Effects of the Selective TrkA Agonist Gambogic Amide on Pigmentation and Growth of Human Hair Follicles In Vitro

The study from 2019 examined the effects of Gambogic Amide, a selective TrkA agonist, on human hair follicle pigmentation and growth in vitro. TrkA, which is expressed in hair follicle melanocytes and keratinocytes, plays a role in cell proliferation, differentiation, and apoptosis, all of which are crucial for hair pigmentation and growth. The study found that Gambogic Amide prevented pigment loss and stimulated hair shaft elongation by increasing melanocyte activation, migration, and dendricity, as indicated by enhanced c-KIT expression in melanocyte sub-populations. Gambogic Amide was shown to maintain pigmentation more effectively than nerve growth factor (NGF), which could decrease pigmentation at higher doses. The treatment did not induce hair dystrophy or premature hair follicle regression and kept hair follicles in the anagen phase, suggesting its potential as an anti-aging treatment for hair health. The study concluded that Gambogic Amide could be a promising agent for protecting hair follicle pigmentation and promoting hair growth. The number of hair follicles used in the study was not mentioned.