Hypophyseal-gonadal system during male aging

The concentration of sex and gonadotropic hormones in blood plasma of 280 reasonably healthy men aged 20-105 was determined using radioimmunoassay kits. Compared to men aged 20-39, the statistically significant decrease in testosterone level was registered in men aged 55-59, the increase in oestradiol in men aged 60-64, progesterone in men aged 55-59, and in LH and FSH in the group aged 65-69. The reactivity of central and peripheral links of the hypothalamic-gonadal system to direct and feed-back control influences alters with age.