Kinetics Of Neurological Function And Immunity In Rats Following Repetitive Mild Traumatic Brain Injury

Objective:Despite growing awareness on repetitive mild traumatic brain injury(rm TBI),whether long-term kinetics of immunologic components in the central and peripheral immune system took part remain equivocal.Current study aimed to provide a quantitative assay for certain immune system parameters in rm TBI rats.Methods: Neurological functions were assessed by modified Neurological Severity Score(mNSS)and Morris Water Mass(MWM),immunologic component from brain and peripheral blood were analyzed by flow cytometry(FCM).Results: 1.(1)Neurological functions of rm TBI rats were seriously impaired.(2)Rats received rm TBI showed significant neurobehavioral deficits during 42 days post-injury(dpi).2.(1)Immune dysfunction was observed in the central nervous system(CNS)after rm TBI in rats.In the injured brain,CD3~+ T cells showed a bimodal increase during the first week and in the chronic phase after rm TBI,and CD3~+CD4+ T cells offered upgrade firstly than descending latter tendency whereas CD3~+CD8+ T cells reversed during 42 dpi.(2)In addition,we also detected that peripheral immune suppression was implicated in the chronic phase after rm TBI.3.CD86+ / CD11b+ M1-like microglia significantly increased at 42 dpi,while CD206+ / CD11b+ M2-like microglia peaked at 7 dpi.Conclusion: 1.Neurobehavioral deficits was long-term after rm TBI in rats.2.Immune dysfunction was observed in the central and peripheral nervous system after rm TBI in rats.Peripheral immune suppression was implicated in the chronic phase after rm TBI in rats.3.M1-like microglia significantly increased in the chronic phase while M2-like microglia peaked in the acute phase after rm TBI in rats.