In animal models, and to a less extent in human studies, SPX was found to be widely expressed at tissue level (7, 8) and involved in diverse functions, including stomach contraction (1), GI tract movement (9), energy balance and weight loss (10), bile acid synthesis (11), appetite control (12, 13), glucose homeostasis (14, 15), lipid metabolism (16, 17), reproduction (18, 19), pain perception (20, 21), stress/anxiety (22, 23), and cardiovascular/renal functions (24). Here, SPX is linked to Anxiety.