mg/kg, intragastric) was administered daily over the 5-week period of cisplatin exposure. Malaise, bodyweight and temperature, pain sensitivity, and endurance running were recorded at baseline and at 5 weekly intervals. RESULTS: Treatment with cisplatin produced severe signs of malaise, marked loss of bodyweight, hypothermia, hyperalgesia and reduction in running time. Treatment with Panax ginseng extract completely prevented all cisplatin-induced alterations. CONCLUSION: These data indicate that treatment with Panax ginseng extract exerted a protective effect in a rat model of cachexia and suggest that Panax ginseng extract may be a therapeutic promising tool for supportive care in oncology.

Evidence for enduring cardiac and multiorgan toxicity after repeated exposure to the synthetic cannabinoid JWH-018 in male rats.

The use of synthetic cannabinoid receptor agonists (SCRAs) represents a public health concern. Besides abuse liability and cognitive impairments, SCRA consumption is associated with serious medical consequences in humans, including cardiotoxicity. The precise mechanisms underlying cardiac or other toxicities induced by SCRAs are not well understood. Here, we used in silico, in vivo, and ex vivo approaches to investigate the toxicological consequences induced by exposure to the SCRA JWH-018. Along with in silico predictive toxicological screening of 36 SCRAs by MC4PC software, adult male Sprague-Dawley rats were repeatedly exposed to JWH-018 (0.25mg/kg ip) for 14 consecutive days, with body temperature and cardiovascular parameters measured over the course of treatment. At 1 and 7 days after JWH-018 discontinuation, multiorgan tissue pathologies and heart mitochondria bioenergetics were assessed. The in silico findings predicted risk of cardiac adverse effects specifically for JWH-018 and other aminoalkylindole SCRAs (i.e., electrocardiogram abnormality and QT prolongation). The results from rats revealed that repeated, but not single, JWH-018 exposure induced hypothermia and cardiovascular stimulation (e.g., increased blood pressure and heart rate) which persisted throughout treatment. Post-mortem findings demonstrated cardiac lesions (i.e., vacuolization, waving, edema) 1 day after JWH-018 discontinuation, which may contribute to lungs, kidneys, and liver tissue degeneration observed 7 days later. Importantly, repeated JWH-018 exposure induced mitochondrial dysfunction in cardiomyocytes, i.e., defective lipid OXPHOS, which may represent one mechanism of JWH-018-induced toxicity. Our results demonstrate that repeated administration of even a relatively low dose of JWH-018 is sufficient to affect cardiovascular function and induce enduring toxicological consequences, pointing to risks associated with SCRA consumption.

Exposure to an enriched environment exerts anxiolytic effects in Sardinian alcohol-preferring rats.

Exposure to an enriched environment (EE) has been reported to generate multiple beneficial effects in rodents, including - among the many - amelioration of anxiety-related behaviors. The present study investigated whether living in an EE produced anxiolytic effects also in selectively bred Sardinian alcohol-preferring (sP) rats. The relevance of this research question relied on two factors: sP rats displayed an inherent, high anxiety-like state under different experimental conditions; exposure to EE reduced operant, oral alcohol self-administration in sP rats. Starting from weaning, male sP rats were kept under 3 different housing conditions: impoverished environment (IE; single housing with no environmental enrichment); standard environment (SE; 3 rats/cage with no environmental enrichment); EE (6 rats/cage with various elements of environmental enrichment). At the age of approximately 80 days, rats were exposed to an elevated plus maze test for assessment of anxiety-related behaviors. Compared to IE and SE rats, EE rats displayed higher basal levels of exploratory activity (i.e., increased number of entries into closed arms). Compared to IE and SE rats, EE rats also displayed a less "anxious" profile, as suggested by the increase in percent number of entries into open arms (OAs), percent time spent in OAs, number of head dips, and number of end-arm explorations in OAs. These data extend the protective (anxiolytic) effects of EE to a proposed animal model of comorbid alcohol use disorder and anxiety disorders.

Analgesic effects of saikosaponin A in a rat model of chronic inflammatory pain.

Saikosaponin A (SSA) is the main active ingredient of roots of the East Asian medicinal plant, Bupleurum falcatum L. The present study was aimed at delving into the analgesic properties of SSA in a model of chronic inflammatory pain. To this end, rats were initially treated intraplantarly with complete Freund's adjuvant for induction of hyperalgesia. Twenty-four hours later, rats were acutely treated with SSA (0, 1 and 2 mg/kg, i.p.) and exposed to the Von Frey monofilament test or Randall-Selitto paw pressure test for assessment of mechanical hyperalgesia. Treatment with 2 mg/kg SSA had analgesic effects: the nocifensive reaction (paw withdrawal) occurred later and required application of the nociceptive stimulus at a stronger pressure. The analgesic effects of SSA were of magnitude comparable to that of the effects exerted by the reference compound, acetyl salicylic acid (100 mg/kg, i.p.). The well-described anti-inflammatory properties of SSA likely underlie its analgesic effects.

Delving into the reducing effects of the GABAB positive allosteric modulator, KK-92A, on alcohol-related behaviors in rats.

Recent studies have demonstrated the ability of the positive allosteric modulator (PAM) of the GABAB receptor (GABAB PAM), KK-92A, to suppress operant alcohol self-administration and reinstatement of alcohol seeking in selectively bred Sardinian alcohol-preferring (sP) rats. The present study was designed to scrutinize the suppressing effects of KK-92A on alcohol-related behaviors; to this end, four separate experiments were conducted to address just as many new research questions, some of which bear translational value. Experiment 1 found that 7-day treatment with KK-92A (0, 5, 10, and 20 mg/kg, intraperitoneally [i.p.]) effectively reduced alcohol intake in male sP rats exposed to the home-cage 2-bottle "alcohol (10% v/v) vs. water" choice regimen with 1 hour/day limited access, extending to excessive alcohol drinking the ability of KK-92A to suppress operant alcohol self-administration. Experiment 2 demonstrated that the ability of KK-92A to reduce lever-responding for alcohol was maintained also after acute, intragastric treatment (0, 20, and 40 mg/kg) in female sP rats trained to lever-respond for 15% (v/v) alcohol under the fixed ratio 5 schedule of reinforcement. In Experiment 3, acutely administered KK-92A (0, 5, 10, and 20 mg/kg, i.p.) dampened alcohol-seeking behavior in female sP rats exposed to a single session under the extinction responding schedule. Experiment 4 used a taste reactivity test to demonstrate that acute treatment with KK-92A (0 and 20 mg/kg, i.p.) did not alter either hedonic or aversive reactions to a 15% (v/v) alcohol solution in male sP rats, ruling out that KK-92A-induced reduction of alcohol drinking and self-administration could be due to alterations in alcohol palatability. Together, these results enhance the behavioral pharmacological profile of KK-92A and further strengthen the notion that GABAB PAMs may represent a novel class of ligands with therapeutic potential for treating alcohol use disorder.

Male and Female Mitochondria Respond Differently after Exercising in Acute Hypoxia.

The use of hypoxic devices among athletes who train in normobaric hypoxia has become increasingly popular; however, the acute effects on heart and brain metabolism are not yet fully understood. This study aimed to investigate the mitochondrial bioenergetics in trained male and female Wistar rats after acute hypoxia training. The experimental plan included exercising for 30 min on a treadmill in a Plexiglas cage connected to a hypoxic generator set at 12.5% O2 or in normoxia. After the exercise, the rats were sacrificed, and their mitochondria were isolated from their brains and hearts. The bioenergetics for each complex of the electron transport chain was tested using a Clark-type electrode. The results showed that following hypoxia training, females experienced impaired oxidative phosphorylation through complex II in heart subsarcolemmal mitochondria, while males had an altered ADP/O in heart interfibrillar mitochondria, without any change in oxidative capacity. No differences from controls were evident in the brain, but an increased electron transport system efficiency was observed with complex I and IV substrates in males. Therefore, the study's findings suggest that hypoxia training affects the heart mitochondria of females more than males. This raises a cautionary flag for female athletes who use hypoxic devices.

Characterization of COR627 and COR628, two novel positive allosteric modulators of the GABA(B) receptor.

The potential efficacy of GABA(B) receptor agonists in the treatment of pain, drug addiction, epilepsy, cognitive dysfunctions, and anxiety disorders is supported by extensive preclinical and clinical evidence. However, the numerous side effects produced by the GABA(B) receptor agonist baclofen considerably limit the therapeutic use of this compound. The identification of positive allosteric modulators (PAMs) of the GABA(B) receptor may constitute a novel approach in the pharmacological manipulation of the GABA(B) receptor, leading to fewer side effects. The present study reports the identification of two novel compounds, methyl 2-(1-adamantanecarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate (COR627) and methyl 2-(cyclohexanecarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate (COR628), which act as GABA(B) PAMs in 1) rat cortical membranes and 2) in vivo assay. Both compounds potentiated GABA- and baclofen-stimulated guanosine 5'-O-(3-[(35)S]thio)-triphosphate binding to native GABA(B) receptors, while producing no effect when given alone. GABA concentration-response curves in the presence of fixed concentrations of COR627 and COR628 revealed an increase of potency of GABA rather than its maximal efficacy. In radioligand binding experiments [displacement of the GABA(B) receptor antagonist, 3-N-[1-((S)-3,4dichlorophenyl)-ethylaminol]-2-(S)hydroxypropyl cyclo-hexylmethyl phosphinic acid ([(3)H]CGP54626)], both COR627 and COR628 increased the affinity of high- and low-affinity binding sites for GABA, producing no effect when administered alone up to a concentration of 1 mM. In vivo experiments indicated that pretreatment with per se ineffective doses of COR627 and COR628 potentiated the sedative/hypnotic effect of baclofen. In conclusion, COR627 and COR628 may represent two additional tools for use in investigating the roles and functions of positive allosteric modulatory binding sites of the GABA(B) receptor.

Comparison of the effect of the GABAΒ receptor agonist, baclofen, and the positive allosteric modulator of the GABAB receptor, GS39783, on alcohol self-administration in 3 different lines of alcohol-preferring rats.

BACKGROUND: Administration of the GABA(B) receptor agonist, baclofen, and positive allosteric modulator, GS39783, has been repeatedly reported to suppress multiple alcohol-related behaviors, including operant oral alcohol self-administration, in rats. This study was designed to compare the effect of baclofen and GS39783 on alcohol self-administration in 3 lines of selectively bred, alcohol-preferring rats: Indiana alcohol-preferring (P), Sardinian alcohol-preferring (sP), and Alko Alcohol (AA). METHODS: Rats of each line were initially trained to respond on a lever, on a fixed ratio (FR) 4 (FR4) schedule of reinforcement, to orally self-administer alcohol (15%, v/v) in daily 30-minute sessions. Once responding reached stable levels, rats were exposed to a sequence of experiments testing baclofen (0, 1, 1.7, and 3 mg/kg; i.p.) and GS39783 (0, 25, 50, and 100 mg/kg; i.g.) on FR4 and progressive ratio (PR) schedules of reinforcement. Finally, to assess the specificity of baclofen and GS39783 action, rats were slightly food-deprived and trained to lever-respond for food pellets. RESULTS: The rank of order of the reinforcing and motivational properties of alcohol was P>sP>AA rats. Under both FR and PR schedules of reinforcement, the rank of order of potency and efficacy of baclofen and GS39783 in suppressing alcohol self-administration was P>sP>AA rats. Only the highest dose of baclofen reduced lever-responding for food pellets; this effect was common to all 3 rat lines. Conversely, no dose of GS39783 altered lever-responding for food in any rat line. CONCLUSIONS: These results suggest that: (i) the strength of the reinforcing and motivational properties of alcohol differ among P, sP, and AA rats; (ii) the reinforcing and motivational properties of alcohol in P, sP, and AA rats are differentially sensitive to treatment with baclofen and GS39783; (iii) the heterogeneity in sensitivity to baclofen and GS39783 of alcohol self-administration in P, sP, and AA rats may resemble the differential effectiveness of pharmacotherapies among the different typologies of human alcoholics; and (iv) the GABA(B) receptor is part of the neural substrate mediating the reinforcing and motivational properties of alcohol.

Environmental enrichment augments binge-like alcohol drinking in Sardinian alcohol-preferring rats.

Exposure of Sardinian alcohol-preferring (sP) rats to an enriched environment (EE) reduced different aspects of operant alcohol self-administration. The present study was aimed at expanding investigation of the effect of EE exposure upon a model of binge drinking composed of daily 1-h drinking sessions with unpredictable access to multiple alcohol concentrations; binge-like alcohol intakes were observed when the drinking session occurred at the last hours of the dark phase of the light/dark cycle. Starting from postnatal day (PND) 21, male sP rats were kept under three different housing conditions: impoverished environment (IE; single housing with no environmental enrichment); standard environment (SE; 3 rats/cage and no environmental enrichment); EE (6 rats/cage and multiple elements of environmental enrichment). From PND 69, rats were exposed daily to a 1-hour drinking session under the 4-bottle "alcohol (10%, 20%, and 30%, v/v) vs. water" choice regimen, during the dark phase, and with timing of alcohol exposure changed each day. In all three rat groups (IE, SE, and EE), alcohol intake increased progressively as the drinking session moved from the first to last hours of the dark phase. The slope of the regression line was steeper in EE than IE and SE rats, suggestive of higher intakes of alcohol in EE than IE and SE rats when the drinking session occurred over the last hours of the dark phase. These results are discussed hypothesizing that the stressful attributes of alcohol expectation were potentiated by the increased "emotionality" that rats living in a comfortable environment (i.e., EE) may experience when facing new, challenging events or environments. Blood alcohol levels, assessed at the end of a final drinking session occurring at the 12th hour of the dark phase, did not differ among the three rat groups and averaged approximately 150 mg%, confirming that this experimental procedure may generate intoxicating levels of alcohol drinking in sP rats.

Exposure to an enriched environment reduces alcohol self-administration in Sardinian alcohol-preferring rats.

Living in an enriched environment (EE) produces a notable impact on several rodent behaviors, including those motivated by drugs of abuse. This picture is somewhat less clear when referring to alcohol-motivated behaviors. With the intent of contributing to this research field with data from one of the few rat lines selectively bred for excessive alcohol consumption, the present study investigated the effect of EE on operant oral alcohol self-administration in Sardinian alcohol-preferring (sP) rats. Starting from Postnatal Day (PND) 21, male sP rats were kept under 3 different housing conditions: impoverished environment (IE; single housing in shoebox-like cages with no environmental enrichment); standard environment (SE; small colony cages with 3 rats and no environmental enrichment); EE (large colony cages with 6 rats and multiple elements of environmental enrichment, including 2 floors, ladders, maze, running wheels, and shelter). From PND 60, rats were exposed to different phases of shaping and training of alcohol self-administration. IE, SE, and EE rats were then compared under (i) fixed ratio (FR) 4 (FR4) schedule of alcohol reinforcement for 20 daily sessions and (ii) progressive ratio (PR) schedule of alcohol reinforcement in a final single session. Acquisition of the lever-responding task (shaping) was slower in EE than IE and SE rats, as the likely consequence of a "devaluation" of the novel stimuli provided by the operant chamber in comparison to those to which EE rats were continuously exposed in their homecage or an alteration, induced by EE, of the rat "emotionality" state when facing the novel environment represented by the operant chamber. Training of alcohol self-administration was slower in EE than IE rats, with SE rats displaying intermediate values. A similar ranking order (IE>SE>EE) was also observed in number of lever-responses for alcohol, amount of self-administered alcohol, and breakpoint for alcohol under FR4 and PR schedules of reinforcement. These data suggest that living in a complex environment reduced the reinforcing and motivational properties of alcohol in sP rats. These results are interpreted in terms of the reinforcing and motivational properties of the main components of EE (i.e., social interactions, physical activities, exploration, novelty) substituting, at least partially, for those of alcohol.

Analgesic properties of a food grade lecithin delivery system of Zingiber officinale and Acmella oleracea standardized extracts in rats.

This study investigated whether (i) the 5:1 combination of standardized extracts of Zingiber officinale and Acmella oleracea is endowed with analgesic effects and (ii) the phospholipid-based formulation of Zingiber officinale and Acmella oleracea extracts (ZAP) potentiated the analgesic effects of the plain extract combination (PEC). To this end, rats were exposed to acute pain (Tail Flick test) and chronic, inflammatory pain [Von Frey monofilament test and Randall-Selitto paw pressure test in rats treated intraplantarily with complete Freund's adjuvant (CFA)]. The plain combination of per se ineffective doses of the two extracts produced analgesic effects in healthy rats. ZAP was more potent and effective than the corresponding doses of PEC. ZAP also produced analgesic effects in CFA-treated rats. Studies are now warranted to assess whether the analgesic properties of ZAP may generalize to humans.

Chronic Red Bull Consumption during Adolescence: Effect on Mesocortical and Mesolimbic Dopamine Transmission and Cardiovascular System in Adult Rats.

Energy drinks are very popular nonalcoholic beverages among adolescents and young adults for their stimulant effects. Our study aimed to investigate the effect of repeated intraoral Red Bull (RB) infusion on dopamine transmission in the nucleus accumbens shell and core and in the medial prefrontal cortex and on cardiac contractility in adult rats exposed to chronic RB consumption. Rats were subjected to 4 weeks of RB voluntary consumption from adolescence to adulthood. Monitoring of in vivo dopamine was carried out by brain microdialysis. In vitro cardiac contractility was studied on biomechanical properties of isolated left-ventricular papillary muscle. The main finding of the study was that, in treated animals, RB increased shell dopamine via a nonadaptive mechanism, a pattern similar to that of drugs of abuse. No changes in isometric and isotonic mechanical parameters were associated with chronic RB consumption. However, a prolonged time to peak tension and half-time of relaxation and a slower peak rate of tension fall were observed in RB-treated rats. It is likely that RB treatment affects left-ventricular papillary muscle contraction. The neurochemical results here obtained can explain the addictive properties of RB, while the cardiovascular investigation findings suggest a hidden papillary contractility impairment.

Suppressing effect of the novel positive allosteric modulator of the GABAB receptor, COR659, on locomotor hyperactivity induced by different drugs of abuse.

COR659 is a recently synthesized positive allosteric modulator (PAM) of the GABAB receptor. Similarly to all GABAB PAMs tested to date, COR659 has been reported to suppress different alcohol-related behaviors in rodents. The present study was designed to assess whether the anti-addictive properties of COR659 extend to drugs of abuse other than alcohol. Specifically, it investigated the effect of COR659 on cocaine-, amphetamine-, nicotine-, and morphine-induced locomotor hyperactivity in mice. To this aim, independent groups of CD1 mice were acutely pretreated with COR659 (0, 10, and 20 mg/kg; i.p.), then acutely treated with cocaine (0 and 10 mg/kg, s.c.), amphetamine (0 and 5 mg/kg; s.c.), nicotine (0 and 0.05 mg/kg; s.c.), or morphine (0 and 20 mg/kg; s.c.), and finally exposed for 60 min to a photocell-equipped motility cage. When given alone, both doses of COR659 were ineffective on spontaneous locomotor activity. Pretreatment with COR659 reduced, or even suppressed, the increase in motility counts induced by cocaine, amphetamine, nicotine, and morphine. Since locomotor hyperactivity is an attribute common to drugs of abuse, the results of the present study constitute the first line of evidence on the extension of the preclinical, anti-addictive profile of COR659 to cocaine, amphetamine, nicotine, and morphine.

Increase in alcohol intake, reduced flexibility of alcohol drinking, and evidence of signs of alcohol intoxication in Sardinian alcohol-preferring rats exposed to intermittent access to 20% alcohol.

BACKGROUND: This study assessed in Sardinian alcohol-preferring (sP) rats a procedure known to promote alcohol drinking and based on the intermittent (once every other day) access to 2 bottles containing alcohol (20%, v/v) and water, respectively (Wise, 1973). METHODS: To this end, sP rats were exposed - under the 2-bottle choice regimen - to: (i) 10% (v/v) alcohol with continuous access (CA10%; i.e., the procedure under which sP rats had been selectively bred); (ii) 10% (v/v) alcohol with intermittent access (IA10%); (iii) 20% (v/v) alcohol with continuous access (CA20%); (iv) 20% (v/v) alcohol with intermittent access (IA20%; the "Wise" condition) (Experiment 1). Additional experiments assessed the influence of (i) adulteration with quinine of the alcohol solution (Experiment 2) and (ii) concurrent presentation of a saccharin solution (Experiment 3) on alcohol drinking under the CA10% and IA20% conditions. Finally, it was assessed whether alcohol drinking under the CA10% and IA20% conditions resulted in motor incoordination at the Rota-Rod task, as a possible sign of alcohol intoxication (Experiment 4). RESULTS: Daily alcohol intake markedly escalated in rats exposed to the IA20% condition, averaging 9.0 g/kg (in comparison with the average intake of 6.5 g/kg in the CA10% rat group). CA20% and IA10% rats displayed intermediate values of daily alcohol intake between those of CA10% and IA20% rats. Alcohol intake was virtually abolished by addition of quinine or by concurrent presentation of the saccharin solution in CA10% rats; conversely, alcohol intake in IA20% rats was only partially affected by gustatory aversion or concurrent presentation of an alternative reinforcer. Finally, alcohol intake in IA20%, but not in CA10%, rats resulted in clear motor-incoordinating effects. CONCLUSIONS: These data suggest that the "Wise" procedure is effective in inducing marked increases in alcohol intake in sP rats. These increases are associated with a reduced flexibility of alcohol drinking (suggesting the development of "behavioral" dependence) and produce signs of alcohol intoxication that are not detected when sP rats are exposed to the more conventional CA10% condition.

The pesticide fipronil injected into the substantia nigra of male rats decreases striatal dopamine content: A neurochemical, immunohistochemical and behavioral study.

Experimental evidence shows that the phenylpyrazole pesticide fipronil exerts neurotoxic effects at central level in rodents, and in particular on nigrostriatal dopaminergic neurons, whose degeneration is well known to cause motor and non-motor deficits in animals and in humans. In order to characterize better the central neurotoxic effect of fipronil, we injected fipronil (15 and 25 µg) dissolved in dimethyl sulfoxide (DMSO) unilaterally into the substantia nigra of male rats. Male rats injected with DMSO unilaterally into the substantia nigra were used as controls. Control and fipronil-treated rats were then tested in different motor (i.e., open field arena, rotarod, tail flick) and non motor tests (novel object recognition, social interaction) 15 days after injection. A systemic challenge dose of the dopamine-agonist apomorphine was also used to study the presence of a rotational behavior. Sixteen days after fipronil or DMSO injection into the substantia nigra, rats were sacrificed, and either striatal dopamine content or substantia nigra tyrosine hydroxylase (TH) immunoreactivity were measured. The results confirm that the unilateral injection of fipronil into the substantia nigra caused the degeneration of nigrostriatal dopaminergic neurons, which leads to a decrease around 50 % in striatal dopamine content and substantia nigra TH imunoreactivity. This occurred together with changes in motor activity and coordination, and in nociception but not in recognition memory and in social interaction, as revealed by the results of the behavioral experiments performed in fipronil-treated rats compared to vehicle-treated rats 15 days after treatment, as found with other compounds that destroy nigrostriatal dopaminergic neurons.

Anxiolytic effect of an extract of Salvia miltiorrhiza roots in rats.

BACKGROUND: Preparations from roots of Salvia miltiorrhiza, a herb widely used in traditional Chinese medicine, have been reported to induce a series of central effects, including sedation. In the wake of this ethnopharmacological information, the present study was designed to assess the anxiolytic potential of an extract of S. miltiorrhiza roots. METHODS: To this end, rats were acutely treated with S. miltiorrhiza extract (0, 50, and 100 mg/kg; i.g.) and exposed to the Elevated Plus Maze (EPM) test. The effect of treatment with S. miltiorrhiza extract on Stress-Induced Hyperthermia (SIH; a physiological response to stressful events) was also evaluated. RESULTS: Treatment with 100 mg/kg S. miltiorrhiza extract produced robust anxiolytic effects at the EPM test; specifically, it increased (a) percent of entries into open arms, (b) percent of time spent in open arms, (c) total number of head dips, (d) number of unprotected head dips, and (e) number of end-arm explorations in open arms, without any alteration in spontaneous locomotor activity. Treatment with 100 mg/kg S. miltiorrhiza extract also suppressed SIH response. The anxiolytic effects produced by 100 mg/kg S. miltiorrhiza extract were comparable to those exerted by acute treatment with 1.5 mg/kg (i.p.) of the reference compound, diazepam. CONCLUSION: These data demonstrate the ability of an extract of S. miltiorrhiza roots to produce anxiolysis in two different rodent models of "anxiety".

Administration of the metabotropic glutamate receptor subtype 5 allosteric modulator GET 73 with alcohol: A translational study in rats and humans.

Preclinical work suggests that GET 73 (N-[4-(trifluoromethyl)benzyl]-4-methoxybutyramide), a novel metabotropic glutamate receptor subtype 5 negative allosteric modulator, may represent a novel pharmacological treatment for alcohol use disorder. Two independent experiments evaluated the effect of acutely administered GET 73 (0, 30, and 100 mg/kg, intragastrically) on alcohol-induced hypolocomotion ( n=72) and sedation/hypnosis ( n=36) in rats. In healthy male volunteers ( n=14), an open-label, randomised, crossover study was conducted to compare adverse events and pharmacokinetic parameters, in two experiments in which 300 mg GET 73 was administered, with and without alcohol, once and thrice. In rats, when administered with alcohol-vehicle, 100 mg/kg, but not 30 mg/kg, GET 73 reduced spontaneous locomotor activity. When administered with alcohol, no dose of GET 73 altered either alcohol-induced hypolocomotion or sedation/hypnosis. In humans, both single and thrice 300 mg GET 73 administration were well tolerated, in the presence and absence of alcohol, with no differences in adverse events. There were no significant differences in relative bioavailability between administering 300 mg GET 73 in the presence or absence of alcohol.

Repeated exposure to alcoholic beer does not induce long-lasting changes in alcohol self-administration and intake in Sardinian alcohol-preferring and Sardinian non-preferring rats.

AIMS: Rats avidly consume non-alcoholic beer, and addition of alcohol to non-alcoholic beer may function as a medium to induce intake of large amounts of alcohol in rats. The present study investigated whether Sardinian alcohol-preferring (sP) and Sardinian non-preferring (sNP) rats, initially exposed to non-alcoholic beer, and subsequently to non-alcoholic beer containing increasing concentrations of alcohol, would develop unusually high alcohol self-administration and drinking behaviours: (i) when alcohol was added to non-alcoholic beer, and (2) once beer was withdrawn and a plain alcohol solution was made available. METHODS: In Experiment 1, rats were exposed to operant, 30-min/day self-administration sessions of non-alcoholic beer with increasing concentrations of alcohol [0, 2.5, 5, 7.5, and 10% (v/v)] for a total of 45 days. After a brief 'beer-fading' phase, the rats were exposed to self-administration sessions of a plain 10% (v/v) alcohol solution. In Experiment 2, the rats were exposed to non-alcoholic beer with increasing concentrations of alcohol [0, 2.5, 5, 7.5, and 10% (v/v)] and water under the 2-bottle choice regimen with unlimited access (24 h/day) for a total of 35 days. After a brief 'beer-fading' phase, the rats were exposed to the choice between a plain 10% (v/v) alcohol solution and water. RESULTS: sP and sNP rats did not differ in self-administration (Experiment 1) and intake (Experiment 2) of non-alcoholic beer. In Experiment 1, as alcohol content increased, the amount of self-administered alcohol increased progressively in sP rats (up to 1-1.2 g/kg) and remained stable in sNP rats (approximately 0.65 g/kg). When the plain 10% alcohol solution was available, the amount of self-administered alcohol in sP rats initially dropped, and tended to increase-up to approximately 0.6 g/kg-on continuing exposure. In sNP rats, their lever-pressing behaviour was rapidly extinguished after beer withdrawal. In Experiment 2, as alcohol content was increased, daily alcohol intake increased progressively in sP rats (up to 8-9 g/kg) and averaged approximately 2.4 g/kg in sNP rats. When the plain alcohol solution was available, daily alcohol intake in sP rats was initially low, reaching control values on continuing exposure; conversely, daily alcohol intake was completely suppressed in sNP rats. CONCLUSIONS: These results suggest that exposure to alcoholic beer resulted in unusually high intakes of alcohol in both sP and sNP rats for as long as non-alcoholic beer was added to alcohol; however, these high levels of alcohol self-administration and intake were not maintained once non-alcoholic beer was withdrawn.