Protective effect of green tea extract on ischemia/reperfusion-induced brain injury in Mongolian gerbils
Author: Jin Tae Hong and Seung Rel Ryu and Hye Jin Kim and Jong Kwon Lee and Sun Hee Lee and Yeo Pyo Yun and Byung Mu Lee and Pu Young Kim
Free radical-induced oxidative damages of macromolecules and cell death are important factors in the pathogenesis of ischemia/reperfusion brain injury. In the present study, an investigation as to whether green tea extract reduces ischemia/reperfusion-induced brain injury in Mongolian gerbils was conducted. The effect of green tea on the ischemia/reperfusion-induced production of hydrogen peroxide, lipid peroxidation and oxidative DNA damage (formation of 8-hydroxydeoxyguanosine), and cell death in addition to locomotor activity was studied. Two doses (0.5 or 2%) of green tea extract were added into the drinking water and to be accessed by animals ad libitum for 3 weeks prior to the induction of ischemia. A global ischemia was induced by the bilateral occlusion of the common carotid arteries for 5 min. Reperfusion was achieved by releasing the occlusion and restoring blood circulation for 48 h. The infarction volumes were 112±31 mm3 and 76±11 mm3 in the 0.5 and 2% green tea pretreated animals compared to 189±12 mm3 in the ischemia/reperfusion animals. Green tea extract also reduced the levels of ischemia/reperfusion-induced hydrogen peroxide (from 1470±170 to 1034±46 and 555±30 nmole/mg protein), lipid peroxidation products (from 1410±210 to 930±40 and 330±20 nmole/mg protein) and 8-oxodG (from 3.9±0.1 to 2.8±0.3 and1.9±0.3 ng/μg DNA, ×10−2) by pretreatment of 0.5 or 2% green tea for 3 weeks, respectively. Moreover, green tea also reduced the number of ischemia/reperfusion-induced apoptotic cells (from 59±12 to 37±8, 15±11 apoptotic cells/high power field in the striatum region) and locomotor activity (from 15140±2940 to 3900±600 and 4100±1200). This study therefore suggests that green tea may be a useful agent for the prevention of cerebral ischemia damage.