Up-regulation of dopamine D1-receptors in the brain of 28-day-old rats exposed to the delta (delta) opioid agonist SNC80 during the preweaning period

Twenty-eight-day-old rats exposed to the delta (delta) opioid receptor agonist SNC80 during the preweaning period exhibited a significant increase in the density and apparent dissociation constant of striatal dopamine D1-receptors. There were no significant effects on the binding characteristics of striatal D2-receptors or on D1- or D2-receptors in the nucleus accumbens. The results suggest that delta-opioid receptor mechanisms might be involved in certain neurological changes observed in offspring of mother addicted to opioids during nursing.