Secretion of immunoreactive beta-endorphin and GnRH by the pig uterus: effects of reproductive status and breed.
Immunoreactive beta-endorphin (ir-BEND) and GnRH (ir-GnRH) have been identified in the pig uterus. The study reported here examined (i) possible biochemical differences between ir-BEND and ir-GnRH present in pig uterine fluids and standard synthetic peptides, and (ii) the secretory profiles of uterine ir-BEND and ir-GnRH during the oestrous cycle and early pregnancy for two breeds of pig, Large White and the highly prolific Chinese Meishan. Reverse phase (RP)-HPLC analysis of concentrated uterine fluids indicated that the majority of ir-BEND eluted with a hydrophobicity similar to that of synthetic BEND 1-31 (BEND) and alpha-N-acetylated BEND 1-31 (Nac-BEND), with a ratio of BEND to Nac-BEND of approximately 1.8:1. The RP-HPLC profiles of ir-GnRH demonstrated a major peak coeluting with synthetic GnRH, along with a minor peak eluting at the void volume. Total content of ir-BEND (pg per uterus) was affected by the interaction of breed with day (P < 0.001), but was independent of reproductive status. In Large White gilts, uterine fluid content of ir-BEND was higher (P < 0.05) on days 10 and 11 than on days 8, 12 and 14; however, in Meishan gilts, ir-BEND decreased from day 8 to days 10 and 11, and remained low on days 12 and 14. Compared to Meishan gilts, Large White gilts had higher ir-BEND concentrations on day 10 (P < 0.01), day 11 (P < 0.0001), day 12 (P < 0.01) and day 14 (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)
Li
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WI
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602.
Jiao
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S
Chen
C L
CL
Bazer
F W
FW
D000818:Animals; D001826:Body Fluids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004971:Estrus / Q000097:blood; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry / Q000378:metabolism*; D011247:Pregnancy; D012098:Reproduction / Q000502:physiology*; D013552:Swine / Q000235:genetics / Q000502:physiology*; D014599:Uterus / Q000378:metabolism*; D001615:beta-Endorphin / Q000737:chemistry / Q000378:metabolism*
D007987:Gonadotropin-Releasing Hormone; D001615:beta-Endorphin