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


CONCLUSIONS
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.
a Physiology Research Center, Department of Physiology, School of Medicine , Iran University of Medical Sciences , Tehran , Iran.
Farinaz
F
Nasirinezhad
b Department of Physiology, School of medicine , Tehran University of Medical Sciences , Tehran , Iran.
Marjan
M
Hosseini
b Department of Physiology, School of medicine , Tehran University of Medical Sciences , Tehran , Iran.
Zohre
Z
Karami
b Department of Physiology, School of medicine , Tehran University of Medical Sciences , Tehran , Iran.
Mahmoud
M
Yousefifard
a Physiology Research Center, Department of Physiology, School of Medicine , Iran University of Medical Sciences , Tehran , Iran.
Autosa
A
Janzadeh
D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D007211:Indoles / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D007278:Injections, Spinal; D008297:Male; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology; D059225:Nociception / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D044406:Receptors, Serotonin, 5-HT3 / Q000378:metabolism; D058831:Serotonin 5-HT3 Receptor Antagonists / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000150:complications / Q000188:drug therapy*; D000077526:Tropisetron
D000700:Analgesics; D007211:Indoles; D044406:Receptors, Serotonin, 5-HT3; D058831:Serotonin 5-HT3 Receptor Antagonists; D000077526:Tropisetron
5-hydroxytryptamine-3; Central neuropathic pain; Clips compression injury; Spinal cord