title: Dietary isoflavone increases insulin-like growth factor-I production, thereby promoting hair growth in mice.
abstract: Sensory neurons release calcitonin gene-related peptide (CGRP) upon activation. We previously demonstrated that CGRP increases insulin-like growth factor-I (IGF-I) production in various tissues of mice including the skin. We demonstrated that isoflavone increases the CGRP synthesis in the dorsal root ganglion (DRG) neurons in rats. Since IGF-I plays a critical role in hair growth, we hypothesized that isoflavones may promote hair growth by increasing the IGF-I production in hair follicles. We examined this hypothesis using wild-type (WT) and CGRP-knockout (CGRP(-/-)) mice. Isoflavone significantly increased the CGRP mRNA levels in DRG neurons isolated from WT mice (P<.01). Administration of isoflavone for 3 weeks increased the dermal levels of CGRP, IGF-I and IGF-I mRNA in WT mice, but not in CGRP(-/-) mice. Isoflavone administration increased the immunohistochemical expression of IGF-I in hair follicle dermal papilla cells in WT mice. Significant enhancements of hair follicle morphogenesis, hair regrowth, and hair pigmentation were also observed in WT mice administered isoflavone. However, none of these effects in WT mice were observed in CGRP(-/-) mice. These observations strongly suggest that isoflavone might increase IGF-I production in the hair follicle dermal papilla cells in mice through increasing CGRP production in the sensory neurons, thereby promoting hair growth associated with melanogenesis in mice.
authors.affiliation: Department of Translational Medical Science Research, Nagoya City University, Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhao
authors.forename: Naoaki
authors.initials: N
authors.lastname: Harada
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurihara
authors.forename: Naomi
authors.initials: N
authors.lastname: Nakagata
authors.forename: Kenji
authors.initials: K
authors.lastname: Okajima
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D020405:Dermis / Q000378:metabolism; D004032:Diet; D005727:Ganglia, Spinal / Q000378:metabolism; D006197:Hair / Q000254:growth & development*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D007529:Isoflavones / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism*; D012879:Skin Physiological Phenomena
chemical_list: D007529:Isoflavones; D012333:RNA, Messenger; C519530:insulin-like growth factor-1, mouse; D007334:Insulin-Like Growth Factor I; D015740:Calcitonin Gene-Related Peptide