Ginsenosides Rb1 and Rd Regulate Proliferation of Mature Keratinocytes Through Induction of p63 Expression in Hair Follicles

Ginsenosides Rb₁ and Rd are the two main types of ginsenosides in Panax ginseng and have been used as an additive to against alopecia. However, the mechanisms involved are largely unknown. To determine how ginsenosides prevent hair loss, we topically applied protopanaxadiol-type ginsenosides Rb₁ and Rd over the shaved skin of B57CL/6 mice, and monitored and assessed them for 35 days. We then investigated the effects of ginsenosides on cell genesis in different phases of adult hair follicles (HFs), using 5-bromo-2'-deoxyuridine as a marker for dividing cells. Moreover, p63, a specific marker and a major regulator of keratinocyte progenitor cells of the multi-layered epithelia, was detected in epidermis. Results indicated that treatment with ginsenosides Rb₁ and Rd increased cell proliferation in both anagen and telogen of HFs. However, it had no significant effect on the survival of cells in the bulge and upper follicle region. Investigation of p63 demonstrated that up-regulation of p63 expression in the matrix and outer root sheath might be one of the mechanisms by which ginsenosides Rb₁ and Rd promote cell proliferation in HFs. Our study reveals a novel mechanism by which ginsenoside promotes hair growth through p63 induction in follicular keratinocytes and indicates that ginsenosides Rb₁ and Rd might be developed as a therapeutic agent for the prevention of hair loss.