OBJECTIVES: Neuropathic pain (NP) is one of the most common forms of chronic pain, yet current treatment options are limited in effectiveness. Peripheral nerve injury activates spinal microglia, altering their inflammatory response and phagocytic functions, which contributes to the progression of NP. Most current research on NP focuses on microglial inflammation, with relatively little attention to their phagocytic function. Early growth response factor 2 (EGR2) has been shown to regulate microglial phagocytosis, but its specific role in NP remains unclear. This study aims to investigate how EGR2 modulates microglial phagocytosis and its involvement in NP, with the goal of identifying potential therapeutic targets. METHODS: Adult male Sprague-Dawley (SD) rats were used to establish a chronic constriction injury (CCI) model of the sciatic nerve. Pain behaviors were assessed on days 1, 3, 7, 10, and 14 post-surgery to confirm successful model induction. The temporal and spatial expression of EGR2 in the spinal cord was examined using real-time quantitative PCR (RT-qPCR), Western blotting, and immunofluorescence staining. Adeno-associated virus (AAV) was used to overexpress EGR2 in the spinal cord, and behavioral assessments were performed to evaluate the effects of EGR2 modulation of NP. CCI and lipopolysaccharide (LPS) models were established in animals and microglial cell lines, respectively, and changes in phagocytic activity were measured using RT-qPCR and fluorescent latex bead uptake assays. After confirming the involvement of microglial phagocytosis in NP, AAV was used to overexpress EGR2 in both in vivo and in vitro models, and phagocytic activity was further evaluated. Finally, eukaryotic transcriptome sequencing was conducted to screen differentially expressed mRNAs, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses to identify potential downstream effectors of EGR2. RESULTS: The CCI model successfully induced NP. Following CCI, EGR2 expression in the spinal cord was upregulated in parallel with NP development. Overexpression of EGR2 via spinal AAV injection enhanced microglial phagocytic activity and increased pain hypersensitivity in rats. Both animal and cellular models showed that CCI or LPS stimulation enhanced microglial phagocytosis, which was further amplified by EGR2 overexpression. Transcriptomic analysis of spinal cord tissues from CCI rats overexpressing EGR2 revealed upregulation of numerous genes associated with microglial phagocytosis and pain regulation. Among them, Lag3 emerged as a potential downstream target of EGR2. CONCLUSIONS EGR2 contributes to the maintenance of NP by enhancing microglial phagocytosis in the spinal dorsal horn.
Animals ; Microglia/metabolism* ; Phagocytosis/physiology* ; Rats, Sprague-Dawley ; Neuralgia/physiopathology* ; Early Growth Response Protein 2/metabolism* ; Male ; Rats ; Spinal Cord/metabolism* ; Sciatic Nerve/injuries*

To investigate the role of p38MAPK signal pathway in spinal cord and dorsal root ganglion (DRG) in rats with phantom limb pain and the effects of specific inhibitors.
 Methods: Healthy adult male SD rats (n=48) were cut off one side of the sciatic under anesthesia to establish a model of phantom limb pain. In addition, the healthy rats were taken as a sham group (group S, n=24). The animals were scored by observing the action of chewing (0=no chewing, 13=the worst chewing) after the operation and were sacrificed on the following day after the operation. The successful model of phantom limb pain were randomly divided into 2 groups: a phantom limb pain group (group P, n=24) and a phantom limb pain plus inhibitor group (group P+I, n=24). SB203580 was given to the rat at 0.8 mg/kg on every Monday until the rats were sacrificed, the rest of the rats received an equal amount of saline. Eight rats from each group were randomly taken for the determination of levels of P-p38MAPK in spinal cord and DRG before administration and on the 4th, 6th, 8th weekend following the administration, respectively.
 Results: In the sham group, no animal developed chewing. Meanwhile, rats in successful model of phantom limb pain group began chewing from the 2nd day after operation with scores at eight to eleven. The chewing scores in the P+I group were reduced after the treatment. Compared with group S, P-p38MAPK levels were elevated in groups of P and P+I (P<0.05 or P<0.01). Compared with group P, P-p38MAPK level was decreased in the group P+I (P<0.05 or P<0.01).
 Conclusion: P38MAPK signal pathway involves in the development of phantom limb pain.
Animals ; Disease Models, Animal ; Enzyme Inhibitors ; pharmacology ; Ganglia, Spinal ; enzymology ; Imidazoles ; pharmacology ; Male ; Mastication ; physiology ; Phantom Limb ; enzymology ; etiology ; physiopathology ; Pyridines ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Sciatic Nerve ; injuries ; Self Mutilation ; enzymology ; physiopathology ; Signal Transduction ; Spinal Cord ; enzymology ; p38 Mitogen-Activated Protein Kinases ; antagonists & inhibitors ; metabolism

PURPOSETo study the effects of transplantation of characterized uncultured stromal vascular fraction (SVF) on sciatic nerve regeneration.

METHODSA 10-mm sciatic nerve defect was bridged using a silicone conduit filled with SVF. In control group, silicone conduit was filled with phosphate-buffered saline alone. In sham-operated group, the sciatic nerve was only exposed and manipulated. The regenerated nerve fibers were studied 8 and 12 weeks after surgery.

RESULTSBehavioral and functional studies confirmed faster recovery of regenerated axons in SVF transplanted animals than in control group (p<0.05). Gastrocnemius muscle mass in SVF transplanted animal was found to be significantly more than that in control group. Morphometric indices of the regenerated fibers showed the number and diameter of the myelinated fibers to be significantly higher in SVF transplanted animals than in control group. In immunohistochemistry, the location of reactions to S- 100 in SVF transplanted animals was clearly more positive than that in control group.

CONCLUSIONSVF transplantation combined with silicone conduit could be considered as a readily accessible source of stromal cells that improves functional recovery of sciatic nerve. It may have clinical implications for the surgical management of acute diabetic patients after facial nerve transection.

Animals ; Diabetes Mellitus, Experimental ; physiopathology ; Immunohistochemistry ; Male ; Nerve Regeneration ; physiology ; Rats ; Rats, Wistar ; Sciatic Nerve ; physiology ; Silicone Elastomers ; pharmacology ; Stromal Cells ; physiology

To investigate the effects of Tongxinluo capsule on sciatic nerve apoptosis in spontaneous type II diabetic KK/Upj-Ay mice, in order to explore its mechanism for improving diabetic peripheral neuropathy (DPN). KK/Upj-Ay mice were selected as the DPN animal model and randomly divided into the model, Tongxinluo low, middle and high group (1, 2, 4 g x kg(-1)). C57BL/6 mice were selected as the control group. Mice were given intragastrically for 12 weeks. Paw withdrawal latency, motor nerve conduction velocity (MNCV) and sensory nerve conduction velocity (SNCV) were detected. Apoptotic rate were detected by FCM. Bcl-2, Bax, Caspase-3 mRNA and protein expression in sciatic nerve were examined by Real-time PCR and Western blot. p38MAPK, p-p38MAPK expression were examined by Western blot. In this study,the authors found that Tongxinluo capsule could increase paw withdrawal latency, MNCV and SNCV. Apoptotic rate of sciatic, the expression of Bax and caspase-3 were lower, while Bcl-2 expression was higher in Tongxinluo group than those in model mice. The expression of p-p38MAPK significantly decreased in Tongxinluo group. The results showed that Tongxinluo capsule has protective effects on diabetic peripheral neuropathy of mice via inhibiting cell apoptosis and suppressing the expression of p-p38MAPK.
Animals ; Apoptosis ; drug effects ; Capsules ; administration & dosage ; Diabetic Neuropathies ; drug therapy ; physiopathology ; Disease Models, Animal ; Drugs, Chinese Herbal ; administration & dosage ; Humans ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Sciatic Nerve ; cytology ; drug effects

BACKGROUNDPain physicians pay close attention to neuropathic pain (NP), since there is currently no ideal treatment. Radial shock wave therapy (RSWT) is a noninvasive treatment to chronic pain of soft tissue disorders. So far, there is no information on the use of RSWT for the treatment of NP. Therefore we observe the effects of RSWT on a NP model induced by chronic constriction injury (CCI) in rats.

METHODSFour different energy densities (1.0, 1.5, 2.0 and 2.5 bar) RSWT administered as a single session or repeated sessions in rats with NP induced by CCI of the sciatic nerve. The analgesic effect was assessed by measuring mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). The safety was assessed through calculating sciatic functional index (SFI).

RESULTSMWT and TWL increased after a single session of RSWT from day 1 to day 5 but returned to baseline levels by day 10. Following repeated sessions of RSWT, both the MWT and TWL were significantly higher than NP group (P < 0.01) for at least 4 weeks. In addition, no significant changes of SFI were observed in any groups after repeated sessions of RSWT and no increased pain or other side effects in any animals.

CONCLUSIONSA single session of RSWT is rapidly effective in the treatment of CCI, but the efficacy maintained in a short period. However, repeated sessions of RSWT have prolonged efficacy.

Animals ; Chronic Pain ; therapy ; High-Energy Shock Waves ; Male ; Neuralgia ; therapy ; Rats, Sprague-Dawley ; Sciatic Nerve ; physiopathology

OBJECTIVETo investigate the effect of 2,5-hexanedione (HD) on degradation of low-molecular-weight neurofilaments (NF-L) in nervous tissue of rats, and to explore the molecular mechanism of n-hexane neuropathy.

METHODSFifty male Wistar rats were randomly divided into one-week poisoning group (n = 10), two-week poisoning group (n = 10), three-week poisoning group (n = 10), four-week poisoning group (n = 10), and control group (n = 10). In the four poisoning groups, a rat model of n-hexane neuropathy was established by intraperitoneal injection of HD (400 mg/kg/d). The change in the sciatic nerve ultrastructure of each rat was observed under an electron microscope. The progression of HD-induced peripheral neuropathy was evaluated using a gait scoring system. The degradation rates of NF-L in the sciatic nerve and spinal cord of each rat were measured by Western Blotting.

RESULTSThe rats showed decrease in muscle strength and abnormal gait after two weeks of HD poisoning and mild or moderate paralysis after four weeks of HD poisoning. The sciatic nerve showed degenerative change, according to electron microscope observation. Compared with the control group, the two-week poisoning group, three-week poisoning group, and four-week poisoning group had the NF-L degradation rates decreased by 25.8%, 70.4%, and 69.7%, respectively, in the supernatant fraction of sciatic nerve, and by 14.7%, 64.6%, and 67.3%, respectively, in the sediment fraction of sciatic nerve, all showing a significant difference (P < 0.01). Compared with the control group, the one-week poisoning group had the NF-L degradation rate decreased by 33.87% in the supernatant fraction of spinal cord, the four-week poisoning group had the NF-L degradation rate increased by 16.2% in the supernatant fraction of spinal cord, and the one-week poisoning group and two-week poisoning group had the NF-L degradation rates decreased by 46.3% and 13.0% in the sediment fraction of spinal cord, all showing a significant difference (P < 0.01).

CONCLUSIONHD poisoning significantly inhibits NF-L degradation in the sciatic nerve, which may be associated with NF degeneration and accumulation in the axons of patients with n-hexane neuropathy.

Animals ; Hexanes ; poisoning ; Hexanones ; pharmacology ; Male ; Nerve Tissue ; drug effects ; metabolism ; physiopathology ; Neurofilament Proteins ; drug effects ; metabolism ; Rats ; Rats, Wistar ; Sciatic Nerve ; drug effects ; metabolism ; physiopathology

Sciatic nerve injury is a common disease of peripheral nerve in clinic. After nerve injury, there are many dysfunctions in motoneurons and muscles following regeneration. Previous studies mostly investigated the aspects related to the injured nerve, and the effect on the recurrent inhibition (RI) pathway of spine following regeneration was not fully understood. Following reinnervation after temporary sciatic nerve crush, the functional alteration of RI was studied. In adult rats, RI between lateral gastrocnemius-soleus (LG-S) and medial gastrocnemius (MG) motor pools was assessed by conditioning monosynaptic reflexes (MSRs) elicited from the cut dorsal roots and recorded from either the LG-S or MG nerves by antidromic stimulation of the synergist muscle nerve. The following results were obtained. (1) The RI of MSRs in rats was almost lost (<5 weeks) after sciatic nerve crush. Although the RI partially recovered following reinnervation (6 weeks), it remained permanently depressed (up to 14 weeks). (2) Sciatic nerve crush on one side did not affect the contralateral RI. (3) Sciatic nerve crush did not induce any motoneuron loss revealed by immunohistochemistry. Peripheral nerve temporary disconnection causes long term alterations in RI pathway which make up motoneuron's function enhance for the alteration of muscle power and suggests that peripheral nerve injury induces long term plastic changes in the spinal motoneuron circuitry.
Animals ; Long-Term Synaptic Depression ; physiology ; Male ; Motor Neurons ; physiology ; Nerve Crush ; Nerve Regeneration ; physiology ; Neuronal Plasticity ; physiology ; Neurons, Afferent ; physiology ; Rats ; Rats, Wistar ; Reflex, Monosynaptic ; physiology ; Sciatic Nerve ; injuries ; physiopathology ; Spinal Cord ; physiopathology ; Spinal Nerve Roots ; physiopathology

The present study is to investigate whether the extracellular signal-regulated kinase (ERK) and cAMP response element binding protein (CREB) signaling pathway contributes to the initiation of chronic constriction injury (CCI)-induced neuropathic pain in rats. Mechanical allodynia was assessed by measuring the hindpaw withdrawal threshold in response to a calibrated series of von Frey hairs. Thermal hyperalgesia was assessed by measuring the latency of paw withdrawal in response to a radiant heat source. The expressions of phosphor-ERK (pERK) and phosphor-CREB (pCREB) were examined using Western blot analysis and immunohistochemistry. An early robust increase in the expression of pERK on the spinal cords ipsilateral to injury was observed on day 1 after CCI, when the CCI-induced behavioral hypersensitivity had not developed yet. Moreover, the upregulation of pERK expression in ipsilateral spinal cord was associated with the increase in pCREB expression in bilateral spinal cord. Intrathecal administration of mitogen-activated protein kinase kinase (MEK) inhibitor U0126 before CCI can efficiently block and delay the CCI-induced mechanical allodynia and thermal hyperalgesia. These data suggest that activation of ERK and CREB in the spinal cord contributes to the initiation of peripheral nerve injury-induced pain hypersensitivity, and an early intervention strategy should be proposed.
Animals ; Butadienes ; pharmacology ; Cyclic AMP Response Element-Binding Protein ; metabolism ; Enzyme Inhibitors ; pharmacology ; Extracellular Signal-Regulated MAP Kinases ; metabolism ; Hyperalgesia ; etiology ; physiopathology ; prevention & control ; Male ; Nitriles ; pharmacology ; Pain ; etiology ; physiopathology ; prevention & control ; Peripheral Nerve Injuries ; complications ; metabolism ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Sciatic Neuropathy ; metabolism ; physiopathology ; Spinal Cord ; metabolism

OBJECTIVETo investigate the changes of GABA-activated currents in isolated dorsal root ganglion neurons in rats with neuropathic pain.

METHODSThe neuropathic pain model was established by chronic constriction injury (CCI) 7 days before electrophysiological-recording. The rat DRG neurons were enzymatically dissociated. Whole-cell patch clamp technique was used to record GABA-activated currents. The changes of currents of injured side and opposite side were expected to compare with control group.

RESULTS(1) The currents of injured side of CCI group were notablely decreased compared with control group (GABA concentration, 0.1-1000 micromol/L). (2) By the contrast, opposite side currents of CCI group increased significantly compared with those in injured side and control group (GABA concentration, 0.01-1000 micromol/L).

CONCLUSIONThe data indicates that the chronic constriction injury change both the function of GABAA receptors of injury side and opposite side. The decrease of pre-synaptic inhibition of GABA may be the possible reason of neuropathic pain.

Animals ; Cell Separation ; Constriction ; Ganglia, Spinal ; pathology ; physiopathology ; Male ; Neuralgia ; etiology ; physiopathology ; Neurons ; metabolism ; physiology ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-A ; metabolism ; physiology ; Sciatic Nerve ; injuries

OBJECTIVETo discuss the operative effects and evaluate how the waiting time before surgery influence the outcome of complex acetabular fractures.

METHODSFrom January 2006 to December 2008, 33 patients, 28 males and 5 females, with complex acetabular fractures were operated in our hospital. All of them were followed up for an average 24 months (ranged, 14 to 47 months). The average age was 42 years (ranged,27 to 57 years). According to the waiting time before surgery, all patients were divided into two groups, namely preoperative waiting time of more than 14 days group and preoperative waiting time of less than 14 days group. Postoperative reduction quality and long-term radiographic results were evaluated according to the Matta radiological systems. The modified Merle d' Aubigne-postel hip scoring system was used for evaluating the functional outcomes. The Mos SF-36 was used to evaluate the quality of life.

RESULTSAnatomical reduction in 28 cases, good in 4 cases, and poor in 1 case. According to the mean Merle d'Aubigne and Postel Score, 22 patients got excellent result, 4 good, 4 fair and 3 bad. Average score of the Mos SF-36 was (70.63 +/- 17.03). When time was measured as a categorical variable, an anatomical reduction and an excellent or good functional outcome were more likely if surgery was performed within 14 days. Postoperative complications: iatrogenic injuries of sciatic nerve in 2 cases, heterotopic ossification in 6 cases,traumatic osteoarthritis in 3 cases, and femoral head necrosis in 1 case.

CONCLUSIONGood image evaluation,correct approaches, appropriate time before surgery and approach, early functional rehabilitation are essential for better outcomes in the treatment of complex acetabular fractures, of which, time to surgery is a crucial and controllable prognostic factor.

Acetabulum ; injuries ; physiopathology ; surgery ; Adult ; Case-Control Studies ; Female ; Fracture Fixation, Internal ; adverse effects ; methods ; Fractures, Bone ; diagnostic imaging ; physiopathology ; surgery ; Humans ; Male ; Middle Aged ; Ossification, Heterotopic ; prevention & control ; Osteoarthritis ; prevention & control ; Postoperative Complications ; prevention & control ; Radiography ; Sciatic Nerve ; injuries ; Time Factors