Abstract
The involvement of spinal transient receptor potential vanilloid 1 (TRPV1) in formalin-evoked pain has remained unclear, because investigation of this kind of pain with selective antagonists has not been conducted. The purpose of this study is to investigate the participation of spinal TRPV1 in formalin-evoked pain with iodo-resiniferatoxin (I-RTX), a potent TRPV1-selective antagonist. I-RTX given intrathecally dose-dependently and significantly decreased the number of flinching responses in the formalin-evoked 1st and 2nd phase with ID50 values (drug dose producing 50% inhibition of response) of 1.0 and 3.8 microg, respectively, and concentration-dependently suppressed capsaicin-evoked calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) release from rat spinal cord slices with an IC50 value (drug concentration producing 50% inhibition of response) of 86 nM. Capsazepine, a classical non-selective TRPV1 antagonist, given intrathecally also inhibited formalin-evoked flinching in both the 1st and 2nd phase with ID50s of 420 and 200 microg, respectively, and CGRP-LI release from rat spinal cord slices with an IC50 of 7.8 microM. Ratios of in-vivo analgesic potencies of I-RTX and capsazepine well reflected their intrinsic in-vitro activity. These findings suggest that spinal TRPV1 participates in the transduction system of formalin-evoked pain.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
