Adenylate cyclase-activating neuropeptides
Adenylate cyclase - activating neuropeptides Neuropeptides are peptides released by neurons as intercellular messengers. Manyhormones released by non-neuronal cells are also of neuropeptide nature. Mostneuropeptides act through G-protein coupled receptors. Melanocortines are a group of peptide hormones derived by post-translational cleavageof the Proopiomelanocortin ( POMC ). These peptides include Adrenocorticotropichormone ( ACTH ), alpha-melanocyte-stimulating hormone ( alpha-MSH ), Beta-melanocyte-stimulating hormone ( beta-MSH ), and Gamma- melanocyte-stimulatinghormone ( gamma-MSH ). Melanocortins act through melanocortin receptors (MC1R, ACTH receptor, MC3R, MC4R, MC5R ).Melacortin receptor signaling is implicated in regulation of the appetite, pigmentation,energy homeostasis, steroidogenesis, and sexual behaviour. Activity of Melanocortin isantagonized by Agouti signaling peptide ( ASP ) and Agouti-related peptide (AGRP ) . Glucagon is a 29 amino acid peptide hormone liberated from islet A cells in thepancreas. Principal activities of Glucagon and GLP-1 (derived asGlucagon from post-translational processing of proglucagon) include regulation ofmetabolic pathways involved n glucose homeostasis , . Urocortin is a member of the corticotropin-releasing hormone family ofpeptides. Its potent suppression of food intake in the brain is mediated by CRH receptors( CRHR1, CRH receptor 2 ). Urocortin participates in the regulation ofanxiety, learning, memory, and body temperature, as well as it possesses neuroprotectiveproperties , . Pituitary adenylate cyclase-activating polypeptide ( PACAP ) is a 38-amino acidpeptide with pleiotropic properties that include modulation of neurotransmitter release,vasodilation, bronchodilation, activation of intestinal motility, increase of insulin andhistamine secretion, as well as stimulation of cell division and/or differentiation. All neuropeptides mentioned above can increase cAMP level which is consideredto be one of the main mediators of their physiological action. For example, PACAPstimulates the release of oxytocin and vasopressin through activation of the cAMP/proteinkinase A (PKA) signaling pathway and melanocortins are known to regulate melanogenesis bycAMP induced pathway, .