Probing the Effects of Stress Mediators on the Human Hair Follicle
December 2007
in “
American Journal of Pathology
”
substance P neuropeptide catagen substance P receptor NK1 neutral endopeptidase mast cell degranulation hair follicle immune privilege MHC class I β2-microglobulin nerve growth factor NGF NGF receptor TrkA p75NTR telogen effluvium alopecia areata anagen scalp skin hair follicles RT-PCR stress-induced hair disorders hair loss immune system stress hormone hair growth cycle hair follicle
TLDR Stress-related substance P may lead to hair loss and negatively affect hair growth.
The document from December 2007 presents a study that explored the effects of substance P, a stress-associated neuropeptide, on human hair follicles. The study demonstrated that substance P induced premature catagen development, down-regulated the substance P receptor (NK1), and up-regulated neutral endopeptidase, which degrades substance P. This was associated with mast cell degranulation and a potential collapse of the hair follicle immune privilege due to up-regulation of MHC class I and β2-microglobulin. Substance P also affected nerve growth factor (NGF) signaling by down-regulating the growth-promoting NGF receptor (TrkA) and up-regulating NGF and its apoptosis- and catagen-promoting receptor (p75NTR). These findings suggest that substance P may contribute to stress-induced hair disorders such as telogen effluvium and alopecia areata. The study used organ-cultured hair follicles from 20 different donor samples, with experiments performed on at least five donor samples per group, and involved 21 human anagen scalp skin hair follicles from three different donors, cultured for 3 days with substance P. Quantitative RT-PCR confirmed the protein expression changes, and the results were statistically significant.
