Self administration of oxycodone by adolescent and adult mice affects striatal neurotransmitter receptor gene expression.

•Adolescent mice self administrated less oxycodone than adult mice did.•Maoa and Npy5r mRNA levels differ significantly between two age groups.•Maoa mRNA levels were higher in mice that had self administered oxycodone.•More gene expressions altered after oxycodone self administration in adolescents.