Epigallocatechin gallate affects survival and metabolism of human sperm

Scope Green tea and its major constituent epigallocatechin gallate (EGCG) have been extensively studied as potential treatment for a variety of diseases. We assessed the influence of EGCG on male fertilizing potential by analyzing different features of human sperm involved in capacitation process. Methods and results Using human normozoospermic samples, we evaluated the effect of EGCG (2 mu M, 20 mu M, 60 mu M) on sperm activities. Our results showed that lower doses of EGCG (from 2 to 20 mu M) increased cholesterol efflux and tyrosine phosphorylation through the estrogen receptor (ER), since ICI 182,780, a specific ER antagonist, abrogated 20 mu M EGCG effects. Besides, we evidenced that EGCG at similar concentrations, increased sperm motility, viability, and phosphorylation of proteins controlling cell survival such as Bcl2, Akt, and Src, via ER. Furthermore, we observed reduction of triglycerides content, induction of lipase, as well as the G6PDH activity. These results address to an increase in energy expenditure. On the contrary, treatment of 60 mu M EGCG produced opposite effects that still appear after ICI cotreatment. Conclusion These results provide a novel mechanism involving ERs through which low doses of EGCG exerted benefits to sperm physiology, also detected data evidence the adverse action of high EGCG concentrations probably related to its prooxidant and antiestrogenic potential.