TPH2 and migraine disorder: A study on WT reported regulatory effects of various components in WT on tryptophan hydroxylase 2 (TPH2, the rate limiting enzyme for 5-HT biosynthesis in brain) promoter, suggesting that the effects of WT on migraine could be due to its stimulating effects on TPH2 promoter and promotion of the 5-HT synthesis and release in the brain [19].