Ovarian hormones Progestins

THE OVARY (ESTROGENS, PROGESTINS, OTHER OVARIAN HORMONES, ORAL CONTRACEPTIVES, INHIBITORS ANTAGONISTS, OVULATION-INDUCING AGENTS)... 

The Ovary (Estrogens, Progestins, Other Ovarian Hormones, Oral Contraceptives, Inhibitors Antagonists, Ovulation-Inducing Agents)... 

Testosterone, the testicular hormone, is identified as a male hormone. Estradiol (17/3), which differs from testosterone only by loss of a methyl group and aromatization of ring A, is the ovarian hormone. Progesterone is the progestational hormone and is essential for fertilization and maintenance of pregnancy. Once again medicinal chemists, by further alteration of structures, have made more potent oral and more useful progestins. 

We have known for a long time that both estrogen and progestin will reduce the production of milk. This probably can be shown with appropriate experiments. It is due to a reduction in the release of prolactin, but also to a direct effect on the mammary tissue. In other words, the ovarian hormones are growth stimulators, and consequently they tend to promote proliferation of tissue, and it is only when the ovarian hormones drop, as they do at the end of pregnancy, that growth stops and lactation is initiated. 

Long-term use of hormone-replacement therapy and concurrent use of progestins appear to contribute to breast cancer risk.7 The use of postmenopausal estrogen-replacement therapy in women with a history of breast cancer generally is considered contraindicated. However, most experts believe that the safety and benefits of low-dose oral contraceptives currently outweigh the potential risks and that changes in the prescribing practice for the use of oral contraceptives are not warranted. Oral contraceptives are known to reduce the risk of ovarian cancer by about 40% and the risk of endometrial cancer by about 60%. 

These hormones are essential for the maintenance of pregnancy. The only natural progestin hormone, progesterone (3.38), is produced by the corpus luteum, an endocrine tissue formed in the ovary by the ruptured ovarian follicle after the level of luteinizing hormone peaks. If pregnancy occurs, the corpus luteum persists for the first three months of the pregnancy after that, its role is taken over by the placenta as the major... 

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