Characterization of wild-type (R100R) and mutated (Q100Q) GABAA alpha 6 subunit in Sardinian alcohol non-preferring rats (sNP)

Sardinian alcohol non-preferring (sNP) rats, selected for their low ethanol preference and consumption, carry a point mutation (R100Q) in the gene coding for GABA(A) receptor alpha(6) subunit, which becomes more sensitive to diazepam-evoked GABA currents. We performed binding studies in the cerebellum of normal (RR) and mutated (QQ) sNP rats using [3H]Ro 15-4513, an inverse agonist for the benzodiazepine site which binds both diazepam insensitive and diazepam sensitive sites. Saturation curves performed on cerebellar membrane from genotyped rats indicated an higher affinity of [3H]Ro 15-4513 for GABA(A) receptors in QQ with respect to RR rats (K(d) values 4.0+/-0.67 and 6.24+/-0.95 nM, respectively), with similar B(max) values (3.5+/-0.25 and 3.9+/-0.39 pmol/mg protein, respectively). Diazepam displacement curves showed a two component model for both genotypes, with similar K(i1) values for QQ and RR (3.6+/-0.62 and 4.9+/-0.33 nM, respectively). In QQ rats diazepam is able to completely displace [3H]Ro 15-4513 (K(i2)=1.48+/-0.27 microM), while in RR rats the diazepam sensitive sites are still present (K(i2)>10 microM). The basal mRNA and protein expression level of the alpha(6) subunit were similar in RR and QQ rats. The electrophysiological profile of oocytes of Xenopus laevis injected with cerebellar synaptosomes showed that ethanol positively modulated GABA-evoked currents significantly more in QQ than in RR rats. These data contribute to the characterization of the function of GABA(A) alpha(6) subunit and its involvement in determining alcohol related behavior.

IDN 5082, a standardized extract of Salvia miltiorrhiza, delays acquisition of alcohol drinking behavior in rats

Recent research demonstrated that extracts from the dried roots of Salvia miltiorrhiza, a valued folk medicine in China, are effective in reducing voluntary alcohol intake in selectively bred Sardinian alcohol-preferring (sP) rats. These studies were conducted in alcohol-experienced sP rats, i.e. rats which had the opportunity to consume alcohol for several weeks before the test with Salvia miltiorrhiza extracts, reproducing the human "active drinking" phase. In contrast, the present study investigated the effect of IDN 5082, a standardized extract of S. miltiorrhiza, on the acquisition of alcohol drinking behavior in sP rats that had never experienced alcohol before the study. Consistently, the first administration of IDN 5082 (0, 25, 50 and 100mg/kg; i.g.) occurred immediately before alcohol presentation. Alcohol was offered under the two-bottle free-choice regimen with unlimited access for 24h per day. Treatment with IDN 5082 was repeated once daily for 10 consecutive days. IDN 5082 dose-dependently delayed acquisition of alcohol drinking behavior; IDN 5082-induced reduction in alcohol intake was compensated by an increase in water intake. These results add further support to the preclinical anti-alcohol profile of S. miltiorrhiza extracts.

Molecular characterization of new polymorphisms at the beta2, alpha1, gamma2 GABA(A) receptor subunit genes associated to a rat nonpreferring ethanol phenotype

Recent preclinical and clinical studies have indicated a possible involvement of the genes encoding for the GABA(A) receptor subunits alpha6, beta2, alpha1 and gamma2 in the genetic susceptibility to alcohol abuse. We have recently found an (R) to (Q) mutation in codon 100 of the alpha6 GABA(A) subunit, that segregated in a rat line selectively bred for its voluntary ethanol aversion, Sardinian alcohol nonpreferring (sNP), but not in their Sardinian alcohol preferring (sP) counterpart, selected for its ethanol preference. In the present study the molecular composition of other GABA(A) subunits (beta2, alpha1 and gamma2) were analyzed in order to further investigate the involvement of the GABA(A) receptors in the genetic predisposition to voluntary alcohol intake. Automated sequencing analysis indicated the presence of six new silent substitutions (289 T-->C in the beta2 gene; 115 G-->A in the alpha1 gene; 157 G-->A, 174 C-->T, 347 A-->G and 385 A-->T in the gamma2 gene), in sNP but not in sP rats. These polymorphisms were linked to the alpha6 R100Q mutation previously described in sNP rats. The strict association between the alpha6 point mutation and the new polymorphisms found in the beta2, alpha1 and gamma2 genes, demonstrate that such genes belong to the same cluster and are inherited together in the rat. These results sustain the synteny for these clusters between the rodent and human genomes, and suggest that mutated GABA(A) beta2, alpha6, alpha1 and gamma2 subunit genes might contribute to the expression of an ethanol nonpreferring phenotype in a rat line that voluntarily avoids alcoholic solutions.

Stable preference for high ethanol concentrations after ethanol deprivation in Sardinian alcohol-preferring (sP) rats

Results of a recent study have demonstrated that exposure to multiple ethanol concentrations and repeated ethanol deprivation periods in Indiana ethanol-preferring (P) rats resulted in the development of an alcohol deprivation effect (ADE; the temporary increase in voluntary ethanol intake after a period of deprivation from ethanol) characterized by consumption of intoxicating amounts of ethanol. The current study was designed to possibly extend these results to Sardinian alcohol-preferring (sP) rats, generated with the same selective program previously used for P rats. To this aim, ethanol-naive sP rats were exposed initially to the home cage four-bottle choice [10%, 20%, and 30% (vol./vol.) ethanol solutions and water] for eight consecutive weeks. Subsequently, rats were divided into two groups: The first group had continuous access to the four-bottle regimen (nondeprived rats), and the second group was exposed to five cycles of 14-day periods of deprivation from ethanol and 14-day periods of reexposure to the four-bottle regimen. An ADE developed after each deprivation period. However, the extra intake of ethanol was limited to the first hour of each reaccess period. Magnitude of ADE did not change with repeated periods of deprivation. However, a shift in preference toward the two highest concentrations of ethanol solutions was evident from the first reexposure to ethanol and was maintained throughout the study. These results provide further evidence on the heterogeneity of ethanol-drinking behavior among rat lines selectively bred for high ethanol preference and consumption.

Proconvulsive effect of the GABA(B) receptor antagonist, SCH 50911, in rats undergoing ethanol withdrawal syndrome

The present study investigated the effect of the GABA(B) receptor antagonist, SCH 50911 [(2S)(+)-5,5-dimethyl-2-morpholineacetic acid], on the occurrence of seizures in ethanol-dependent rats undergoing ethanol withdrawal syndrome. The acute administration of nonconvulsive doses of SCH 50911 (0, 100, 170 and 300 mg/kg, i.p.) resulted in a dramatic facilitation of spontaneous seizure occurrence. This finding, together with the reported ability of the GABA(B) receptor agonist, baclofen, to suppress seizures associated to ethanol withdrawal syndrome, suggests that the GABA(B) receptor may be part of the neural substrate underlying the hyperexcitability of ethanol withdrawal syndrome.

GABA(B)-receptor mediation of the inhibitory effect of gamma-hydroxybutyric acid on intestinal motility in mice

The effect of acutely administered gamma-hydroxybutyric acid (GHB) and GHB receptor antagonist, NCS-382, on the propulsive activity in the mouse small intestine was assessed by measuring the transit of an orally administered, non absorbable marker. Both GHB (0, 25, 50, 100, 200 and 300 mg/kg; i.p.) and NCS-382 (0, 25, 50 and 75 mg/kg; i.p.) induced a dose-dependent inhibition (up to 50-60%) of the marker transit. Pretreatment with the GABA(B) receptor antagonist, SCH 50911 (100 mg/kg; i.p.), resulted in the blockade of the inhibiting effect of both GHB and NCS-382. These results suggest that the constipating effect of GHB and NCS-382 are secondary to stimulation of the GABA(B) receptor.

Differences in ethanol-induced conditioned taste aversion in Sardinian alcohol-preferring and Sardinian alcohol-nonpreferring rats

In the present study, we investigated whether aversion to the pharmacological effects of ethanol developed to a differential extent in selectively bred Sardinian alcohol-preferring (sP) and Sardinian alcohol-nonpreferring (sNP) rats, and whether this different response was consistent with their genetically determined differences in ethanol preference and consumption. To this purpose, a conditioned taste aversion paradigm was used. Male sP and sNP rats were exposed to five sessions in which a 20-min availability of a saccharin solution (1 g/l) was paired to the injection of ethanol (0, 0.5, or 1 g/kg, i.p.), delivered immediately after removal of the saccharin bottle (conditioning phase). Subsequently, the choice between saccharin solution and water was offered for 18 consecutive daily 20-min sessions (postconditioning phase). Ethanol at 1g/kg produced a marked aversion to saccharin in sNP rats: The reduction in saccharin intake was already evident on the second day of the conditioning phase and lasted for 15 days of the postconditioning phase. In contrast, this dose of ethanol elicited a modest, if any, conditioned taste aversion in sP rats, although blood ethanol levels were comparable to those assessed in sNP rats. These results indicate the existence of a differential degree of aversion to the postingestional effects of ethanol between sP and sNP rats, and support the suggestion that it may contribute, at least in part, to the opposite preference for and consumption of ethanol monitored in these rat lines.

Procedure of bidirectional selective outbreeding for production of two rat lines differing in sensitivity to the sedative/hypnotic effect of gamma-hydroxybutyric acid

The exogenous administration of gamma-hydroxybutyric acid (GHB), a constituent of the mammalian brain where it likely functions as a neurotransmitter or a neuromodulator, exerts a number of pharmacological effects, including sedation and hypnosis. The present paper describes a procedure for selective breeding of two rat lines which markedly differ in sensitivity to the sedative/hypnotic effect of GHB. Selective breeding originated from Wistar rats showing opposite sensitivity to the sedative/hypnotic effect of 1 g/kg GHB (i.p.). 'Sensitive' Wistar rats, defined as those individuals displaying values of r = sleep time/onset greater than the upper 15th percentile, were mated to generate the GHB-sensitive (GHB-S) line; conversely, 'resistant' Wistar rats (r-values lower than the lower 15th percentile) were mated to generate the GHB-resistant (GHB-R) line. Upper and lower 15th percentiles were also used to establish the selection cut-offs and criteria for rats of subsequent generations. Specifically, r-values of GHB-S rats were required to be r > or =8 on two separate tests with GHB; r-values of GHB-R rats were required to be r < or =2 on two separate tests with GHB. In each of the three generations produced to date, GHB-S rats showed significantly shorter onset, longer sleep times and greater r-scores than GHB-R rats. The selective breeding of GHB-S and GHB-R rats: (a) suggests that sensitivity to GHB is under genetic control, and (b) may constitute a unique model for investigation of the physiological function of GHB.

Selective breeding of two rat lines differing in sensitivity to GHB and baclofen

Two Wistar-derived rat lines, one sensitive (GHB-S) and the other resistant (GHB-R) to the anesthetic effect of gamma-hydroxybutyric acid (GHB), have been selectively bred. GHB-S and GHB-R rats were also sensitive and resistant, respectively, to the anesthetic effect of baclofen, the prototype GABA(B) receptor agonist, suggesting that they may be useful to elucidate not only the role of endogenous GHB but also that of GABA(B) receptors in sleep and anesthesia.

Alcohol stimulates motor activity in selectively bred Sardinian alcohol-preferring (sP), but not in Sardinian alcohol-nonpreferring (sNP), rats

The present study was conducted to evaluate the effect of low doses of ethanol on motor activity in selectively bred Sardinian alcohol-preferring (sP) and Sardinian alcohol-nonpreferring (sNP) rats. Ethanol was acutely administered at the doses of 0, 0.25, and 0.5 g/kg (i.p.) immediately before rat exposure to an open-field arena for 15 min. The number of square crossings, used as index of motor activity, was significantly lower in saline-treated sP than in saline-treated sNP rats, suggestive of a genetically determined higher emotional state in sP than in sNP rats. Ethanol administration resulted in a dose-dependent, significant increase in the number of square crossings in sP rats, whereas it was completely ineffective in sNP rats. These results suggest to us that a positive relationship exists between ethanol preference and ethanol-induced motor stimulation in sP/sNP rat lines.

Different sensitivity to ethanol in alcohol-preferring sP and -nonpreferring sNP rats

BACKGROUND AND OBJECTIVES

Clinical research has proposed that initial sensitivity to ethanol may be negatively correlated with levels of subsequent ethanol intake; consistently, alcohol-preferring P rats were found to be less sensitive to the ataxic and sedative/hypnotic effects of ethanol than -nonpreferring NP rats. The present study investigated the initial sensitivity to the ataxic and sedative/hypnotic effects of ethanol and to the sedative/hypnotic effects of pentobarbital and diazepam in selectively bred Sardinian alcohol-preferring sP and -nonpreferring sNP rats.

METHODS

In experiment 1, time to lose (onset) and regain (sleep time) the righting reflex after the acute intraperitoneal (ip) administration of 3.0 and 3.5 g/kg ethanol were measured in sP and sNP rats. In experiment 2, sP and sNP rats were required to perform a motor coordination task on a Rota-Rod after the acute intragastric administration of 2.0, 2.5, and 3.0 g/kg ethanol. Experiment 3 assessed onset and sleep time in sP and sNP rats after the acute injection of pentobarbital (40 mg/kg; ip) and diazepam (15 and 20 mg/kg; ip).

RESULTS

In experiment 1, sP rats took shorter times to lose the righting reflex and regained this reflex over longer periods of time and at lower blood ethanol levels than sNP rats. In experiment 2, ethanol affected motor coordination to a greater extent in sP than sNP rats. In contrast, results from experiment 3 showed that sP and sNP rats were not differentially sensitive to the sedative/hypnotic effects of pentobarbital and diazepam.

CONCLUSIONS

The results of experiments 1 and 2 suggest that sP rats possess a genetically determined, greater sensitivity to the motor impairing and sedative/hypnotic effects of ethanol than sNP rats. Although caution should be adopted before hypothesizing any comparison to humans, these results may feature sP rats as an experimental model of those subsets of human alcoholics with initial high sensitivity to ethanol challenges. Finally, the results of experiment 3 suggest a minimal involvement of the benzodiazepine and barbiturate recognition sites in the differential sensitivity to ethanol of sP and sNP rats.

Potential use of medicinal plants in the treatment of alcoholism

The present paper briefly reviews the most relevant experimental data on the reducing effect of some medicinal herbs on voluntary alcohol intake in animal models of alcoholism. Pueraria lobata, Tabernanthe iboga, Panax ginseng, Salvia miltiorrhiza and Hypericum perforatum proved to be effective in decreasing alcohol consumption. Reduction of alcohol absorption from the gastrointestinal system appears to be a common feature among most of the above plants. These data suggest that medicinal plants may constitute novel and effective pharmacotherapies for alcoholism.

Development of short-lasting alcohol deprivation effect in sardinian alcohol-preferring rats

Alcohol deprivation effect (ADE), defined as a temporary increase in voluntary alcohol intake following a period of alcohol abstinence, was evaluated in selectively bred Sardinian alcohol-preferring (sP) rats. Alcohol was initially offered in free choice with water for 35 consecutive days (predeprivation phase). Subsequently, one group of rats was deprived of alcohol for 1, 3, 7, 15, 30, 90 or 180 consecutive days, while the second group had continuous access to alcohol (deprivation phase). Once alcohol was re-presented, alcohol intake in alcohol-deprived rats was recorded 1 and 24 h after alcohol re-presentation and compared to that monitored in alcohol-nondeprived rats over the same time periods (postdeprivation phase). Alcohol deprivation for 3 to 30 days resulted in a significant increase in voluntary alcohol intake only in the first hour of re-access. These results demonstrate the development of ADE in sP rats. However, the rapid return of alcohol intake to control levels is discussed as evidence in favor of a set-point mechanism capable of regulating alcohol-drinking behavior in sP rats.

Mechanism of the antialcohol effect of gamma-hydroxybutyric acid

Treatment with gamma-hydroxybutyric acid has been reported to effectively decrease alcohol craving and consumption as well as alcohol withdrawal symptoms in alcoholics. We describe the results of animal studies demonstrating the ability of gamma-hydroxybutyric acid to reduce (1) the severity of ethanol withdrawal signs in rats rendered physically dependent on ethanol and (2) voluntary ethanol intake in selectively bred Sardinian alcohol-preferring rats. Furthermore, we review experimental data suggesting that gamma-hydroxybutyric acid and ethanol have several pharmacological effects in common. Relevant similarities are: (1) stimulation of firing rate of dopaminergic neurons and dopamine release in specific rat brain areas; (2) development of cross-tolerance to the motor-impairing effects after repeated administration in rats; 3) abuse potential, as indicated by self-administration of pharmacologically relevant doses of gamma-hydroxybutyric acid in rats and mice; (4) induction of anxiolytic effects in rats; and (5) induction of similar discriminative stimulus effects, as evidenced by symmetrical generalization in a drug discrimination study in rats. These lines of evidence are discussed in relation to gamma-hydroxybutyric acid exerting its antialcohol effects by a substitution mechanism.

Characterization of the discriminative stimulus effects of gamma-hydroxybutyric acid as a means for unraveling the neurochemical basis of gamma-hydroxybutyric acid actions and its similarities to those of ethanol

The present paper reviews the drug discrimination studies, both from the literature and from this laboratory, conducted to investigate the pharmacological profile of the discriminative stimulus effects of gamma-hydroxybutyric acid. Collectively, the results of these studies suggest that: (1) the discriminative stimulus effects of gamma-hydroxybutyric acid are composed of different cues, each one being the effect of gamma-hydroxybutyric acid on a specific receptor system; (2) the proportion of each component cue varies as the training dose of gamma-hydroxybutyric acid is increased; (3) the gamma-aminobutyric acid B-mediated cue is a major ingredient of the mixed stimulus of gamma-hydroxybutyric acid, but it is more prominent at high training doses than at low training doses of gamma-hydroxybutyric acid; and (4) positive modulation of the gamma-aminobutyric acid A receptor is a relevant part of the discriminative stimulus effects of low gamma-hydroxybutyric acid doses. Finally, data indicating symmetrical generalization between the discriminative stimulus effects of a specific range of doses of gamma-hydroxybutyric acid and those of ethanol are discussed in regard to their further support of the hypothesis that gamma-hydroxybutyric acid may exert its antialcohol effects through a substitution mechanism.

Ability of baclofen in reducing alcohol intake and withdrawal severity: I--Preclinical evidence

BACKGROUND

The similarities between the pharmacological effects of the gamma-aminobutyric acid receptor agonist, baclofen, and the alcohol-substituting agent, gamma-hydroxybutyric acid, led us to investigate whether baclofen was capable of reducing (a) ethanol withdrawal syndrome in ethanol-dependent rats and (b) voluntary ethanol intake in ethanol-preferring rats.

METHODS

In experiment 1, Wistar rats were rendered physically dependent on ethanol by the repeated administration of intoxicating doses of ethanol for 6 consecutive days. Baclofen was acutely administered intraperitoneally at doses of 10, 20, and 40 mg/kg. In experiment 2, baclofen (0, 2.5, 5, and 10 mg/kg, intraperitoneally) was administered once a day for 14 consecutive days to ethanol-preferring sP rats that had continuous access to ethanol (10%, v/v) and water under the two-bottle free choice regimen.

RESULTS

In experiment 1, baclofen dose-dependently decreased the intensity of ethanol withdrawal signs; furthermore, 20 mg/kg of baclofen protected from audiogenic seizures in ethanol-withdrawn rats. In experiment 2, baclofen selectively and dose-dependently reduced voluntary ethanol intake; a compensatory increase in water intake left total fluid intake virtually unchanged.

CONCLUSIONS

These results are in close agreement with those of a preliminary clinical study and suggest that baclofen may constitute a novel therapeutic agent for alcoholism.

Ability of baclofen in reducing alcohol intake and withdrawal severity: I--Preclinical evidence

BACKGROUND

The similarities between the pharmacological effects of the gamma-aminobutyric acid receptor agonist, baclofen, and the alcohol-substituting agent, gamma-hydroxybutyric acid, led us to investigate whether baclofen was capable of reducing (a) ethanol withdrawal syndrome in ethanol-dependent rats and (b) voluntary ethanol intake in ethanol-preferring rats.

METHODS

In experiment 1, Wistar rats were rendered physically dependent on ethanol by the repeated administration of intoxicating doses of ethanol for 6 consecutive days. Baclofen was acutely administered intraperitoneally at doses of 10, 20, and 40 mg/kg. In experiment 2, baclofen (0, 2.5, 5, and 10 mg/kg, intraperitoneally) was administered once a day for 14 consecutive days to ethanol-preferring sP rats that had continuous access to ethanol (10%, v/v) and water under the two-bottle free choice regimen.

RESULTS

In experiment 1, baclofen dose-dependently decreased the intensity of ethanol withdrawal signs; furthermore, 20 mg/kg of baclofen protected from audiogenic seizures in ethanol-withdrawn rats. In experiment 2, baclofen selectively and dose-dependently reduced voluntary ethanol intake; a compensatory increase in water intake left total fluid intake virtually unchanged.

CONCLUSIONS

These results are in close agreement with those of a preliminary clinical study and suggest that baclofen may constitute a novel therapeutic agent for alcoholism.

Dissociation of ethanol and saccharin preference in sP and sNP rats

BACKGROUND

It has been proposed that ethanol intake and consumption of sweet tasting solutions are positively correlated in rodents. Experiment 1 of the present study investigated whether selectively bred ethanol-preferring (sP) and -nonpreferring (sNP) rats differed, consistently with the above hypothesis, as to saccharin intake and preference. Experiment 2 evaluated whether saccharin addition to the ethanol solution, likely resulting in a highly palatable fluid, would result in an increase in voluntary ethanol intake in sP rats.

METHODS

The saccharin solution was offered, in free choice with water, at a fixed concentration of 1 g/liter for 6 consecutive days in Experiment 1A or at ascending concentrations (0.002 to 16.4 g/liter, doubling the concentration every day) in Experiment 1B. In Experiment 2, 1 g/liter saccharin was added to the standard 10% ethanol solution and offered to sP rats in free choice with water for 7 consecutive days.

RESULTS

In both Experiments 1A and 1B, sP and sNP rats showed avidity for the saccharin solution with marginal line difference in saccharin intake and preference. In Experiment 2, daily ethanol intake remained stable at baseline levels (6-7 g/kg), irrespective of the saccharin addition to the ethanol solution.

CONCLUSIONS

The results of Experiments 1A and 1B suggest that saccharin drinking behavior in sNP rats deviates from the hypothesis that saccharin and ethanol intakes may co-vary; thus, at least in sNP rats, saccharin and ethanol intakes do not appear to be influenced by the same genetic factors. The results of Experiment 2 provide further support to the existence of a central set-point mechanism that regulates daily ethanol intake in sP rats, likely based on the pharmacological effects of ethanol.

Contribution of GABA(A) and GABA(B) receptors to the discriminative stimulus produced by gamma-hydroxybutyric acid

The present study examined the involvement of GABA(A) and GABA(B) receptors in the discriminative stimulus effects of gamma-hydroxybutyric acid (GHB). Rats were trained to discriminate either 300 or 700 mg/kg GHB IG from water using a T-maze, food-reinforced drug-discrimination procedure. The direct GABA(B) agonist, baclofen, substituted completely for both training doses of GHB; its potency to substitute for GHB increased moderately as the training dose of GHB was increased. The positive GABA(A) modulator, diazepam, substituted partially for 300 mg/kg GHB, but failed to elicit GHB-appropriate responding in rats trained with the higher GHB dose. Finally, the GABA(B) antagonist, CGP 35348, completely blocked the discriminative stimulus effects of the high training dose of GHB, but only partially antagonized the effects of the low training dose. These results suggest that (a) GHB produces a compound stimulus, and (b) both GABA(B)- and GABA(A)-mediated cues are prominent components of this compound stimulus; the contribution of each component, however, appears to vary as the training dose of GHB is increased.

Salvia miltiorrhiza extract inhibits alcohol absorption, preference, and discrimination in sP rats

Experiment 1 of the present study investigated the ability of a standardized extract of Salvia miltiorrhiza in reducing voluntary ethanol intake in ethanol-preferring rats of the sP line. Ethanol intake occurred under the two-bottle free-choice regimen between 10% (v/v) ethanol and water in daily 4-h scheduled access periods; water was present 24 h/day. Intragastric administration of 200 mg/kg Salvia miltiorrhiza extract resulted in approximately 40% reduction in ethanol intake and preference throughout the 4-day treatment. This effect of Salvia miltiorrhiza extract was likely due to its ability of altering ethanol absorption from the gastrointestinal tract. Indeed, Experiments 2 and 3 of this study demonstrated that 200 mg/kg Salvia miltiorrhiza extract reduced blood ethanol levels (BELs) up to 60% in comparison to control rats, when ethanol was given IG, whereas it failed to modify BELs when ethanol was injected IP. The reducing effect of Salvia miltiorrhiza extract on ethanol absorption may have therefore resulted in an attenuated perception of the psychoactive effects of ethanol sought by ethanol-drinking rats. Consistently, the results of Experiment 4 of the present study demonstrated that a combination of 200 mg/kg Salvia miltiorrhiza extract IG and 1 or 2 g/kg ethanol IG resulted in a partial blockade of the discriminative stimulus effects of ethanol in sP rats trained to discriminate these doses of ethanol from water in a drug discrimination procedure. Collectively, the results are discussed as being suggestive that drugs curbing ethanol absorption from the gastrointestinal tract may constitute a novel strategy for controlling excessive alcohol consumption in human alcoholics.

Reduction of blood ethanol levels by the gamma-hydroxybutyric acid receptor antagonist, NCS-382

The present study demonstrates that the gamma-hydroxybutyric acid receptor antagonist, NCS-382, markedly reduces blood ethanol levels (BELs) in rats when ethanol is administered via the intragastric route, whereas it is completely ineffective when ethanol is injected IP. The reducing effect of NCS-382 on BELs is likely due to a lessened absorption of ethanol from the gastrointestinal tract.