Periadolescent nicotine exposure reduces cocaine reward in adult mice

Fully mature mice exposed to low levels of nicotine during periadolescence exhibited reductions in the rewarding and subjective effects of cocaine. Th ese results provide converging validity that periadolescent nicotine exposu re can permanently decrease a subject's sensitivity to the reinforcing effe cts of cocaine. These changes were noted long after exposure, suggesting th at nicotine may have altered neural systems mediating drug reward. Since re ductions in the rewarding value of abused drugs are associated with increas ed self-administration, periadolescent nicotine exposure might increase the risk for substance abuse problems. The study thus provides biological supp ort that nicotine might serve a "gateway" function for substance abuse.