About Testosterone

Testosterone is produced primarily by the testes in men, although it also can be produced by the adrenal glands and other sites including adipose tissue and bone. It is responsible for testes descent and reproductive tract development in the fetus, development of male secondary sex characteristics in puberty, and the production of sperm. Testosterone production in men begins in utero, rises sharply in puberty, and then declines with age (Pic. 2). Indeed, the Massachusetts Male Aging Study showed that total serum testosterone levels decline by 1.6% per year starting at age 40. Testosterone is also produced by the ovaries, the adrenal glands, and tissues such as adipose tissue and skin in women, although serum concentrations are almost 20-fold lower in pre-menopausal women compared to age-matched men. Interestingly, testosterone levels also decline with age in women. This age-dependent reduction in testosterone is not restricted to humans, as it is also seen in older male rats and mice (>20 months of age) in conjunction with a decline in fertility, although whether levels decline in aged female animals has not been investigated.

睾酮主要由男性睾丸产生的，尽管它也可以由肾上腺和其他网站，包括脂肪组织和骨来制造。它负责睾丸下降和生殖道发育的​​胎儿，在青春期男性第二性征发育和精子的产生。睾酮的男子开始在子宫内，在青春期急剧上升，然后随年龄增长而下降（如图2）。事实上，马萨诸塞州男性老龄化研究表明，总血清睾酮水平每年以1.6％开始于40岁。睾酮也由卵巢，肾上腺，以及诸如脂肪组织和皮肤的妇女组织生产下降，但血清浓度几乎20倍相比，年龄匹配的男性绝经前妇女低。有趣的是，睾酮水平下降，也随着年龄的妇女。这睾酮年龄依赖性的减少并不限于人类，因为它是在旧的雄性大鼠和小鼠（> 20月龄）与生育率下降结合也看出，虽然水平是否在老年雌性动物下降尚未调查。