Women today can expect to live one-third of their lives after menopause (Gavaler 1991). Moreover, a large proportion of postmenopausal women are at least moderate consumers of alcohol(1) (Gavaler 1993a; Gavaler and Rosenblum 1994). The effects of alcohol on hormone levels in this large population are of interest for several reasons. First, the normal hormonal changes of menopause are associated with increased risk for certain diseases of the bones and heart. By affecting hormone levels, alcohol might influence the occurrence or progress of these diseases.
Second, alcohol-hormone interactions may influence the development of alcohol induced liver disease in those postmenopausal women who are heavier drinkers.
Finally, postmenopausal women are the ideal female population in which to study the effect of alcohol on hormones in women. Before menopause, hormone levels fluctuate daily, depending on the stage of the menstrual cycle. After menopause, hormone levels remain constant (at their new postmenopausal levels). It is therefore easier to measure alcohol-induced changes in hormone levels in post-than in premenopausal women.
HORMONAL REGULATION BEFORE AND AFTER MENOPAUSE
Before examining the effects of alcohol, it will be helpful to review the hormonal regulation of the reproductive cycle and the changes that occur during a natural menopause. The female reproductive cycle is governed primarily by two groups of hormones: the gonadotropins-luteinizing hormone (LH) and follicle stimulating hormone (FSH)-and the estrogens. Every 28 days or so, the gonadotropic hormones cause follicles to develop in the ovaries. On the 14th day of the cycle, one of these follicles ovulates (i.e., produces an ova). Estrogen is secreted during the growth of the follicles; after ovulation, large amounts of estrogen are secreted from the secretory gland (corpus luteum) that replaces the follicle. As long as estrogen concentrations remain high, LH and FSH are inhibited and will not initiate development of additional follicles. Two weeks after ovulation, if pregnancy does not occur, the corpus luteum degenerates and the ovarian hormones (e.g., estrogen) decrease dramatically, LH and FSH no longer are inhibited, and menstration begins.
When a woman reaches approximately 40 to 50 years of age, her reproductive cycle usually becomes irregular, and ovulation does not take place during many of these cycles. During this time, few follicles still remain that can be stimulated by FSH and LH; and as the number of follicles decrease, the production of estrogens also decreases. When estrogen production falls below a certain threshold, the estrogens can no longer inhibit the production of the gonadotropins and the oscillatory cycle stops, resulting in menopause.
The loss of significant amounts of estrogen from the woman's system often results in substantial physiological adjustments (e.g., "hot" flashes, fatigue, anxiety). Estrogens are commonly prescribed to alleviate these unpleasant symptoms or other adverse health consequences of menopause. This practice is known as estrogen replacement therapy.
However, the body's production of estrogen does not cease entirely after menopause. Estrogens also can be produced from another class of hormones called androgens. Androgens are produced in the ovaries and in the adrenal glands located atop the kidneys. In men, androgens are the primary sex hormones; for example, the androgen testosterone is responsible for the development of the male characteristics, such as increased body hair and bone growth, and the development of spermatozoa. In women, the androgens have only a slight masculinizing effect. Instead, they travel through the bloodstream to body fat, where they are converted to estrogens through a process called aromatization.
ALCOHOL'S EFFECTS ON HORMONES AFTER MENOPAUSE
Estrogen levels after menopause are influenced by factors that affect androgen production or aromatization. …