Age at menopause has implications for fertility and risk of hormonally related chronic diseases. Some pesticides disrupt reproductive hormones or are toxic to the ovary, but little is known about the association between pesticide exposure and timing of menopause. Cox proportional hazards modeling was used to examine the association between use of pesticides and age at menopause among 8,038 women living and working on farms in Iowa and North Carolina. Premenopausal women aged 35-55 years were followed from enrollment (1993-1997) to the date of their last menstrual period, or their follow-up interview (1999-2003) if still premenopausal. Women who experienced surgical menopause were censored at the date of surgery. Approximately 62% of the women reported ever mixing or applying pesticides; women who had never used pesticides were the comparison group for all analyses. After control for age, smoking status, and past use of oral contraceptives, the median time to menopause increased by approximately 3 months for women who used pesticides (hazard ratio = 0.87, 95% confidence interval: 0.78, 0.97) and by approximately 5 months for women who used hormonally active pesticides (hazard ratio = 0.77, 95% confidence interval: 0.65, 0.92). Pesticide use may be associated with a later age at menopause.

Pesticide Exposure and Timing of Menopause The Agricultural Health Study

To characterize the nature of insulin action on ovarian cells, an in vitro system of swine granulosa cells was developed in which 3- to 50-fold stimulation of progesterone production was observed in response to insulin under serumfree or sparsely (1%) serum-supplemented conditions. These studies demonstrate that optimal cell density is critical for the full expression of insulin action, and that the dose-dependent responses of granulosa cells to insulin are also significantly influenced by the maturational status of the parent follicle. The striking (>30-fold) responses of medium-sized and healthy preovulatory follicles to insulin were not attributable to the presence or absence of atresia or to a selective inhibition of progesterone′s catabolism to 20a-dihydroprogesterone, since 20a-dihydroprogesterone production was also markedly increased in response to insulin. The mechanisms subserving insulin action were explored further by testing the capacity of insulin to 1) increase progesterone accumulation in ...

Mechanisms Subserving Insulin′s Differentiating Actions on Progestin Biosynthesis by Ovarian Cells: Studies with Cultured Swine Granulosa Cells

Impact of endosulfan (thiodan) EC 35 on behavior and dynamics of oocyte development in the teleostean fish, Colisa (Trichogaster) fasciatus.

Testicular degeneration was observed in genetically selected sucrose-fed diabetic rats. The changes consisted of atrophy of the seminiferous tubules, thickening of the tubular basement membrane, marked reduction of the spermatogenesis and Leydig cell hyperplasia. None of these changes was observed in age-matched starch-fed siblings.

Testicular degeneration in genetically selected sucrose-fed diabetic rats☆

Ascorbic acid has long been associated with fertility, but no consistent study of its mechanism of action in reproductive tissues has been made. This article considers how three of ascorbic acid's principal functions, namely its promotion of collagen synthesis, its role in hormone production, and its ability to protect cells from free radicals, may explain its reproductive actions. Data relating to both ovary and testis are reviewed since ascorbate accumulates in both tissues. Both gonads exhibit cycles of tissue remodeling and of peptide and steroid secretion that can be assumed to be ascorbate-dependent. Ascorbic acid may also prevent gametes from damage by free radicals during production and fertilization. Preliminary data on the concentrations of ascorbic acid in serum and follicular fluid from women undergoing in vitro fertilization are presented. They suggest that the supply of ascorbic acid to the ovary might be a limiting factor in the ability of the preovulatory follicle to grow in response to gonadotropin stimulation. It is concluded that ascorbic acid is a key compound in gonadal physiology on which further research is needed and that a reappraisal of its potential clinical value in the treatment of various types of male and female infertility would be timely.

Amar Chatterjee

Papers

Prevention of testicular degeneration in alloxanized rats by the use of cortisone

Activity of the corpora lutea in alloxan diabetic rats

Role of ascorbic acid on the uterotrophic activity of estrogen

Role of cortisone in the prevention of alloxan diabetic oestrous cycle inhibition in rats.