• DOI:10.1097/ALN.0b013e3181cd7920
• Corpus ID: 11913166

Spinal 5-HT7 Receptors Play an Important Role in the Antinociceptive and Antihyperalgesic Effects of Tramadol and Its Metabolite, O-Desmethyltramadol, via Activation of Descending Serotonergic Pathways

@article{Yanarate2010Spinal5R,
  title={Spinal 5-HT7 Receptors Play an Important Role in the Antinociceptive and Antihyperalgesic Effects of Tramadol and Its Metabolite, O-Desmethyltramadol, via Activation of Descending Serotonergic Pathways},
  author={Omer Yanarateş and Ahmet Bulent Dogrul and Vedat Yıldırım and Altan Şahin and Ali Sızlan and Melik Seyrek and {\"O}zg{\"u}r Akg{\"u}l and Orhan Kozak and Ercan Kurt and Ulku Aypar},
  journal={Anesthesiology},
  year={2010},
  volume={112},
  pages={696-710}
}

• O. Yanarateş, A. Dogrul, +7 authors U. Aypar
• Published 1 March 2010
• Biology, Medicine
• Anesthesiology

Background:Tramadol is an analgesic drug, and its mechanism of action is believed to be mediated by the &mgr;-opioid receptor. A further action of tramadol has been identified as blocking the reuptake of serotonin (5-HT). One of the most recently identified subtypes of 5-HT receptor is the 5-HT7 receptor. Thus, the authors aimed to examine the potential role of serotonergic descending bulbospinal pathways and spinal 5-HT7 receptors compared with that of the 5-HT2A and 5-HT3 receptors in the antinociceptive and antihyperalgesic effects of tramadol and its major active metabolite O-desmethyltramadol (M1) on phasic and postoperative pain models. Methods:Nociception was assessed by the radiant heat tail-flick and plantar incision test in male Balb-C mice (25-30 g). The serotonergic pathways were lesioned with an intrathecal injection of 5,7-dihydroxytryptamine. The selective 5-HT7, 5-HT2, and 5-HT3 antagonists; SB-269970 and SB-258719; ketanserin and ondansetron were given intrathecally. Results:Systemically administered tramadol and M1 produced antinociceptive and antihyperalgesic effects. The antinociceptive effects of both tramadol and M1 were significantly diminished in 5-HT-lesioned mice. Intrathecal injection of SB-269970 (10 &mgr;g) and SB-258719 (20 &mgr;g) blocked both tramadol- and M1-induced antinociceptive and antihyperalgesic effects. Ketanserin (20 &mgr;g) and ondansetron (20 &mgr;g) were unable to reverse the antinociceptive and antihyperalgesic effects of tramadol and M1. Conclusions:These findings suggest that the descending serotonergic pathways and spinal 5-HT7 receptors play a crucial role in the antinociceptive and antihyperalgesic effects of tramadol and M1.