Adolescent male rats display attenuated taste avoidance learning relative to adults and fail to demonstrate a US pre-exposure effect

Current research suggests that adolescence is a period of increased risk for drug use. One such line of work which substantiates this claim is that of conditioned taste avoidance (CTA) learning where adolescents consistently display weaker avoidance with both abused and non-abused drugs than their adult counterparts, an effect generally thought to underlie weaker aversive effects in adolescents. There is no existing research investigating whether these weakened aversive effects influence the ability of adolescents to demonstrate a US pre-exposure effect, a phenomenon predicated on reaction to the aversive properties of drugs during pre-exposure. In the present experiment, male adolescent rats were given five spaced pre-exposure injections of lithium chloride and subsequently given repeated pairings of saccharin with LiCl to induce avoidance. Consistent with past reports, adolescents displayed weaker taste avoidance compared to adults and did not display an effect of US pre-exposure while adults did. The present work is consistent with past research which reports that adolescents display weaker avoidance than adults. Further, the reported age differences in avoidance learning could potentially mediate the adolescent failure to demonstrate a US pre-exposure effect. We argue that the aversive properties of drugs, indexed by CTA, limit drug use and abuse. These weekend avoidances are consistent with past research and substantiate further research that posits adolescence as a risk period for drug use.