Ethanol induces locomotor activating effects in preweanling Sprague-Dawley rats.

ARIAS, C.; MLEWSKI E.C.; MOLINA, JC; SPEAR, NE

ALCOHOL

ELSEVIER SCIENCE INC

Año: 2009 vol. 43 p. 13 - 23

0741-8329

Abuse of drugs exerts biphasic motor activity effects, which seem to be associated with their motivational effects. In the case of ethanol,heterogenous rat strains appear to be particularly sensitive to the sedative effects of the drug. In contrast, ethanol’s activating effects havebeen consistently reported in rats genetically selected for ethanol affinity. Heightened ethanol affinity and sensitivity to ethanol’s reinforcementare also observed in nonselected rats during early ontogeny. In the present study, we examined psychomotor effects of ethanol (1.25and 2.5 g/kg) in 8-, 12-, and 15-day-old pups. Motor activity in a novel environment was assessed 5e10 or 15e20 min following drugtreatment. Rectal temperatures and latency to exhibit the righting reflex were recorded immediately after locomotor activity assessment.Ethanol exerted clear activating effects at 8 and 12 days of age (Experiments 1a and 1b) and to a lesser extent at 15 days. At this age, ethanolenhanced locomotor activity in the first testing interval (Experiment 1b) and suppressed locomotion at 15e20 min (Experiment 1a). Ethanol-mediated motor impairment was more pronounced in the youngest group (postnatal day 8) than in the older ones. Blood ethanol concentrationswere equivalent in all age groups. The present study indicates that preweanling rats are sensitive to ethanol’s stimulating effectsduring the second postnatal week, and suggest that specific periods during early ontogeny of the rat can provide a valuable framework forthe study of mechanisms underlying ethanol’s stimulation and reinforcement effects.