The steroidogenic capacity of the aging rat testis

Factors bearing on the steroidogenic capacity of the aging testis have been examined in Sprague-Dawley rats between 3 and 24 months of age. Neither the number nor the binding affinity of testicular receptors for 125I-hCG changed with age. The ability of the aging testis to synthesize cholesterol from octanoate was similarly undiminished. Testicular conversion of cholesterol to pregnenolone, the gonadotropin-responsive, rate-limiting portion of the androgenic pathway, remained near young adult levels with advancing age. The rate at which the testis converted pregnenolone to testosterone actually increased by almost 25% in the oldest rats. Hence, the steroidogenic capacity of the Sprague-Dawley rat testis does not decline with advancing age.