title: Ligand-dependent activation of the melanocortin 5 receptor: cAMP production and ryanodine receptor-dependent elevations of [Ca(2+)](I).
abstract: The melanocortins are involved in the regulation of various cognitive and physiological processes such as learning, feeding, immune suppression, pigmentation, and sebum production. Five melanocortin receptors have been identified, of which the melanocortin 5 receptor (MC5R) has the most widespread distribution. This subtype is found in the brain, and at numerous peripheral sites including the skin where it is expressed in the sebaceous glands. The purpose of this study was to identify the peptide that functions as a natural ligand at the MC5R in the skin. alpha-MSH, ACTH1-39, ACTH1-17, ACTH1-10, and ACTH4-10 all increased the production of cAMP in HEK293 cells transfected with the mouse MC5R. alpha-MSH and ACTH1-17 were the most potent in this respect. In addition, all peptides stimulated a rapid and transient increase in [Ca(2+)](i), and, ACTH1-10 was the most potent. The increases in [Ca(2+)](i) were of intracellular origin, but not associated with inositol phosphate production. The elevations in [Ca(2+)](i) were reduced by ruthenium red and procaine and it is therefore possible that they were mediated via ryanodine receptors.
authors.affiliation: Department of Biomedical Sciences, University of Bradford, Bradford, United Kingdom.
authors.forename: M J
authors.initials: MJ
authors.lastname: Hoogduijn
authors.forename: S
authors.initials: S
authors.lastname: McGurk
authors.forename: N P M
authors.initials: NP
authors.lastname: Smit
authors.forename: P H
authors.initials: PH
authors.lastname: Nibbering
authors.forename: J
authors.initials: J
authors.lastname: Ancans
authors.forename: A
authors.initials: A
authors.lastname: van der Laarse
authors.forename: A J
authors.initials: AJ
authors.lastname: Thody
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004396:Coloring Agents / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D007424:Intracellular Fluid / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D051379:Mice; D010446:Peptide Fragments / Q000494:pharmacology; D011343:Procaine / Q000494:pharmacology; D018043:Receptors, Corticotropin / Q000235:genetics / Q000378:metabolism*; D044101:Receptors, Melanocortin; D012430:Ruthenium Red / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D000521:alpha-MSH / Q000494:pharmacology
chemical_list: D000779:Anesthetics, Local; D004396:Coloring Agents; D007295:Inositol Phosphates; D008024:Ligands; D010446:Peptide Fragments; D018043:Receptors, Corticotropin; D044101:Receptors, Melanocortin; D019837:Ryanodine Receptor Calcium Release Channel; C086971:melanocortin 5 receptor; D012430:Ruthenium Red; C011393:ACTH (1-10); D011343:Procaine; D000521:alpha-MSH; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; C028238:ACTH (1-17); C011394:ACTH (4-10); D002118:Calcium