Intrathecal injection of corticotropin inhibited nitric-oxide synthase-positive neuron increase in rat spinal cord after formalin-induced hyperalgesia.
OBJECTIVE
To study the effects of corticotropin (Cor) on formalin-induced hyperalgesia and the change of nitric-oxide synthase (NOS)-positive neurons in spinal dorsal horn in rats.


METHODS
Measurement of pain intensity rating (PIR), NADPH-d histochemistry, and Fos immunohistochemistry were adopted.


RESULTS
The increases of NOS-positive neurons, Fos, NOS/Fos double labelling neurons of the spinal dorsal horn and the PIR after formalin injection were markedly inhibited by intrathecal injecting (ith) Cor (0.5-1.5 U), which were obviously attenuated by L-arginine (Arg, 5-15 nmol, ith), the substrate of NOS.


CONCLUSIONS
Cor inhibits formalin-induced hyperalgesia by the decrease of NOS-positive neurons in the spinal dorsal horn of rats.
Zhou
H J
HJ
Department of Physiology, Third Military Medical University, Chongqing, China.
Li
H D
HD
Li
X C
XC
Ruan
H Z
HZ
Zhao
B Y
BY
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D005260:Female; D005557:Formaldehyde; D006930:Hyperalgesia / Q000139:chemically induced / Q000201:enzymology*; D007278:Injections, Spinal; D008297:Male; D009474:Neurons / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D010147:Pain Measurement; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000201:enzymology*
D016760:Proto-Oncogene Proteins c-fos; D005557:Formaldehyde; D000324:Adrenocorticotropic Hormone; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat