Opioid control of prolactin secretion in late pregnant rats is mediated by tuberoinfundibular dopamine neurons.
Prolactin (PRL) secretion from the anterior pituitary is tonically inhibited by tuberoinfundibular dopamine (TIDA) neurons in the arcuate nucleus of the hypothalamus. During late pregnancy, TIDA neuronal activity is reduced allowing the expression of an antepartum PRL surge. We show here that continuous infusion of the opioid receptor antagonist naloxone (10 mg/h) during the night preceding parturition completely abolished the antepartum PRL surge and significantly increased TIDA neuronal activity. These data indicate that endogenous opioid neurons facilitate PRL secretion at the end of pregnancy by suppressing TIDA neuronal activity.
Department of Anatomy and Structural Biology and Neuroscience Research Centre, School of Medical Sciences, University of Otago, P.O. Box 913, Dunedin, New Zealand.
Zane B
ZB
Andrews
David R
DR
Grattan
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism*; D007743:Labor, Obstetric / Q000378:metabolism*; D008473:Median Eminence / Q000187:drug effects / Q000378:metabolism; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018847:Opioid Peptides / Q000378:metabolism*; D011247:Pregnancy / Q000378:metabolism*; D011388:Prolactin / Q000097:blood / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D009292:Narcotic Antagonists; D018847:Opioid Peptides; D015102:3,4-Dihydroxyphenylacetic Acid; D009270:Naloxone; D011388:Prolactin; D004298:Dopamine