Harman S M, Danner R L, Roth G S
Endocrinology. 1978 Feb;102(2):540-4. doi: 10.1210/endo-102-2-540.
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.
其他人曾报道，老年雄性大鼠的睾酮血药浓度以及睾丸间质细胞对促性腺激素的反应（注射后1小时内）均降低。尽管与同品系的年轻（3 - 4个月）或成熟（12个月）动物相比，我们实验中24 - 26月龄老年Sprague - Dawley大鼠的血浆睾酮静息水平也较低，但皮下注射人绒毛膜促性腺激素3天可恢复其分泌功能，使睾酮水平与同样受到刺激的年轻大鼠无异。在短期实验中，老年大鼠在单次静脉注射人绒毛膜促性腺激素1小时后，对其睾酮分泌反应确实减弱，这与之前的报道一致，但在2小时时观察到刺激水平恢复正常，并持续至24小时。这些发现与老年男性睾丸对促性腺激素内在低反应性的表现不同，可能代表老年大鼠睾丸间质细胞因促黄体生成素普遍水平较低而处于慢性刺激不足的状态。
