Immunohistochemical study of synaptophysin expression in rat hippocampus during aging

Abstract

AbstractBackgroundIn the process of aging, there is a general decrease in the physiological functions of the body, including cognitive ones. Cognitive abilities are a decisive factor in determining the quality of life of older people.Method2 groups were formed: group 1 ‐ rats at the age of 12 months (n = 10), group 2 ‐ rats at the age of 24 months (n = 10). The degree of expression of synaptophysin and the relative area of the immunoreactive material in the dorsal and ventral hippocampus were determined.ResultImmunohistochemical study using antibodies against synaptophysin in 12‐ and 24‐month‐old animals revealed a crescent‐shaped distribution of immunoreactive material in the neuropil of the pyramidal layer CA1‐CA4 of the dorsal hippocampus, most pronounced in old animals. In 24‐month‐old animals, an increase in the degree of expression of the immunoreactive material in the neuropil of the pyramidal, radial and molecular layers CA1 and CA3 of the dorsal hippocampus was revealed. In 12‐month‐old animals, in the neuropil of the pyramidal layer in CA1 and CA3 of the ventral hippocampus, a high degree of orderliness was found in the arrangement of dendrites in the radial layer and the distribution of immunoreactive material over the surface of the dendrites in the pyramidal and radial layers of the hippocampus, the most pronounced in CA1. At the same time, no age‐dependent increase in the degree of expression of the immunoreactive material was found in the ventral hippocampus. We also did not reveal a significant increase or decrease in the relative area of the immunoreactive material in either the dorsal or ventral hippocampus.ConclusionDuring aging in rats at the age of 24 months, an increase in the degree of expression of synaptophysin‐immunoreactive material in the neuropil of the pyramidal, radial and molecular layers CA1 and CA3 of the dorsal hippocampus was revealed, which may be associated with the redistribution of synaptic vesicles in the presynaptic part of the synapses with their predominant localization in the presynaptic membranes, which determines the increase in the degree of expression of synaptophysin.