Short-Term Ovarian Responses to some Pituitary Hormones Infused In Vivo in Pigs and Sheep

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Abstract
Changes in ovarian function were measured after the administration of hormones in the mid-luteal phase of the estrous cycle in pigs and sheep. Ovarian venous blood was collected for three successive 40-min. or 60-min. periods while saline was infused at a rate approximating the rate of collection. In pigs, for the middle 40-min. period, LH was added to the saline for nine animals and FSH, prolactin and melengestrol acetate were similarly tested. Control animals (six) received only saline during the entire period. LH increased the rate of secretion of progesterone by increasing the concentration of the steroid in plasma while the rate of blood flow remained unchanged. FSH and prolactin also enhanced progesterone production in the two animals receiving each of these hormones. Whether these effects resulted from direct action on the ovary is not known. Melengestrol acetate had no effect. In sheep, during the middle third of the experimental period, LH, FSH, or prolactin was infused into treated animals. LH, tested in 12 ewes, stimulated the rate of progesterone secretion by increasing both the rate of ovarian blood flow and the concentration of steroid in the plasma. FSH produced a similar though less pronounced effect, but only two animals were tested. The one animal that received prolactin behaved like the seven controls. Wide variations between animals were seen in response to similar treatments, but the rate of flow of blood was almost always negatively correlated with the concentration of progesterone in the plasma. Copyright © 1969. American Society of Animal Science. Copyright 1969 by American Society of Animal Science

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