Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil ; Instituto Nacional de Neurociência Translacional São Paulo, Brazil.
Front Neuroanat. 2012 Oct 26;6:45. doi: 10.3389/fnana.2012.00045. eCollection 2012.
Aging-related changes in the brain have been mostly studied through the comparison of young adult and very old animals. However, aging must be considered a lifelong process of cumulative changes that ultimately become evident at old age. To determine when this process of decline begins, we studied how the cellular composition of the rat brain changes from infancy to adolescence, early adulthood, and old age. Using the isotropic fractionator to determine total numbers of neuronal and non-neuronal cells in different brain areas, we find that a major increase in number of neurons occurs during adolescence, between 1 and 2-3 months of age, followed by a significant trend of widespread and progressive neuronal loss that begins as early as 3 months of age, when neuronal numbers are maximal in all structures, until decreases in numbers of neurons become evident at 12 or 22 months of age. Our findings indicate that age-related decline in the brain begins as soon as the end of adolescence, a novel finding has important clinical and social implications for public health and welfare.
大脑的衰老相关变化主要通过比较年轻成年动物和非常老年动物来研究。然而，衰老必须被视为一个终身的累积变化过程，最终在老年时变得明显。为了确定这个衰退过程开始的时间，我们研究了大鼠大脑的细胞组成如何从婴儿期到青春期、成年早期和老年期发生变化。我们使用各向同性分馏器来确定不同脑区的神经元和非神经元细胞的总数，发现神经元数量在青春期（1 至 2-3 个月龄）之间会显著增加，随后出现广泛而渐进的神经元丢失趋势，这种趋势早在 3 个月龄时就已经开始，此时所有结构中的神经元数量达到最大值，直到 12 或 22 个月龄时神经元数量明显减少。我们的研究结果表明，大脑的衰老相关衰退早在青春期结束时就已经开始，这一新发现对公共卫生和福利具有重要的临床和社会意义。
