Effects Of Acute Hyperglycemia On Nerve Injury In A Rat Model Of Intracerebral Hemorrhage

Background and Objective:Intracerebral hemorrhage (ICH) is subtype of stroke with high morbidity and mortality accounting for about10-15%of all strokes worldwide. Primary brain injury is induced by occupying effect of hematoma after ICH, and second brain injury such as a series of pathological changes around the hematoma also contributes to poor outcome of patients with ICH. Recent evidence suggests that admission hyperglycemia has a deleterious effect on survival and functional outcome in patients with ICH. Our study employed an acute hyperglycemia rat model of ICH to investigate whether acute hyperglycemia exacerbates nerve injury following ICH.For a long time autophagy has been considered as an important catabolic process that can deliver cytoplasmic material to the lysosome for degradation. Autophagy promotes cell survival by elimination of damaged organelles and proteins aggregates, as well as by facilitating bioenergetic homeostasis. Autophagy plays an important part in many human diseases. Recent research has indicated that autophagy is activated after ICH and autophagy may takes part in the pathophysiological procedure of ICH. However, it remains controversial as to whether autophagy is harmful or beneficial after ICH. The level of autophagy is associated with the physiological or pathological state of cells and environment around the cells. Our study investigated two reliable makers of autophagy -microtubule-associated protein light chain-3(LC3) and Beclin-1in order to examine the effect of acute hyperglycemia on cell autophagy around the hematoma after ICH.Methods:Male adult Sprague-Dawley rats were randomly divided into four groups as follows.(1) C group-control group.(2) G group-acute hyperglycemia group.(3) I group-ICH model group.(4) IG group-pre-hemorrhage hyperglycemia group. Autologous blood was collected from the right femoral artery and then delivered into the right caudate nucleus to create ICH model. A50%glucose solution (6ml/kg) was intraperitoneally injected30min before the experiments (autologous blood infusion) to create ICH with hyperglycemia model. Twenty-four hours after the operation corner turn test and forelimb use asymmetry test were used to examine the neurological deficits. Assessments of hematoma, brain water content and HE method of staining were used to observe and estimate the histopathologic change around the hematoma. Additionally, LC3and beclin-1around the hematoma were investigated by Western blot and immunohistochemistry to survey changes in autophagy after ICH.Results:1. The behavioral tests scores including corner turn test and forelimb use asymmetry test scores and brain water content were elevated24h after ICH (P <0.05). Twenty-four hours after ICH paraffin sections (hematoxylin and eosin staining) showed brain edema, uneven distribution of cells, loss of neurons and lymphocytic infiltration around the hematoma.2. Immunohistochemical investigation of LC3and Beclin-1performed24h after the operation revealed numerous LC3and Beclin-1positive cells that were deeply stained around the hematoma, while immunohistochemical staining for LC3and Beclin-1in control group was weak. The results of western blot showed that LC3and the Beclin-1protein level around the hematoma were increased24h after ICH. 3. Acute hyperglycemia without ICH did not affect the neurological deficits scores and the brain water content of the ipsilateral basal ganglia. But acute hyperglycemia was associated with increased forelimb use asymmetry test scores and brain water content24h after ICH (P<0.01).4. Acute hyperglycemia without ICH did not affect the levels of two reliable makers of autophagy-LC3and Beclin-1. But acute hyperglycemia led to weak immunohistochemical staining for LC3as well as Beclin-1and declined LC3and Beclin-1protein levels around the hematoma24h after ICH.Conclusion:1. Neurological deficits and edema were induced by ICH and autophagy is activated after ICH.2. Acute hyperglycemia exacerbated neurological deficits and edema in a rat model of ICH and reduced cell autophagy around the hematoma.