Environment, human reproduction, menopause, and andropause.
Open Access
- 1 July 1993
- journal article
- review article
- Published by Environmental Health Perspectives in Environmental Health Perspectives
- Vol. 101 (suppl 2), 91-100
- https://doi.org/10.1289/ehp.93101s291
Abstract
As the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator is an integrator of hormonal, metabolic, and neural signals, it is not surprising that the function of the hypothalamogonadal axis is subject to the influence of a large array of environmental factors. Before puberty, the central nervous system (CNS) restrains the GnRH pulse generator. Undernutrition, low socioeconomic status, stress, and emotional deprivation, all delay puberty. During reproductive life, among peripheral factors that effect the reproductive system, stress plays an important role. Stress, via the release of corticotropin-releasing factor (CRF), eventually triggered by interleukin 1, inhibits GnRH release, resulting in hypogonadism. Effects of CRF are probably mediated by the opioid system. Food restriction and underweight (anorexia nervosa), obesity, smoking, and alcohol all have negative effects on the GnRH pulse generator and gonadal function. Age and diet are important determinants of fertility in both men and women. The age-associated decrease in fertility in women has as a major determinant chromosomal abnormalities of the oocyte, with uterine factors playing a subsidiary role. Age at menopause, determined by ovarian oocyte depletion, is influenced by occupation, age at menarche, parity, age at last pregnancy, altitude, smoking, and use of oral contraceptives. Smoking, however, appears to be the major determinant. Premature menopause is most frequently attributable to mosaicism for Turner Syndrome, mumps ovaritis, and, above all, total hysterectomy, which has a prevalence of about 12-15% in women 50 years old. Premature ovarian failure with presence of immature follicles is most frequently caused by autoimmune diseases or is the consequence of irradiation or chemotherapy with alkylating cytostatics. Plasma estrogens have a physiological role in the prevention of osteoporosis. Obese women have osteoporosis less frequently than women who are not overweight. Early menopause, suppression of adrenal function (corticoids), and thyroid hormone treatment all increase the frequency of osteoporosis. Aging in men is accompanied by decreased Leydig cell and Sertoli cell function, which has a predominantly primary testicular origin, although changes also occur at the hypothalamopituitary level. Plasma testosterone levels, sperm production, and sperm quality decrease, but fertility, although declining, is preserved until senescence. Stress and disease states accelerate the decline on Leydig cell function. Many occupational noxious agents have a negative effect on fertility.(ABSTRACT TRUNCATED AT 400 WORDS)Keywords
This publication has 103 references indexed in Scilit:
- The Effect of Nitrofurazone on the Endocrine, Secretory and Spermatogenic Functions of the Rat TestisAndrologia, 2009
- Influence of diet on plasma steroid and sex plasma binding globulin levels in adult menThe Journal of Steroid Biochemistry and Molecular Biology, 1989
- Gonadal function in male heroin and methadone addictsInternational Journal of Andrology, 1988
- Effect of dietary components, including lignans and phytoestrogens, on enterohepatic circulation and liver metabolism of estrogens and on sex hormone binding globulin (SHBG)Journal of Steroid Biochemistry, 1987
- Increased 2-Hydroxylation of Estradiol as a Possible Mechanism for the Anti-Estrogenic Effect of Cigarette SmokingNew England Journal of Medicine, 1986
- Intratesticular unconjugated steroids in elderly menJournal of Steroid Biochemistry, 1986
- Female Fecundity as a Function of AgeNew England Journal of Medicine, 1982
- Factors affecting the age at menopauseJournal of Biosocial Science, 1979
- Male Age and Fertility Results From Ireland Prior to 1911Population Index, 1975
- Effect of parathion on the uptake and metabolism of androgens in rodent sex accessory organsToxicology and Applied Pharmacology, 1974