The cell body or soma in the dosal root ganglion (DRG) is normally excitable and this excitability can increase and persist after an injury of peripheral sensory neurons. In a rat model of radicular pain, an intraforaminal implantation of a rod that chronically compressed the lumbar DRG ("CCD" model) resulted in neuronal somal hyperexcitability and spontaneous activity that was accompanied by hyperalgesia in the ipsilateral hind paw. By the 5th day after onset of CCD, there was a novel upregulation in neuronal expression of the chemokine, monocyte chemoattractant protein-1 (MCP-1 or CCL2) and also its receptor, CCR2. The neurons developed, in response to topically applied MCP-1, an excitatory response that they normally do not have. CCD also activated non-neuronal cells including, for example, the endothelial cells as evidenced by angiogenesis in the form of an increased number of capillaries in the DRG after 7 days. A working hypothesis is that the CCD induced changes in neurons and non-neuronal cells that may act together to promote the survival of the injured tissue. The release of ligands such as CCL2, in addition to possibly activating nociceptive neurons (maintaining the pain), may also act to preserve injured cells in the face of ischemia and hypoxia, for example, by promoting angiogenesis. Thus, somal hyperexcitability, as often said of inflammation, may represent a double edged sword.
Animals ; Chemokine CCL2 ; metabolism ; Ganglia, Spinal ; cytology ; pathology ; Hyperalgesia ; pathology ; Neuroglia ; cytology ; Nociceptors ; cytology ; Pain ; pathology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Compression ; physiopathology ; Up-Regulation

Intermediate filaments, including nestin and vimentin, are found in specific cell types in central nervous system (CNS) tissues, particularly immature glial cells and multipotent progenitor cells. In the present study, the expression patterns of nestin and vimentin in the spinal cords of rats with experimental autoimmune encephalomyelitis (EAE) and the response of cells containing filaments against acute autoimmune injury were examined by immunohistochemistry. Nestin immunostaining was only weakly detected in vascular endothelial cells but not in any cell types in the spinal cord in normal and adjuvant-immunized rats. At the peak stage of EAE, nestin-immunoreativity was recognized in some astrocytes in the gray matter and white matter. Vimentin was immunopositive in some astrocytes and macrophages in EAE lesions, while vimentin was normally detected in ependymal cells of central canals in the rat spinal cords.We postulate that normal animals may contain multipotent progenitor cells in the spinal cord parenchyma as well as in the subpial lesion and ependyma. Multipotent progenitor cells may activate to transform into necessary cells, including neurons, astrocytes or oligodendrocytes, depending on CNS needs. Appropriate control of progenitor cells in the injured CNS is an alternative choice for CNS remodeling.
Animals ; Encephalomyelitis, Autoimmune, Experimental/*metabolism/pathology ; *Gene Expression Regulation ; Intermediate Filament Proteins/*metabolism ; *Nerve Tissue Proteins ; Rats ; Rats, Inbred Lew ; Spinal Cord/cytology/*metabolism/pathology ; Stem Cells/cytology ; Vimentin/*metabolism

OBJECTIVETo determine cell proliferation and nestin expression in the ependyma of adult rat spinal cord after injury.

METHODSRat spinal cord injury models were established by aneurysm clip compression, and nestin expression and proliferation of ependymal cells at different times were shown with pathological and immuno-histochemical staining.

RESULTSEpendymal cells adjacent to the injured site demonstrated a dramatic increase in nestin expression 24 hours after compression. Proliferating cell nuclear antigen was positive, and significant proliferation was observed after 7 days. Nestin expression was down regulated as time went by.

CONCLUSIONNormally quiescent mature ependymal cells appear to revert to an embryonic state in response to spinal cord injury.

Animals ; Cell Division ; Ependyma ; cytology ; metabolism ; Immunohistochemistry ; Intermediate Filament Proteins ; biosynthesis ; Male ; Nerve Tissue Proteins ; Nestin ; Rats ; Rats, Wistar ; Spinal Cord Injuries ; metabolism ; pathology

OBJECTIVETo observe the expressions of the substance P (SP) mRNA and neurokinin-1 receptor (NK-1R) in the posterior horn of the L5 - S2 spinal cord in the rat model of chronic prostatitis pain, and to investigate the changes in the activation of astrocytes and influence of SP on this activation in rat spinal cord astrocytes cultured in vitro.

METHODSThe rat model of chronic prostatitis pain was established by injection of complete Freund's adjuvant (CFA) and assessed by the tail flick threshold test, the control rats injected with sodium chloride and all observed at 0, 14 and 28 days. Changes in the expressions of SP mRNA, NK-1R, glial fibrillary acidic protein (GFAP), tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthase (iNOS) in the posterior horn of the L5 - S2 spinal cord were detected by RT-PCR and Western blot. Rat spinal cord astrocytes were cultured in vitro and divided into a control group, cultured with ITS cell culture fluid, and two experiment groups, with Group 1 stimulated with SP at the concentration of 10(-9) - 10(-6) mol/L for 12 hours followed by determination of the expressions of TNF-alpha, IL-1beta, NO and NOS by ELISA and nitrate reductase and colorimetric methods, and Group 2 at 10(-7) mol/L for 0, 24, 48 and 72 hours followed by detection of the GFAP expression by Western blot.

RESULTSThe expressions of SP mRNA, NK-1 R, GFAP, TNF-alpha and iNOS in the posterior horn of the L5 - S2 spinal cord were obviously higher in the rat prostatitis pain models than in the controls, successively higher at 28 than at 14 and 0 d (P < 0.01), and so was the expression of GFAP at 28 than at 14 d in the experiment groups (P < 0.05). SP induced a gradual increase at 10(-7) mol/L in the expression of GFAP in the spinal cord astrocytes at 0 -72 h, significantly different from that of the control group (P < 0.01), and it promoted the excretion of TNF-alpha and IL-1beta and the activity of NO and NOS at 10(-9) - 10(-6) mol/L at 12 h in a concentration-dependent manner, with marked differences between the experiment and control groups (P < 0.01, P < 0.05). But a decreased excretion of IL-1 beta was observed in the 10(-6) mol/L group, though with no significant difference from the control (P > 0.05).

CONCLUSIONChronic prostatitis pain could upregulate the expressions of the excitatory transmitter SP and receptor in the L5 - S2 spinal cord, and result in the activation of astrocytes and increased excretion of proinflammatory cytokines, which may be associated with the persistence and generalization of prostatitis pain.

Animals ; Astrocytes ; metabolism ; Chronic Disease ; Male ; Nitric Oxide Synthase Type II ; metabolism ; Pain ; metabolism ; Prostatitis ; metabolism ; Rats ; Receptors, Neurokinin-1 ; metabolism ; Spinal Cord ; cytology ; metabolism ; pathology ; Substance P ; metabolism

OBJECTIVETo observe the effects of mecobalamin on the expression of apoptosis-related proteins, Bax and Bcl-2, in neurons after peripheral nerve injury, and to explore the role of neuron apoptosis in peripheral nerve regeneration after injury.

METHODSThirty healthy adult male wistar rats were randomly divided into sham-operation group, model group, and mecobalamin group, with 10 rats in each group. A rat model of left sciatic nerve semi-injury was established using forceps. Rats in the mecobalamin group were fed mecobalamin, while rats in the sham-operation group and model group were given the same dose of normal saline. The protein expression of Bax and Bcl-2 in neurons was measured at 14 days after operation. A semi-quantitative analysis of Bax and Bcl-2 proteins was performed by image analysis technology.

RESULTSThe model group had significantly increased Bax protein expression and significantly reduced Bcl-2 protein expression in spinal cord anterior horn motor neurons and ganglion sensory neurons compared with the sham-operation group (P<0.05). Compared with the model group and sham-operation group, the mecobalamin group had significantly reduced Bax protein expression and significantly increased Bcl-2 protein expression in spinal cord anterior horn motor neurons and ganglion sensory neurons (P<0.05).

CONCLUSIONMecobalamin has anti-apoptotic effect, and it contributes to neurological function recovery possibly by inhibiting the death of injured neurons.

Animals ; Apoptosis ; Male ; Neurons ; cytology ; drug effects ; Peripheral Nerve Injuries ; metabolism ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; Rats ; Rats, Wistar ; Sciatic Nerve ; pathology ; Spinal Cord ; cytology ; Vitamin B 12 ; analogs & derivatives ; pharmacology ; bcl-2-Associated X Protein ; metabolism

Spinal cord injury (SCI) causes not only loss of sensory and motor function below the level of injury but also chronic pain, which is difficult and challenging of the treatment. Repetitive transcranial magnetic stimulation (rTMS) to the motor cortex, of non-invasive therapeutic methods, has the motor and sensory consequences and modulates pain in SCI-patients. In the present study, we studied the effectiveness of rTMS and the relationship between the modulation of pain and the changes of neuroglial expression in the spinal cord using a rat SCI-induced pain model. Elevated expressions of Iba1 and GFAP, specific microglial and astrocyte markers, was respectively observed in dorsal and ventral horns at the L4 and L5 levels in SCI rats. But in SCI rats treated with 25 Hz rTMS for 8 weeks, these expressions were significantly reduced by about 30%. Our finding suggests that this attenuation of activation by rTMS is related to pain modulation after SCI. Therefore, rTMS might provide an alternative means of attenuating neuropathic pain below the level of SCI.
Animals ; Astrocytes/*cytology ; Calcium-Binding Proteins/metabolism ; Disease Models, Animal ; Immunohistochemistry ; Male ; Microfilament Proteins/metabolism ; Microglia/*cytology ; Nerve Tissue Proteins/metabolism ; Neuralgia/etiology ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries/complications/pathology/*therapy ; *Transcranial Magnetic Stimulation

OBJECTIVETo observe the expressions of nestin and glial fibrillary acidic protein (GFAP) and their association with reactive astrocytes following spinal cord injury in adult rats.

METHODSAdult rats with compression injury of the spinal cord were divided into 7 groups (n=6) and examined at 1, 3, and 5 days and at 1, 2, 4 and 8 weeks after the injury. The recovery of the locomotor function after the injury was evaluated with Basso, Beattie and Bresnahan (BBB) scale, and the degree and scope of the spinal injury were assessed using toluidine blue staining. Immunohistochemistry, double immunofluorescent labeling and an image analysis system were employed to observe nestin and GFAP expression and cell proliferation in different regions of the spinal cord.

RESULTSThe bilateral hind limb locomotor function of the rats declined severely 24 h after the spinal cord injury and underwent substantial recovery in 1 or 2 weeks after the injury, but followed by rather slow recovery afterwards. Toluidine blue staining of the spinal cord 24 h after the injury showed significant pathological changes in the neurons. The extension of the tissue injury increased with time till 1 week after the spinal cord injury. The site of injury and the adjacent tissues presented with markedly increased nestin and GFAP expressions 24 h after the injury, and nestin+/GFAP(-) cells dominated in the ependymal region around the central canal, whereas nestin+/GFAP+ dominated in the in other regions, showing significant difference from the control group. Nestin and GFAP expression reached the peak level 3 to 7 days after the injury and declined gradually till reaching nearly the control level at 2 weeks.

CONCLUSIONCompression injury of the spinal cord induces up-regulated expressions of nestin and GFAP, and nestin expression is positively correlated to the reactive astrocytes, which, along with the neural stem cells, respond to spinal nerve injury and possibly play a role in repair of the central nervous system injury.

Animals ; Astrocytes ; pathology ; Glial Fibrillary Acidic Protein ; biosynthesis ; genetics ; Intermediate Filament Proteins ; biosynthesis ; genetics ; Male ; Nerve Tissue Proteins ; biosynthesis ; genetics ; Nestin ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spinal Cord Injuries ; metabolism ; pathology ; Stem Cells ; cytology ; metabolism ; Up-Regulation