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OBJECTIVE@#To study the effects of electroacupuncture (EA) in chronic constrictive injury (CCI) rat model and the expression of N-methyl-D-aspartate receptor type 2B (NR2B) in ipsilateral spinal dorsal horn in rats to explore the analgesic mechanisms of EA.@*METHODS@#According to the random number table, totally 180 rats were evenly divided into a sham group, a CCI group, and an EA group. CCI model was conducted with four 4-0 chromic gut ligatures loosely ligated around the left sciatic nerve 1 cm above the trifurcation. Rats in the EA group received 2 Hz EA therapy bilaterally at acupoints of Zusanli (ST 36) and Sanyinjiao (SP 6) once daily (30 min/d) for 30 days after surgery. Paw withdrawal thresholds (PWTs) were measured on 0 (baseline), 1, 3, 7, 15, 30 days after surgery. Rats were sacrificed on 0, 1, 3, 7, 15 and 30 days after surgery, and the L4-5 segments of spinal cord were removed to detect the expression of NR2B by immunohistochemistry and quantitative polymerase chain reaction.@*RESULTS@#PWTs in the CCI group were significantly lower than the sham group at Day 1-30 after surgery, and reached its lowest at Day 1 (P<0.01). After EA treatment, the PWTs recovered rapidly and were significantly higher than those in the CCI group on 3, 7, 15 and 30 days after surgery (P<0.01). The numbers of NR2B-immunoreactive cells of the CCI group significantly increased after CCI surgery compared with the sham group (P<0.01). Compared with the CCI group, stimulation of EA markedly decreased the numbers of NR2B-immunoreactive cells at Day 3, 7, 15 and 30 (P<0.05). In the sham group, NR2B mRNA was expressed at a low level. It increased after CCI surgery, which increased rapidly at Day 7 (P<0.01) and reached its peak value at Day 15 (P<0.01). After EA stimulation, relative quantity of NR2B mRNA expression was less than that in the CCI group at Day 15 and 30 (P<0.05).@*CONCLUSIONS@#Low frequency of EA had antinociceptive effect in CCI rat model. The analgesic effects of EA might be through the inhibition of NR2B.
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Objective To investigate the effect of hyperbaric oxygen(HBO)on p38 MAPK signal pathway in neuropathic pain,and explore its mechanism. Methods The experiment was divided into two parts with thirty SD rats in each part. Each part was then randomly divided into 3 groups:sham operation group(S group),chronic constriction group(CCI group)and hyperbaric oxygen group(HBO group),with 10 rats in each group. Part one:Pain?related behavior were detected on 3 day,7 day,14 day,28 day after operation. Phosphorylative p38 was detected by Western blot method and the P2X4 receptor was detected by immunohistochemistry method on the 28th day. Part two:All the rats were treated with SB203580. Pain?related behavior were detected on 3 day,7 day,14 day,28 day after operation. P2X4 receptor was detected by immunohistochem?istry method on the 28th day. Results CCI and HBO groups were significantly lower than S group in pain?related behaviors(P0.05). Though the expression of P2X4 receptor in CCI group and HBO group was significantly higher than that in S group(P0.05). Conclusion Hyperbaric oxygen therapy can affect the expression of p38 MAPK through P2X4 receptor in rats of neuropathic pain.
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Objective To investigate the expression of nuclear factor kappa B(NF-Κb)in the lumbar spinal cord in chronic constrictive injury(CCI)of the sciatic nerve.Methods Foay-eight male Sprague-Dawley rats were divided into 2 groups(n=24 in each).The operation group received CCI of the sciatic nerve and the sham-operation group received a sham operation as a control.Their mechanical and thermal nociceptive thresholds were assessed with paw withdrawal latency (PWL) using von Frey filaments and radiant heating.Four rats were sacrificed at each time point and segments of their lumbar spinal cords were examined using Western blotting.Results Mechanical and thermal stimulation thresholds were reduced significantly after the operation.Expression of NF-Κb protein increased significantly in the ipsilateral dorsal horn of the spine compared with the contralateral side and compared with the sham-operation group.NF-Κb protein expression began to increase on the 1 st day after the operation,reached a peak at the 7th day,and stayed high throughout the experiment.Conclusion NF-Κb in the dorsal horn of the spine may be involved in neuropathie pain after CCI.
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BACKGROUND: The effect of chronic administration of 4-methylcatechol known as a neurotrophic factor inducer on the allodynia and spinal neurotrophic factors was investigated in chronic constrictive injury of sciatic nerve in rats. METHODS: With the Sprague Dawly rat, sciatic nerve was loosely ligated with 4-0 chromic catgut and neuropathic pain model was made. The threshold for tactile allodynia was measured with von Frey hair by up-down method and cold allodynia was measured by dropping 20microliter of 100% acetone on the dorsum of the injured foot. 4-Methylcatechol (100microgram/kg, intraperitoneal) was injected once a day for 14 days and the effect on allodynia was compared with saline injected group. At 3, 7 and 14 days after injection, lumbar spinal cord was harvested and the mRNA content of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) was measure by real time PCR. RESULTS: Mechanical and cold allodynia improved from 7 days after 4-methylcatechol administration. NGF and BDNF in spinal cord decreased compared to sham operated group. BDNF in lumbar spinal cord has increased tendency after treatment without statistical significance. CONCLUSIONS: Chronic intraperitoneal administration of 4-methylcatechol may improve tactile and cold allodynia in chronic constrictive injury rat model of neuropathic pain. The BDNF mRNA in spinal cord might increase after 4-methylcatechol treatment.