title: The role of calcitonin gene-related peptide (CGRP) in the generation and maintenance of mechanical allodynia and hyperalgesia in rats after intradermal injection of capsaicin.
abstract: This study was designed to assess the role of calcitonin gene-related peptide (CGRP) and its receptor in the generation and maintenance of secondary mechanical allodynia and hyperalgesia induced by intradermal injection of capsaicin in rats. Paw withdrawal responses (PWRs) to von Frey hairs with different bending forces applied on the rat paw were tested in this study. CGRP(8-37), a specific antagonist of CGRP 1 receptors, was delivered through a microdialysis fiber inserted across the dorsal horn. Post- and pretreatment paradigms were followed. When CGRP(8-37) was administered 1h after capsaicin injection, the mechanical allodynia and hyperalgesia were partially reversed in a dose-dependent manner. On the other hand, when rats were treated with CGRP(8-37) prior to capsaicin injection, the PWRs to von Frey applications were significantly reduced as compared to control animals. Collectively, these results suggest that CGRP receptors present in the dorsal horn are involved in the generation and maintenance of nociceptive behaviors associated with cutaneous inflammation.
authors.affiliation: Department of Anatomy and Neuroscience, Marine Biomedical Institute, The University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1069, USA.
authors.forename: Rui-Qing
authors.initials: RQ
authors.lastname: Sun
authors.forename: Nada B
authors.initials: NB
authors.lastname: Lawand
authors.forename: William D
authors.initials: WD
authors.lastname: Willis
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology / Q000502:physiology* / Q000627:therapeutic use*; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D002211:Capsaicin / Q000633:toxicity*; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology*; D007271:Injections, Intradermal; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology / Q000627:therapeutic use*; D010812:Physical Stimulation / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000502:physiology
chemical_list: D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D010446:Peptide Fragments; D018015:Receptors, Calcitonin Gene-Related Peptide; C058636:calcitonin gene-related peptide (8-37); D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin