Study On The Effect And Mechanism Of Progesterone On The Repair Of Acute Brain Injury In Rats Using Magnetic Resonance Imaging

Objective To define MR imaging value in the acute brain injury and provide new ideas for clinical diagnosis and treatment,we analyzed the effects of progesterone repairment of acute traumatic brain injury(TBI)in rats and explore its related mechanisms by employing Multi-modal MRI and pathology.Materials and methods The 63 rats were randomly divided into three experimental groups: normal control group(NC group,n=7),traumatic brain group(TB group,n=28)and the PROG treatment group(TP group,n=28).The TBI model was established on experimental rats by modified Feeney's weight-dropping method.TP group and TB group were divided into 4 sub groups(3 h group,24 h group,1 week group,2 week group),which each sub group got 7 rats.All goups were received conventional MRI,DWI and DTI.The TP group were injected PROG intraperitoneally(16 mg/kg)at 30 minutes post-injury,6 hours post-injury,12 hours post-injury,24 hours post-injury and daily every day after injury,until the end of experiment.The TBI lesion volume were measured on the MRI T2 WI images.The paired two-tailed t-test were performed to compare the lesion volume between TP and TB groups at different time points.The ADC values of the edema area were measured on the ADC images at different time points.The one way ANOVA and multiple comparison in ANOVA were performed to compare the difference of ADC among the NC group,the TB group and the TP group.The FA values of the ipsilateral corpus callosum were measured on the FA images at different time points.The one way ANOVA and multiple comparison in ANOVA were performed to compare the difference of FA values among the three groups.For all tests,p < 0.05 was considered significant.We randomly extract 2 rats for pathological HE staining at the each time after injury,which observing the pathological changes of the lesion.Results1.Conventional MRI results: T2 WI showed that TB group and TP group has different extent of hemorrhage or edema in the acute stage of brain injury.The lesion volume gradually increased after injury 3h and 24 h reached the peak,whereas 1week and 2weeks gradually reduced.The TP group restore better than that in the TB group,but there was no significant difference between the two groups.2.DWI results: In TB group,the ADC of the edema area was significantly elevated at3 h(0.779±0.015),peaked at 24h(0.882±0.103),but gradually decreased on 1week(0.845±0.031)and 2w(0.764±0.021).In TP group,ADC was gradually increased on3h(0.757±0.018),peaked on 24h(0.849±0.07),but gradually decreased on 1week(0.799±0.044)and 2w(0.723±0.016).The ADC at 3h,1w and 2w were statistically significant between the two groups(P<0.05).3.DTI results:In TB group,the FA value of ipsilateral corpus callosum began to decline after 3h(0.388±0.056),compared with NC group,24h(0.360±0.042)and 1w(0.259±0.055)decreased significantly,but after 2 weeks gradually increased,whereas still below NC group.In TP group,the FA value of ipsilateral corpus callosum began to decline after 3h(0.394±0.042),24h(0.372±0.060)and 1w(0.354±0.059)decreased significantly,then after 2 weeks gradually increased.Compared with TB group,the FA value of 3h and 24 h had no statistical difference,but the 1w and 2w was statistically significant(P<0.05).4.Pathological results: After 3h,TB and TP group showed obvious swelling,cell edema,brain parenchyma and subarachnoid hemorrhage.The vascular space increased,and abnormal neurons(partial necrosis)were observed.24 h hemorrhage and edema reach peak,and abnormal neurons increased.There was no significant difference between the two groups in 3h and 24 h.After 1w,the cell edema and hemorrhage reduced,but the TP group was significantly more than that of TB group.The number of abnormal neurons in the 2 week group was less than that in the 24h group.Glial cells,vascular proliferation and Heme deposition were observed.Compared with TB group,TP group had less edema.Conclusion1.Progesterone reduce the lesion volume of traumatic brain injury in TBI rats,improve brain edema and promote lesion healing process.2.DWI can be quantitatively reflect the changes of traumatic brain edema.ADC value is a reliable indicator of quantitative assessment of brain edema.Progesterone can reduce vascular edema caused by traumatic brain injury.3.FA can be quantitatively reflect the situation of TBI white matter damage,and indirectly reflect the functional prognosis of TBI rats.Progesterone can promote the white matter repair in acute TBI rats.