The Effect of Delayed Administration of Green Tea Polyphenol, (-)-epigallocatechin-3-gallate, on the Change of Putrescine Level and Hippocampal Neuronal Cell Damage after Transient Global Ischemia in Gerbil

Abstract

Objective：(-)-Epigallocatechin gallate(EGCG) ‘a green tea polyphenol’ is a potent antioxidant and known to reduce the free radical-induced lipid peroxidation. In our previous study, systemic administration of EGCG immediately after ischemia has been shown to inhibit the hippocampal neuronal damage in the gerbil model of global ischemia. Polyamines, especially putrescine(PU) is thought to be important in the generation of brain edema and neuronal cell damage associated with various types of excitotoxic neuronal injury. We investigate the effects of delayed administration of EGCG on the changes in polyamine levels and neuronal damage after transient global ischemia in gerbils. Methods：To produce transient global ischemia, both common carotid arteries were occluded for 3 min with micro-clips. The gerbils were treated with EGCG(50mg/kg, i.p.) immediately or 2hr after ischemia. Putrescine levels were examined in the cerebral cortex and hippocampus 24 hours after ischemia using high per-formance liquid chromatography. Results：PU levels in the cerebral cortex and hippocampus were increased significantly after the ischemia. The administrations of EGCG immediately after the ischemia attenuated the ischemia-induced increase of PU level, however, 2 hr delayed EGCG administration did not reduce the increase of PU level. EGCG administered immediately or 2 hr after ischemia significantly reduced neuronal damage in the hippocampal CA1 region, respectively. Conclusion：These findings suggest that EGCG may has a promise in the management of stroke.