| Acute spinal cord injury was a kind of serious damage of nervous system, SCI may cause the movement function barrier, often leaves behind the serious disability. It brought huge burden to the individuals, the families and the soeiety. So,it was improtant to treat ASCI so that to recover or reduce the damage of nervous system. SCI can be divided into Primary ASCI and secondary ASCI. Primary ASCI was mechanical damage.The degree of damage were determined When damage happened. Primary ASCI was nonreversible,and no effeetive method can be used to treat: Secondary ASCI happened after the Primary ASCI,it was reversible and could be controlled. Seeondary ASCI determined the results of ASCI,so the key to treat ASCI was the treatment of Secondary ASCI. Now the Strategies of treating ASCI were protecting neurons and preventing neurons apoptisis. Inflammation that starts within minutes and continues for days after the injury is known to significantly contribute to the secondary neuronal damage, which is a major cause of motor dysfunction after SCI.Peroxisome proliferator-activated receptor (PPAR) and retinoid X receptor are ligand-activated transcription factors of the nuclear hormone receptor superfamily. PPARγagonist rosiglitazone is neuroprotective after traumatic brain injury via anti-inflammatory and anti-apoptosis mechanisms. There are few researches on the function of PPARγagonist on SCI, such as whether it can protect the neural neurons, promote the growth of axons in the remaining neurons and inhibit apoptosis. This study aims to investigate minimizing secondary lesion expansion, apoptotic markers, infiltration of macrophages or activation of microglia, and the expression of inflammatory, anti-oxidant and the repair function of PPARγagonist rosiglitazone in the rats after SCI and related mechanism, which will provide treatment strategy for SCI. Part 1 Expression of PPARγafter acute spinal cord injuryObjective To investigate the expression of Peroxisome proliferator -activated receptor gamma (PPARγ) after actue spinal cord injury. Methods: Rats were randomized into two groups, the sham-operated group and the injuried group, Allen's method was used to make actue spianl cord injury. Rats were sacrificed at 1d,3d,7d,14d after injury. The expression of Peroxisome proliferator-activated receptor gamma(PPARγ) were assessed by immunohistochemicalmethod,reverse transcriptase polymerase chain reaction ( RT-PCR) and Western bloting. Results The spinal cord injury group displayed obvious up regulation of PPARγmRNA and protein compared with the sham group(p<0.05). The expression of PPARγincreased 1d after spinal cord injury , which reached its peak 3 days after spinal cord injury. Conclusion Peroxisome proliferator-activated receptor gamma (PPARγ) may be partially involved in the secondary pathogenesis of spinal cord injury and may be a therapeutic target of spinal cord injury.Part 2 Effect of PPARγagonists rosiglitazone on cell apoptosis following spinal cord injury in ratsObjective To investigate the effect of PPARγagonists on neural cell apoptosis after spinal cord injury in rats. Methods: The rats were divided into two groups including sham group, control group(injury without treatment),cured group (injury with PPARγagonists rosiglitazone ip), Allen's method was used to make actue spianl cord injury. Rats were sacrificed at 1d,3d,7d,14d after injury. The samples were examined with hemotoxylin and eosin staining, electron microscopy, DNA ladder ,and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and the expression of bax,bcl-2 by reverse transcriptase polymerase chain reaction (RT-PCR) and Western bloting. The neurofuntion of spinal cord was measured by BBB score. Results The apoptosis cells positive for TUNEL and bax,bcl-2expression were detectable in control and cured groups. In the cured group,the number of apoptotic cells and the express of bax were decreased and the neurofunction of the spinal cord improved as compared with those in the control group.But the express of bcl-2 were increased as compared with those in the control group. Conclusion:PPARγagonists can reduce the numbers of apoptotic cells and promote the nerve function recovery after spinal cord injury.Part 3 Attenuation of Acute In?ammatory Response by PPARγagonists rosiglitazone after spinal cord injury in ratsObjective In the present study, we investigated the efficacy of PPARγagonists rosiglitazone in attenuation of SCI-induced in?ammatory disease after spinal cord injury in rats. Methods: The rats were divided into two groups including sham group, control group(injury without treatment),cured group (injury with PPARγagonists, rosiglitazone), Allen's method was used to make actue spianl cord injury. Rats were sacrificed at 12h,24h,72h after injury. The expression of TNF-a IL-1β,iNOS were assessed by immunohistochemicalmethod, TNF- a,IL-1β,MMP-9 and TIMP-1 mRNA were measured by reverse transcriptase polymerase chain reaction (RT-PCR) and Real-time Polymerase chain reaction (RT-PCR). Neutrophil infiltration were assessed by Myeloperoxidase activity assay. MMP-9 activity assay were by Gelatin zymography. The expression of HSP27,HSP70 were assessed by Western bloting . Results TNF-a,IL-1β,MMP-9 ,TIMP-1 HSP27,HSP70 were increased after spianl cord injury. The levels of TNF-a, IL-1β, MMP-9 and iNOS at 12–72h after SCI were significantly attenuated in PPARγagonists treatment rats comparison to SCI animals . MPO and MMP-9 activity was reduced significantly, indicated reduced Neutrophil infiltration. Treating rats subjected to SCI injury with rosiglitazone led to a further significant enhancement of the expression of HSP27, HSP70 and TIMP-1 in the injured tissue. Conclusion:PPARγagonists rosiglitazone can reduces the development of inflammation and tissue injury associated with spinal cord injury.Part 4 Endogenous stem cell proliferation induced by PPARγagonists rosiglitazone after spinal cord injury in ratsObjective Previous studies have demonstrated that the brain and spinal cord contain endogenous neural stem cells/progenitor cells. Used BrdU labeling in vivo, we investigated the efficacy of PPARγagonists rosiglitazone in promotion of the proliferation and differentiation of endogenous neural stem cells/progenitor cells after spinal cord injury(SCI)in rats. Methods: The rats were divided into two groups including sham group, control group(injury without treatment),cured group (injury with PPARγagonists, rosiglitazone), Allen's method was used to make actue spianl cord injury. Rats were sacrificed at 12h,24h,72h after injury. To label the activated and proliferating endogenous neural stem cells/progenitor cells, animals received one intraperitoneal injection of BrdU at 50 mg/kg per day. The tissue was analyzed using immunohisto -chemical detection to study the response of endogenous neural stem cells/progenitor cells. Results There were many cells with positive Nestin or BrdU expression surrounding the central canal proved that initiation of Nestin expression in cells occurred as result of the injury after SCI. BrdU-positive cells were detected in the spinal cord section in the control group; BrdU or Nestin positive cells in cured group were increased after spinal cord injury. Compared to the controls, the number of BrdU or Nestin positive cells were increased(p<0.05) after SCI, there were no difference between 3d and 7d groups. The immunofluorescence with anti-BrdU and anti-Nestin double label showed the following the same results. But the BrdU-positive cells were increased signifcantly than Nestin positive cells. Conclusion PPARγagonists rosiglitazone can increases the population of endogenous neural stem cells after spinal cord injury in adult rats.Part 5 PPARγagonists rosiglitazone Modulates GAP-43 and Neurotrophins in after spinal cord injury in ratsObjective There are numerous studies reporting on the crucial roles of neurotrophins and GAP-43 in neuronal survival and sprouting after spinal cord injury. we investigated the effect of PPARγagonists on GAP-43 and Neurotrophins after spinal cord injury in rats. Methods The rats were divided into two groups including sham group, control group(injury without treatment),cured group (injury with PPARγagonists, rosiglitazone), Allen's method was used to make actue spianl cord injury. Rats were sacrificed at 12h,24h,72h,120h,168h after injury. The expression of GAP-43, NGF and BDNF were assessed by RT-PCR and Western bloting. Results The spinal cord injury group displayed obvious up regulation of NGF, BDNF mRNA and protein compared with the sham group(p<0.05). The expression of NGF increased 3d after spinal cord injury,The expression of BDNF reached its peak 5 days and GAP-43 reached its peak 3-5 days after spinal cord injury. Treating rats subjected to SCI injury with rosiglitazone led to a further significant enhancement of the expression of GAP-43, NGF, BDNF in the injured tissue. Conclusion PPARγagonists rosiglitazone can plays an important role in modulating the levels of GAP-43 and Neurotrophins after spinal cord injury.
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