Dietary isoflavone increases insulin-like growth factor-I production, thereby promoting hair growth in mice

Dihydrotestosterone inhibits hair growth in mice by inhibiting insulin-like growth factor-I production in dermal papillae

“…We previously reported that stimulation of sensory neurons increased IGF-I production in dermal papillae through increase of its transcription, thereby promoting hair growth in mice [18]. We also reported that administration of isoflavone increased dermal IGF-I production by increasing transcription of CGRP, thereby promoting hair growth in wild-type mice, but not in CGRP-knockout mice [19]. These observations suggest that DHT may inhibit IGF-I production in dermal papillae by decreasing CGRP levels through interaction with the androgen receptor in mice.…”

“…We previously demonstrated that CGRP released from sensory neurons increased IGF-I production in dermal papillae of mice, thereby promoting hair growth [18,19]. Since fibroblasts are capable of producing IGF-I [41], it is possible that CGRP increases IGF-I production in dermal fibroblasts.…”

“…We previously demonstrated that IGF-I production in dermal papillae was increased and hair growth was promoted after sensory neuron stimulation in wild-type mice, but not in CGRP-knockout mice [18,19]. We further showed that combined administration of capsaicin and isoflavone improved alopecia in patients with androgenetic alopecia by increasing IGF-I production [18].…”

“…These observations suggest that sensory neurons may play a critical role in promotion of hair growth by the following mechanisms: exogenous substances such as capsaicin and isoflavone and endogenous substances such as anandamide and prostaglandins activate TRPV1 in sensory neurons, thereby increasing CGRP release from nerve endings [20]. CGRP in turn acts on dermal papilla cells, matrix cells, and keratinocytes to increase IGF-I production, thereby promoting hair growth [4,5,11,19].…”

Progress in Relevant Growth Factors Promoting the Growth of Hair Follicle

“…This further explained that exogenous IGF-1 in promoting hair follicle growth acted on other cells but not the dermal papilla and proved again that IGF-1 secreted by the dermal papilla played a paracrine role in division, proliferation, differentiation of the hair follicle cell. Experiments in vivo showed that either systemic or local skin injection of IGF-1 could not significantly change the growth of wool, however, IGF-1 was essential to maintain hair growth, especially in the early stages of the hair cycle, which could prevent hair follicles from entering the catagen prematurely (Zhao et al, 2011). Overexpression of IGF-binding protein 5 (IGFBP-5) in the human hair xenografts obtained from straight-and curly-haired individuals was found to result in the decreased expression of several extracellular matrix proteins and disassembly of adhesional junctions, resulting in twisted hair shafts as well as an unusual deposition of hair cuticle that may be derived from the disturbance of normal proliferation and differentiation (Sriwiriyanont et al, 2011).…”