Effect Of Hyperbaric Oxygen On Diffuse Injured Rats' Brain Histopathology And Learning Or Memory Ability

As traumatic brain injury is a disease with high incidence , death and disability, a lot of scholars studied it in every field. Diffuse axonal injury(DAI) is one important type of diffuse brain injury(DBI). Since Strich reported DAI in 1956, more and more investigation proved its importance with appliance of CT ^ MRI or other mordern instrument. No matter diffuse axonal injury is sole or accompanied with other types, it is responsible for bad outcome and high mortality. Clinical evidence proved that hyperbaric oxygen therapy can alleviate cerebral ischemia and oedema, debase intracranial pressure significantly, improve head trauma recovery, while different oxygen pressure and occasion with different head trauma grade, type and duration make the outcome different. To observe the treatment effect of hyperbaric oxygen on rats after diffuse brain injury and explored the mechanisms, we studied post-injured brain oedema, neuron degeneration and-4-necrosis, astrocyte hyperplasia and rats's learning and memory ablity under HBO. We also made immunohistochemistry staining of neurofilament (NF)> GFAP and choline-acetyltransferase (ChAT) and examined them under light microscopy. We hope this study will be helpful to clinical head trauma treatment.We produced head-injured animal model by an weight-dropt device designed by Marmarou, observed the pathology at different time after trauma (includes 6h, 1 d,2d,3d, 1 w,2w,3w ) and that of under 0.2 MPa hyperbaric oxygen, examined the conditioned reflex number(CN) of rats with Y-maze, and made immunohistochemistry staining on paraffin slices. We found that: ゛fter trauma, diffuse neuronal degeneration and necrosis occurred, brain water content increased distinctively, NF staining showed that axonal rupture presented, while HBO group is quite different, the number of damaged neurons was decreased, brain water content also decreased significantly (P<0.05); 〨FAP staining showed that a lot of astrocyte appeared after trauma especially in hippocampus area, astrocytes of HBO 3 weeks group were fewer and more feeble than those of control group; (3)CN of DBI rats were greater than those normal rats(P<0.05), CN of HBO group were significantly less than control group if rats were not trained before trauma(P<0.05), while if rats were trained before trauma, the difference of CN was not statistically significant between HBO group and control group; @ ChAT staining showed that ChAT positive cholinergic fibers in hippocampus were little nearly blank, while under HBO positivecholinergic fibers in hippocampus were greater. These results showed that: l.HBO may alleviate diffuse degeneration and necrosis and oedema after trauma; 2.DBI rats' learning ability and memory were damaged while HBO may improve rats learning disability; 3.HBO may protect and activate neurons in hippocampus, restrain cholinergic neurons degeneration, increase ChAT positive fibers'expression, this maybe one of the mechanisms of HBO improving learning disability of brain injured rats. 4.Three weeks HBO treatment may inhabit astrocyte hyperpalsia.