Antinociception with intrathecal alpha-methyl-5-hydroxytryptamine, a 5-hydroxytryptamine 2A/2C receptor agonist, in two rat models of sustained pain

Masayuki Sasaki, Hideaki Obata, Shigeru Saito, Fumio Goto
Anesthesia and Analgesia 2003, 96 (4): 1072-8, table of contents

UNLABELLED: Type 2 serotonin (5-hydroxytryptamine [5-HT](2)) receptors in the spinal cord have been reported to mediate antinociception using pain threshold tests, but little is known about the actions of spinal 5-HT(2) receptors in sustained pain. In rats, we examined antinociceptive effects of the intrathecal administration of a 5-HT(2A/2C) receptor agonist, alpha-methyl-5-HT maleate (alpha-m-5-HT), using the formalin test and the chronic constriction injury (CCI) model. An intrathecal catheter was implanted for injection of drugs. In the formalin test, flinches were counted from Minute 1 to 2 and Minute 5 to 6 (Phase 1) and then for 1-min periods at 5-min intervals from 10 to 60 min (Phase 2). In rats with CCI, hind paw withdrawal latency after thermal stimulation was measured. In the formalin test, intrathecal administration of alpha-m-5-HT (1 to 100 microg) dose-dependently suppressed the number of flinches in both Phases 1 and 2. In the CCI model, intrathecally administered alpha-m-5-HT (10 to 100 microg) attenuated thermal hyperalgesia in a dose-dependent manner. These effects were reversed by intrathecal pretreatment with a 5-HT(2A/2C) antagonist, ketanserin (30 microg), or a muscarinic receptor antagonist, atropine (30 microg). These findings suggest that spinal 5-HT(2A/2C) receptors mediate antinociception in inflammatory pain and neuropathic pain, and the muscarinic receptors contribute to this action.

IMPLICATIONS: Activation of spinal 5-hydroxytryptamine(2A/2C) receptors mediate antinociception in rat-sustained pain models such as inflammatory pain and neuropathic pain, and spinal muscarinic receptors are involved in this action.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"