Circadian rhythm of serum immunoreactive inhibin in young and elderly men.
Serum testosterone (T) levels and inhibin levels decline with normal male aging. In addition, in young men, serum T levels demonstrate a circadian variation that is blunted or lost with normal aging. The purpose of this study was to determine whether serum immunoreactive inhibin levels also demonstrate a circadian variation in young men and if normal aging has an effect on the 24 hr serum inhibin pattern. Hourly blood samples were obtained for 24 hr from 7 young (age 25-35 yr) and 7 elderly (age 65-72 yr) healthy men. Serum inhibin and testosterone levels were measured by RIA. Similar to T, serum inhibin levels demonstrated a circadian pattern in young men. Elderly men also demonstrated a circadian rhythm in serum inhibin, with an average amplitude that was not significantly different from that found in young men, despite the fact that the average 24-hr inhibin level in the elderly men was significantly lower than in the young men. These results demonstrate that immunoreactive inhibin, like T, displays a circadian rhythm in the serum of adult men and the inhibin biorhythm is maintained in elderly men.
Tenover
J S
JS
Department of Medicine, University of Washington School of Medicine, Seattle.
Bremner
W J
WJ
D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood* / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007265:Inhibins / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D013739:Testosterone / Q000097:blood
D013739:Testosterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone