Active Component in Green Tea Catechins and Effective Intake Period for Prevention of Age-related Brain Dysfunction

Abstract

Objective: We previously found that green tea catechins (GT-catechin) decrease oxidative damage to DNA and suppress brain dysfunction in aged senescence-accelerated mice (SAMP10). To clarify the effect of GT-catechin on suppression of brain dysfunction, we compare the effect on learning ability among several catechins and examined the essential intake period for prevention of brain dysfunction.Methods: Male SAMP10 mice were allowed free access to water containing epigallocatechin gallate (EGCG, 0.06 mg/ml), epigallocatechin (EGC, 0.03 mg/ml), GT-catechin (0.2 mg/ml), or green tea extract (0.66 mg/ml). Learning ability of mice was measured using a step-through passive avoidance task.Results: SAMP10 mice exhibit brain dysfunction with aging. However, learning ability was significantly higher in mice that drank GT-catechin and EGCG than same-aged control mice that drank water. EGCG was an important component, but EGC had no effect on learning ability. The learning ability was significantly improved in mice that ingested EGCG for > 5 months, and tended to improve in mice that ingested EGCG for 2 or 3 months. Next, the level of synaptophysin, a marker of presynapse, tended to be higher in mice that ingested EGCG but not in mice that ingested EGC. The levels of synaptophysin were significantly higher in mice ingested GT-catechin and green tea extract than control mice.Conclusion: The intake of EGCG, the major catechin in green tea, but not EGC, suppressed age-related brain dysfunction. The effective intake period of EGCG was > 5 months for suppression of brain dysfunction.