Effect of topical application of raspberry ketone on dermal production of insulin-like growth factor-I in mice and on hair growth and skin elasticity in humans
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Naoaki Haradaa, Kenji Okajimaa, Corresponding Author Contact Information, E-mail The Corresponding Author, Noriko Narimatsua, Hiroki Kuriharab and Naomi Nakagatac
aDepartment of Translational Medical Science Research, Nagoya City University Graduate School of Medical Sciences, Kawasumi 1, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
bDepartment of Physiological Chemistry and Metabolism, University of Tokyo Graduate School of Medicine, Tokyo, Japan
cDivision of Reproductive Engineering, Center for Animal Resources and Development, Kumamoto University, Japan
Received 10 September 2007;
revised 21 December 2007;
accepted 12 January 2008.
Available online 5 March 2008.
Abstract
Sensory neurons release calcitonin gene-related peptide (CGRP) on activation. We recently reported that topical application of capsaicin increases facial skin elasticity and promotes hair growth by increasing dermal insulin-like growth factor-I (IGF-I) production through activation of sensory neurons in mice and humans. Raspberry ketone (RK), a major aromatic compound contained in red raspberries (Rubus idaeus), has a structure similar to that of capsaicin. Thus, it is possible that RK activates sensory neurons, thereby increasing skin elasticity and promoting hair growth by increasing dermal IGF-I production. In the present study, we examined this possibility in mice and humans. RK, at concentrations higher than 1 μM, significantly increased CGRP release from dorsal root ganglion neurons (DRG) isolated from wild-type (WT) mice and this increase was completely reversed by capsazepine, an inhibitor of vanilloid receptor-1 activation. Topical application of 0.01% RK increased dermal IGF-I levels at 30 min after application in WT mice, but not in CGRP-knockout mice. Topical application of 0.01% RK increased immunohistochemical expression of IGF-I at dermal papillae in hair follicles and promoted hair re-growth in WT mice at 4 weeks after the application. When applied topically to the scalp and facial skin, 0.01% RK promoted hair growth in 50.0% of humans with alopecia (n = 10) at 5 months after application and increased cheek skin elasticity at 2 weeks after application in 5 females (p < 0.04). These observations strongly suggest that RK might increase dermal IGF-I production through sensory neuron activation, thereby promoting hair growth and increasing skin elasticity.
Purchase the full-text article
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Naoaki Haradaa, Kenji Okajimaa, Corresponding Author Contact Information, E-mail The Corresponding Author, Noriko Narimatsua, Hiroki Kuriharab and Naomi Nakagatac
aDepartment of Translational Medical Science Research, Nagoya City University Graduate School of Medical Sciences, Kawasumi 1, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
bDepartment of Physiological Chemistry and Metabolism, University of Tokyo Graduate School of Medicine, Tokyo, Japan
cDivision of Reproductive Engineering, Center for Animal Resources and Development, Kumamoto University, Japan
Received 10 September 2007;
revised 21 December 2007;
accepted 12 January 2008.
Available online 5 March 2008.
Abstract
Sensory neurons release calcitonin gene-related peptide (CGRP) on activation. We recently reported that topical application of capsaicin increases facial skin elasticity and promotes hair growth by increasing dermal insulin-like growth factor-I (IGF-I) production through activation of sensory neurons in mice and humans. Raspberry ketone (RK), a major aromatic compound contained in red raspberries (Rubus idaeus), has a structure similar to that of capsaicin. Thus, it is possible that RK activates sensory neurons, thereby increasing skin elasticity and promoting hair growth by increasing dermal IGF-I production. In the present study, we examined this possibility in mice and humans. RK, at concentrations higher than 1 μM, significantly increased CGRP release from dorsal root ganglion neurons (DRG) isolated from wild-type (WT) mice and this increase was completely reversed by capsazepine, an inhibitor of vanilloid receptor-1 activation. Topical application of 0.01% RK increased dermal IGF-I levels at 30 min after application in WT mice, but not in CGRP-knockout mice. Topical application of 0.01% RK increased immunohistochemical expression of IGF-I at dermal papillae in hair follicles and promoted hair re-growth in WT mice at 4 weeks after the application. When applied topically to the scalp and facial skin, 0.01% RK promoted hair growth in 50.0% of humans with alopecia (n = 10) at 5 months after application and increased cheek skin elasticity at 2 weeks after application in 5 females (p < 0.04). These observations strongly suggest that RK might increase dermal IGF-I production through sensory neuron activation, thereby promoting hair growth and increasing skin elasticity.