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Objective To evaluate the effect of B-vitamins(B1,B6,B12)on diabetic neuropathic pain (DNP)in rats.Methods 104 male SD rals weighing 200-230 g were randomly divided into 13 groups(n=8 each):group Ⅰ control(group C);group Ⅱ DNP;group Ⅲ DNP+ normal saline(solvent of vitamins,group NS);group Ⅳ,Ⅴ,Ⅵ DNP+vitamin B1 10,33 or 100mg/kg,kg(group B1 10,group B133,group B1 100);group Ⅶ,Ⅷ,Ⅺ DNP+vitamin B6 10,33 or 100 mg/kg(group B6 10,group B633,group B6100);group Ⅹ,Ⅲ,ⅫDNP+vitamin B12 0.5,1.5 or 4.5 mg/kg (group B12 0.5,group B121.5,group B124.5)and group ⅩⅢ DNP+vitamin B1 10/B6 33/B12 1.5 mg/kg(group VBC).Diabetes was induced with intraperitoneal(IP) streptozocin mg/kg in group Ⅱ-ⅩⅢ.B-vitamins were give.IP once a day for 14 consecutive days starting from 14 d after IP streptozocin in group Ⅳ-ⅩⅢ.Venous blood samples were taken before(baseline)and 3 d after IP streptozocin for determination of blood glucose level. Successful induction of diabetes was defined as blood glucose > 14.6 mmol/L. Mechanical paw withdrawal threshold to yon Frey stimuli (MWT) and paw withdrawal latency to thermal nociceptive stimulus (TWL) were measured 2 days before and 14 days after IP streptozocin and on the 1, 3, 7, 14 days of B-vitamin administration. Animals with pain threshold measured at 14 days after IP streptozocin decreasing by less than 15% of the baseline were excluded from the study. The animals were sacrificed after the last pain threshold measurement and L4,5 lumbar segment of the spinal cord and dorsal root ganglions (DRG) were removed for determination of p-CREB expression using immuno-histuchemistry. Results MWT was significantly lower and TWL was significantly shorter and the expression of p-CREB was significantly higher in the other groups than in group C. B-vitamin administration significantly reduced thermal and mechanical hyperalgesia induced by diabetes and down-regulated the expression of p-CREB in a dose-dependent manner as compared with group DNP. The inhibitory effect of vitamin B complex against thermal and mechanical hyperalgesia was significantly stronger and the expression of p-CREB was significantly lower in group VBC as compared with group B110, group B633 and group B121 .5 respectively. Conclusion B-vitamains can attenuate DNP through inhibition of phospberylation of CREB in the spinal dorsal horn and DRG.
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Objective To evaluate the effect of curcumin on diabetic neuropathic pain (DNP) in rats. Methods Forty-eight male SD rats weighing 200-230 g were randomly divided into 6 groups ( n = 8 each) : group Ⅰ normal control (group C); group Ⅱ DNP (group D) ; group Ⅲ DNP+ DMSO (solvent of curcumin) (group DD) and group Ⅳ , Ⅴ , Ⅵ DNP + curcumin 50, 100 or 200 mg/kg ( group DC50, 100, 200 ). Diabetes was induced with intraperitoneal (IP) streptozocin 75 mg/kg in group Ⅱ -Ⅵ. Curcumin 50, 100 and 200 mg/kg were given IP once a day for 14 consecutive days starting from 14 d after streptozocin in group Ⅳ , Ⅴ and Ⅵ respectively. Venous blood samples were taken before and 72 h after IP streptosocin for determination of blood glucose level. Successful induction of diabetes was defined as blood glucose > 14.6 mmol/L. Mechanical paw withdrawal threshold to yon Frey stimuli (MWT) and paw withdrawal latency to thermal nociceptive stimulus (TWL) were measured 2 d before and 14 d after IP streptesocin and on the 1, 3, 7, 14 d of curcumin administration. Animals with pain threshold measured at 14 d after IP streptozocin decreasing by less than 15% of the baseline were excluded from the study. The animals were sacrificed after the last pain threshold measurement and the lumbar segment of the spinal cord and p65 was significantly higher in group D than in group C ( P < 0.05). Curcumin administration significantly reduced thermal and mechanical hyperalgesia induced by diabetes and down-regulated the expression of p-JNK and horn and DRG.
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Objective To determine whether chronic constriction injury (CCI) to sciatic nerve is associated with changes in the phosphorylation of CREB in dorsal root ganglia ( DRG) and superficial dorsal horn neurons of the spinal cord.Methods Thirty-two adult female SD rats weighing 230-270 g were randomly divided into 4 groups (n = 8 each): Ⅰ blank control;Ⅱ sham operation; Ⅲ CCI 2w and Ⅳ CCI 4w. The animals were anesthetized with intraperitoneal pentobarbital 40 mg?kg-1. Right sciatic nerve was exposed and 4 ligatures were placed on the right sciatic nerve at 1 mm interspace with 3-0 silk suture. Paw withdrawal threshold to mechanical stimulation (von Frey filament) applied to plantar surface ( MWT) and paw withdrawal latency to thermal stimulation (radiant heat) (TWL) were measured before operation (baseline) and 14 days (group Ⅰ,Ⅱ and Ⅲ) or 28 days (group Ⅳ) after nerve ligation. The animals were killed the next day and the L4,5 segment of the spinal cord and L5 dorsal root ganglion were removed for determination of expression of phosphorylated-CREB-immuno-reaction(pCREB-IR) using immuno-histochemistry. The pCREB-IR cells both in DRG and superficial dorsal horn neurons were quantified and analyzed. Results The animals developed mechanical and thermal hyperalgesia on the 14th day after CCI (in group CCI 2w) . The hyperalgesia was greatly attenuated on the 28th day after CCI. Interestingly enough the animals in sham operation group (Ⅱ) also developed mechanical hyperalgesia to some extent on the 14th day after operation. The number of pCREB-IR cells was significantly increased in the ipsilateral L5 DRG and superficial dorsal horn in group Ⅲ(CCI 2w) as compared to sham operation group ( P
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Objective To investigate the effects of a highly selective protein kinase A (PKA) inhibitor, H89, injected intrathecally (IT) on hyperalgesia and phosphorylation of cAMP element binding protein(pCREB) in the dorsal horn neurons of the spinal cord induced by chronic constriction injury (CCI) to the sciatic nerve.Methods Fifty-eight adult female SD rats weighing 230-270 g were used in this study. CCI was produced by 4 loose ligatures place on the sciatic nerve of right hind leg at 1 mm interspace with 3-0 silk suture. The experiment was carried out in two parts. In part Ⅰ 28 animals were randomized to receive H89 1 (group H1), 2 (group H2 ) or 4 nmol (group H4) or 10 ?l of DMSO (the solvent) 10mmol?L-1 (control group) intrathecally (IT) (n = 7 each) 7 days after surgery. The paw-withdrawal latency following mechanical (MWL) and thermal stimulation (TWL) were recorded before (baseline) and 15, 30 and 60 min after drug administration. In part Ⅱ 24 rats were randomized to receive H89 1, 2 or 4 nmol or 10 ?l of DMSO 10 mmol?L-1 IT as in part Ⅰ (group H1, H2, H4 and control group, n = 6 each) . Another 6 animals received 10 ?l of DMSO 10 mmol?L IT 7 days after sham operation. The animals were killed 30 min after drug administration and lumbar (L4.5) segment of spinal cord was removed for determination of pCREB expression in the dorsal horn neurons of spinal cord using immuno-histochemical technique. Results MWL and TWL were significantly increased after drug administration in group H2(at 15min) and group H4(at 15 and 30 min) as compared to the baseline values(P
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Aim To investigate the effect of intrathecal injection(it) of minocycline(MC),a selective microglia inhibitor,on the maintenance of pain in a murine model of cancer pain.Methods Forty-two male C3H/He mice were randomly divided into 3 groups(n=14 each):sham+PBS group was operated and received 10 ?l PBS injection into calcaneus medullary space;sarcoma+PBS group and sarcoma+MC group were operated and received 2?105 sarcoma cells/10 ?l PBS implantation into calcaneus medullary space.On the PID11(post-implantation day 11),10 mice were taken from each group randomly,sarcoma+PBS group and sham+PBS group were received 0.9% NS(5 ?l) it sarcoma+MC group was received MC(1 nmol,5 ?l) it Mechanical pain threshold and cold hyperalgesia assay were measured before and after it at 0.5,1,2,4,8,24 h.The last 4 mice of each group were received a normally non-noxious palpation of the ipsilateral heel 90 min on the PID12 after it,then the animals were killed and L4-6 segment of spinal cord was removed for analysing the c-fos expression(by immunohistochemistry).Results Bone cancer pain decreased the mechanical and cold pain threshold and activated the c-fos expression in the spinal cord;MC it transient attenuated bone cancer pain-induced hyperalgesia and allodynia and suppressed the expression of c-fos protein.Conclusion The activation of microglia in the spinal cord may be involved in the maintenance of bone cancer pian.