the-aps.org>meetings>eb

Melanocyte Stimulating Hormones and Their Receptors
Sponsored by the APS Water & Electrolyte Homeostasis Section

Melanocyte stimulating hormones (MSHs) are peptides of α-, β-, and γ primary structure derived from the ACTH-β-endorphin precursor proopiomelanocortin (POMC).  Initially identified by the property of α- and β-MSH to induce melanin dispersion in skin of amphibians and reptiles, a broad array of other functions has been recognized for these peptides through the identification of a family of five melanocortin receptors.  These receptors are members of the G protein-coupled receptor family and signal through activation of adenylate cyclase and stimulation of cyclic adenosine-3’,-5’-monophosphate production.  The action of MSH’s was originally thought to reflect the function of an endocrine system in which pituitary POMC was processed into the peptides, which were then secreted into the circulation.  However, current evidence indicates that POMC is expressed in numerous regions of the central nervous system and in other tissues, and that MSH peptides exert many of their effects locally.  This symposium will present the latest information on these peptides, their receptors, and their physiologic actions.  The initial presentation will describe the regulation of POMC processing in its major sites of expression.  The next talk will characterize the features of the melanocortin receptors and their signaling pathways.  Subsequent presentations will review the effects of MSH peptides on energy metabolism and the development of obesity, and on cardiovascular and renal function and the regulation of blood pressure.  This symposium will provide listeners with a broad overview of the actions of MSH peptides acting through their receptors and point to exciting avenues for future research.