RÉSUMÉ
Objective To evaluate the role of spinal cord tumor necrosis factor receptor-associated factor 6 (TRAF6)/nuclear factor kappa B (NF-κB)signaling pathway in the development of diabetic neuropathic pain (DNP)in rats.Methods Clean-grade healthy adult male Sprague-Dawley rats,aged 2 months,weighing 180-230 g,in which IT catheters were implanted,were used in this study.Streptozotocin 60 mg/kg was intraperitoneally injected after IT catheterization to establish the model of DNP.Twelve DNP rats were divided into 2 groups (n =6 each) by a random number table method:DNP group and DNP plus TRAF6 inhibitor group (group DTR).Another 6 age-matched Sprague-Dawley rats were used as normal control group (group NC).The rats in group DC and group DTR received IT injection of dimethyl sulfoxide 10 μl and TRAF6 inhibition 10 μg,respectively,once a day for 7 consecutive days starting from day 21 after establishing the model.The mechanical paw withdrawal threshold (MWT) was determined before establishing the model (T1),on 7,14 and 21 days after establishing the model (T2-4),and on 1,4 and 7 days after IT injection (T5-7).The rats were sacrificed after the last MWT measurement,and the L3-5 segments of the spinal cord were removed for determination of the expression of TRAF6 and NFκB p65 by Western blot.Results Compared with group NC,the MWT at T3-7 in group DC and at T3-6 in group DTR was significantly decreased,and the expression of spinal TRAF6 and NF-κB p65 was up-regulated in DC and DTR groups (P＜0.05).Compared with group DC,the MWT was significantly increased at T6-7,and the expression of spinal TRAF6 and NF-κB p65 was down-regulated in group DTR (P ＜ 0.05).Conclusion Spinal cord TRAF6/NF-κB signaling pathway is involved in the development of DNP in rats.
RÉSUMÉ
Objective To evaluate the effect of intrathecal cardamonin on diabetic neuropathic pain (DNP) in rats.Methods Healthy adult male Sprague-Dawley rats,aged 2 months,weighing 180-220 g,were included in the study.Diabetes mellitus was produced by intraperitoneal injection of streptozotocin 60 mg/kg after intrathecal catheterization.When decrease in pain threshold＞50％ of the baseline at 21 days after diabetes mellitus was produced,the induction of DNP was considered successful.Twenty-four rats with DNP were divided into 4 groups (n=6 each) using a random number table:group DNP,rapamycin group (group R),cardamonin 50 μg group (group D50) and cardamonin 100 μg group (group D100).Another 6 healthy age-matched rats were used as normal control (group C).In DNP,R,D50 and D100 groups,dimethyl sulfoxide 10 μl,rapamycin 5 μg and cardamonin 50 μg and 100 μg were intrathecally injected,respectively,once a day for 7 consecutive days starting from 21 days after successful estabiishment of the model.Mechanical paw withdrawal threshold (MWT) was measured before establishment of the model,on 7,14 and 21 days after establishment of the model,and on 1,4 and 7 days after intrathecal injection.The rats were sacrificed after the last MWT measurement,and their L3-5 segments of the spinal cord were removed for determination of the expression of S6K,p-S6K and synapsin Ⅱ by Western blot.Results Compared with group C,MWT was significantly decreased,and the expression of spinal S6K,p-S6K and synapsin Ⅱ was up-regulated in group DNP (P＜0.05 or 0.01).Compared with group DNP,MWT was significantly increased,and the expression of spinal S6K,p-S6K and synapsin Ⅱ was down-regulated in R,D50 and D100 groups (P＜0.05 or 0.01).Compared with group D50,MWT was significantly increased,and the expression of spinal S6K,p-S6K and synapsin Ⅱ was down-regulated in group D100 (P＜0.05).Conclusion Intrathecal cardamonin can relieve DNP in rats,and the mechanism is related to inhibiting spinal mammalian target of rapamycin activity and down-regulating the expression of synapsin Ⅱ.