The Influence Of TMP To The Expression Of MiRNA-24and Bim In The Rat Acute Spinal Cord Injury

Chapter One:IntroductionAcute spinal cord injury (SCI) is a kind of high disabling central nervous system trauma caused by injury, its incidence has been high in recent years. Spinal cord injury can be divided into two major categories including primary injury and secondary injury. Currently on the international researches focuses on how to reduce the secondary injury, enhance the recovery of spinal cord function. MiRNAs are small RNAs widely existing in the organism, which have extensive regulation roles in life activities. Studies have found that miRNA-24takes apart in the process of acute spinal cord injury, and it can inhibit cell apoptosis. Our team also found the expression of miRNA-24significantly changes after SCI, but its effect and mechanism in SCI are not clear. Ligustrazine whose chemical name is tetramethylpyrazine(TMP), is a kind of biological activity ingredient from the rhizoma ligustici wallichii, having the exact effect in the treatment of cardiovascular disease. In recent years, studies about TMP have found it can protect spinal cord function after SCI, but its mechanism in the SCI needs further research. Therefore, this study based on the rat acute spinal cord injury model, uses the technology of molecular biology to detect the changes of miRNA-24, Bim protein and apoptosis, discusses the relationship between miRNA-24, Bim and cell apoptosis, analyzes the influence of TMP for miRNA-24and Bim, provides the scientific theory basis for the clinical treatment of SCI.Chapter Two:the relationship between miRNA-24, Bim and apoptosis in the acute spinal cord injuryObjective By detecting the expression of miRNA-24, Bim and cell apoptosis after SCI, analyzes the relationship between miRNA-24, Bim and apoptosis in the rat acute spinal cord.Materials and methodsForty eight adult male SD rats divided into two groups, normal control group (n=12) and spinal cord injury group (n=36). Rats in normal control group were only subjected to laminectomy, rats in spinal cord injury group were subjected to the modified Allen’s weight drop impacting to make the rat spinal cord injury model, these rats were divided into1,3,7day three groups according to the time points,12rats in each group. Kill the rats and extract specimens according to the time points, use the real-time PCR, immunohistochemical and Tunel to detect miRNA-24,Bim and cell apoptosis after SCI, verify their changes in the rat spinal cord tissue after SCI. Using SPSS17.0software to analyze data, and make the correlation study between the two of three indexes, analyzes the relationship between miRNA-24, Bim and cell apoptosis.Results(1) After SCI, the Ct value of miRNA-24increased significantly in rats spinal cord tissues, peaked in the third day, then gradually decreased; Compared with normal control group, the Ct value of SCI group are statistically difference (P<0.05) in the first, third and seventh day. The Ct value of miRNA-24were positive related to the cell apoptosis, r=0.962, P<0.01, means the expression of miRNA-24were negative related to cell apoptosis.(2) The average gray value of Bim significantly decreased after SCI, then increased gradually; SCI group and normal control group have obvious difference in the first, third and seventh day (P<0.01). The average gray value of Bim were negative related to the cell apoptosis (r=-0.927, P<0.01), means the expression of Bim were positive related to cell apoptosis.(3) The Ct value of miRNA-24were negative related to the average gray value of Bim (r=-0.809, P<0.01), suggesting that the expression of miRNA-24were negative related to Bim. Conclusions(1) miRNA-24and Bim may take apart in the process of cell apoptosis after rats acute spinal cord injury;(2) miRNA-24were negative related to the expression of Bim, Bim might be a key to the process of miRNA-24taking apart in cell apoptosis after rats SCI. Chapter There:The influence of TMP to the expression of miRNA-24and BimObjectiveBy comparing the various in the NS group and TMP group, analysis the influence of TMP to the expression of Bim protein and miRNA-24, verify the effect of TMP in SCI, and discuss the possible mechanism of TMP.Materials and methods72adult male SD rats were randomly divided into two groups, making spinal cord injury model, the rats in TMP group were given2%hydrochloric acid ligustrazine injection200mg/kg by intraperitoneal injection, once a day, five days; NS group use The same amount and frequency NS as a control treatment. Kill the rats and extract specimens according to the time points, detect miRNA-24, Bim and cell apoptosis after SCI, using t test analyze the differences of two groups at each time points, verify the effect of TMP in SCI, research the influence of TMP to the expression of miRNA-24and Bim after SCI, discuss the possible mechanism of TMP in SCI.Results(1) The miRNA-24Ct values of TMP group is significantly lower than NS group in the7th day after SCI (P<0.05), the first and third day have no obvious difference.(2) The Bim average gray value of TMP group is significantly higher than NS group in the7th day after SCI(P<0.05). (3) The apoptosis index of TMP group is significantly lower than NS group in the third and seventh day (P<0.05), means the TMP can inhibit cell apoptosis after SCI.Conclusions(1) TMP can reduce the cell apoptosis in spinal cord tissue after SCI.(2) TMP can increase the expression of miRNA-24and decrease the expression of Bim in the rat spinal cord tissue after SCI, it may be one mechanism of TMP inhibit cell apoptosis.