Riddle D R, Forbes M E
Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1010, USA.
Neurobiol Aging. 2005 Jul;26(7):1035-50. doi: 10.1016/j.neurobiolaging.2004.09.010. Epub 2004 Nov 24.
Measures of metabolic activity can provide useful indices of the effects of aging on neural function, since sustained changes in neural activity alter metabolic demand and the activity of metabolic enzymes. Previous reports of effects of aging on key enzymes for oxidative metabolism are mixed, however, with some reports that activity declines in the aging brain and others that activity remains stable or increases. We used high-resolution, quantitative histochemistry to test whether cytochrome oxidase (CO) activity changes in the forebrain during adulthood and senescence, measuring activity in each layer of the hippocampus and several cerebral cortical areas. In most forebrain regions, average cytochrome oxidase activity was slightly higher in middle-aged than in young adult rats but did not differ between middle-aged and old rats. Thus, there was no significant change in cytochrome oxidase activity with senescence. Additional analyses indicated that cytochrome oxidase activity is regulated regionally in the brain, as well as focally, and that differences in regional regulation may contribute to variation in CO activity among individuals, which was greater in young and old rats than in middle-aged animals.
代谢活动的测量可以为衰老对神经功能的影响提供有用的指标，因为神经活动的持续变化会改变代谢需求和代谢酶的活性。然而，先前关于衰老对氧化代谢关键酶影响的报道并不一致，一些报道称衰老大脑中的酶活性下降，而另一些报道则称酶活性保持稳定或增加。我们使用高分辨率定量组织化学方法，来测试成年期和衰老期前脑细胞色素氧化酶（CO）活性是否发生变化，测量海马体各层和几个大脑皮层区域的活性。在大多数前脑区域，中年大鼠的平均细胞色素氧化酶活性略高于年轻成年大鼠，但中年大鼠和老年大鼠之间没有差异。因此，随着衰老，细胞色素氧化酶活性没有显著变化。进一步分析表明，细胞色素氧化酶活性在大脑中受到区域和局部调节，区域调节的差异可能导致个体间CO活性的差异，这种差异在年轻和老年大鼠中比中年动物更大。
