M. Ferin

Mechanisms Regulating the Menstrual Cycle in Women

Publisher Summary This chapter discusses the mechanisms regulating the menstrual cycle in women. It discusses the events in the early and late proliferative period of the menstrual cycle, the main emphasis being on the relationship between FSH and estrogens. The chapter presents evidence indicating that the rising titer of estrogens is the trigger of the preovulatory LH release. It also discusses studies that relate to the control of the secretion of progesterone by the corpus luteum and of the duration of the postovulatory period. The chapter describes the manner in which the available physiological information may be incorporated into a model of the menstrual cycle. It presents some results of computer simulation studies based on this model. In a study described in the chapter, FSH and LH were measured by radioimmunoassay and progesterone by the radioligand method. To measure plasma estradiol and estrone, a radioimmunoassay was used employing antibodies that were made by the application of the hapten principle.

Radioimmunoassay of plasma estrone and estradiol

Estradiol-17β-succinyl-BSA was used as an antigen to produce antibodies to estradiol (E2). The antibodies did not cross react significantly with other steroids except estron (E1) and was used in the development of a radioimmunoassay for E1 and E2. Following purification with rivanol, the antibodies were polymerized using ethyl chloroformate. Tracers were added to the plasma before extraction and sephadex LH-20 column chromatography was used to separate E1 from E2. After incubation with polymerized antibodies which were mixed with 3H-E1 or 3H-E2, the free and protein bound fractions were separated by centrifugation. Sample concentrations were obtained from reference standard curves. The water blank of the method is 11±1 picograms (pg). The lower limit of sensitivity is 50 pg. The coefficient of variation for measurement of plasma estrone and estradiol was 8–18% and 4–17% respectively.

Studies with Antibodies to Steroids

Publisher Summary This chapter presents the studies with antibodies to steroids. The uses of antibodies to steroids are infinite. The possibility to carry out an “immunological adrenalectomy” by active immunization against hydrocortisone or other adrenal hormones was contemplated. The present study focuses on passive immunization techniques. Antibodies to steroids were to be used as physiological tools to study the role of steroids in specific reproductive processes. Other than by binding the hormone in the circulation, and preventing it from reaching its target organs, antibodies to steroids have no biological activity. They have unique advantages over conventional approaches, such as the administration of conventional steroid antagonists, and surgical removal of the endocrine glands. Steroid antibodies have been used to develop radioimmunoassays for plasma steroids.