Behavioral effects of intraventricular injections of low doses of ethanol, acetaldehyde, and acetate in rats: studies with low and high rate operant schedules

Motor Stimulant Effects of Ethanol Injected into the Substantia Nigra Pars Reticulata: Importance of Catalase-Mediated Metabolism and the Role of Acetaldehyde

“…Thus, compared to other drugs that have been used both systemically and intracranially, the present doses of ethanol injected into the brain were generally lower when expressed as a fraction of the systemic dose range. Finally, it should be emphasized that in the present studies, as well as the previous papers involving intraventricular infusions (Arizzi et al, 2003;Correa et al, 2003a, b), none of the behavioral signs of administration of a high dose of ethanol (ie, ataxia, suppressed locomotion, suppressed lever pressing) were observed at any of the doses tested. Taken together, this evidence indicates that the doses of ethanol used in the present studies (0.175-2.8 mmol) were not excessively high.…”

“…A previous paper from our laboratory reported that brain extract levels of ethanol following intraventricular infusion of 2.8 mmol were 9.6-23.7 mg/100 ml (Correa et al, 2003a, p 370), which were lower than reported values of peak brain ethanol concentrations obtained from AA and Wistar rats that selfadministered ethanol (means approximately 65-71 mg/ 100 ml; Nurmi et al, 1999). Based upon the results of the experiment involving ethanol injected into SNr, and previous studies showing that acetaldehyde and ethanol acted on locomotion and operant responding over a similar dose range following intraventricular injections (Correa et al, 2003a, b;Arizzi et al, 2003), acetaldehyde was injected in a dose range of 0. 35, 0.7, 1.4, or 2.8 mmol (acetaldehyde: 15.41, 30.83, 61.67, or 123.34 mg).…”

“…Previous studies from our laboratory have demonstrated that central (ie, intraventricular) administration of low doses of ethanol in rats produce behavioral stimulant effects (Arizzi et al, 2003;Correa et al, 2003a, b). The neurochemistry and neuroanatomy of this effect are still unknown, but in view of research demonstrating that GABA is involved in some of the neurochemical and physiological effects of ethanol (Mereu and Gessa, 1985;Marrosu et al, 1989;Grobin et al, 1998;Criswell et al, 1993;Grant and Lovinger, 1995), brain areas at which GABA mechanisms modulate motor activity offer potential substrates for the motor actions of ethanol.…”

“…The doses employed in the present study were at or below the doses that were used in recently published articles involving intraventricular administration (Arizzi et al, 2003;Correa et al, 2003a, b;Crankshaw et al, 2003), and were lower than those used in several earlier papers (Brown et al, 1978;Smith et al, 1984). Also, as described in detail by Correa et al (2003a, Selection of Intraventricular Doses, pp 369-370), the highest dose of intraventricular ethanol that was used in that study was 650-5200 times lower than a typical systemic dose in rats such as 1.0 g/kg (eg, Quertemont et al, 2003).…”

“…Peripherally administered acetaldehyde has been shown to decrease motor activity under several conditions . In contrast, acetaldehyde administered into the lateral ventricles was shown to increase locomotor activity (Correa et al, 2003b), and to increase lever pressing rate on a differential reinforcement of low rates 30 s schedule (DRL30), which is an operant paradigm that generates low rates of responding and therefore is sensitive to the stimulant or disinhibiting effects of drugs (Arizzi et al, 2003). Thus, it has been hypothesized that central acetaldehyde can be partially responsible for the motoractivating effects of ethanol.…”