The Molecular Pathology Of Experimental Brain Injury: The Map-2, Cox-2, Of Gdnf, The Expression Of Caspase-3 Reactivity Regularity

In the present experiment studies, an acute traumatic model of lateral cortical impact was employed to study expressive changes of microtubule associated protein -2 ( MAP - 2) , cyclooxygenase - 2 ( COX - 2) , glial cell line - derived neurotrophic factor ( GDNF) , caspase - 3 mRNA and protein after brain injury in rats. Immunocytochemical staining , Western Blotting, nucleic acid in situ hybridization with an oligonucleotide probe and computer image analysis were used to detect the dynamic changes of MAP - 2 mRNA, COX - 2 mRNA, GDNF mRNA, and caspase - 3 mRNA in the cortex after moderate traumatic brain injury (TBI). Tissue sections from every animal were double - labeled with the antibodies of MAP -2, COX -2, GDNF, Caspase -3 and either the neuron - specific antibody neuronal nuclear protein ( NeuN) or the astroglial -specific marker glial fibrillary acidic protein ( GFAP). We carried out a series of research to explore the effects and mechanism of MAP - 2 , COX - 2 , GDNF , Caspase - 3 during TBI and tried to provide some useful theory basis for both the treatment of TBI in the practice and forensic medicine. This study can be divided into five parts as below.Part I Built the lateral cortical impact model of experimental brain injury in ratsDeveloping an ideal animal model was the foundation factor to research the mechanism of TBI, the changes of morphology and ultrastructure were observed. The contusing device was adapted from the impact method described by Feeney, including three parts; guide tube, weight, and animal stand. Force of 355. 09Kpa was produced by a 30g weight dropped from 25cm height.Morphologically these injuries progress from hemorrhages in white matter directly under contused cortex during the first hours after injury to the development of a necrotic cavity by 24 hours. By 3 -4 days post - injury, this cavitati-on was well developed and macrophages laden with hemosiderin (phagocytosis) were scattered throughout the area. The cavitation appears to expand over the subsequent two weeks and by 15 days is lined with fibroblast - like element and macrophages.The ultrastructural changes of neuron, glial and capillary were observed in different interval groups at the same force. The swollen mitochondria with partly dissolved crista, vacuolations of neuron plasma and swollen epithelium of capillary were manifested in early stage (Ih post - injury). By 24h after the impact, the swollen mitochondria with completely dissolved crista could be seen in the neurons near the edge of the contused area. The vacuolations of plasma appear to expand over neurons. The " dark neuron" could be seen from 3h post - injury. A lot of capsule and high density substances were manifested in neurons by 7 days after impact. The method described in this report reliably produces a traumatic focal lesion of the cerebral cortex of the rat which may serve as a model for cortical contusion. In this study, the slowly expanding necrotic cavitation of cortex after focal impact trauma must represent a stage of phagocytosis of debris of cells killed immediately by mechanical forces. There may be secondary events initiated by focal cortical impacts which continue over a period of weeks and expand the area of cell death to include cells which initially survived the impact. If such secondary events could be understood and controlled, perhaps the extent of injury and functional loss could be lessened. It could be applied to the forensic practice in expertizing the time course after traumatic brain injury.Part II The dynamically changes of MAP - 2 and the gene expression of MAP -2 mRNA after TBIMicrotubules play important functional and architectural roles in neurons. In addition to their structural capacities, microtubules are involved in a number of neuronal functions, including growth cone development, synaptogenesis, and neuronal morphogenesis. Microtubule - associated protein 2 ( MAP - 2 ) is a principal protein component of microtubules and highly compartmentalized in the cell body and dendrites while exclude...