Gonadotropin inhibitory substances

Moudgal, N. R.; Sairam, M.R.; Raj, Himanshu

doi:10.1016/0016-6480(69)90025-2

Cited by 1 publication

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“…Additional LH may be necessary for support beyond this period, at least for the maintenance of pregnancy, as suggested by the observations of Alloiteau and Bouhours (14), of Loewit et al (15) and of Mougdal et al (16,17). The autonomy of steroidogenic function of the rat corpus luteum for approximately one week is somewhat similar to that which has been reported for sheep (18) and swine (19) corpora lutea, but appears to differ in that another hormone, prolactin, is necessary to prevent its biosynthetic product (progesterone) from being converted to a progestationally inactive form (20a-hydroxypregn-4-en-3-one).…”

Section: Discussionmentioning

confidence: 84%

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy¹

1970

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The effects of hypophysectomy and of replacement therapy with prolactin upon in vitro biosynthesis of progesterone and 20a-hydroxypregn-4-en-3-one and of several lipid constituents in isolated corpora lutea of pseudopregnant rats have been investigated. Pseudopregnancy was induced by mechanical stimulation of the uterine cervices of rats in which first estrus and ovulation were synchronized by sc administration of 4 IU pregnant mare serum gonadotropin (PMS) at 30 days of age. Hypophysectomy, performed on the second day after ovulation, resulted in marked inhibition of net in vitro synthesis of progesterone in corpora lutea obtained at autopsy 5 days later. In contrast, in vitro synthesis of 20a-hydroxypregn-4-en-3-one was markedly stimulated by this treatment, with the result that "total progestin" (progesterone plus 20a-hydroxypregn-4-en-3-one) synthesis was not significantly altered. Prolactin treatment (200 M g NIH-P-S6, twice daily) completely prevented these changes, actually increasing the level of progesterone synthesis above that of the intact, pseudopregnant controls, as well as decreasing the level of synthesis of 20«-hydroxypregn-4-en-3-one below that of the same control animals. Under the same experimental conditions, estradiol administration effectively induced cornification of vaginal mucosae and distention of uteri with fluid only in those rats which were hypophysectomized but received no prolactin; prolactin administration abolished both these responses, confirming the ability of this hormone to induce secretion of progesterone in "progestational" amounts. No effect of estradiol itself upon synthesis of either steroid, either in the absence or presence of prolactin, was observed. Levels of cholesterol (both free and esterified) in corpora lutea were not altered significantly as a result of hypophysectomy, but prolactin treatment increased concentration of both forms of this lipid. In vitro incorporation of acetate-l-u C in both free cholesterol and esterified sterols was decreased as a result of hypophysectomy. Prolactin therapy resulted in only slight increases in acetate-l-14 C incorporation into these compounds in the absence of the pituitary, in marked contrast to the previously observed ability of this hormone to effect approximately 10-fold increases in synthesis of these compounds in intact rats. Incorporation of acetate-l-14 C into longchain fatty acids of 4 classes of lipids (sterol esters, triglycerides, phospholipids and free fatty acids) was not significantly altered by hypophysectomy, but was markedly augmented by prolactin treatment. (Endocrinology 86: 634, 1970)

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Section: Discussionmentioning

confidence: 84%

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy¹

1970

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Gonadotropin inhibitory substances

Cited by 1 publication

References 16 publications

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy¹

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy¹

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Gonadotropin inhibitory substances

Cited by 1 publication

References 16 publications

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy1

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy1

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Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy¹

Effects of Prolactin Upon Cholesterol Metabolism and Progesterone Biosynthesis in Corpora Lutea of Rats Hypophysectomized During Pseudopregnancy¹