Effects of transient cerebral isehemia on expression of AQP-4 of hippocampal in aged rats

Objective To investigate the effects of transient cerebral isehemia on expression of AQP-4 of hippocampal in aged rats. Methods One-hundred and sixty healthy Wistar rats aged 19-21 months weighing 420-670 g were randomly divided into 4 groups (n=40 each): group Ⅰ sham operation (S) and group Ⅱ,Ⅲ, Ⅳwere subjected to 1, 3 and 5 rain global cerebral ischemia respectively. Global cerebral ischemia was produced by simultaneous occlusion of two vertebral and two carotid arteries according to pulsinelli. Global cerebral isehemia was confirmed by loss of consciousness, pale conjunctiva, diluted pupil and straight line EEG tracing. Four animals were decapitated and brains were removed for histological examination with light microscope and determination of brain water content (W/D weight ratio), expression of AQP-4 (by SABC immano-histochemical technique) and detection of neuronal apoptosis (by TUNEL) in hippocampus at 12 h,1,2,3 and 7 d after global cerebral ischemia. Results There was no significant difference in brain water content and expression of AQP-4 in hippocampus among group Ⅱ ,Ⅲ and group S. Brain water content and AQP-4 expression and neuronal apoptosis in hippocampus were significantly higher in group Ⅳ than in group S. Hippoeampal histological damage was severest in group Ⅳ . Conclusion Transient cerebral ischemia can induce cerebral edema through up-regulation of AQP-4 expression in the brain tissue in aged rats. Key words: lschemic attack, transient; Aquaporina; Hippoeampus; Aged