Baseline locomotor activity significantly predicts the stimulating effects of ethanol in preweanling Sprague-Dawley rats.

ARIAS, C.; MILLER, S.; MOLINA, J.C.; SPEAR, N.E.

Buenos Aires

Congreso; International society for Comparative Psychology; 2008

Heterogeneous adult rats with higher baseline activity (?high responders?; HR) respond differentially to drugs of abuse when compared to ?low responders? (LR). For example, HR, but not LR, are sensitive to stimulating effects of ethanol and other drugs of abuse. HR tend to ingest more ethanol. Again, these studies used adult rats; but there is not much information about these phenotypes during early ontogeny. The present study examined responsiveness to ethanol in infants with high or low baseline activity. On postnatal day (PD) 11, baseline activity was measured. On PD12, locomotor effects of intragastric ethanol (0.0, 1.25 or 2.5 g/kg) were tested at 5-10 or 25-30 minutes post-administration. Ethanol (2.5 g/kg) exerted marked stimulatory effects at 5 minutes, and suppressed locomotion 25 minutes post-administration. Baseline activity significantly predicted the stimulating effects of ethanol, but not the motor suppressive effects. Baseline activity was not associated with other effects of ethanol, such as hypothermia or loss of righting reflex. As was the case with adult rats, baseline activity in infant rats seems to be a good predictor of the stimulating effects of ethanol. Future research on behavioral phenotypes during early ontogeny may also predict increased response to drugs of abuse.