Pituitary portal plasma levels of oxytocin during the estrous cycle, lactation, and hyperprolactinemia.
The median eminence receives fibers from both parvocellular and magnocellular OT neurons in the hypothalamus. The OT neuronal terminal in the median eminence is secretory and is the major source of the neuropeptide in the blood of pituitary portal vessels. The OT secretion into pituitary portal plasma increases by ovarian steroids, PRL, and the suckling stimulus. The OT secretion into the blood of pituitary portal vessels changes in parallel with the altered secretion of PRL from the pituitary. Because of correlative association between pituitary portal plasma OT and systemic plasma PRL and much abundant evidence for a direct stimulatory action of OT on PRL release, we propose that the pituitary portal vascular system serves as the window for the central OT neurotransmission to the pituitary lactotropes.
Sarkar
D K
DK
Department of Veterinary and Comparative Anatomy, College of Veterinary Medicine, Washington State University, Pullman 99164-6520.
Frautschy
S A
SA
Mitsugi
N
N
D000758:Anesthesia; D000818:Animals; D004971:Estrus / Q000097:blood*; D005260:Female; D006966:Hyperprolactinemia / Q000097:blood*; D007774:Lactation / Q000097:blood*; D008102:Liver Circulation; D008473:Median Eminence / Q000033:anatomy & histology / Q000378:metabolism*; D010121:Oxytocin / Q000097:blood* / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D012756:Sheep; D014660:Vasoactive Intestinal Peptide / Q000097:blood
D014660:Vasoactive Intestinal Peptide; D010121:Oxytocin; D011388:Prolactin