Intervention effect of Tuina pressing and kneading the Huantiao (GB30) acupoint on NF-κB p65 protein at spinal cord dorsal horn in sciatica rats / 中国骨伤

OBJECTIVE@#To observe the analgesic effect of Tuina by pressing and kneading the Huantiao (GB30) acupoint on rats with chronic constriction injury (CCI) and to explore the analgesic mechanism of Tuina on sciatica rats.@*METHODS@#Thirty-two SPF male SD rats weighing 180 to 220 g were randomly divided into fore groups:blank group (without any treatment), sham group (only exposed without sciatic nerve ligating), model group (sciatic nerve ligating) and Tuina group (manual intervention after lsciatic nerve ligating). The CCI model was prepared by ligating the right sciatic nerve of the rats, on the third day of modeling, the rats in the Tuina group were given pressing and kneading the Huantiao (GB30) point for 14 days, and the changes of paw withdrawal threshold(PWT), paw withdrawal latency(PWL) were measured before and on the 1st, 3rd, 7th, 10th, 14th and 17th days after modeling. The changes of sciatic functional index(SFI) were measured before and on the 1st and 17th day after modeling. The morphological changes of the sciatic nerve were observed by hematoxylin-eosin(HE) staining;and the differences in NF-κB protein expression in the right dorsal horn of the spinal cord of rats were detected.@*RESULTS@#Following modeling, there was no significant difference in PWT, PWL and SFI between the blank group and the sham group (P>0.05), but the PWT, PWL and SFI of the model group and the Tuina group decreased significantly (P<0.01). After manual intervention, the pain threshold of rats in Tuina group increased. On the 8th day of manual intervention (the 10th day after modeling), PWT in Tuina group increased significantly compared with that in model group (P<0.01). On the 5th day of manual intervention (the 7th day after modeling), the PWL of the massage group was significantly higher than that of the model group (P<0.01). The pain threshold of rats in Tuina group continued to rise with the continuous manipulation intervention. After 14 days of manipulative intervention, the sciatic nerve function index of rats in the Tuina group increased significantly(P<0.01). Compared with the blank group and sham group, the myelinated nerve fibers of sciatic nerve in the model group were disordered and the density of axons and myelin sheath was uneven. Compared with the model group, the nerve fibers of rats in the Tuina group were gradually continuous and the axons and myelin sheath were more uniform than those in the model group. Compared with the blank group and sham group, the expression of NF-κB protein in the right spinal dorsal horn of the model group was significantly increased(P<0.01). Compared with the model group, the expression of NF-κB protein in the right spinal dorsal horn of rats in Tuina group decreased significantly(P<0.01).@*CONCLUSION@#Pressing and kneading the Huantiao (GB30) point restores nerve fiber alignment;and improves the PWT、PWL and SFI in the CCI model by decreasing NF-κB p65 protein expression in the spinal dorsal horn. There fore, Tuina demmstrates an analgesic effect and improves the gait of rats with sciatica.

Mechanism of Chuanxiong Rhizoma intervention on central sensitization of Panx1-Src-NMDAR-2B signaling pathway in neuropathic pain model rats / 中国中药杂志

Excitatory toxicity(ET) is an important factor of neuropathic pain(NPP) induced by central sensitization(CS), and the association of pannexin-1(Panx1)-Src-N-methyl-D-aspartate receptor subunit 2 B(NMDAR-2 B) is an important new pathway for ET to initiate CS. The present study confirmed whether the central analgesic effect of Chuanxiong Rhizoma extract(CRE) was achieved through the synchronous regulation of the brain and spinal pathways of Panx1-Src-NMDAR-2 B. In this study, dynamic and simulta-neo-us microdialysis of the brain and spinal cord in vivo combined with behavioristics, high performance liquid chromatography(HPLC)-fluorescence detection, microdialysis analysis(ISCUS~(flex)), ultrasensitive multifactorial electrochemiluminescence immunoassay, ELISA, and Western blot was employed to investigate the protein expression of NMDAR-2 B, Src, and Panx1, extracellular excitatory amino acids, cytokines, energy metabolites, and substance P in spinal dorsal horn(SDH) and anterior cingulate cortex(ACC) after CRE intervention with the rat model of spared sciatic nerve injury(SNI) as the experimental tool. Compared with the sham group, the SNI group exhibited diminished mechanical withdrawal threshold(MWT)(P<0.01), increased cold spray scores(P<0.01), glutamate(Glu), D-serine(D-Ser), and glycine(Gly) in extracellular fluids of ACC, and Glu, D-Ser, interleukin-1β(IL-1β), and lactic acid(Lac) in extracellular fluids of SDH(P<0.05), dwindled tumor necrosis factor(TNF-α)(P<0.05), and elevated protein levels of NMDAR-2 B, Src, and Panx1 in ACC(P<0.05). Compared with the SNI model rats, high-and medium-dose CRE(CRE-H/M) could potentiate the analgesic activity as revealed by the MWT test(P<0.05) and CRE-M enabled the decrease in cold spray scores(P<0.05). CRE-H/M could inhibit the levels of Glu, D-Ser and Gly in the extracellular fluids of ACC(P<0.05), and the levels of Glu in the extracellular fluids of SDH(P<0.05) in SNI rats. CRE-M significantly increased the levels of glucose(Gluc), Lac, interferon-gamma(IFN-γ), keratinocyte chemoattractant/human growth-regulated oncogenes(KC/GRO), and IL-4 in extracellular fluids of SDH in SNI rats(P<0.05). CRE-H/M/L could also inhibit the levels of NMDAR-2 B, Src and Panx1 in ACC and SDH in SNI rats(P<0.05). The central analgesic effect of CRE is presumedly related to the inhibited release of excitatory amino acid transmitters(Glu, D-Ser and Gly) in ACC and SDH of SNI rats, decreased protein expression of NMDAR-2 B, Src and Panx1 in the two regions, and the regulation of the Panx1-Src-NMDAR-2 B pathway in the spinal cord and brain. The above findings partially clarified the scientific basis of clinical analgesic effect of Chuanxiong Rhizoma.

Effect of wrist-ankle acupuncture on the expression of glutamate and NMDA receptor of the spinal dorsal horn in rats with neuropathic pain / 针刺研究

OBJECTIVE: To observe the effect of wrist-ankle acupuncture (WA) stimulation at "R4"- "R5" - "R6" on the expression of glutamate (Glu) and phosphorylated protein NMDAR1(p-NMDAR1) of the spinal dorsal horn in spared nerve injury (SNI) rats, so as to explore its mechanism underlying improvement of SNI. METHODS: A total of 36 SD rats were randomly divi-ded into sham operation, model and WA groups, with 12 rats in each group. The SNI procedure comprised an axotomy and ligation of the tibial and common peroneal nerves leaving the sural nerve intact. Rats of the WA group were treated by acupuncture at "R4"-"R5"-"R6" points from the 5th day to the 14th day after modeling. The mechanical pain thresholds were measured before and 5, 10 and 14 d after SNI, respectively. The cold allodynia was dectected by Acetone solution dropped onto the lateral plantar surface of the paw. Glu content and p-NMDAR1 expression of spinal dorsal horn were detected by 1H-MRS, ELISA and immunohistochemistry Methods. RESULTS: Compared with the sham operation group, the mechanical pain threshold of the model group was significantly decreased (P<0.01), the duration of cold stimulation foot contraction was increased (P<0.01), and the Glu content and p-NMDAR1 expression in the spinal dorsal horn were significantly increased (P<0.05, P<0.01). After WA intervention, the mechanical pain threshold was significantly increased (P<0.01), the duration of cold stimulation was significantly shortened (P<0.01), and Glu content and p-NMDAR1 protein expression of spinal dorsal horn were decreased significantly (P<0.05, P<0.01) in the WA group compared with the model group. CONCLUSION: WA can reduce pain sensitivity in rats with neuropathic pain, possibly by inhibiting the expression of Glu and p-NMDAR1 in the spinal dorsal horn.

Study on Mechanism of Analgesic Effect of 8-O-acetyl-safalinoside on Chronic Inflammatory Pain Model Rats / 中国药房

OBJECTIVE： To study the mechanism of analgesic effect of 8-O-acetyl-safalinoside （8-OaS） on chronic inflammatory pain model rats. METHODS ：Totally 30 male SD rats were divided into sham operation group （normal saline ）， model group （normal saline ），8-OaS low-dose ，medium-dose and high-dose groups （3，10，30 μg/kg），with 6 rats in each group. Except for sham operation group ，other groups were given planter injection of Freund ’s complete adjuvant to induce chronic inflammatory pain model. After successful modeling ，the rats in each group were given corresponding drugs intrathecally ，once a day，for 7 consecutive days. Then Von-Frey filaments were used to detect the planter pain threshold of the rats in each group ；the area under the planter pain threshold curve of each group and the half effective dose （ED50）of 8-OaS were calculated. Another 36 male SD rats were divided into sham operation group （normal saline ），model group （normal saline ）and 8-OaS group （dose of ED50），and the modeling method and administration route were the same as above. Immunofluorescence histochemical staining was used to observe the positive expression of ionized calcium binding adapter molecule 1（Iba-1）and signal molecule phosphorylated p38 mitogen-activated protein kinase （p-p38 MAPK）；Western blotting assay was used to determine the expression of Iba- 1，p-p38 MAPK，IL-1β，IL-6 and TNF-α in spinal dorsal horn of rats. RESULTS：Compared with sham operation group ，plantar pain threshold and area under the curve in model group were reduced significantly （P＜0.01）. Compared with model group ，plantar pain threshold increased significantly after 5，6，7 days of administration in 8-OaS low-dose group （P＜0.05），plantar pain threshold and area under the curve in 8-OaS medium-dose and high-dose groups were increased significantly （P＜0.05 or P＜0.01）. Most of above indexes in each dose group of 8-OaS were signifficantly different ，and ED 50 of 8-OaS was 18.87 μ g/kg. Results of immunohistochemistry staining and Western blotting showed that p-p 38 MAPK was mainly expressed in Iba- 1 positive cells. Compared with sham operation group ，the fluorescence density of Iba- 1 and p-p 38 MAPK in spinal dorsal horn ，the expression of Iba-1，p-p38 MAPK，IL-6，IL-1β and TNF-α were significantly increased in model group（P＜0.05 or P＜0.01）. Compared with model group ，the fluorescence density of Iba- 1 and p-p 38 MAPK in spinal dorsal horn ，the expression of Iba- 1，p-p38 MAPK， IL-6，IL-1β and TNF-α were decreased significantly in 8-OaS group （P＜0.05）. CONCLUSIONS ：Intrathecal administration of 8-OaS can effectively alleviate chronic inflammatory pain in rats. The mechanism may be related to the inhibition of the phosphorylation of p 38 MAPK and the expression of IL- 6，IL-1β and TNF-α.

Effect of sciatic nerve pulsed radiofrequency glial activation levels in spinal dorsal horn in chronic constriction injury rat models and its analgesia effect / 吉林大学学报(医学版)

Objective: To observe the effect of sea tic nerve pulsed radiofrequency (PRF) on the activation levels of microglia cells and astrocytes in spinal dorsal horn in the chronic constriction injury (CCD rat models, and to explore the relationships between the analgesic mechanism of sciatic nerve PRF and the activation levels of microglia cells and astrocytes in the spinal dorsal horn- Methods: Forty male SD rats were randomly divided into CCI shamoperation+RPF sham group (SS group). CC1 sham-operation + RPF group (SP group). CCI+RPF sham group (CS group). CCI+ RPF group (CP group) ( n 10). PRF was applied on the sciatic nerve on the 4th day after CC1 operation for 120 s, with a maximum temperature of 42"C. The mechanical withdrawal thresholds (MWT) and thermal paw withdrawal latencies 0. 05). Conclusion- PRF on sciatic nerve can relieve the neuropathic pain (NT) of the CCI rat models: PRF on saatic nerve can inhibit activation of the microglia cells in the spinal dorsal horn. The analgeac mechanism of PRF on sciatic nerve may be associated with the inhibition of the activation of microglia cells in the spinal dorsal horn.

Effects of intrathecal injection of M_ERK2-shRNA adenovirus on diabetic neuropathic pain in mouse / 解剖学报

Objective To explore the mechanism of extracellular regulated protein kinase 2 (ERK2) in diabetic neuropathic pain(DNP) mice. Methods Forty mice were randomly divided into four groups: control group, DNP group, siERK2-DNP group (intrathecal injection of M_ERK2-shRNA adenovirus), siRNA-DNP group (intrathecal injection of siRNA adenovirus). The pain threshold was detected after the model made successfully, the mechanical pain threshold was detected before moulding, after moulding 2 weeks, 4 weeks and 6 weeks. Spinal cord tissues were taken after 6 weeks, and the expression of ERK2 and nuclear factor ΚB (NFΚB) in the posterior horn of the spinal cord was detected by Western blotting and immunohistochemistry. Results Compared with the control group, the pain threshold of DNP group and siRNA-DNP group decreased significantly, the expression of ERK2 and NFKB increased significantly (P0. 05). Conclusion The marked down-regulation of ERK2 may be one of the important mechanisms affecting neuronal injury in the spinal dorsal horn of diabetic neuropathic pain.

Expression of the NMDA receptor in the rat model of orchialgia / 中华男科学杂志

Objective@#To explore the expression of the N-methyl-D-aspartate (NMDA) receptor in the rat model of orchialgia and its possible mechanisms.@*METHODS@#According to Yoshioka's method, the male rats in the control group were injected with 0.2 ml saline, and those in the experimental group with 0.2 ml 2% acetic acid solution. Then we tested the behavioral responses of the rats and determined the expressions of the subunits NR1 and NR2B of the NMDA receptor in the dorsal root ganglion and spinal dorsal horn by Western blot, RT-qPCR and immunofluorescence staining.@*RESULTS@#The withdrawal latency was decreased in the model rats, reaching the lowest value at 4 hours after modeling, significantly lower than in the controls (［4.15 ± 0.84］ vs ［12.32 ± 1.05］, P 0.05).@*CONCLUSIONS@#The NMDA receptor plays an important role in pathogenesis of orchialgia in rats. In the early stage of pain, upregulating the expression of the subunit NR2B of the NMDA receptor can mediate peripheral hyperalgesia and consequently orchialgia.

Up-regulation of P2X7 Receptors Contributes to Spinal Microglial Activation and the Development of Pain Induced by BmK-I / 神经科学通报·英文版

Previous work has demonstrated that the sensitization of spinal neurons and microglia is important in the development of pain behaviors induced by BmK I, a Na channel activator and a major peptide component of the venom of the scorpion Buthus martensi Karsch (BmK). We found that the expression of P2X7 receptors (P2X7Rs) was up-regulated in the ipsilateral spinal dorsal horn after BmK I injection in rats. P2X7R was selectively localized in microglia but not astrocytes or neurons. Similarly, interleukin 1β (IL-1β) was selectively up-regulated in microglia in the spinal dorsal horn after BmK I injection. Intrathecal injection of P2X7R antagonists largely reduced BmK I-induced spontaneous and evoked pain behaviors, and the up-regulation of P2X7R and IL-1β in the spinal cord. These data suggested that the up-regulation of P2X7Rs mediates microglial activation in the spinal dorsal horn, and therefore contributes to the development of BmK I-induced pain.

Low-Frequency Electroacupuncture Alleviates Chronic Constrictive Injury-Induced Mechanical Allodynia by Inhibiting NR2B Upregulation in Ipsilateral Spinal Dorsal Horn in Rats / 中国结合医学杂志

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.

Effect of sciatic nerve pulsed radiofrequency glial activation levels in spinal dorsal horn in chronic constriction injury rat models and its analgesia effect / 吉林大学学报(医学版)

Objective:To observe the effect of sciatic nerve pulsed radiofrequency (PRF) on the activation levels of microglia cells and astrocytes in spinal dorsal horn in the chronic constriction injury (CCI) rat models, and to explore the relationships between the analgesic mechanism of sciatic nerve PRF and the activation levels of microglia cells and astrocytes in the spinal dorsal horn.Methods:Forty male SD rats were randomly divided into CCI shamoperation+RPF sham group (SS group) , CCI sham-operation+RPF group (SP group) , CCI+RPF sham group (CS group) , CCI+RPF group (CP group) (n=10) .PRF was applied on the sciatic nerve on the 4th day after CCI operation for 120s, with a maximum temperature of 42℃.The mechanical withdrawal thresholds (MWT) and thermal paw withdrawal latencies (TWL) were measured to evaluate mechanical hyperalgesia and thermal hyperalgesia 1dbefore operation (D0) and 1, 3, 5, 7dafter operation (D1, D3, D5, D7) .Western blotting method was used to detect the protein expression levels of ionized calcium binding adapter molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP) in the ipsilateral spinal dorsal horn of L3-5after pain behavioral test (D7) .Results:Compared with SS group, the rats in CS group after CCI had the significant behavioral changes, such as hallux valgus, lameness, toe bending, and foot raising during walking;MWT and TWL were decreased significantly (P＜0.01) ;the expression levels of Iba-1and GFAP proteins in the ipsilateral spinal dorsal horn were increased significantly (P＜0.05) .Compared with CS group, the behavioral changes of the rats in CP group (D5, D7) such as hallux valgus, lameness, toe bending, and foot raising during walking were alleviated significantly;MWT and TWL were increased significantly (P＜0.01) ;the Iba-1protein expression level in spinal dorsal horn was downregulated significantly (P＜0.05) and the GFAP protein expression level did not change significantly (P＞0.05) .Conclusion:PRF on sciatic nerve can relieve the neuropathic pain (NP) of the CCI rat models;PRF on sciatic nerve can inhibit activation of the microglia cells in the spinal dorsal horn.The analgesic mechanism of PRF on sciatic nerve may be associated with the inhibition of the activation of microglia cells in the spinal dorsal horn.

Effect of osthole on p38 MAPK signaling related pathway of rat model with inflammatory radicular pain induce by nucleus pulposus in the spinal horn / 中国药理学通报

Aim To observe the effect of epidurally application of osthole on the model of nucleus pulposusinduced inflammatory radicular pain and the expression of p38 MAPK signaling related pathway in the spinal dorsal horn of rats.Methods The model of radicular pain was generated by putting nucleus pulposus to the L5 dorsal root ganglion (DRG).50％ MWT was measured using Von Frey filaments to calculate mechanical pain threshold before and after operation.50 μL of 20 g · L-1 osthole was administered epidurally in group Ost and 50 μL of 100 mL · L-1 DMSO in group DMSO at postoperative day (POD).The expression of phosphorylated p38 (p-p38),IL-18 and IL-18R in the lumbar spinal dorsal horn was detected by Western blot.IL-18 mRNA was assessed by real-time PCR.Results The mechanical pain threshold significantly decreased after operation (P ＜ 0.05),while the expression of protein p-p38 MAPK,IL-18,IL-18R and IL-18 mRNA was significantly different.Compared with DMSO group,50％ MWT was significantly increased and accompanied with the decrease of protein p-p38,IL-18,IL-lgR and IL-18 mRNA in Ost group after drug administration (P ＜ 0.05).The correlation analysis between protein concentration of p38 MAPK and IL-18 mRNA showed that the Spearman correlation coefficient was 0.9 (P ＜ 0.05).Conclusion p-p38 and IL-18 of spinal dorsal horn participate in the rat model with inflammatory radicular pain induced by nucleus pulposus,and IL-18R plays a role in maintenance of the pain.Osthole administered epidurally in the early stage of pain could alleviate the pain for a long time,which may be related with inhibiting p38 MAPK signaling related pathways.

Effects of intrathecal injection Roscovitine on the pain behavior and the expression of ERK1/2 and PPARγ protein in spinal cord in rats with neuropathic pain / 中华行为医学与脑科学杂志

Objective To investigate the effects of intrathecal injection of Roscovitine on the pain behavior and the expression of pERK1/2 and pPPARγ receptor in spinal cord in rats with neuropathic pain.Methods Fifty-two male adult Sprague-Dawley rats of 220～ 250 g were randomly divided into 4 groups:Sham+DMSO group (dimethyl sulfoxide,S+D group),Sham+Roscovitine (S+R) group,CCI+ DMSO group (I+D),CCI+ Roscovitine (I+R) group.The corresponding drugs were administered by intrathecal injection from the seventh day after CCI once a day for 14 days.The right hind paw mechanical threshold value (PMWT) was measured by Von Frey filament and paw thermal withdrawal latency(PWTL) was measured by Hargreaves methods before 1 day and 3 d,7 d,10 d,14 d after surgery.The spinal cord lumbar enlargement was taken at 14 d after surgery,and Cdk5,p35,phosphorylated ERK protein (pERK),total ERK protein (ERK),phosphorylated PPARγprotein (pPPARγ) and total PPARγ protein (PPARγ) were detecteded by Western blot.Results Roscovitine was administered by intrathecal injection alleviated mechanical allodynia and thermal hyperalgesia of CCI rats.Compared with I+D group,PWMT in I+R group at 7 d,10 d,14 d after administration((4.65±0.08)g,(6.47±0.12)g,(7.90±0.19)g,) vs ((3.71 ±0.06)g,(2.45±0.17)g,(2.31±0.15)g) (Fgroup =505.71,P＜0.05,Ftime×group =15.33,P＜0.05),PWTL((9.22±0.33) s,(13.52±0.43) s,(12.63±0.88) s) vs ((8.02±0.20) s,(5.90±0.28) s,(5.40±0.38) s) (Fgroup =355,P＜0.05,F time×group =8.589,P＜0.05) were significantly increased.Compared with I+D group(p35 (0.58±0.02),pERK (1.12±0.13),pPPARγ (0.77±0.16)),p35 (0.46±0.04,F=11.06,P＜0.05) and pERK(0.79±0.11,F =22.91,P＜ 0.05) in I+ R group,were significantly dereased,and the expression of pPPARγ(0.99±0.13,F =17.62,P＜0.05))was significantly increased.Conclusion Intrathecal injection Roscovitine can alleviate both mechanical allodynia and thermal hyperalgesia in rats with neuropathic pain,and its mechanisms may be related to the inhibition of Cdk5/p35 and ERK activity,enhancement of PPARγ activity in the spinal dorsal horn.

Modulation of Pain and Itch by Spinal Glia / 神经科学通报·英文版

Chronic pain and itch are a pathological operation of the somatosensory system at the levels of primary sensory neurons, spinal cord and brain. Pain and itch are clearly distinct sensations, and recent studies have revealed the separate neuronal pathways that are involved in each sensation. However, the mechanisms by which these sensations turn into a pathological chronic state are poorly understood. A proposed mechanism underlying chronic pain and itch involves abnormal excitability in dorsal horn neurons in the spinal cord. Furthermore, an increasing body of evidence from models of chronic pain and itch has indicated that synaptic hyperexcitability in the spinal dorsal horn might not be a consequence simply of changes in neurons, but rather of multiple alterations in glial cells. Thus, understanding the key roles of glial cells may provide us with exciting insights into the mechanisms of chronicity of pain and itch, and lead to new targets for treating chronic pain and itch.

Involvement of NF-κB and the CX3CR1 Signaling Network in Mechanical Allodynia Induced by Tetanic Sciatic Stimulation / 神经科学通报·英文版

Tetanic stimulation of the sciatic nerve (TSS) triggers long-term potentiation in the dorsal horn of the spinal cord and long-lasting pain hypersensitivity. CX3CL1-CX3CR1 signaling is an important pathway in neuronal-microglial activation. Nuclear factor κB (NF-κB) is a key signal transduction molecule that regulates neuroinflammation and neuropathic pain. Here, we set out to determine whether and how NF-κB and CX3CR1 are involved in the mechanism underlying the pathological changes induced by TSS. After unilateral TSS, significant bilateral mechanical allodynia was induced, as assessed by the von Frey test. The expression of phosphorylated NF-κB (pNF-κB) and CX3CR1 was significantly up-regulated in the bilateral dorsal horn. Immunofluorescence staining demonstrated that pNF-κB and NeuN co-existed, implying that the NF-κB pathway is predominantly activated in neurons following TSS. Administration of either the NF-κB inhibitor ammonium pyrrolidine dithiocarbamate or a CX3CR1-neutralizing antibody blocked the development and maintenance of neuropathic pain. In addition, blockade of NF-κB down-regulated the expression of CX3CL1-CX3CR1 signaling, and conversely the CX3CR1-neutralizing antibody also down-regulated pNF-κB. These findings suggest an involvement of NF-κB and the CX3CR1 signaling network in the development and maintenance of TSS-induced mechanical allodynia. Our work suggests the potential clinical application of NF-κB inhibitors or CX3CR1-neutralizing antibodies in treating pathological pain.

Allopregnanolone suppresses mechanical allodynia and internalization of neurokinin-1 receptors at the spinal dorsal horn in a rat postoperative pain model

BACKGROUND: To identify a new strategy for postoperative pain management, we investigated the analgesic effects of allopregnanolone (Allo) in an incisional pain model, and also assessed its effects on the activities of the primary afferent fibers at the dorsal horn. METHODS: In experiment 1, 45 rats were assigned to Control, Allo small-dose (0.16 mg/kg), and Allo large-dose (1.6 mg/kg) groups (n = 15 in each). The weight bearing and mechanical withdrawal thresholds of the hind limb were measured before and at 2, 24, 48, and 168 h after Brennan's surgery. In experiment 2, 16 rats were assigned to Control and Allo (0.16 mg/kg) groups (n = 8 in each). The degree of spontaneous pain was measured using the grimace scale after the surgery. Activities of the primary afferent fibers in the spinal cord (L6) were evaluated using immunohistochemical staining. RESULTS: In experiment 1, the withdrawal threshold of the Allo small-dose group was significantly higher than that of the Control group at 2 h after surgery. Intergroup differences in weight bearing were not significant. In experiment 2, intergroup differences in the grimace scale scores were not significant. Substance P release in the Allo (0.16 mg/kg) group was significantly lower than that in the Control group. CONCLUSIONS: Systemic administration of Allo inhibited mechanical allodynia and activities of the primary afferent fibers at the dorsal horn in a rat postoperative pain model. Allo was proposed as a candidate for postoperative pain management.

Effect of Low-frequency Electroacupuncture on Substance P Expression in the Spinal Dorsal Horn in SNI Neuralgia Rats / 上海针灸杂志

Objective To investigate the intervening effect of low-frequency electroacupuncture on rat neuralgia and its regulating effect on substance P (SP) in the spinal dorsal horn. Method SD rats were randomized to normal, sham operation (sham SNI), operation (SNI) and electroacupuncture (SNI+EA) groups, 8 rats each. A rat model of neuralgia was made by spared sciatic nerve injury (SNI). Points Zusanli(ST36) and Kunlun(BL60) on the operation side were given 2 Hz electroacupuncture once daily for 14 days. The rat hind paw withdrawal threshold (PWT) was measured on the operation side to observe its pain hypersensitivity. SP-positive expression in the spinal dorsal horn on the operation side was determined by immunofluorescence. Result Operative side PWT decreased significantly in the SNI group of rats (P<0.01). Electroacupuncture increased operative side PWT in the SNI neuralgia rats (P<0.01). Pain threshold onthe healthy side had no marked change in the SNI group of rats (P>0.05). SP-positive expression in the spinal dorsal horn increased on the operation side (P<0.01) and also on the healthy side (P<0.05) in the SNI group of rats. Electroacupuncture decreased SP-positive expression in the spinal dorsal horn on the operation side in the SNI rats (P<0.01). Electroacupuncture did not significantly change SP-positive expression in the spinal dorsal horn on the healthy side (P>0.05). PWT on the operation and healthy sides and SP-positive cell expression in the spinal dorsal horn on the operation and healthy sides had no marked changes in the SNI group of rats (P>0.05). Conclusion Low-frequency electroacupuncture can relieve rat neuralgia. Its mechanism may be related to it inhibiting SP-positive expression in the spinal dorsal horn on the operation side.

Effect of intrathecal injection of dexmedetomidine on the behavioral activity, pain degree and expression of protein kinase C in the spinal dorsal horn in rat models of chronic neuropathic pain / 中国比较医学杂志

Objective To analyze the effect of intrathecal injection of dexmedetomidine on the behavioral activity, pain degree and expression of protein kinase C in spinal dorsal horn of rat models of chronic neuropathic pain, and to investigate the analgesic mechanism of dexmedetomidine.Methods 75 healthy male rats were randomly divided into observation group, model group and control group, 25 rats in each group.Chronic sciatic nerve injury model was established in the observation group and model group.After modeling, intrathecal dexmedetomidine intervention was used in the observation group.The model group was treated with saline injection and there was no intervention in the control group.Before the modeling (BM)and at 3(D3), 5(D5), 7(D7), and 14 (D14)days after medicine administration, the behavioral capacity was evaluated by cumulative evaluation method and movement function evaluation, and the assessment of pain degree (mechanical withdrawal method and thermal withdrawal latency pain threshold detection method), PKC staining score (immunohistochemical SABC method), PKC mRNA assay (RT-PCR method) and PKC protein expression (Western blot) were conducted and the data were statistically analyzed.Results ① Before modeling, the behavior, the cumulative scores of motor function, MWT, and TWL showed no significant differences between the different groups (P>0.05).After modeling, the model group and observation group showed that the cumulative scores and motor function scores were increased significantly, MWT and TWL decreased significantly, and the changes in the observation group were significantly lower than those in the model group (P<0.05).After modeling, the cumulative scores, motor function scores, MWT, and TWL were significantly different between the groups (P<0.05).② The expression of PKC was negative in the control group and positive in the model group.In the observation group, after the initial establishment of model, the PKC was strongly positive, and along with the prolonged treatment, the PKC expression intensity was decreased, and only weakly positively expressed at 14 d.③ After modeling, the observation group and model group showed that the PKC mRNA and PKC protein expression levels were significantly higher than that of the control group (P<0.05).With the continuous drug administration, the PKC mRNA and PKC in the observation group were decreasing, and reached a level close to that of the control group at 14 d of drug administration.From the third day after modeling, at the same time points, the amount of PKC expression in the observation group was significantly lower than that in the model group (P<0.05).Conclusions Intrathecal injection of dexmedetomidine can improve the behavior of rat models with chronic neuropathic pain, and reduce the degree of pain.It may be related to the inhibition of protein kinase C expression in the spinal dorsal horn.

Metformin attenuates bone cancer pain by inhibiting expression of p-STAT3 / 中国药理学通报

Aim To investigate the effects of metformin on phospho-signal transducers and activators of transcription 3(p-STAT3) expression in the spinal dorsal horn in rats with bone cancer pain(BCP).Methods Healthy female SD rats weighing 200~220 g were randomly divided into four groups(n=12 each): Sham+NS, Sham+Metformin, BCP+NS, BCP+Metformin groups.Normal saline or metformin(200 mg·kg-1) was given intraperitoneally once a day at 7~14 day after surgery in four groups.Mechanical withdrawal threshold(MWT) was measured on-1, 3, 5, 7, 10, 12, 14 day after BCP.The L4-6 segments of spinal cords were used to detect the expression of p-STAT3 by Western blot and immunohistochemical staining technique after the behavioral test was completed on day 14.Results Intraperitoneal injection of metformin reversed hyperalgesia and suppressed the expression of p-STAT3 in BCP rats.Conclusion Metformin can attenuate BCP by inhibiting the expression of p-STAT3 in the spinal dorsal horn.

Expression of GDF10 in spinal cord in a rat model of neuropathic pain / 中国病理生理杂志

AIM: To observe the expression change of growth and differentiation factor 10 ( GDF10 ) in the spinal cord of the rats with neuropathic pain .METHODS:Male SD rats (n=60) were used.The neuropathic pain was induced by ligation of left L 5 spinal nerves of the animals .The paw withdrawal threshold was detected 1 d before surgery , and 0 d, 1 d, 3 d, 10 d and 21 d after surgery.The changes of GDF10 in the dorsal horn of L5 spinal cord were detected by immunofluorescence staining and Western blot .RESULTS:The paw withdrawal threshold of the rats with spinal nerve ligation was decreased from 1 d after surgery until 3 d with obvious difference compared with the na ve rats ( P<0.05 ) , continuously decreased until 10 d, and then stabilized at 21 d.The GDF10 was located in the cytoplasm of the neurons in the dorsal horn of L5 spinal cord detected by immunofluorescence staining .The expression of GDF10 in L5 dorsal horn de-tected by immunofluorescence staining was reduced after surgery , significantly decreased from 10 d ( P<0.05) until more than 21 d after surgery in spinal nerve ligation group compared with na ve group.GDF10 in L5 spinal cord detected at 10 d after surgery by Western blot was significantly down-regulated in spinal nerve ligation group compared with na ve group (P<0.05).CONCLUSION:Spinal nerve ligation induces the decrease in GDF 10 expression in spinal dorsal horn .The down-regulation of GDF10 may contribute to the regulation of hyperpathia caused by mechanical stimulation after the injury of spinal nerve .

The roles of spinal microglial Src-family kinases in diabetic neuropathic pain / 实用医学杂志

Objective To explore the roles of spinal microglial Src-family kinases (SFKs) in diabetic neuropathic pain. Methods Male Sprague-Dawley rats, weighing 200 ~ 220 g, were used in the experiments. The level of p-SFKs in spinal dorsal horn was detected by single immunofluorescence staining on day 7th , 14th and 28th after intraperitoneally injection of Streptozotocin (STZ) and its location was detected by double immunofluorescence staining. The changes of 50% paw-withdrawal thresholds of rat were detected by behavioral tests when PP2 , a specific inhibitor of SFKs , was intrathecally administered before intraperitoneally injection of STZ. Results Compared with vehicle group, the blood glucose level increased on day 1 (P < 0.001) and the hyperglycemia persisted at least for 28 days (P < 0.001) after intraperitoneally administered of STZ (50 mg/kg). Paw-withdrawal threshold (PWT) decreased gradually from day 1 (P < 0.05) and reached the minimum on day 28 (P < 0.001) after STZ administration. Meanwhile, the expression of p-SFKs in spinal dorsal horn markedly increased on day 7 (P < 0.01), day 14 (P < 0.01) and day 28 (P < 0.01). The p-SFKs was mainly co-localized only with microglia , but not with neurons or with astrocytes. Intrathecally administered of PP2 before STZ reversed STZ-induced mechanical hyperalgesia. Conclusion Microglial SFKs in spinal dorsal horn maybe play a pivotal role in diabetic neuropathic pain.