Differences in inflammatory pain in nNOS-, iNOS- and eNOS-deficient mice.
To assess the relative importance of the isoforms of nitric oxide synthase (NOS) in inflammatory pain, we directly compared pain behaviour and paw thickness after intraplantar injection of complete Freund's adjuvant (CFA) in wild-type (WT) mice and in mice lacking either inducible (iNOS), endothelial (eNOS) or neuronal NOS (nNOS). In mice deficient for nNOS, thermal hyperalgesia was reduced by approximately 50% compared to wild type mice at 4 and 8h after CFA injection, and mechanical hypersensitivity was absent. The only change in pain behaviour in iNOS and eNOS deficient mice compared to WT mice was a more rapid recovery from thermal hyperalgesia. A compensatory up-regulation of nNOS in dorsal root ganglia (DRG) and spinal cords of iNOS and eNOS knockout mice was excluded using RT-PCR. However, an increase of iNOS gene expression was found in spinal cords of eNOS and nNOS deficient mice. To study the downstream effects of nNOS deficiency on DRG neurones, we assessed their immunoreactivity for calcitonin gene-related peptide (CGRP) and cytokines. We found a significant reduction in the CFA induced increase in CGRP immunoreactive neurones as well as in CGRP gene expression in nNOS deficient mice, whereas the percentage of cells immunopositive for tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) was unchanged. These results support the proposed role of nNOS in sensitization of DRG neurones, and might indicate that CGRP is involved in this process.
Boettger
Michael Karl
MK
Department of Neurology, Julius-Maximilians-University, Josef-Schneider-Str 11, 97080, Würzburg, Germany.
Uceyler
Nurcan
N
Zelenka
Marek
M
Schmitt
Angelika
A
Reif
Andreas
A
Chen
Yong
Y
Sommer
Claudia
C
D000818:Animals; D001522:Behavior, Animal; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D005260:Female; D005620:Freund's Adjuvant; D005727:Ganglia, Spinal / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000276:immunology; D006930:Hyperalgesia / Q000276:immunology / Q000503:physiopathology*; D007249:Inflammation / Q000139:chemically induced / Q000150:complications*; D053583:Interleukin-1beta / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052248:Nitric Oxide Synthase Type I / Q000235:genetics; D052247:Nitric Oxide Synthase Type II / Q000235:genetics; D052250:Nitric Oxide Synthase Type III; D010146:Pain / Q000276:immunology / Q000503:physiopathology*; D013116:Spinal Cord / Q000201:enzymology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D005620:Freund's Adjuvant; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496321:Nos1 protein, mouse; C496317:Nos2 protein, mouse; C496315:Nos3 protein, mouse; D015740:Calcitonin Gene-Related Peptide