TPH1 and irritable bowel syndrome: The same group inhibited Tph1 in mice by treating them with LP533401.60 This molecule, designed for use in irritable bowel syndrome, inhibits GDS without affecting BDS.61 Pharmacological inhibition of Tph1 decreased the levels of GDS in these mice, prevented bone loss and could treat osteoporosis.60In vitro, GDS significantly reduces osteogenic differentiation and mineralization of rat calvarial cells with concomitant reduction of osteoblast marker genes.62 These findings indicate the existence of a gut/bone axis.63,64