The new compound GET73, N-[(4-trifluoromethyl)benzyl]4-methoxybutyramide, Regulates hippocampal Aminoacidergic transmission possibly via an allosteric modulation of mGlu5 receptor. Behavioural evidence of its "anti-alcohol" and anxiolytic properties.

The present article attempts to provide, on the basis of data emerging from studies carried out in our laboratories, a summary of the chemical and pharmacological properties of the new compound N-[(4-trifluoromethyl)benzyl]4- methoxybutyramide (GET73). Particular emphasis is given to findings obtained in vivo and in vitro suggesting that an allosteric modulation of metabotropic glutamate receptor 5 (mGlu5 receptor) by GET73 may represent the mechanism underlying the effects of the compound produced on rat hippocampal glutamate and GABA transmission. Furthermore, behavioural findings demonstrating how this new compound reduces alcohol intake, displays anxiolytic properties, and influences spatial memory in rats are also summarized. Since mGlu5 receptors play an important role in regulating several central actions of drugs of abuse, and the hippocampus is a crucial brain area involved in addiction, anxiety, and spatial memory, a possible link between mGlu5 receptor allosteric modulation and the profiles of action of GET73 is proposed, although to date no studies have yet explored GET73 binding at the mGlu5 receptor orthosteric and/or allosteric sites. Following a brief overview of glutamatergic neurotransmission, mGlu receptor structures and activation mechanisms, the general properties of mGlu5 receptor and its allosteric modulators are described in the first part of the review.

gamma-Hydroxybutyrate modulation of glutamate levels in the hippocampus: an in vivo and in vitro study.

The effect of gamma-hydroxybutyric acid on extracellular glutamate levels in the hippocampus was studied by microdialysis in freely moving rats and in isolated hippocampal synaptosomes. Intra-hippocampal (CA1) perfusion with gamma-hydroxybutyric acid (10 nM-1 mM) concentration-dependently influenced glutamate levels: gamma-hydroxybutyric acid (100 and 500 nM) increased glutamate levels; 100 and 300 microM concentrations were ineffective; whereas the highest 1 mM concentration reduced local glutamate levels. The stimulant effect of gamma-hydroxybutyric acid (100 nM) was suppressed by the locally co-perfused gamma-hydroxybutyric acid receptor antagonist NCS-382 (10 microM) but not by the GABA(B) receptor antagonist CGP-35348 (500 microM). Furthermore, the gamma-hydroxybutyric acid (1 mM)-induced reduction in CA1 glutamate levels was counteracted by NCS-382 (10 microM), and it was also reversed into an increase by CGP-35348. Given alone, neither NCS-382 nor CGP-35348 modified glutamate levels. In hippocampal synaptosomes, gamma-hydroxybutyric acid (50 and 100 nM) enhanced both the spontaneous and K(+)-evoked glutamate efflux, respectively, both effects being counteracted by NCS-382 (100 nM), but not by CGP-35348 (100 microM). These findings indicate that gamma-hydroxybutyric acid exerts a concentration-dependent regulation of hippocampal glutamate transmission via two opposing mechanisms, whereby a direct gamma-hydroxybutyric acid receptor mediated facilitation is observed at nanomolar gamma-hydroxybutyric acid concentrations, and an indirect GABA(B) receptor mediated inhibition predominates at millimolar concentrations.

Synthesis of 2-amino-5-sulfanyl-1,3,4-thiadiazole derivatives and evaluation of their antidepressant and anxiolytic activity.

Recently a series of 2-amino-5-sulfanyl-1,3,4-thiadiazole derivatives bearing different substituents were synthesized and screened pharmacologically in order to evaluate their central nervous system activity. The purpose of this study was to evaluate the effects of the title compounds on CNS activity by varying the substituents in the thiadiazole moiety. It was found that some of these compounds possess marked antidepressant and anxiolytic properties comparable in efficiency to the reference drugs Imipramine and Diazepam. The most potent compound 3k was further investigated to complete its pharmacological profile with respect to undesired side effects. Behavioral results showed that 3k is a very promising compound, characterized by a mixed antidepressant-anxiolytic activity accompanied by a therapeutic dose range that is essentially 2 orders of magnitude less than that at which side effects such as sedation and amnesia are evident.

Neuroprotective effect of gamma-hydroxybutyrate in transient global cerebral ischemia in the rat.

The effect of gamma-hydroxybutyrate on the histological and behavioral consequences of transient brain ischemia was studied in the four vessel occlusion rat model. In saline-treated animals, 30 min ischemia caused a massive loss of neurons in the hippocampal CA1 subfield (normal neurons: 14%, 5%, 23% and 30% on the 3rd, 10th, 15th and 65th day after ischemia, respectively). gamma-Hydroxybutyrate - 300 mg/kg intraperitoneally (i.p.) 30 min before or 10 min after arteries occlusion, followed by 100 mg/kg i.p. twice daily for the following 10 days - afforded a highly significant protection (normal neurons on the 3rd, 10th, 15th and 65th day after ischemia: 88% and 91%, 80% and 80%, 91% and 90%, 72% and 71% in rats receiving the first dose before or after arteries occlusion, respectively). The ischemia-induced sensory-motor impairment was significantly attenuated in rats receiving the first dose of gamma-hydroxybutyrate before arteries occlusion. Finally, the ischemia-induced impairment in spatial learning and memory, evaluated starting 27 days after the ischemic episode, was significantly attenuated by gamma-hydroxybutyrate, either injected first at 30 min before or 10 min after arteries occlusion. Lower doses of gamma-hydroxybutyrate had no significant effect. In conclusion, these results indicate that gamma-hydroxybutyrate provides significant protection against both histological and behavioral consequences of transient global cerebral ischemia in rats.

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.

Gamma-hydroxybutyric acid reducing effect on ethanol intake: evidence in favour of a substitution mechanism.

Experiment 1 in the present study investigated the time course and dose range of gamma-hydroxybutyric acid (GHB) to reduce voluntary ethanol intake in selectively bred Sardinian ethanol-preferring (sP) rats. Ethanol (10%, v/v) and tap water were offered under the two-bottle free choice regimen with unlimited access. GHB (200, 300, and 400 mg/kg, i.p.) was administered 15 20 min prior to the start of the dark phase of the light-dark cycle. Ethanol and water intakes were recorded at different time intervals during the dark phase. GHB significantly reduced ethanol intake at doses of 300 and 400 mg/kg; statistical significance occurred only at the 15-min and 30-min observation times. The GHB dose of 300 mg/kg was devoid of any sedative effect, as demonstrated in Experiment 2 by the lack of any impairment of spontaneous locomotor activity. Finally, this dose of GHB was also found to exert a robust anxiolytic effect in sP rats tested on the elevated plus maze (Experiment 3). Collectively, the results of the present study demonstrate that a non-sedative and anxiolytic dose of GHB effectively reduced voluntary ethanol intake in sP rats. The rapid onset of the reducing effect of GHB on ethanol intake, as well as its anxiolytic effect, are discussed in terms of adding further support to the hypothesis that GHB may control alcohol craving and consumption in humans by substituting for ethanol's reinforcing effects.

Reduction of voluntary ethanol intake in ethanol-preferring sP rats by the cannabinoid antagonist SR-141716.

The present study assessed the efficacy of the cannabinoid CB1 receptor antagonist, SR-141716, in reducing voluntary ethanol intake in selectively bred Sardinian alcohol-preferring (sP) rats. Ethanol (10%, v/v) and food were available in daily 4 h scheduled access periods; water was present 24 h/day. The acute administration of a 2.5 and a 5 mg/kg dose of SR-141716 selectively reduced ethanol intake, whereas a 10 mg/kg dose of SR-141716 reduced to a similar extent both ethanol and food intake. These results suggest that the cannabinoid CB1 receptor is involved in the mediation of the ethanol-reinforcing effects in sP rats.

High sensitivity to gamma-hydroxybutyric acid in ethanol-preferring sP rats.

Sensitivity to the sedative effect of gamma-hydroxybutyric acid (GHB), an endogenous constituent of mammalian brain as well as an effective drug in the pharmacotherapy of alcoholism, was evaluated in rats of the selectively bred, ethanol-preferring sP and non-preferring sNP lines. GHB (0.75 and 1.0 g/kg) was administered i.p. to ethanol-naive sP and sNP rats. Times to lose (onset) and recover (sleep time) the righting reflex following GHB injection were measured. At both doses, sP rats showed a greater sensitivity to the effects of GHB than did sNP rats, as evidenced by significantly shorter onset and longer sleep time. The results of the present study indicate that genetically controlled sensitivity to the sedative effect of GHB is positively correlated to ethanol preference in sP and sNP rats and suggest a possible involvement of the brain GHB system in predisposition to ethanol preference.

Induction of DNA fragmentation and DNA repair synthesis in human and rat hepatocytes by diethylstilbestrol.

The synthetic estrogen diethylstilbestrol (DES), a known human carcinogen, was examined for cytotoxicity, and the induction of DNA damage and repair in primary cultures of human and rat hepatocytes. In both species concentrations of DES ranging from 5.6 to 18 micrograms/ml constantly produced reduction of cell viability and DNA fragmentation in dose-related amounts. However, large individual quantitative differences in the sensitivity to the cytotoxic and DNA-damaging activities of DES were observed among cultures derived from the 5 human donors. DES capability of eliciting DNA-excision repair was weak but statistically significant in both human and rat hepatocytes. Taken as a whole these results contribute to support the hypothesis of a genotoxic mechanism in DES-induced carcinogenesis.

Hormones and handedness: left-hand bias in female congenital adrenal hyperplasia patients.

An excess of left-handers among males has been attributed to early androgen exposure. This theory was supported by our observation that girls with congenital adrenal hyperplasia (CAH) are more left-biased than their normal sisters. Male CAH patients, with prenatal androgen exposure similar to that of unaffected brothers, had typical male-handedness patterns.