Abstract |
The present study was designed to investigate which subtypes of 5-HT receptors are involved in 5-HT-induced hyperalgesia using behavioral assessment of hyperalgesia. 5-HT and various putative agonists for 5-HT receptor subtypes (5-HT(1A, 2, 3)) were intradermally injected into the rat ipsilateral hindpaw. Paw-withdrawal latency to radiant heat stimulation was examined every 15 min for 2 h. Injection of 5-HT (30 microg) and 5-HT2A receptor agonist (alpha-methyl 5-HT; 0.86 mg/kg) significantly reduced the paw-withdrawal latency. On the other hand, injection of 5-HT3 receptor agonists (2-methyl 5-HT; 0.86 mg/kg, m-CPG; 8 mg/kg) did not produce hyperalgesia. Furthermore, pretreatment with 5-HT2A receptor antagonist ( ketanserin), but not with 5-HT3 receptor antagonist ( tropisetron), attenuated the behavioral response after the injection of 5-HT. These findings strongly suggest that the 5-HT2A receptor subtype, but not the 5-HT3 subtype, is involved in 5-HT-induced hyperalgesia in acute injury and inflammation in the rat. In situ hybridization histochemistry revealed the presence of 5-HT2 receptor mRNA in a subpopulation of both large and small neurons in the rat dorsal root ganglia.
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Authors | Atsushi Tokunaga, Misako Saika, Emiko Senba |
Journal | Pain
(Pain)
Vol. 76
Issue 3
Pg. 349-355
(Jun 1998)
ISSN: 0304-3959 [Print] United States |
PMID | 9718253
(Publication Type: Journal Article)
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Chemical References |
- RNA, Messenger
- Receptor, Serotonin, 5-HT2A
- Receptors, Serotonin
- Serotonin Antagonists
- Serotonin Receptor Agonists
- Serotonin
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Topics |
- Animals
- Behavior, Animal
(drug effects)
- Dose-Response Relationship, Drug
- Ganglia, Spinal
(drug effects, physiology)
- Hot Temperature
- Hyperalgesia
(metabolism, physiopathology)
- In Situ Hybridization
- Male
- Peripheral Nervous System
(physiopathology)
- RNA, Messenger
(biosynthesis)
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A
- Receptors, Serotonin
(biosynthesis, physiology)
- Serotonin
(physiology)
- Serotonin Antagonists
(pharmacology)
- Serotonin Receptor Agonists
(pharmacology)
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