A Study of Heat Shock Protein Hsp40 Expression in the Brain of Normotensive and Hypertensive Rats after Long-Term Social Isolation

Recently, the effects of social isolation have been actively studied due to its negative impact on the mental and cognitive processes of higher nervous activity in humans and animals. At the cellular level, the damaging effects of social isolation to brain structures remain poorly studied. Here, we examined the expression of heat shock protein Hsp40 in the neocortex and hippocampus of normotensive rats of Wistar (NWR) and Wistar-Kyoto (WKY) genotypes and spontaneously hypertensive rats (SHR) following 14-week isolation. Hsp40 expression of in the brain was evaluated using immunohistochemical labeling followed by quantitative microscopic analysis. The mRNA expression of the Dnajc6 gene, one of the neuron-specific genes of the family, was accessed using quantitative PCR in the frontal cortex and hippocampus. We found that Hsp40 expression was higher in WKY and SHR rats compared to NWRs in neocortical layers II, III, and IV. Isolation increased Hsp40 expression in neocortical layer V. Same differences in Hsp40 expression were revealed in the hippocampus. Specifically, the higher expression was observed in the CA1, CA3 fields and the dentate gyrus of WKY and SHR rats compared to NWR rats, and in the dentate gyrus, the differences were observed between WKY and SHR rats. Isolation increased Hsp40 expression in all the groups studied, but this effect was more pronounced in SHRs. Thus, social isolation damaged cells in the neocortex and hippocampus stimulating the expression of Hsp40.