Abstract:

Objective   To investigate the protection of heat shock protein 70(HSP70) on the rat brain after experimental intra-cerebral hemorrhage and their effects on expression of Bcl2 and Bax proteins of nerve cells. Methods   60 Wistar rats were randomly divided into the sham operated group(n=30)， and the itra-cerebral hemorrhage group(n=30). Each group was divided into 6h, 12h, 1d, 2d, 3d and 7d groups according to time. 2μL of normal saline was injected into the caudate nucleus in the sham operated group， and 2μL of collagenase Ⅳ was injected into the caudate nucleus in the intra-cerebral hemorrhage group. Rats were killed at each time point and then their brains were isolated. Expressions of HSP70， Bax and Bcl-2 proteins in the cerebral tissue at different times were detected by using immunohistochemistry.  Results   Expressions of HSP70， Bcl-2 and Bax in the itra-cerebral hemorrhage group were higher than those in the sham operated group(P<0.01). HSP70 appeared at 6h, reached a maximum on 3d， and gradually decreased on 7d. Bcl-2 expression appeared at 6h, reached the maximum on 1d, maintained a  high state of expression on 2d, and then gradually decreased. The Bax expression reached the peak at 12h and 3d,  showed a downward trend on 1d,  and gradually decreased on 7d. Conclusions   This study demonstrates that high expression of HSP70 has an obvious protective effect on the intracerebral hemorrhage rat model, and it promotes expression of the anti-apoptotic protein Bcl-2, reduces expression of the proapoptotic protein Bax, and increases the Bcl-2/Bax ratio, thus inhibiting brain cell apoptosis and exerting a protective effect on nerve cells.

Key words: Heat-shock proteins 70； Bax protein； Bcl-2 protein； Cerebral hemorrhage