Immunoneutralization of beta-endorphin blocks prolactin release during suckling without affecting tuberoinfundibular dopaminergic neural activity.
The effect of immunoneutralization of beta-endorphin on the suckling-induced prolactin increase and on the activity of the tuberoinfundibular dopaminergic (TIDA) neurons was determined in lactating female rats between days 8 - 12 post-partum. Two antisera were used in the immunoneutralization studies. Both were specific for beta-endorphin, exhibiting little cross reactivity with met- or leu-enkephalin or dynorphin. Antisera to beta-endorphin completely abolished the suckling-induced prolactin increase indicating that this endogenous opioid peptide is involved in this response. Suckling significantly inhibited DOPA accumulation in the median eminence and antiserum to beta-endorphin did not prevent this inhibition. Additionally, 5-endorphin antiserum significantly reduced TIDA neural activity even in pup-deprived dams. These results indicate that beta-endorphin is involved in the prolactin secretory response to suckling but that inhibition of TIDA neuronal activity is not its mechanism of action. Other possible mechanisms are discussed.
Jaworski
R P
RP
Department of Zoology, Center for Neuroscience, Miami University, Oxford, OH 45056, USA.
Callahan
P
P
Janik
J
J
D000818:Animals; D000918:Antibody Specificity; D001111:Arcuate Nucleus of Hypothalamus / Q000502:physiology*; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004298:Dopamine / Q000502:physiology*; D005260:Female; D007106:Immune Sera / Q000494:pharmacology*; D007774:Lactation; D008297:Male; D008473:Median Eminence / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014371:Tuber Cinereum / Q000502:physiology*; D001615:beta-Endorphin / Q000037:antagonists & inhibitors* / Q000502:physiology
D007106:Immune Sera; D001615:beta-Endorphin; D004295:Dihydroxyphenylalanine; D011388:Prolactin; D004298:Dopamine