Effects Of Sulfotanshinone Sodium Injection On Neuronal Apoptosis In The Spinal Dorsal Horn Of Rats With Chronic Neuropathic Pain

Objective To investigate the effects of Sulfotanshinone Sodium Injection (SSI) on the neuronal apoptosis in spinal dorsal in a rat model of chronic neuropathic pain (NP),and to evaluate the therapeutic effects and potential (possible) mechanism of Sulfotanshinone Sodium Injection in the neuropathic pain.Methods One hundred and eight adult male Wistar6-8weeks rats weighing180～220g were randomly divided into3groups as follows:sham operation group(group S); group chronic constrictive injury (CNP); group Sulfotanshinone Sodium Injection (SSI).In group S,the right sciatic nerves were exposed but not ligated and in other groups(In group CNP and SSI)four ligatures were placed around the right sciatic nerve at1mm intervals with4-0silk thread according to the methods of Bennett. In group CNP STSI25mg/kg was injected intraperitoneally (IP) once a day starting from the end of operation until the animals were sacrificed before one day, rats in group S and CNP received the equal volume of saline(5ml/kg).Mechanical and thermal pain threshold were measured by paw withdrawal latencies at one day before operation and3,7and14days (T!-4)after CCI. Twelve animals in each group were sacrificed at each time points after the measurement of mechanical withdrawal threshold(MWT)and thermal withdrawal latency(TWL).Six lumbar segments (L4-6) were immediately removed for determination of Bcl-2and caspase-3expression in spinal dorsal horn (by immune-histochemistry), the other six lumbar segments (L4～6) were examined the content of MDA and SOD activity by (biochemical methods) in homogenized spinal cord.Results Compared with group S, PWT and PWL were significantly decreased at, the expression of Bcl-2and caspase-3were up-regulated,the content of MDA were upgrade and SOD activity were descend at T2-4in group CNP and SSI(P<0.05). Compared with group CNP, PWT and PWL were significantly increased, the expression of Bcl-2was up-regulated, the expression of caspase-3was down-regulated,the content of MDA were downgrade and the SOD activity were ascend at T2～4in group SSI(P<0.05). Compared with group T2, PWT and PWL were significantly decreased, the expression of Bcl-2and caspase-3were up-regulated in group CNP and SSI(P<0.05).Compared with T3, PWT and PWL were significantly increased, the content of MDA were downgrade and the SOD activity were ascend in group CNP and SSI(P<0.05).Conclusion Intraperitoneal Sulfotanshinone Sodium Injection can mitigate neuropathic pain in rates through the inhibition of spinal cord tissue oxidative stress and the reduction of the spinal dorsal horn neurons apoptosis.