Morgenstern Nicolás A, Lombardi Gabriela, Schinder Alejandro F
Laboratory of Neuronal Plasticity, Leloir Institute - CONICET, Avenida Patricias Argentinas 435, (1405) Buenos Aires, Argentina.
J Physiol. 2008 Aug 15;586(16):3751-7. doi: 10.1113/jphysiol.2008.154807. Epub 2008 Jun 19.
The dentate gyrus of the hippocampus generates neurons throughout life, but adult neurogenesis exhibits a marked age-dependent decline. Although the decrease in the rate of neurogenesis has been extensively documented in the ageing hippocampus, the specific characteristics of dentate granule cells born in such a continuously changing environment have received little attention. We have used retroviral labelling of neural progenitor cells of the adult mouse dentate gyrus to study morphological properties of neurons born at different ages. Dendritic spine density was measured to estimate glutamatergic afferent connectivity. Fully mature neurons born at the age of 2 months display approximately 2.3 spines microm(-1) and maintain their overall morphology and spine density in 1-year-old mice. Surprisingly, granule cells born in 10-month-old mice, at which time the rate of neurogenesis has decreased by approximately 40-fold, reach a density of dendritic spines similar to that of neurons born in young adulthood. Therefore, in spite of the sharp decline in cell proliferation, differentiation and overall neuronal number, the ageing hippocampus presents a suitable environment for new surviving neurons to reach a high level of complexity, comparable to that of all other dentate granule cells.
海马体的齿状回在整个生命过程中都会产生神经元，但成年神经发生呈现出明显的年龄依赖性下降。尽管在衰老的海马体中神经发生速率的降低已被广泛记录，但在这样一个不断变化的环境中产生的齿状颗粒细胞的具体特征却很少受到关注。我们利用逆转录病毒标记成年小鼠齿状回的神经祖细胞，来研究不同年龄出生的神经元的形态学特性。通过测量树突棘密度来估计谷氨酸能传入连接。2个月大时出生的完全成熟的神经元显示出大约2.3个棘/微米，并在1岁小鼠中保持其整体形态和棘密度。令人惊讶的是，在10个月大的小鼠中出生的颗粒细胞，此时神经发生速率已下降了约40倍，其树突棘密度达到了与成年早期出生的神经元相似的水平。因此，尽管细胞增殖、分化和总体神经元数量急剧下降，但衰老的海马体为新存活的神经元提供了一个合适的环境，使其能够达到与所有其他齿状颗粒细胞相当的高度复杂性。
