Expression of bystin in reactive astrocytes induced by ischemia/reperfusion and chemical hypoxia in vitro

In this study, we investigated the effects of ischemia/reperfusion and chemical hypoxia on the morphology, cell viability and expression of bystin and glial fibrillary acidic protein (GFAP) in primary cultured astrocytes which were prepared by the subculture method. The astrocytes in Hank's medium without glucose and serum (oxygen–glucose deprivation, ischemic cells) were first exposed to 1% O2 and then to 21% O2 (normoxia), or treated with different concentrations of CoCl2 or NaN3 for different periods. Relevant observations and measurements were then conducted. The findings showed that treatment with 1% O2 for 0.5 or 3 h could induce a characteristic ‘reactive’ morphology and a significant increase in cell viability and total protein amount. The western blot analysis showed that treatment with 1% O2 for 0.5 or 3 h also induced a significant increase in the expression of bystin and that the response of bystin to mild ischemia was much more sensitive than that of GFAP. Similar results were also found in the cells treated with mild chemical hypoxia. The data demonstrated for the first time that mild ischemia and hypoxia could activate astrocytes and that bystin is a much more sensitive marker in activated astrocytes induced by ischemia and hypoxia as compared to GFAP. The significant up-regulation of bystin suggests that bystin may play an important role in the activation of astrocytes as well as in the neuroprotective role of hypoxic and ischemic preconditioning.