PRENATAL EXPOSURE TO MORPHINE ALTERS BRAIN MU-OPIOID RECEPTOR CHARACTERISTICS IN RATS

Prenatal morphine exposure alters neither the binding capacity nor the affinity of ligand binding to mu opioid receptors of adult male brain s. However, males have significantly higher B-max in the hypothalamus than ovariectomized females. In females, prenatal exposure to morphine reduces the B-max of CL opioid receptors 25% in the hypothalamus and preoptic area. Estrogen treatment increases the B-max of mu opioid rec eptors in the striatum of all ovariectomized females but in the hypoth alamus only of morphine-exposed females, thereby eliminating the sex d ifference observed in control animals.