Hormonal Regulation of the Reproductive Tract in Female Mammals

Abstract

INTRODUCTION +1131This review covers only a small part of what has recently become an enormous literature on hormonal regulation of the fe male reproductive tract. We used the fo llowing guidelines in selecting papers fo r review: 1. The reproductive tract is exposed to varying levels of sex steroids during the menstrual and estrous cycles. With the advent of radioimmunoassay techniques, these patterns are now known more precisely than at any previous time. 2. The steroids are concentrated in the target cells of the tract by mechanisms that. because of recent findings in steroid receptor interactions, are more fu lly understood than ever before. Here we pay particular attention to reports of fluctuations in receptor levels during reproductive cycles and pregnancy and to the correlation between such changes and the fluctuat ing levels of steroids in plasma. 3. Within the target cells, the steroids interact with the cell machinery to produce multiple effects. This is the frontier of the modern research effort on hormone actions; the potential fo r future success here is enor mous. So far, however, species and organ differences have thwarted attempts to define any universal principles of hormone action, although evidence is accumulat ing in favor of the idea that one of the key endpoints of steroid hormone action is the production of specific RNA molecules.As to our method of selecting reports to review, we have chosen those that illustrate the interactions between estrogens and progestins in regulating the growth and fu nction of the tract, that point to the complexity of these interactions, and that serve as guidelines fo r fu ture study. No attempt was made to be comprehensive. Some emphasis has been placed on the reproductive tract of primates because of our special interests. Further ANNUAL REVIEWS 274BRENNER & WEST Additional information is available in a recently published series of definitive reviews concerned with various aspects of endocrine control of the fe male reproduc tive system (66). These include the effects of steroid hormones on uterine metabo lism (20S); endocrine control of implantation (IS3); the overall role of hormones in pregnancy (76, 16 1); various aspects of the biosynthesis, metabolism, and uterine binding of estrogens (42, 61, 178, 18S); the biosynthesis, metabolism, and physiologi cal role of progesterone (3S, .59, 104, 14S); the effects of hormones on the anatomy and physiology of the cervix (63, 128); and the biological effects of oral contraceptive steroids (168). STEROID LEVELS DURING REPRODUCTIVE CYCLES Menstrual CyclesESTROGENS The cyclic pattern of estrogen secretion in nonhuman primates has been investigated in the rhesus monkey (11)(12)(13)(14)78, 8S, 86,100, IS7,207), cynomol gus monkeys (163), bonnet macaques (120), baboons (186), and chimpanzees (6S). It is generally agreed that in the rhesus monkey the level of estradiol (E2Pm peripheral plasma during the early fo llicular phase (days 1-8) is "'SO pg/ml, and that about 4 days before the luteinizing hormone (LH) peak there...

Oestradiol and Progesterone: Soluble Receptor Levels and Metabolism in the Uterus of the Ovariectomized Ewe

“…ln laboratory animals the synthesis of soluble receptors for both oestradiol and progesterone is in part regulated by oestradiol [see Brenner and West (1975) for a review]. The results reported here for the ewe indicate that in this species also the oestradiol secreted to induce oestrus is a major regulator of these two receptor proteins.…”

Effects of ovariectomy and steroid hormones on vaginal smooth muscle contractility

“…[9][10][11] Steroid hormones are critical for maintaining the integrity of female genital tissue structure and function. [12][13][14][15][16][17] The thickness and rugae of the vaginal wall, as well as vaginal lubrication, are estrogen dependent. 18,19 In addition, estrogens have been shown to enhance genital sensation and maintain blood flow.…”

Murine Vaginal Colonization Model for Investigating Asymptomatic Mucosal Carriage of Streptococcus pyogenes

“…The anatomy and physiology of the murine vaginal mucosa are quite similar to those of the human vaginal mucosa, and both respond similarly to estrogen cycling, with thickening and proliferation of the epithelial surface and accumulation of glycogen in the intermediate and superficial layers, although to a lesser degree in mice than in humans (16). While mice have a 10-to 25-fold lower level of serum estrogen, they respond dramatically to exogenous estradiol treatment, with enhanced glycogen deposition, intense epithelial proliferation, and increased epithe-lial cell thickness, which overall presents a more human-like vaginal profile (17,18). In addition, human and murine vaginal secretions have similar compositions, with similar concentrations of glucose (3.3 mM and 4.4 mM, respectively) and lactate (6.2 mM and 8.4 mM, respectively) (19).…”