Alterations in the somatodendritic structure of spiny neurons in human putamen during physiological aging

Abstract

Abstract Introduction. The striatum is involved in regulation of cognitive functions and behavior, including planning motor behavior, decision making, motivation, and rewarding. The human striatum contains the putamen, in whose medium spiny neurons certain qualitative and quantitative alterations in somatodendritic structure occur with aging. Materials and methods . The morphometric parameters of spiny neurons in the striatum of humans (females) during the second maturity period and senility were investigated. The Golgi silver impregnation method was used as the staining technique. The following parameters were assessed: the area of neuronal body, the number of dendrites, the number of free ends of all dendrites, the largest dendritic field radius, the total length of all dendrites, the dendritic field area, and the specific density of dendrites. Results . It was demonstrated that in terms of soma size, the number of dendrites, the number of free ends of dendrites, and specific density of dendrites, there are negligible differences in spiny neurons in the putamen in humans of both ages in the samples under study. The parameters of the largest dendritic field radius, the total length of all dendrites and the dendritic field area for the senile individuals were significantly lower (p<0.05) than for the mature ones by 11, 13, and 15%, respectively. The total number of spines per 100 µm of dendrite in senile individuals was lower by 18% compared to that in women during the second period of maturity. The features of distribution of spines of different types over the putamen neurons in mature and senile individuals show the role played by mushroom-like spines in preservation and maintenance of synaptic connections required to ensure the elementary functions of putamen neurons. Conclusions . Hence, we have demonstrated reduction in dendrite length and density of dendrite spines upon aging in women. The results broaden the views about the nature of plastic alterations that take place in cerebral neurons in humans upon aging.