The role of the medial-external subnucleus of the medial parabrachial nucleus in hypertonic NaCl-induced concurrent and delayed-sequential flavor avoidance learning

Sex differences in adult Wistar rats in the voluntary consumption of ethanol after pre-exposure to ethanol-induced flavor avoidance learning

Vulnerability to ethanol abuse may be a function of the balance between the opposing (aversive and rewarding) motivational effects of the drug. The study of these effects is particularly important for understanding alcohol addiction. Research in this field seems to point out that ethanol effects are determined by a set of internal factors (sex, ethanol intake history, etc.), as well as by environmental conditions surrounding the individual (i.e., stress) and, of course, the interactions between all these factors. This work explores sex differences in sensitivity to aversive effects of ethanol using the procedure of flavor avoidance learning (FAL), as well as the effect of this learning experience on subsequent voluntary ethanol consumption, in adult rats. The results obtained indicated a slight sex based difference in the amount of FAL acquired in that females acquisition was weaker (experiment 1), and a differing influence of previous experience with the aversive effects of ethanol on the voluntary consumption of the drug for each sex (experiment 2). In particular, it was observed that female ethanol-naive rats showed a higher intake level and preference for ethanol than both ethanol-experienced female rats and ethanol-naive male rats. In contrast, the ethanol-experienced male rats showed a greater consumption of and preference for ethanol than ethanol-naive male rats and ethanol-experienced female rats. These data are discussed noting a range of possible explicative factors (sex hormones, hedonic processing, etc.), but further studies are warranted to elucidate the mechanisms by which ethanol pre-exposure influences the subsequent intake of ethanol differently by sex.