Effects of Hypophysiotrophic Factors (2)	

The action of each of the hypophysiotrophic hormones is not limited strictly to a single pituitary hormone: for example, TRH (the physiological releaser of TSH) is a potent releaser of prolactin, and in some circumstances releases ACTH and GH; gonadotrophin-releasing hormone (GnRH) releases both luteinising hormone (LH) and follicle-stimulating (FSH); and somatostatin inhibits secretion of GH, TSH, and a wide variety of other nonpituitary hormones. The principal inhibitor of prolactin secretion is dopamine, but this potent bioamine, acting directly on the pituitary, also inhibits TSH and gonadotrophin secretion. Additionally, under some circumstances, it inhibits GH secretion.