Spinal 5-HT3 receptor mediates nociceptive effect on central neuropathic pain; possible therapeutic role for tropisetron

Abstract

Objectives: To test the analgesic effect of 5-HT-3 receptor antagonist, tropisetron, in a clip compression injury model of spinal cord pain in rats.

Methods: Four weeks post compression of the spinal cord at lumbar level, tropisetron was administered intrathecally at 100 μg and 150 μg dosages. Behavioral tests were assessed before administration. Fifteen minutes after injection, behavioral tests were repeated. Randall-Sellitto and plantar test was used for mechanical and thermal hyperalgesia, respectively. Mechanical and cold allodynia were evaluated by Von Frey filament and acetone droplets, respectively. The analgesic effect of tropisetron was compared with intrathecal administration of salicylate. Locomotor score was evaluated by Basso, Beattie and Bresnahan (BBB) test every week after spinal cord injury.

Results: Intrathecal administration of tropisetron, decreased hyperalgesia and mechanical allodynia, but not cold allodynia were observed after compression of the spinal cord.

Conclusion: Blockade of 5-HT-3 receptors by tropisetron at the spinal level induces an antinociceptive effect on chronic central neuropathic pain and suggests that this compound may have potential clinical utility for the management of central neuropathic pain, particularly in patients with hyperalgesia and tactile allodynia.

Keywords:

• 5-hydroxytryptamine-3
• Spinal cord
• Central neuropathic pain
• Clips compression injury

Disclaimer statements

Contributors MH and ZK participated in data collection. FN, MY, and AJ participated in analysis, interpretation and study design. MH and ZK wrote first draft of the work. FN and AJ revised it critically for important intellectual content. All authors have provided final approval of the version to be published and has agreed to be accountable for all aspects of the work.

Funding None.

Conflicts of interest None.

Ethics approval The protocol of present experimental study were reviewed and approved by the ethic committee of Iran University of medical sciences, Tehran, Iran. Throughout the study, the researchers adhere to guidelines of the “Guide for the Care and Use of Laboratory Animals.”