Roles of adenosine and serotonin receptors on the antinociception of sildenafil in the spinal cord of rats.

Hyung Gon Lee, Woong Mo Kim, Cheon Hee Park, Myung Ha Yoon

Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Dong-gu, Gwangju, Korea.

Yonsei medical journal 2010 Nov

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The phosphodiesterase 5 inhibitor sildenafil has antinociceptive effects, mediated by an increase in cGMP. This study examined the role of spinal adenosine and serotonin receptors played in the antinociceptive effects of intrathecal sildenafil. Intrathecal catheters were inserted into the subarachnoid space of Sprague-Dawley male rats as a drug delivery device. Pain was induced by injecting formalin into the plantar surface of rats and observing nociceptive behavior (flinching response) for 60 minutes. Then, the effects of intrathecal adenosine and serotonin receptor antagonists on the antinociceptive activity of intrathecal sildenafil were examined. Intrathecal sildenafil suppressed the flinching response in a dose-dependent manner during phases 1 and 2 in the formalin test. Both CGS 15943 and dihydroergocristine decreased the antinociceptive effects of sildenafil during phases 1 and 2 in the formalin test. Intrathecal sildenafil effectively attenuated the pain evoked by formalin injection. Both adenosine and serotonin receptors may be involved in the antinociceptive action of sildenafil at the spinal level.

Citation

Hyung Gon Lee, Woong Mo Kim, Cheon Hee Park, Myung Ha Yoon. Roles of adenosine and serotonin receptors on the antinociception of sildenafil in the spinal cord of rats. Yonsei medical journal. 2010 Nov;51(6):960-4