Endocrinology, Vol 102, 540-544, Copyright © 1978 by Endocrine Society

ARTICLES

Testosterone secretion in the rat in response to chorionic gonadotrophin: alterations with age

SM Harman, RL Danner and GS Roth

It has been reported by others that both prevailing blood concentrations of testosterone and Leydig cell response to gonadotrophin (up to 1 h after injection) are reduced in the aged male rat. Although resting levels of plasma testosterone in our aged (24-26 months old) Sprague-Dawley rat are also depressed compared with young (3-4 months) or mature (12 months) animals of the same strain, subcutaneous injection with human chorionic gonadotrophin for 3 days restores secretory function, producing testosterone levels indistinguishable from those of similarly stimulated younger rats. In short term experiments, old rats did show a diminished testesterone secretory response to human chorionic gonadotrophin 1 h after a single intravenous injection, consistent with previous reports, but restoration of normal stimulated levels was observed by 2 h, and persisted up to 24 h. These findings differ from the demonstrated intrinsic testicular hyporesponsiveness to gonadotrophin of aged men, and probably represented a state of chronic understimulation of the aged rat Leydig cells, due to low prevailing levels of LH.

This article has been cited by other articles:

				I.-s. Kim, H.B. Siril Ariyaratne, and S.M.L. C. Mendis-Handagama Changes in the Testis Interstitium of Brown Norway Rats with Aging and Effects of Luteinizing and Thyroid Hormones on the Aged Testes in Enhancing the Steroidogenic Potential Biol Reprod, May 1, 2002; 66(5): 1359 - 1366. [Abstract] [Full Text] [PDF]