Figure 1. Experimental Design, Sire Self-Admin.

A. Experimental Design. Sires self-administered saline or morphine for 60 continuous days before being paired with drug-naïve females for breeding. Dams were separated from sires and raised pups independently. F1 progeny were pair-housed with littermates throughout adolescence and behavioral testing. All F1 behavioral testing occurred in adulthood. B. Total infusions of either morphine or saline earned by sires prior to mating. Animals that had access to morphine earned more infusions than animals receiving saline. C. Male and female progeny were weighed weekly after weaning. Paternal morphine exposure resulted in a slight increase in body weight in both male (saline, n=11; morphine, n=14) and female (saline, n=11; morphine, n=14) litters. Overall male progeny gained more weight than female offspring.). Data shown mean ± SEM; * p<0.05