The role of uterine and ovarian hormones in luteolysis: A comparison amongspecies

Luteolytic mechanisms have evolved in mammals to improve reproductive effic iency. The hormonal interactions that control the onset and progress of lut eolysis are complex. They involve endocrine and paracrine signals that link the corpus luteum, uterus and posterior pituitary gland. Current concepts concerning these interactions will be examined in the five major domestic u ngulate species commonly raised in Europe and North America (cattle, sheep, goats, pigs and horses). Some of these interactions are similar across spe cies. All five depend on prostaglandin F-2 alpha secreted from the uterus, to induce luteolysis. Three hormones, progesterone, estradiol and oxytocin interact to regulate uterine secretion of PGF(2 alpha). Oxytocin is an acut e stimulus for uterine PGF(2 alpha) secretion. Progesterone and estradiol i nteract to regulate uterine secretary responsiveness to oxytocin. Precisely how these hormones interact varies across species.