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Background The main system of central ethanol (EtOH) oxidation is mediated by the enzyme catalase. By reacting with H2 O2, brain catalase forms compound I (the catalase- H2 O2 system), which is able to oxidize EtOH to acetaldehyde ( ACD) in the brain. We have previously shown that ACD regulates EtOH motivational properties and possesses reinforcing effects by itself. In this study, we investigate the effects of alpha-lipoic acid ( ALA), a scavenging agent for H2 O2, on oral EtOH self-administration. Methods To this end, we trained Wistar rats to orally self-administer EtOH (10%) by nose poking. The effect of intraperitoneal pretreatment with ALA was evaluated during (i) maintenance of EtOH self-administration, (ii) EtOH self-administration under a progressive ratio ( PR) schedule of reinforcement, and (iii) oral EtOH priming to induce reinstatement of EtOH seeking behavior. Moreover, we tested the effect of ALA on saccharin (0.05%) reinforcement, as assessed by oral self-administration. Results The results indicate that ALA dose-dependently reduced the maintenance, the break point of EtOH self-administration under a PR and the reinstatement of EtOH seeking behavior without suppressing saccharin self-administration. Conclusions These results support that ALA may have a potential use in alcoholism treatment. [ABSTRACT FROM AUTHOR]

Acetaldehyde (ACD), the first metabolite of ethanol (EtOH) appears to be involved in many of the psychoactive effects of its parent compound, including EtOH-induced activation of the mesolimbic dopamine (DA) system, thereby suggesting that ACD may participate in EtOH motivational properties. -cysteine (Lcys), a thiol compound sequestering ACD, is able to prevent the behavioral effect of EtOH and ACD. Here we show that the stimulatory effect of both EtOH and ACD on the mesolimbic DA system is prevented by Lcys pretreatment. Male Wistar rats were implanted with a microdialysis probe in the nucleus accumbens shell (NAccs), and pretreated intraperitoneally with Lcys (30 mg/kg) before intragastric administration of EtOH (1 g/kg) or ACD (20 mg/kg) or before intraperitoneal administration of morphine (2.5 mg/kg). Pretreatment with Lcys prevented both EtOH and ACD-induced DA release in the NAccs without influencing morphine-induced DA release, suggesting that Lcys specifically affects EtOH-induced DA release possibly through ACD sequestering. Our results underscore the role of ACD on EtOH-induced stimulation of DA mesoaccumbens system and support the notion that thiol compounds such as Lcys, by modulating EtOH-derived ACD bioavailability, would blunt EtOH rewarding properties. [ABSTRACT FROM AUTHOR]