Evidence that neuropeptide Y (NPY) released into the hypophysial-portal circulation participates in priming gonadotropes to the effects of gonadotropin releasing hormone (GnRH).
NPY exhibits modulatory activity at both the adenohypophysial and the central levels of the rat hypothalamic-pituitary-gonadal axis. In the present studies, the secretion and physiological activity of endogenous irNPY was examined. We have shown that: (i) irNPY is secreted into the hypophysial-portal circulation, (ii) hypophysial-portal concentration profiles of irNPY and irGnRH are parallel throughout the rat estrous cycle, and (iii) removal of endogenous NPY via immunoneutralization inhibits the steroid-induced LH surge in ovariectomized rats. From these observations, we speculate that NPY secreted into the hypophysial-portal circulation participates in priming of gonadotropes to the actions of GnRH on the afternoon of the preovulatory surge.
Sutton
S W
SW
Clayton Foundation Laboratories for Peptide Biology, Salk Institute, La Jolla, CA 92037.
Toyama
T T
TT
Otto
S
S
Plotsky
P M
PM
D000818:Animals; D004031:Diestrus / Q000097:blood; D004971:Estrus / Q000097:blood; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000097:blood / Q000502:physiology*; D007116:Immunization, Passive; D007986:Luteinizing Hormone / Q000378:metabolism; D009478:Neuropeptide Y / Q000097:blood / Q000276:immunology / Q000502:physiology*; D010902:Pituitary Gland / Q000098:blood supply*; D011168:Portal System; D011359:Proestrus / Q000097:blood; D051381:Rats
D009478:Neuropeptide Y; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone