title: Levorphanol-sensitive [3H]naloxone binding in developing brainstem following prenatal morphine exposure.
abstract: Levorphanol-sensitive [3H]naloxone binding was measured in brainstems of fetuses and postnatal offspring of rats injected with morphine or saline or pairfed with morphine-injected animals during the last half of gestation. Brainstem receptor concentrations in saline-injected animals decreased by 25% from gestation day 21 to postnatal day 60, while [3H]naloxone binding affinity doubled during the same interval. Chronic morphine exposure decreased receptor concentration at the 21st day of gestation by 28-48%, without changing binding affinity. However, the number and affinity of [3H]naloxone binding sites in morphine-injected animals were not different from controls at 60 days postnatally.
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D007981:Levorphanol / Q000494:pharmacology*; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000378:metabolism*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D011957:Receptors, Opioid; D007981:Levorphanol; D009270:Naloxone; D009020:Morphine