The role of endogenous neurokinin A in changes in the excitability of spinal neurons during adjuvant-induced, peripheral inflammation was examined by determining the effect of a selective NK2 receptor antagonist, GR103537, on the nociceptive flexor reflex in rats. Intrathecal administration of GR103537 (1.4-14 nmol) dose-dependently attenuated the increased activity of the flexor reflex ipsilateral to the inflamed paw. The activity of GR103537 at NK2 receptors was confirmed by blockade of the facilitation of the reflex by neurokinin A but not substance P in normal rats. These results indicate that endogenous neurokinin A increases the excitability of spinal neurons during persistent peripheral inflammation.
Bibliographical noteFunding Information:
The authors thank Dr. Ann Parsons for helpful discussions and comments on the manuscript. The work was supported by a grant from the National Institutes of Health (NS 17702, V.S. Seybold).
- flexor reflex
- neurokinin A
- neurokinin receptor
- spinal cord