Previously, we have demonstrated that policosanol from Chinese wax suppressed testosterone(T)-induced alopecia in mice. However, the underlying mechanism remained to be determined. Herein, we investigated the mechanism of policosanol against androgenetic alopecia (AGA). AGA was induced in Kunming mice by subcutaneous administration of testosterone propionate for 60 d. Policosanol (0.5 %, 1% or 2%) was applied topically on the back of mice. Finasteride (2%) was applied topically as a positive control. The serum T and estradiol (E2) concentrations were determined by ELISA after 28 and 60 days of treatment. The cutaneous expression or activity of key mediators of hair growth, such as alkaline phosphatase (ALP), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF), was measured. MTS assay was performed to evaluate cell proliferation in cultured human dermal papilla cells (DPCs) treated with dihydrotestosterone (DHT). Western blotting was performed to evaluate the protein expression of Bax, Bcl2, TGF-β2, caspase-9, and caspase-3. We found lower T and T/E2 ratio in mice treated with policosanol than in the model group. Policosanol suppressed premature hair follicle entry into the regression phase, as shown by improving VEGF and EGF expression and ALP activity. The MTS assay showed that policosanol markedly inhibited the apoptosis of DHT-treated DPCs. Western blotting showed that policosanol significantly reduced the protein expression of TGF-β2, cleaved caspese-9, cleaved caspase-3, and Bax, and increased that of Bcl2. The optimal effect was obtained with 12.50 g/mL policosanol. In conclusion, policosanol prevents androgenetic alopecia by regulating hormone levels and suppressing premature hair follicle entry into the regression phase.
Keywords: Androgen; Cytokines; Dermal papilla cells; Estradiol; Policosanol; Protein.
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