Abstract
Purpose: Interest in the augmentation of hair growth for functional and aesthetic purpose has increased dramatically in recent years. Many hair growth products have been released, but most of these have not been proven scientifically. This study aims to measure the hair growth effect of azelaic acid and vitamin $B_6$, which have been known as hair growth materials, in animal models. Methods: Six weeks old C57BL/6 mice were used in this study and hair of mice were removed by topical treatment. The mice were divided into five experimental groups according to the testing material such as saline (negative control), propylene glycol(vehicle control), azelaic acid, vitamin B6 and azelaic acid plus vitamin B6 in combination. Hair growth was documented photographically and histologically, and then analysed by the high quality hair analysis program system. The quantity of endocrine factors, IGF-I and TGF-${\beta}1$ in the skin of mice was measured by PCR analysis. Results: The topical treatment of azelaic acid and vitamin B6 in combination for 2 weeks to dorsal skin accelerated hair regrowth more than other groups. The azelaic acid and vitamin $B_6$-combined treatment also promoted hair follicle elongation and thickness compared to the others. Histologic studies showed increased number of basal cells in azelaic acid and vitamin $B_6$-combined treatment. Furthermore, the azelaic acid and vitamin $B_6$-combined group significantly increased the expression of IGF-I but decreased the expression of TGF-${\beta}1$ in the skin of mice compared to other groups. Conclusion: These results suggest that azelaic acid and vitamin $B_6$, when used together, have an additive effect and might be used as hair growth materials.
