(-)-Epigallocatechin-3-gallate decreases the impairment in learning and memory in spontaneous hypertension rats

Oxidative stress induced by hypertension has been reported to cause alterations in neural cytoarchitecture and cognitive dysfunction. Green tea catechins, especially (-)-epigallocatechin-3-gallate (EGCG), have potent antioxidative properties and protect against various oxidative damages. In this study, we examined the impact of hypertension in rats on locomotor activity, learning, and memory, and EGCG was tested for its potential therapeutic effects in treating hypertension-induced impairment. Blood pressure was measured by the tail-cuff method to confirm high blood pressure in spontaneous hypertension rats (SHRs). Locomotor activity in the open field was increased in SHRs, along with learning and memory impairment in the Morris water maze. Daily EGCG treatment reduced the progressive increase in blood pressure in SHRs, and prevented most of the increased locomotor activity in addition to improving learning and memory. EGCG treatment also decreased the increased level of lipid peroxide production in SHRs and enhanced the antioxidation power in plasma that was observed to be decreased in SHRs. EGCG also decreased the concentration of reactive oxygen species in the hippocampi of SHRs. These indicate a therapeutic effect of EGCG in treating hypertension-induced learning and memory impairment, most probably through its powerful antioxidative properties.