Serotonin [5-hydroxytryptamine (5-HT)] released from mast cells or platelets in peripheral tissues is one of the important inflammatory mediators in pain and hyperalgesia. The involvement of 5-HT in pain is complex because it could inhibit or facilitate nociceptive transmission, reflecting the presence of multiple 5-HT subtype receptors on peripheral and central nociceptors. The present study aimed to investigate the involvement of 5-HT2B in 5-HT-induced pain and whether the subtype exists in dorsal root ganglion (DRG) neurons. Injecting the 5-HT or 5-HT2 agonist in hindpaws of mice induced significant hyperalgesia to mechanical stimuli, which was inhibited by the 5-HT2B/2C antagonist but not by 5-HT1A, 5-HT 2A , or 5-HT3A antagonists. Therefore, 5-HT2B or 5-HT2C may be involved in 5-HT-induced mechanical hyperalgesia. The 5-HT2B/2C antagonist also blocked 5-HT-induced transient [Ca 2+] signaling in DRG neurons. All subtypes of 5-HT receptors except 5-HT2C and 5-HT6 are present in DRGs. In situ hybridization also demonstrated 5-HT2B mainly expressed in small-to medium-diameter DRG neurons that respond to pain. Likely, 5-HT2B mediates 5-HT-induced mechanical hyperalgesia in mice.
|Number of pages||9|
|Journal||Journal of Neuroscience|
|State||Published - 26 Jan 2011|