As males age, systemic testosterone (T) levels decline. T regulates executive function, a collection of cognitive processes that are mediated by the mesocorticolimbic system. Here, we examined young adult (5 months) and aged (22 months) male Fischer 344 × Brown Norway rats, and measured systemic T levels in serum and local T levels in microdissected nodes of the mesocorticolimbic system (ventral tegmental area (VTA), nucleus accumbens (NAc), medial prefrontal cortex (mPFC), and orbitofrontal cortex (OFC)). We also measured androgen receptor (AR) immunoreactivity (-ir) in the mesocorticolimbic system. As expected, systemic T levels decreased with age. Local T levels in mesocorticolimbic regions - except the VTA - also decreased with age. Mesocorticolimbic T levels were higher than serum T levels at both ages. AR-ir was present in the VTA, NAc, mPFC, and OFC and decreased with age in the mPFC. Taken together with previous results, the data suggest that changes in androgen signaling may contribute to changes in executive function during aging.

中文翻译：

---

衰老对雄性大鼠中皮质皮质系统中睾丸激素和雄激素受体的影响。

随着男性年龄的增长，全身性睾丸激素（T）水平下降。T调节执行功能，这是由中皮层皮质系统介导的认知过程的集合。在这里，我们检查了成年雄性（5个月）和成年（22个月）雄性Fischer 344×棕色挪威大鼠，并测量了中皮质皮质系统微切结点（腹侧被盖区（VTA））中血清中的全身T水平和局部T水平。伏伏核（NAc），内侧前额叶皮层（mPFC）和眶额叶皮层（OFC））。我们还测量了中皮层皮质系统中的雄激素受体（AR）免疫反应性（-ir）。正如预期的那样，全身性T水平随年龄下降。除VTA外，中皮质皮质区的局部T水平也随着年龄而降低。在两个年龄段，中皮质皮质T水平均高于血清T水平。在VTA，NAc，mPFC，和OFC，并且随着年龄的增长而降低。结合以前的结果，数据表明雄激素信号的变化可能有助于衰老过程中执行功能的变化。