| Hypothalamic-Pituitary Function |
| 1. Reproductive Hormone System |
| This research, which was performed from 1977 to 1979, evaluated the hypothalamic-pituitary-testicular system, then correlated the endocrine studies with sexual history. Baseline plasma samples were obtained and a two-hour LHRH test was performed to measure pituitary gonadotropin reverse. This was followed by injection of human chorionic gonadotropin (hCG) to evaluate testis secretory reserve. A second injection was given the next morning. Blood samples were obtained after the injection of hCG and the following morning. |
| Plasma gonadotropins were assayed by double-antibody radioimmunoassay; plasma testosterone and dihydrotestosterone by radioimmunoassay; plasma estrone and estradiol by charcoal radioimmunoassay; and free testosterone by an ion-exchange technique (Harman and Danner, 1977; Harman and Tsitouras, 1980; Harman et al., 1980; S.M. Harman, 1981). Stored lyophilized plasma samples obtained at earlier ages were also assayed and their testosterone levels correlated with the sexual-behavior histories of the same subjects. |
| 2. Hypothalamic-Posterior Pituitary Function |
| The effect of age on this endocrine system was determined cross-sectionally by assessment of the change in plasma-AVP levels in response to both a secretory stimulus (hypertonic saline) and an inhibitory stimulus (ethanol). The tests were performed from 1974 to 1976 in a small, carefully selected subset of the BLSA population. |
| Ethanol infusion test. In a subset of the subjects who were given ethanol intravenously, AVP responses were followed (see, "Metabolism of Drugs," for a description of the ethanol-infusion protocol). Subjects abstained from all alcohol for at least 21 days before the study. AVP was measured by radioimmunoassay (Robertson et al., 1973). Samples of venous blood were obtained at short intervals during the ethanol infusion and for five hours thereafter (Vestal et al., 1977). |
| Hypertonic saline infusion test. Very careful screening of volunteers to exclude subjects with renal, hepatic, or cardiac disease was necessary. A two-hour infusion of 3% NaC1 was given at a rate of 0.1 ml/kg body weight per minute after a 12-hour period of dehydration. Blood samples were collected every 20 minutes during the infusion (Helderman et al., 1978). |
