title: The mouse paw withdrawal assay: a method for determining the effect of calcitonin gene-related peptide on cutaneous heat nociceptive latency time.
abstract: Previously we have shown that calcitonin gene-related peptide (CGRP) modulates nociception and the effect of opioid analgesics in the central nervous system of mice. Cutaneous primary afferent nerve terminals also contain a high concentration of CGRP, however the lack of a suitable method for assessing cutaneous nociceptive latency changes in the hindpaw skin of the mouse hindered our investigations. We report here on the development of an assay to investigate the effect of CGRP on nociception in the dorsal hindpaw skin. Subcutaneous injection of CGRP produced a modest elevation of withdrawal latency time at doses that were two orders of magnitude greater than the physiologic levels determined in naive animals by radioimmunoassay. This elevation of threshold was minimal when compared to the elevation produced by mepivacaine. These results indicate that subcutaneous injection of CGRP into the dorsal hindpaw skin of the mouse produces a modest increase in paw withdrawal latency times at high, non-physiologic doses.
authors.affiliation: Department of Pharmacology and Toxicology, Virginia Commonwealth University/Medical College of Virginia, Richmond 23298-0613.
authors.forename: M A
authors.initials: MA
authors.lastname: Saxen
authors.forename: S P
authors.initials: SP
authors.lastname: Welch
authors.forename: W L
authors.initials: WL
authors.lastname: Dewey
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D006358:Hot Temperature; D007279:Injections, Subcutaneous; D008297:Male; D008619:Mepivacaine / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D009619:Nociceptors / Q000187:drug effects*; D010147:Pain Measurement / Q000379:methods*; D011863:Radioimmunoassay; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D012879:Skin Physiological Phenomena
chemical_list: D008619:Mepivacaine; D015740:Calcitonin Gene-Related Peptide