Brain-derived nerve factor (BDNF) protein expression was upregulated by approximately 12-fold in supernatants obtained from balding as compared to nonbalding DP cells (P < 0.001). Expressions of neurotrophin-3 and β-nerve growth factor were also upregulated. On the other hand, protein expressions of insulin-like growth factor (IGF)-1 and its binding proteins as well as those of the vascular endothelial growth factor (VEGF) family were significantly downregulated in the balding scalp. Conclusions:  Neurotrophic factors, especially BDNF, may be important in mediating the effects of androgens on hair follicles, serving as a negative regulatory control signal. Further studies may lead to novel pharmacologic interventions in AGA.

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