title: Inhibition of lipopolysaccharide-induced microglia activation by calcitonin gene related peptide and adrenomedullin.
abstract: Calcitonin gene related peptide (CGRP) and adrenomedullin are potent biologically active peptides that have been proposed to play an important role in vascular and inflammatory diseases. Their function in the central nervous system is still unclear since they have been proposed as either pro-inflammatory or neuroprotective factors. We investigated the effects of the two peptides on astrocytes and microglia, cells of the central nervous system that exert a strong modulatory activity in the neuroinflammatory processes. In particular, we studied the ability of CGRP and adrenomedullin to modulate microglia activation, i.e. its competence of producing and releasing pro-inflammatory cytokines/chemokines that are known to play a crucial role in neuroinflammation. In this work we show that the two neuropeptides exert a potent inhibitory effect on lipopolysaccharide-induced microglia activation in vitro, with strong inhibition of the release of pro-inflammatory mediators (such as NO, cytokines and chemokines). Both CGRP and adrenomedullin are known to promote cAMP elevation, this second messenger cannot fully account for the observed inhibitory effects, thereby suggesting that other signaling pathways are involved. Interestingly, the inhibitory effect of CGRP and adrenomedullin appears to be stimulus specific, since direct activation with pro-inflammatory cytokines was not affected. Our findings clarify aspects of microglia activation, and contribute to the comprehension of the switch from reparative to detrimental function that occurs when glia is exposed to different conditions. Moreover, they draw the attention to potential targets for novel pharmacological intervention in pathologies characterized by glia activation and neuroinflammation.
authors.affiliation: Division of Neuroscience, Cellular Neurophysiology Unit, San Raffaele Scientific Institute, via Olgettina 58, I-20132 Milano, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Consonni
authors.forename: Stefano
authors.initials: S
authors.lastname: Morara
authors.forename: Franca
authors.initials: F
authors.lastname: Codazzi
authors.forename: Fabio
authors.initials: F
authors.lastname: Grohovaz
authors.forename: Daniele
authors.initials: D
authors.lastname: Zacchetti
mesh_terms: D053607:Adrenomedullin / Q000494:pharmacology*; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D018920:Coculture Techniques; D000242:Cyclic AMP / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D018925:Chemokines; D015850:Interleukin-6; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D014409:Tumor Necrosis Factor-alpha; C104782:adrenomedullin (22-52); D053607:Adrenomedullin; D009569:Nitric Oxide; D000242:Cyclic AMP; D052247:Nitric Oxide Synthase Type II; D015740:Calcitonin Gene-Related Peptide