Induction of alpha-calcitonin gene-related peptide mRNA expression in rat dorsal root ganglia by heat stress involves the heme oxygenase-1/carbon monoxide pathway

SD rats were pretreated with whole body hyperthermia (rectal 42degreesC) for 15 min. The level of calcitonin generelated peptide (CGRP) in plasma, and alpha- and beta-CGRP mRNA as well as heme oxygenease-1 and heme oxygenase-2 mRNA in dorsal root ganglia were determined by radioimmunoassay and semi-quantitative reverse-transcription polymerase chain reaction, respectively. Heat stress induced only the expression of alpha-CGRP or heme oxygenease-1 but not beta-CGRP or heme oxygenase-2 mRNA, and the release of CGRP and induction of alpha-CGRP mRNA expression were abolished by pretreatment with Zinc protoporphyrin IX, the heme oxygenase inhibitor, or methylene blue, the inhibitor of soluble guanylate cyclase. These results indicate that induction of alpha-CGRP mRNA expression in rat DRG by heat stress involves the heme oxygenase-1/carbon monoxide pathway. (C) 2001 Elsevier Science Ltd. All rights reserved.