the unconditioned stimulus pre-exposure effect induced by ethanol, and cross-familiarization between licl and ethanol in preweanling rats.

ARIAS, C.; REVILLO, D.A.; SPAER, N.E.

Congreso; International Society for Developmental Psychobiology; 2011

Preexposure to LiCl delays acquisition of taste aversion learning induced by the same (the unconditioned stimulus preexposure effect, US-PE) or by an alternative drug (cross-familiarization). These effects have been studied almost exclusively in adult rats, a developmental stage in which the US-PE is strongly modulated by the context, while in the infant rat such effect seems to be context-independent. Taste aversion induced by ethanol is mediated by hypothermia, and this ethanol effect can be modulated by means of opioid antagonists. Blocking this neurochemical system attenuates the US-PE induced by morphine. The present study examined the US-PE induced by ethanol, and cross-familiarization between LiCl and ethanol in preweanling rats, and the role of the context and the opioid system in such effects. Preexposure to ethanol delayed acquisition of ethanol or LiCl-induced conditioned taste aversion. Cross-familiarization between ethanol and LiCl was unaffected by a shift in the context between preexposure and conditioning, or by blocking the opioid system at preexposure. However the US-PE induced by ethanol was attenuated by means of context manipulations or by the administration of an opioid antagonist at preexposure. These results suggest that US-PE induced by ethanol may be related to conditioned-tolerance to the hypothermic effect of ethanol, while alternative mechanisms seem to underlie cross-familiarization between ethanol and LiCl. Additionally, the present study shows evidence of context modulation of an interference paradigm in preweanling rats.