The aminoacid sequence of several hypothalamic peptides.
Many physiologically potent peptides have been isolated from the hypothalamus and are found to be localised in neurosecretory vesicles in hypothalamic neurones. They are also found in the brain outside the hypothalamus in many different projection systems where they perform functions unrelated to pituitary regulation. Changes in visceral function, appetite, and emotional state can be induced by these substances. Most of the peptides shown here are also secreted by pituitary cells themselves, iii where they form an intrinsic ΓÇÿparacrineΓÇÖ (cell-to-cell) communicating system. The endogenous opioid peptides are a large group of substances that act like morphine by binding to various classes of opioid receptors. Included in this category are the enkephalins and the endorphins. All of the peptides listed (and many others not shown) influence pituitary activity, but their function in normal regulation is not fully understood. Acting on the hypothalamus, substance P stimulates the release of GH and LH; neurotensin stimulates the release of GH: angiotensin 11 stimulates the release of ACTH and ADH; and the endogenous opioids stimulate the secretion of ACTH, prolactin and GH, and inhibit LH. VIP is an important PRF responsible (at least in the rat) for response to stress and in part to suckling.
