title: Antinociceptive effects of dexmedetomidine via spinal substance P and CGRP.
abstract: The aim of this study was to examine the role played by substance P and calcitonin gene-related peptide (CGRP) within the dorsal horn of the spinal cord in engagement of antinociception evoked by dexmedetomidine (DEX). Paw withdrawal threshold (PWT) to mechanical stimulation was determined after chronic intrathecal infusion of DEX and enzyme-linked immunosorbent assay (ELISA) was employed to examine the levels of spinal substance P and CGRP. Our results show that PWT was significantly increased by intrathecal administration of DEX in rats (P< 0.05vs.vehicle control, n = 20 in each group). Also, intrathecal infusion of DEX significantly decreased the concentrations of substance P and CGRP as compared with vehicle control (P< 0.05 DEXvs.vehicle control, n = 20 in each group). Blocking α2-adrenoreceptors (α2-AR) blunted the decreases of substance P and CGRP levels and the enhancement of PWT evoked by DEX. Additionally, a linear relationship was observed between PWT and the levels of spinal substance P (r = 0.87;P< 0.005) and CGRP (r = 0.85;P< 0.005). Moreover, blocking individual substance P and CGRP receptors amplified PWT without altering substance P and CGRP levels. Thus, DEX plays a role in stimulating α2-AR receptors, which thereby decreases substance P and CGRP levels within the dorsal horn. This contributes to DEX-evoked antinociception.
authors.affiliation: Shandong University, Jinan City, Shandong 250012, P.R. China.
authors.forename: Ruiqin
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Qi
authors.affiliation: Department of Anesthesiology, Wuxi Forth People's Hospital and Affiliated Hospital of Jiangnan University, Jinan, Shandong 250012, P. R. China.
authors.forename: Junlong
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Anesthesiology, Wuxi Forth People's Hospital and Affiliated Hospital of Jiangnan University, Jinan, Shandong 250012, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ji
authors.affiliation: Department of Anesthesiology, Wuxi Forth People's Hospital and Affiliated Hospital of Jiangnan University, Jinan, Shandong 250012, P. R. China.
authors.forename: Dengxin
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Anesthesiology, Wuxi Forth People's Hospital and Affiliated Hospital of Jiangnan University, Jinan, Shandong 250012, P. R. China.
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Shen
authors.affiliation: Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China.
authors.forename: Weifu
authors.initials: W
authors.lastname: Lei
keywords: Calcitonin gene-related peptide (CGRP); Dexmedetomidine; Dorsal horn; Pain modulation; Substance P