Serum testosterone concentration decreases with age in humans and rodents. Accordingly, old male mice show changes in locomotor activity rhythms: a lengthened free-running period and decreased activity levels among others. To investigate whether testosterone replacement improves the age-related decline in circadian rhythmicity, we examined the effects of testosterone on the circadian rhythms of wheel running activity in old male mice. Intact male C57BL/6J mice (18-22 months old) were subcutaneously implanted with silicone tubes packed with testosterone propionate (TP) or cholesterol. TP treatment significantly decreased the daily wheel running revolutions in a normal light/dark (LD) cycle and in constant darkness (DD), but did not affect the free-running period. The same experiment performed on young male gonadectomized mice (3-5 months old) demonstrated that TP treatment significantly increased activity levels in both LD and DD. These results suggest that testosterone replacement exacerbates the age-related decline in circadian rhythmicity.

中文翻译：

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睾酮对老年小鼠昼夜节律的影响。


人类和啮齿动物的血清睾酮浓度随着年龄的增长而降低。因此，老年雄性小鼠表现出运动活动节律的变化：自由奔跑时间延长和活动水平降低等。为了研究睾酮替代是否可以改善与年龄相关的昼夜节律下降，我们研究了睾酮对老年雄性小鼠轮跑活动昼夜节律的影响。完整的雄性 C57BL/6J 小鼠（18-22 个月大）皮下植入装有丙酸睾酮 (TP) 或胆固醇的硅胶管。 TP处理显着降低了正常光/暗（LD）循环和持续黑暗（DD）下的每日车轮运行转数，但不影响自由运行期。对年轻雄性腺切除小鼠（3-5 个月大）进行的相同实验表明，TP 治疗显着提高了 LD 和 DD 的活动水平。这些结果表明，睾酮替代会加剧与年龄相关的昼夜节律下降。