Methionine Dependence of Hair Maintenance in C57BL/6 Mice

Hair-follicle keratinocytes contain high levels of cysteine, which is derived from methionine, rapidly proliferate, and form the hair shaft. The high proliferation rate of hair-follicle keratinocytes resembles that of aggressive cancer cells. In the present study, we determined the effect of a methionine-deficient diet on hair loss (alopecia) in mice with or without homocysteine supplementation.

Mice were fed a normal rodent diet (2020X, ENVIGO) (Group 1); a methionine-choline-deficient diet (TD.90262, ENVIGO) (Group 2); a methionine-choline-deficient diet with a 10 mg/kg/day supply of homocysteine administered by intra-peritoneal (i.p.) injection for 2 weeks (Group 3). In Group 2, mice were fed a methionine-choline-deficient diet for an additional 2 weeks but with 10 mg/kg/day of i.p. l-homocysteine and the mice were observed for two additional weeks. Subsequently, the mice were fed a standard diet that included methionine. Hair loss was monitored by photography.

After 14 days, hair loss was observed in Group 2 mice on a methionine-restricted diet but not in Group 3 mice on the methionine-restricted diet which received i.p. homocysteine. In Group 2, at 2 weeks after methionine restriction, hair loss was not rescued by homocysteine supplementation. However, after restoration of methionine in the diet, hair growth resumed. Thus, after 2 weeks of methionine restriction, only methionine restored hair loss, not homocysteine.

Hair maintenance requires methionine in the diet. Future experiments will determine the effects of methionine restriction on hair-follicle stem cells.