Original Articles

Intrathecal injection of corticotropin inhibited nitric-oxide synthase-positive neuron increase in rat spinal cord after formalin-induced hyperalgesia.

Authors: Hong-jie Zhou, Hai-di Li, Xi-cheng Li, Huai-zhen Ruan, Bang-yun Zhao

Abstract

AIM:
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.
CONCLUSION:
Cor inhibits formalin-induced hyperalgesia by the decrease of NOS-positive neurons in the spinal dorsal horn of rats.
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