HSP70 expression in the hippocampal CA3 subfield in different chronic stress models

This study examined the heat shock protein 70 (HSP70) expression in hippocampal CA3 subfield of rats in different chronic stress models. The chronic restraint stress (CRS) and the chronic mild stress (CMS) models were used in this study. Observation of exploratory behavior in an open field test indicated stress level. The expression of HSP70 in hippocampal CA3 subfield was measured by immunohistochemical methods. The results showed that the number of quadrant crossing in both CRS and CMS groups decreased more than that of the control (P < 0.01). CRS group crossing decreased more than CMS group. Damage in the hippocampus of the CMS group occurred later and to a less extent than that of the CRS group. Compared with CMS group, the expression of HSP70 was greater in the CRS group. Moreover, increased stress duration enhanced these effects. These results show that the CRS model affects both exploratory behavior and HSP70 expression in the hippocampus more dramatically than the CMS model.