title: Cardiovascular and renal actions of melanocyte-stimulating hormone peptides.
abstract: OBJECTIVE
  Melanocyte stimulating hormones (MSHs, melanocortins) have important roles in feeding and energy metabolism and in inflammation. Recent observations have uncovered major functions for these peptides, particularly gamma-MSH, in cardiovascular regulation and sodium metabolism.
  
  
  RESULTS
  Both alpha- and gamma-MSH acutely elevate blood pressure and heart rate through central stimulation of sympathetic nervous outflow. This action of alpha-MSH is mediated by the melanocortin 4 receptor (MC4R), whereas sympathetic nervous stimulation by gamma-MSH does not involve its receptor MC3R but rather is likely due to activation of a sodium channel in the central nervous system. In contrast, gamma-MSH deficiency in rodents, or disruption of MC3R, leads to marked salt-sensitive hypertension, again through a central mechanism: a small dose of exogenous peptide delivered into the cerebroventricular system of mice with gamma-MSH deficiency restores blood pressure to normal. This salt-sensitive hypertension is accompanied by the development of insulin resistance; the mechanism linking these two consequences of a high-salt diet is not yet known but may involve activation of the sympathetic nervous system.
  
  
  CONCLUSIONS
  The study of MSH peptides in blood pressure regulation offers a new opportunity to gain insight into the mechanisms underlying salt sensitivity and its link to insulin resistance, and to new therapies.
authors.affiliation: Division of Nephrology, San Francisco General Hospital, University of California San Francisco, San Francisco, CA 94143, USA. mhumphreys@medsfgh.ucsf.edu
authors.forename: Michael H
authors.initials: MH
authors.lastname: Humphreys
mesh_terms: D000818:Animals; D002319:Cardiovascular System / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance; D007668:Kidney / Q000378:metabolism*; D009074:Melanocyte-Stimulating Hormones / Q000502:physiology*; D044101:Receptors, Melanocortin / Q000502:physiology; D012377:Rodentia / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D044101:Receptors, Melanocortin; D009074:Melanocyte-Stimulating Hormones; D012964:Sodium