ABSTRACT
Objective To investigate the effect of reactive oxygen species(ROS) on P2X3 receptor-mediated neuropathic pain. Methods Neuropathic pain model was induced in female Sprague Dawley rats by chronic compression of dorsal root ganglia (CCD), and the CCD rats were randomly divided into 4 groups (each group containing 10 rats): Saline group (NS group); PBN 100 mg/kg treatment group; PBN 30 mg/kg treatment group; and PBN 10 mg/kg treatment group. The specific agonist of P2X3 receptor, α, β-meATP (50 nmol in 50 μL), was subcutaneously injected into the plantar surface of the right hind paws of each rat 30 minafter PBN or NS injection. The spontaneous paw flinching times and withdrawing time were observed for 15 min after injection and the paw lift time per minute (PLTPM) in every 2 minutes was calculated. Results Pre- treatmentwith PBN inhibited α, β-meATP-induced spontaneous pain in a dose-dependent manner. Compared with the NS group, PBN 100 mg/kg group significantly inhibited flinching response during the first 6 min (P<0. 05), while the rats in PBN 30 mg/kg group only had significantly attenuated flinching response during the second to the fourth minute compared with NS group(P<0. 05). Conclusion Oxygen free radical scavenger can effectively alleviate the neuropathic pain caused by CCD and P2X3 receptor agonist-induced spontaneous pain. ROS may act as a messenger in P2X3 receptor-mediated pain signaling transmission.
ABSTRACT
Aim To investigate the changes of phosphorylated p38 mitogen-activated protein kinase(p-p38MAPK)in the spinal cord following chronic compression of dorsal root ganglion(CCD)in rats, and to explore the correlation between chronic neuropathic pain and p38MAPK.Methods The animal model of neuropathic pain following chronic compression of dorsal root ganglion was established.36 male Sprague-Dawley rats were randomly divided into Naive group(n=4),Sham group(n=16),CCD group(n=16).Sham group and CCD group were also divided into 5,7,14 d and 21 d group respectively(n=4),Western blot analysis was used to investigate the expression of the phosphorylated active form of p38MAPK (p-p38MAPK) in the spinal dorsal horn in rats after CCD.Results p-p38MAPK protein was expressed in spinal cord among all three groups,but there were no significant differences between Naive group and Sham group.Compared to Naive and Sham group, rats in CCD group showed significant increase of the expression of p-p38MAPK protein in spinal cord.Compared with that of Sham group,protein expression of p-p38MAPK in cytosol in the spinal dorsal horn in 5,7,14 d and 21 d of post-surgery increased respectively 138.1%(P