Endometrial immunoreactive beta-endorphin increases during mid-estrous cycle and early pregnancy in gilts.
Immunoreactive (ir) beta-endorphin (BEND) was recently identified in porcine uterine fluids. In the study reported here, we examined the hypothesis that porcine endometrium serves as a source of uterine fluid ir-BEND during the estrous cycle and early pregnancy. Endometrial ir-BEND was chromatographically characterized, sites of ir-BEND synthesis were immunocytochemically localized, and concentrations of endometrial ir-BEND during the estrous cycle and early pregnancy were measured. Sephadex G-50 chromatographic profiles of endometrial extracts from Day 15 of the estrous cycle revealed three distinct peaks of ir-BEND, with the first peak occurring near void volume and the second and third peaks coinciding with standard porcine beta-lipotropin and standard porcine BEND, respectively. Reverse-phase HPLC C18 chromatographic profiles indicated that endometrial ir-BEND contained both standard BEND and alpha-N-acetylated BEND. Immunocytochemical studies demonstrated ir-BEND in the surface and glandular epithelial cells of the endometrium, with immunostaining most prominent in the apical portion of epithelial cells. Concentrations of ir-BEND in endometrial tissues were higher on Days 14-15 than on Days 8-12 during the estrous cycle and pregnancy (p less than 0.05); however, values were not different in pregnant and cyclic gilts. Biochemical and immunocytochemical evidence supports our hypothesis that ir-BEND present in uterine fluids is derived from the endometrium. The increase in endometrial ir-BEND concentration during Days 14-15 in cyclic and pregnant gilts indicates that ovarian steroids may influence the synthesis of endometrial ir-BEND.
Li
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Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602.
Wu
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Chen
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D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004717:Endometrium / Q000737:chemistry / Q000378:metabolism*; D004971:Estrus / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011863:Radioimmunoassay; D013552:Swine / Q000378:metabolism*; D013997:Time Factors; D001615:beta-Endorphin / Q000032:analysis / Q000378:metabolism*
D001615:beta-Endorphin