Remission of hair loss and induction of hair regrowth by botulinum neurotoxin A in mice

Abstract

The present research concerns the use of botulinum neurotoxin serotype A (BoNT/A) in preventing hair loss and favoring hair regrowth in subjects suffering alopecia areata. The model used was the relatively common form of hair loss, which arises spontaneously in C57BL/6 (B6) and B6×129Sv substrains. These mice initiate losing their hairs at the 3rd–4rd month of age, predominantly in the head–neck region, with alopecia quickly proceeding in a nuchal–caudal direction over all the back. We found that mice subjected to a single BoNT/A microinjection (15 pg/mouse), subcutaneously into the alopecic area, showed a significant long-lasting reduction of hair loss and stimulation of the hair follicle regeneration. Because of numerous endogenous molecules like growth factors, cytokines, hormones and neuropeptides profoundly influencing the hair follicle cycle, we suggest that BoNT/A, which blocks the release of various presynaptic neuromediators, could inhibit hair loss and induce hair regrowth by blocking the release of pro-inflammatory factors responsible for neurogenic inflammation. We can hypothesize that BoNT/A application could be useful to treat the androgenetic alopecia and other forms, such as stress-induced hair loss, caused by neurogenic inflammation and/or autoimmune pathologies, by chemotherapies, and more generally by hormonal dysfunctions. Further studies will improve our knowledge about this relevant thematic of research.