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Pulsatile Luteinizing Hormone Secretion In The Castrate Male Bovine: Effects Of Testosterone Or Estradiol Replacement Therapy, B. D. Schanbacher, M. J. D'Occhio, T. W. Gettys

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Luteinizing hormone (LH) secretory profiles have been determined for the male bovine following castration and steroid replacement therapy. Serum LH concentrations increased approximately threefold during the first week following castration and thereafter remained elevated (6.6 ± .7 ng/ml). Castrates not receiving steroid replacement showed a rhythmic pattern of LH release that was of high frequency (mean pulse interval; 85 ± 5 min) and high amplitude (mean peak concentration, 11.2 ± 1.4 ng/ml). Chronic administration of estradiol-17β via subdermal Silastic implants reduced mean serum LH concentrations (2.1 ± .3 ng/ml) and blocked the pulsatile pattern of LH release in all steers. …