Chemoprevention of smoke-induced alopecia in mice by oral administration of l-cystine and vitamin B6

Summary Background We previously demonstrated that high doses of environmental cigarette smoke (ECS) induce alopecia in mice. This effect was prevented by the oral administration of N-acetylcysteine (NAC), an analogue and precursor of l -cysteine and reduced glutathione. Objectives The present study aimed at assessing whether l -cystine, the oxidized form of l -cysteine, which is a key hair component, may behave like NAC in inhibiting ECS-induced alopecia and modulating the mechanisms responsible for this condition. Methods C57BL/6 mice were exposed whole-body to ECS in a smoking machine. Groups of mice received in the diet, at three dose levels, a mixture of l -cystine with vitamin B6, which plays a role in l -cystine incorporation in hair cells. Occurrence of alopecia areas and apoptosis of hair bulb cells were evaluated for up to 6 months of exposure, and the time course induction of micronucleated erythrocytes in peripheral blood was investigated. Results The frequency of micronucleated erythrocytes was increased by ECS, irrespective of treatment with l -cystine/vitamin B6. ECS-induced alopecia and apoptosis of hair bulb cells in all exposed mice. l -Cystine/vitamin B6 inhibited alopecia in a dose-dependent fashion. Conclusions High-dose ECS induces apoptosis-related alopecia in mice, and oral administration of l -cystine/vitamin B6 is an effective preventive treatment.