Serum concentrations of luteinizing hormone, growth hormone, and prolactin in untreated and estradiol-treated ovariectomized ewes after immunoneutralization of hypothalamic neuropeptide Y.
Ovine antiserum against a conjugate of porcine neuropeptide Y (NPY) with bovine thyroglobulin was infused repeatedly into one lateral ventricle of five ovariectomized (ovx) ewes before and after subcutaneous injection of estradiol-17 beta (E beta). Serum concentrations of LH, growth hormone (GH), and prolactin (PRL) were measured at 10-min intervals before E beta and at approximately hourly intervals 8 to 18 h after E beta injection. Control ewes were infused with ovine serum from animals immunized against bovine thyroglobulin. Basal episodic profiles (pre-E beta) of LH, GH, and PRL were similar in ovx ewes infused with control or anti-NPY serum. Injection of E beta induced a surge-like increase of serum LH, which began at 12.6 h after E beta in ewes infused with anti-NPY and at 14.4 h after E beta in ewes infused with control antiserum (P < .05). The magnitude of the E beta-induced surge of LH was not different between treatments. In addition to initiating a surge-like release of LH over the period 12 to 18 h after E beta, serum GH was transiently increased during the period between 10 and 15 h after E beta. In contrast, serum PRL was increased during the entire period between 8 and 18 h after E beta. Based on the effects of immunoneutralization, endogenous NPY in the brain of E beta-treated ovx ewes seems to restrain or delay the onset of the surge-like secretion of LH and probably GnRH, but endogenous NPY does not affect the episodic pulsatile releases of LH characteristic of ovx ewes.(ABSTRACT TRUNCATED AT 250 WORDS)
Malven
P V
PV
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
Haglof
S A
SA
Jiang
H
H
D000818:Animals; D018592:Cross-Over Studies; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D007031:Hypothalamus / Q000737:chemistry; D007106:Immune Sera / Q000276:immunology / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood*; D009478:Neuropeptide Y / Q000032:analysis / Q000276:immunology / Q000502:physiology*; D010052:Ovariectomy / Q000662:veterinary; D011388:Prolactin / Q000097:blood*; D011897:Random Allocation; D012756:Sheep / Q000276:immunology / Q000378:metabolism*; D013954:Thyroglobulin / Q000276:immunology
D007106:Immune Sera; D009478:Neuropeptide Y; D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone; D013006:Growth Hormone; D013954:Thyroglobulin