The Effect of Prostaglandin F2α on Relaxin Release Differs in the Cyclic and Pregnant Sow
Relaxin is known classically as a hormone of pregnancy with high levels produced by the corpus luteum (CL) of the sow. However, recently relaxin has been localized in luteal tissue of the pseudopregnant pig (Fields and Fields, 1985) and in the nonpregnant pig throughout the cycle (Ali et al., 1986). Luteal relaxin immunoactivity was highest from days 7 to 15 of the cycle with a decline by day 18 coincident in time with luteolysis, defined functionally as a decline in serum progesterone and occurring between days 14 and 18 of the sow estrous cycle (Cavazos et al., 1969). Whether prostaglandin F2α (PGF2α), postulated as the major signal for luteolysis in this species (Moeljono et al., 1976), is also responsible for relaxin release from the CL of the cycle is not known and was an objective in this study using exogenous prostaglandin.
KeywordsCorpus Luteum Estrous Cycle Serum Progesterone Ovarian Artery Luteal Tissue
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