Background: The mammalian target of rapamycin (mTOR) is known to regulate cell growth, and it also participates in pain transmission as has been recently verified in inflammatory and neuropathic pain models. The targeting of mTOR represents a new strategy for the control of chronic pain. In the present study, we investigated the effect of mTOR in the expression of PSD95 and NR2B-PSD95 or GluA2-PSD95 interaction ratio in a chronic constriction injury (CCI) mice model.Methods: Paw mechanical withdrawal threshold (PMWT) and paw withdrawal thermal latency (PWTL) were respectively used to assess mechanical allodynia and thermal hyperalgesia after CCI operation and intrathecal injection of rapamycin. Western blot and co-immunoprecipitation were used to investigate the effects of rapamycin on the expression of PSD95 and interaction ratio of NR2B-PSD95 or GluA2-PSD95 in the spinal dorsal horn of mice.Results: Our study demonstrated that the inhibition of spinal mTOR with intrathecal injections of rapamycin (1 mu g/5 mu L) for days 1-6 after CCI surgery led to an obvious decrease in CCI-induced neuropathic pain. Rapamycin significantly reduced the PMWT of CCI mice, whereas there was no significant effect on PWTL. The active form of the mTOR signaling pathway (p-mTOR, p-4EBP1 and p-p70S6k) at the spinal level remarkably increased in CCI mice, and rapamycin could inhibit this up-regulation. The increased expression of PSD95 and the interaction ratio of GluA2-PSD95 or NR2B-PSD95 could also be inhibited by intrathecal injection of rapamycin.Conclusion: These data suggest that the mTOR pathway is activated in the spinal dorsal horn in CCI-induced neuropathic pain, and the intrathecal injection of rapamycin can reduce mechanical allodynia. Our findings indicate that spinal mTOR is an important component of CCI-induced neuropathic pain, and mTOR may be a potential target for chronic pain therapy. (C) 2013 Published by Elsevier Inc.

Objective To investigate influences of flurbiprofen axetil on kidney,platelet aggregation and coagulation function.Methods Thirty-six healthy female Sprague Drawley (SD)rats were randomly divided into six groups (6 rats in each group):cancer+normal saline group(CN),cancer+flurbiprofen axetil 10 mg/kg group(CK10),cancer+flurbiprofen axetil 25 mg/kg group (CK25),cancer+ flurbiprofen axetil 50 mg/kg group (CK50),flurbiprofen axetil 50 mg/kg group (K50),and sham+normal saline(sham).Flurbiprofen axetil or normal saline was administered intraperitoneally twice a day from day 14 to day 21 after injection of Walker256 tumour cells into one tibia.Rats were sacrificed to obtain blood from abdominal aorta on the 21th day.Then the levels of blood urea nitrogen (BUN),creatinine (Cr),sodion,Potassium ion,protrombin time(PT),activated partial thromboplastin time (APTF),fibrinogen (Fib),platelet aggregation (PA) were detected and pathological changes of kidney were observed.Results Respectively compared with the sham and C groups,the levels of BUN in the CK50 (9.9 ± 1.5) mmol/L and K50 (9.7±1.4) mmol/Lgroups increased obviously 7 days after intraperitoneal injection of flurbiprofen axetil (P＜0.05),and the levels of sodion in the CK50(137±8) mmol/L and K50 (138±8) mmol/L groups and potassium ion in the CK50 (3.9±0.3) mmol/Land K50 (3.9±0.4) mmol/Lgroups reduced significantly (P＜0.05),and the levels of Cr,PT,APTT,Fib and PA were no statistical difference (P＞0.05).Respectively compared with the sham and C groups,the levels of Cr,BUN,sodion,Potassium ion,Cr,PT,A PTT,Fib and PA were no statistical difference obviously in the CK10 and CK25 groups(P＞0.05).The main pathological changes in the CK50 and K50groups were glomerular narrow and poor supplement with blood in capillaries,while in the sham,C,CK10 and CK25 groups,there were no pathological changes observed.Conclusions Intraperitoneal injection of flurbiprofen axetil in a certain range of dose was not found to impair platelet aggregation and coagulation function in a model of bone cancer pain in the rat.However,in large dose,there were obviously influences on the metabolism of BUN,sodion and potassium ion as well asinfusion of capillaries of renal glomeruli in rats.

Objective To investigate the effects of repeated injection of flurbiprofen axetil on pain behaviors and side effects in a rat model of bone cancer pain.Methods 24 female SD rats were randomly divided into 3 groups(n=8) as follows.Sham group (S group): intra-tibial injection of 10 μl Hank's solution.Tumor group (T group): intra-tibial injection of 10 μl 4×105 Walker 256 mammary gland carcinoma cells.Flurbiprofen axetil group (Fa group): intraperitoneal injection of flurbiprofen axetil on day 15 to 21 after tumor model.Paw withdrawal mechanical threshold (PWMT) was tested on day 1 before surgery and days 1,3,5,7,10,14,15,17,19,21,24 after surgery.The blood,liver,kidney and ipsilateral tibial bone of all rats were obtained on day 24 to examine the pathological changes.Results ① Compared to S group,the PWMT in T group decreased significantly at day 5 after tumor surgery [(10.92±1.04) g vs (9.01±1.49) g,P＜0.05],and peaked at day 14 after surgery.Compared to T group,the PWMT in Fa group increased obviously at day 17[(6.64±1.70) g vs (4.06±1.69) g,P＜0.05].At day 21,the PWMT in Fa group was lower than that in S group [(8.04±0.81) g vs (10.31±1.35) g,P＜0.05].② The results of bleeding and clotting tests [prothrombin time(PT),activated partial prothrombin time (APTT),thrombin time (TT),fibrinogen (FIB),platelet (PLT)],hepatic and renal functional tests [glutamic-pyruvic transaminase (ALT),aspartate amino-transaminase (AST),total protein (TP),urea (UREA),creatinine (CREA)]had no significant difference among S group,T group and Fa group.③ HE staining revealed that there were no significant pathological changes in liver and renal tissue after repeated intraperitoneal injection of flurbiprofen axetil.Live tumor cells were found in tibia marrow cavities in both T and Fa groups.Conclusions Repeated intraperitoneal injection of flurbiprofen axetil could significantly attenuate bone cancer pain in rats while having no influence on hepatic and renal functions as well as hemostatic function.

Objective To investigate the analgesic efficacy of intrathecal injection of RC-13,a competitive kinesin superfamily protein 17 antagonist,in a mouse model of bone cancer pain.Methods Forty male C3H/HeJ mice,aged 6-8 weeks,weighing 20-25 g,were randomly divided into 5 groups (n=8 each): sham operation group (group S); bone cancer pain + 5 μl dimethyl sulfoxide (DMSO) group (group R0); bone cancer pain + 2.5 μg RC-13 group (group R1); bone cancer pain + 5 μg RC-13 group (group R2) and bone cancer pain + 10 μg RC-13 group (group R3).In groups R0-3,bone cancer pain was induced by implantation of α-min-imal essence medium (α-MEM) containing osteosarcomaNCTC 2472 cells into the intramedullary space of right femur.In group S,culture medium α-MEM containing no cancer cell was injected instead.10％ DMSO 5 μl and RC-13 2.5 μg/5 μl,5μg/5μ1 and 10 μg/5 μ1 dissolved in 10％ DMSO were injected intrathecally in groups R0-3,respectively,once a day for 3 consecutive days starting from 14th day after inoculation of the tumor cells.Pain behavior was assessed by the paw withdrawal mechanical threshold (PWMT) and spontaneous lifting times (SLTs) measured at 1 day before inoculation and at 3,5,7,10,14 days after inoculation.The same tests were also performed at 1,3,5 and 7 days after administration in groups R0-3.Results Compared with group S,PWMT was significantly decreased and SLTs were increased at 7-14 days after inoculation in the other groups (P ＜ 0.05).Compared with group R0,PWMT was significantly increased and SLTs were reduced at 1 day after administration in group R1,at 1and 3 days after administration in group R2,and at 1,3 and 5 days after administration in group R3 (P ＜ 0.05).Compared with group R1,PWMT was significantly increased and SLTs were reduced at 3 days after administration in group R2,and at 1,3 and 5 days after administration in group R3 (P ＜ 0.05).Compared with group R2,PWMT was significantly increased and SLTs were reduced at 1 and 3 days after administration in group Rs (P ＜ 0.05).Conclusion Intrathecal RC-13,a competitive kinesin superfamily protein 17 antagonist,has a good analgesic efficacy in a mouse model of bone cancer pain and the efficacy is dose-dependent.