Analysis of the role of CRH in the regulation of hair cycle using CRH knockout mouse

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The objective of the present study is to elucidate the role of the cutaneous CRH-POMC system on the regulation of the murine hair cycle. In the prededing year (2003) we demonstrated that psychological stress prolonged the telogen stage of the hair cycle via the action of CRH which was strongly expressed in follicular keratinocytes and sebaceous gland cells. In the present year (2004) we analyzed the possible mechanism of depilation induced hair cycling using CRH knockout mouse and wild mouse.The result showed that the rapid expression and production of nerve growth factor(NGF) in the early anagen stage (anagen I-III) in follicular keratinocytes, sebaceous gland cells and smooth muscle cells. Glial cell line-derived neutrophic factor(GDNF), substance P(SP), ACTH and melanocyte stimulating hormone(MSH) were also found to fluctuate during the depilation induced hair cycling. Subsequently SP positive nerve fibers and activated mast cells increased in number in the dermis and adipose tissue. There was no difference in their expression and production between both mouse models.We postulate a surge in NGF production and subsequent release of SP from nerve endings are significant in the induction and progression of the spontaneous hair cycling. There is a possibility that these neurotrophilic factors stimulate the expression of cutaneous POMC without the presence of CRH.