PT  - JOURNAL ARTICLE
AU  - Pamela A. Pierce
AU  - Guo-Xi Xie
AU  - Stephen J. Peroutka
AU  - Jon D. Levine
TI  - Dual Effect of the Serotonin Agonist, Sumatriptan, on Peripheral Neurogenic Inflammation
AID  - 10.1136/rapm-00115550-199621030-00008
DP  - 1996 May 01
TA  - Regional Anesthesia: The Journal of Neural Blockade in Obstetrics, Surgery, & Pain Control
PG  - 219--225
VI  - 21
IP  - 3
4099  - http://rapm.bmj.com/content/21/3/219.short
4100  - http://rapm.bmj.com/content/21/3/219.full
SO  - Reg Anesth Pain Med1996 May 01; 21
AB  - Background and Objectives Sumatriptan is a novel drug for migraine headache pain, which, on the basis of its mechanism of action, may have therapeutic potential in other pain states. Sumatriptan inhibits neurogenic inflammation in dural vessels by activating the 5-HTIB and 5-HTID inhibitory serotonin (5-hydroxytryptamine [5-HT]) receptor subtypes on terminals of trigeminal neurons. This study was designed to determine the role of sumatriptan in peripheral pain mechanisms by detecting whether 5-HT1B and 5-HT1D receptors and the recently cloned excitatory 5-HT7 receptor, for which sumatriptan displays moderate binding affinity, are present in peripheral sensory neurons, and by determining the effect of sumatriptan on peripheral neurogenic inflammation.Methods A polymerase chain reaction (PCR) technique was used to detect mRNA for 5-HT receptors in rat lumbar dorsal root ganglia. Rat knee joint plasma extravasation was used to determine the effect of sumatriptan on peripheral neurogenic inflammation.Results The mRNA for the sumatriptan-activated receptors 5-HT1B, 5-HT1D, and 5-HT7, was detected in lumbar dorsal root ganglia. In rat knee joint, capsaicin-activated C-fibers stimulated plasma extravasation to 273 ± 62% of baseline. Low-concentration sumatriptan (50 nM) significantly inhibited capsaicin-induced plasma extravasation to 106 ± 6% of baseline. High-concentration sumatriptan (1 μM) significantly enhanced capsaicin-induced plasma extravasation to 572 ± 55% of baseline.Conclusions Sumatriptan inhibits peripheral neurogenic inflammation, probably via 5-HT1B/1D receptors, and may be a novel therapy for inflammatory pain states. However, high concentrations (> 200 nM) may enhance neurogenic inflammation, possibly by activation of 5-HT7 receptors, which may explain lack of migraine relief and excessive injection site pain in 20-30% of patients treated with sumatriptan.