Protective effects of the green tea polyphenol (-)-epigallocatechin gallate against hippocampal neuronal damage after transient global ischemia in gerbils.

Recent studies have shown that green tea polyphenols reduce free radical-induced lipid peroxidation. Oxygen free radical injury plays an important role in neuronal damage induced by brain ischemia and reperfusion. The purpose of this study was to examine whether (-)-epigallocatechin gallate (EGCG) would reduce neuronal damage after transient global ischemia in the gerbils because EGCG has a potent antioxidant property as a green tea polyphenol. To produce transient global ischemia, both common carotid arteries were occluded for 3 min with microaneurysmal clips. The gerbils were treated with EGCG (10, 25, or 50 mg/kg, i.p.) immediately after ischemia. Neuronal cell damage in the hippocampal CA1 region was evaluated quantitatively 5 days after ischemia by a blinded investigator. EGCG at the dose of 10 mg/kg failed to reduce hippocampal neuronal damage. However, EGCG when administered at the dose of 25 or 50 mg/kg significantly reduced hippocampal neuronal damage in a dose-dependent manner (P<0.001, respectively). The present results show that the green tea polyphenol, EGCG, has a neuroprotective effect against neuronal damage following global ischemia in the gerbils.