Korean J Pain.  2006 Jun;19(1):17-21. 10.3344/kjp.2006.19.1.17.

Evaluation for the Effects of Intrathecal Sildenafil on the Formalin- and Thermal-induced Nociception of Rats

• Yoon MH
• Bae HB
• Shin DJ
• Kim CM
• Jeong ST
• Kim SJ
• Choi JI

• KMID: 2278011
• DOI: http://doi.org/10.3344/kjp.2006.19.1.17

Abstract

BACKGROUND: Cyclic guanosine monophosphate (cGMP) plays an important role in the modulation of nociception. Although local sildenafil produces antinociception, by increasing cGMP through the inhibition of phosphodiesterase 5, the effect of spinal sildenafil has not been determined. The authors evaluated the effects of intrathecal sildenafil on the nociceptive behavior evoked by formalin injection and thermal stimulation.
METHODS
Lumbar intrathecal catheters were implanted into rats, with formalin and Hot-Box tests used as nociceptive models. The formalin-induced nociceptive behavior (flinching response) and withdrawal latency to radiant heat were measured, and the general behaviors also observed.
RESULTS
The intrathecal administration of sildenafil produced dose-dependent suppression of the flinches in both phases in the formalin test, and increased the withdrawal latency in the Hot-Box test. No abnormal behaviors were noted.
CONCLUSIONS
Sildenafil, an inhibitor of phosphodiesterase 5, is active against the nociceptive state evoked in the spinal cord by formalin and thermal stimulations. Accordingly, spinal sildenafil may be useful in the management of pain.

Keyword

antinociception; cyclic guanosine monophosphate; phosphodiesterase; sildenafil; spinal cord

MeSH Terms

Animals
Catheters
Cyclic Nucleotide Phosphodiesterases, Type 5
Formaldehyde
Guanosine Monophosphate
Hot Temperature
Nociception*
Pain Measurement
Rats*
Spinal Cord
Sildenafil Citrate
Cyclic Nucleotide Phosphodiesterases, Type 5
Formaldehyde
Guanosine Monophosphate