Effects of topical application of EGCG on testosterone-induced hair loss in a mouse model.

We investigated the effect of topical epigallocatechin-3-gallate (EGCG) on testosterone (T)-induced hair loss in mice. Marked hair loss was observed at the T-injected site, and topical EGCG significantly reduced the hair loss (P < 0.05). TUNEL staining showed apoptosis of follicular epithelial cells in the T-injected groups where topical EGCG was found to significantly diminish T-induced apoptosis (P < 0.05). Topical EGCG down-regulated the T-induced expression of androgen receptor but did not down-regulate 17 beta-hydroxysteroid dehydrogenase (HSD) and three beta-HSD expression. Analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS) on serum and tissue samples revealed no significant difference in T and dihydrotestosterone concentrations between the T-injected and T + EGCG groups. Thus, we found that T injection in a mouse model induces hair loss by apoptosis of the hair follicles rather than through the androgen metabolic pathway and also saw that T-induced apoptosis of hair follicles was reduced by topical EGCG.