CRH and depressive disorder: Animal experiments proved that SNP can regulate the hypothalamic–pituitary–adrenal (HPA) axis, and a single pretreatment extract can relieve the increases in serum corticosterone (CORT) and plasma corticotropin-releasing hormone (CRH) levels induced by acute stress, as well as elevating the mRNA expression of the hippocampal glucocorticoid receptor to combat depression [26].