Symmetrical generalization between the discriminative stimulus effects of gamma-hydroxybutyric acid and ethanol: Occurrence within narrow dose ranges
ABSTRACT Gamma-hydroxybutyric acid (GHB) has been shown to reduce ethanol consumption and suppress ethanol withdrawal syndrome both in laboratory animals and humans. The present study was designed to assess the similarity between the discriminative stimulus effects, or subjective feelings, of GHB and ethanol using a T-maze, food-reinforced drug discrimination procedure. Three groups of rats were trained to discriminate ethanol (1.0 or 2.0 g/kg; p.o.) or GHB (300 mg/kg; p.o.) from water. In the 1.0 g/kg ethanol-trained rats, substitution for ethanol was an inverted U-shape function of GHB dose, with only 300 mg/kg GHB resulting in complete substitution for ethanol. No dose of GHB elicited selection of ethanol-appropriate arm higher than 10% in the 2.0 g/kg ethanol-trained group. In the 300 mg/kg GHB-trained rats, complete substitution for GHB occurred only at the dose of 1.0 g/kg ethanol. Doses of ethanol lower or higher than 1.0 g/kg did not substitute for GHB. The results of the present study indicate that symmetrical generalization between ethanol and GHB occurred within narrow dose ranges. They are discussed in terms of common neurotransmitter systems involved in the mediation of GHB and ethanol effects.
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ABSTRACT: Gamma-hydroxybutyric acid has been proposed as a pharmacotherapy for alcoholism in part based on similar discriminative stimulus effects as ethanol. To date, drug discrimination studies with gamma-hydroxybutyric acid and ethanol have exclusively used rodents or pigeons as subjects. To evaluate possible differences between species, sex, and route of administration, this study investigated the substitution of gamma-hydroxybutyric acid (intragastrically or intramuscularly) for ethanol 30 or 60 min after administration in male (n=6) and female (n=7) cynomolgus monkeys trained to discriminate 1.0 and 2.0 g/kg ethanol. At least one dose of gamma-hydroxybutyric acid completely or partially substituted for ethanol in three of the 13 monkeys tested, with each case occurring in female monkeys. Ethanol-appropriate responding did not increase with gamma-hydroxybutyric acid dose. Monkeys were more sensitive to the response rate decreasing effects of gamma-hydroxybutyric acid administered intramuscularly compared with intragastrically. The lack of gamma-hydroxybutyric acid substitution for ethanol suggests that these drugs have different receptor bases for discrimination. Furthermore, the data do not strongly support shared discriminative stimulus effects as the rationale for gamma-hydroxybutyric acid pharmacotherapy for alcoholism.Behavioural Pharmacology 08/2008; 19(4):317-24. DOI:10.1097/FBP.0b013e328308f20d · 2.19 Impact Factor
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ABSTRACT: With the use of [3H]gamma-hydroxybutyric acid, binding experiments allowed the screening of new compounds as ligands of gamma-hydroxybutyric acid receptors. Starting from the acid-alcohol gamma-hydroxybutyric acid structure, structure-activity relation analysis and lead optimization highlighted gamma-hydroxybutyric acid derivatives with significantly increased affinities, when compared with the affinity of gamma-hydroxybutyric acid. Further pharmacological studies with the use of gamma-hydroxybutyric acid derivatives allowed the characterization of the first competitive antagonist acting at gamma-hydroxybutyric acid receptors (NCS 382).Alcohol 05/2000; 20(3):227-36. DOI:10.1016/S0741-8329(99)00086-5 · 2.04 Impact Factor
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ABSTRACT: Accumulating evidence shows the efficacy of the gamma-aminobutyric acid (GABA(B)) receptor agonist baclofen in reducing alcohol intake in rats, but no studies have been performed in alcoholics. In the present preliminary study we investigated the effect of short-term baclofen administration on craving for alcohol, ethanol intake, and abstinence from alcohol in alcoholic individuals. Ten male current alcoholic individuals were admitted to the study. Baclofen was orally administered for 4 weeks, at a dose of 15 mg/day refracted in three times per day for the first 3 days, with the dose increased to 30 mg/day for the remaining 27 days. Each subject was checked as an outpatient every week for the 4 weeks; at each visit (T0-T4) craving level was evaluated by the Alcohol Craving Scale (ACS), and abstinence from alcohol was assessed based on the individual's self-evaluation, family member interview, and the main biological markers of alcohol abuse. A self-reported alcohol intake was recorded as the mean number of standard drinks consumed per day. Nine subjects completed the study; of these, two subjects continued to drink alcohol although they substantially reduced their daily drinks in the first week of treatment, whereas seven maintained abstinence throughout the experimental period. Craving was significantly reduced from the first week of the drug administration (p < 0.01) and remained so throughout the entire treatment period. Participants also reported that obsessional thinking about alcohol disappeared. Values of gamma-glutamyltranspeptidase, alanine aminotransferase, and mean cellular volume significantly decreased by the end of the study. Tolerability was fair in all participants; headache, vertigo, nausea, constipation, diarrhea, abdominal pain, hypotension, increased sleepiness, and tiredness were present as side effects in the first stage of the treatment. No participants showed craving for the drug. With the limitations of the low number of individuals evaluated and the open design, this preliminary clinical study supports the preclinical evidence on the effect of baclofen in reducing alcohol intake. The anticraving properties of the drug suggest a possible role of baclofen in the treatment of individuals with alcohol problems.Alcoholism Clinical and Experimental Research 01/2000; 24(1):67-71. DOI:10.1111/j.1530-0277.2000.tb04555.x · 3.31 Impact Factor