The expression of heat shock protein 70 in cultured mouse astrocytes after hypoxia/reoxygenation

Objective To investigate the expression of heat shock protein 70(HSP70) mRNA and the immunoreactivity in cultured mouse astrocytes after exposure to hypoxia/reoxygenation. Methods Mouse cerebral cortical astrocytes from 1 2 days newborn Kunming mice were undergone the pure culture and exposed to hypoxia. The duration of hypoxia was 3, 6, 12, 24 and 48 hours. After 24 hours hypoxia, the reoxygenation time was 0, 3, 6, 12, 24 and 48 hours. The expressions of HSP70 mRNA and HSP70 protein were detected by in situ hybridization and immunohistochemiscal methods, respectively. Results The HSP70 mRNA expression was shown by in situ hybridization 3 hours after hypoxia, and the expression of HSP70 mRNA increased with lengthening hypoxic time. The peak time of the HSP70 mRNA expression was 6 hours. There was no HSP70 mRNA expression in controls. The expression of HSP70 protein could hardly be detected after hypoxic. After the treatment of reoxygenation in astrocytes, the expression of HSP70 mRNA could be detected, and the expression of HSP70 protein could also be detected. Conclusion Although the hypoxia could induce the expression of HSP70 mRNA, the synthesis of HSP70 protein could only be observed after reoxygenation. It is possible that HSP70 might play a protective role in hypoxia/reoxygenation of astrocytes.