Activating effects of ethanol during the course of early ontogeny in the rat.

ARIAS, C.; MLEWSKI, E. C.; MOLINA, J.C.; SPEAR, N.E.

Congreso; International Society for Developmental Psychobiology; 2007

Sveral drugs of abuse exert biphasic (activating vs sedative) motor activity effects that may be associated with different motivational effects (positive vs aversive reinforcement). In the case of ethanol, heterogenous rat strains appear to be particularly sensitive to its sedative effects. Activating effects have been reported particularly in rat strains genetically selected for their ethanol affinity (P rats: Rodd et al. 2004; Waller et al., 1986; HAD strain: Krimmer et al., 1991; Rodd et al., 2004; sP strain: Agabio et al., 2001; UChA strain: Quintanilla et al., 1999; AA strain: Paivarinta et al., 1993). Recently, we have reported that infant rats are sensitive to the appetitive effects of a low (0.5 g/kg) or a relatively high ethanol dose (2.0 g/kg) during the initial state of intoxication (Molina et al., 2007). The goal of the present study was to examine psychomotor effects of moderate-to-high ethanol doses (1.25 and 2.5 g/kg; respectively) in 8, 12 and 15-day-old pups during the rising phase of the blood ethanol concentration curve. Infants from a heterogeneous rat strain (Sprague-Dawley) were sensitive to ethanol?s stimulating effect early in ontogeny. This effect was clearly observed during the rising phase of the blood ethanol curve, in which ethanol has been reported to induce appetitive effects (Molina et al., 2007). This effect was more evident in younger pups (PD 8 and PD 12) than in those at the older age (PD 15). These age differences can not be explained by variation in blood ethanol concentration across age. The ontogenetic profile of ethanol?s activating effects is similar to that for affinity for ethanol ingestion and sensitivity to appetitive effects of the drug (Arias and Chotro, 2006; Hunt et al., 1991; Truxell and Spear, 2004; Sanders and Spear, 2007). Ethanol-induced motor impairment and decreased body temperature coexist with the stimulating effect of the drug in all ages. Specific stages in ontogeny may represent an appropriate experimental niche, alternative to genetic and phylogenetic approaches, for the analysis of mechanisms regulating drug-related motor and motivational effects, and possible associations between these processes.