Reversal of the antinociceptive effects of intrathecally administered serotonin in the rat by a selective 5-HT3 receptor antagonist.
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Abstract
The ability of the highly selective 5-HT3 receptor antagonist ICS 205-930 (3 alpha-tropanyl-1H-indole-3-carboxylic acid ester) to block the increase in tail flick (TFL) and hot plate latencies (HPL) produced by intrathecally (i.t.) administered serotonin (5-HT) was examined in pargyline pretreated rats. ICS 205-930 (0.1 microgram, i.t.) blocked the ability of 5-HT (200 micrograms) to increase TFL and HPL. Significant hyperalgesia, as measured by a decrease in TFL and HPL compared to saline controls, also resulted from either the coadministration of ICS 205-930 (10 micrograms) and 5-HT (200 micrograms) or from ICS 205-930 (100 micrograms) alone. These data suggest an important role for 5-HT3 receptors in modulating spinal nociceptive responses.