Multiple 5-Hydroxytryptamine (5-HT) Receptors Are Involved in the Melittin-induced Nociceptive Responses in Rat I. Role of Peripheral 5-HT Receptor.
- Author:
Hong Kee SHIN
1
;
Seo Eun LEE
Author Information
1. Department of Physiology, College of Medicine, Hanyang University, Seoul 133-791, Korea. shinhg@hanyang.ac.kr
- Publication Type:Original Article
- Keywords:
Melittin;
Nociceptive responses;
Peripheral 5-HT receptors
- MeSH:
Animals;
Edema;
Hypersensitivity;
Inflammation;
Melitten;
Methysergide;
Rats*;
Receptors, Serotonin;
Serotonin*
- From:The Korean Journal of Physiology and Pharmacology
2007;11(5):221-226
- CountryRepublic of Korea
- Language:English
-
Abstract:
Melittin-induced tonic pain model is characterized by local inflammation, edema, spontaneous flinchings, and sustained mechanical hypersensitivity. These nociceptive responses are mediated through selective activation of capsaicin-sensitive primary afferent fibers by melittin. The present study was undertaken to elucidate the role of peripheral 5-hydroxytryptamine (5-HT) receptors in the melittin-induced nociceptive responses. Changes in mechanical threshold, flinching behaviors and paw thickness were measured in rat intraplantarly injected with melittin (40microgram/paw) alone or treated together with melittin and 5-HT receptor antagonists. WAY-100635 (100microgram & 200microgram/paw), isamoltane hemifumarate (100microgram & 200microgram/paw), methysergide maleate (60microgram, 120microgram & 200microgram/paw) and ICS-205,930 (100microgram & 200microgram/paw) were intraplantarly injected 20 min before melittin injection. All 5-HT receptor antagonists tested in this experiment significantly attenuated the ability of melittin to reduce mechanical threshold and to induce flinching behaviors. 5-HT receptor antagonists, except ICS-205,930, had mild inhibitory effect on melittin-induced edema. These experimental findings suggest that multiple peripheral 5-HT receptors are involved in the melittin-induced nociceptive responses.
