Study On Ultrastructure And Glucose Transporter Of Blood-brain Barrier Around Hematoma

Background and purposeSpontaneous cerebral hemorrhage is a common and often fatal subtype of stroke, which is mainly caused with hypertension. If a patient survives the ictus, resulting hematoma within brain parenchyma triggers a series of events leading to secondary insults and severe neurological deficits. More studies are needed to understand the underlying mechanisms of ICH-induced brain injury and to evaluate therapeutic interventions.The blood-CSF barrier, the vascular-endothelial barrier and the arachnoid barrier together form the blood-brain barrier. The blood vessels within brain have a very large surface area that promote the exchange of oxygen, amino acids and sugar between blood and brain. The blocking function is achieved by tight junction between endothelial cells. Blood-brain barrier plays an important role in maintaining a constant environment within and around the brain so that normal function continues and foreign or harmful substances are kept out. Compared with peripheral capillary endothelial cells, blood brain barrier characterized by four sections: tight connection exists between endothelial cells; Fewer vesicles are responsible for substances exchange; Dendrites of astrocyte are attached to endothelial cells; Peculiar enzymes exist.GLUT1 (glucose transporter type one) is responsible for steady state of blood sugar in all tissues, especially brain tissue on molecular level, which plays a key role in two steps such as glucose transportation and metabolism. Glut family consists of six subtypes while GLUT1 has been defined as the main subtype for brain tissue. In whole brain glutl includes two kinds of molecular subtypes, one of which weighs 55000dal, the other 45000dal. The former mainly locates in capillary endothelial cell while the latter in oligodendroglia. However, there is few experimental observation reported on blood-brain barrier around hematoma in rats model.Recent studies showed than cerebral hemorrhage affected structure and function of blood-brain barrier around hematoma. Some studies found that blood brain barrier was destroyed 6h after injecting blood into rat brain and gave rise to brain edema afterwards, meanwhile gradually deteriorated within 72hrs in patients with hypertensive intracerebral hemorrhage; Under electron microscope, it is showed that the damage of blood brain barrier was increased in direct proportion to length of time and the patients presenting a relevant clinical manifestation.Activities of GLUT1 in blood brain barrier, detected by immunohistochemistry, was enhanced after 12hrs after cerebral hemorrhage and downregulated 72hrs after cerebral hemorrhage.Initial attitudes on functional changes of blood-brain barrier around hematoma in patients with cerebral hemorrhage and its mechanism have been achieved. More researchers are needed to describe the morphological changes of blood -brain barrier in patient. In present study, we are destined to observe blood-brain barrier with electron microscope and detect glutl with immunohistochemistry so as to define the neuropathology of cerebral hemorrhage and to refine the treatment for cerebral hemorrhage.Material and method1. Establishment of model of cerebral hemorrhage in rat50 healthy adult male SD rats were randomly divided into five groups: 0.2mm, 0.6 mm and lmm after anterior fontanel group, collagenase groups, collagenase /heparin group, control group, rat model with cerebral hemorrhage is established by injecting collagenaseIV/heparin-saline or collagenase into caudate nucleus. The neurological deficit score at different time after injecting was acquired by observing the behavior of rat according to Longza method.2. Observation on ultrastructure and glucose transporter type one of blood-brain barrier around hematoma in ratRat model with cerebral hemorrhage is established by injecting collagenaseIV /heparin-saline into caudate nucleus. Forty rats weighing 210~250g were randomly divided into five groups :sham-operation group, 12 hours group after cerebral hemorrhage,24hours, 48hours, 72 hours. Activities of GLUT1 in brain capillary endothelia cell were detected with immunohistochemistry while morphological change of blood-brain barrier was watched by electron microscope.3. Observation on ultrastructure and glucose transporter type one of blood-brain barrier around hematoma in hypertensive patient28 patients with cerebral hemorrhage and hypertension in our hospital from 2/2003 to 1/2005 were carried out removing hematoma by stereotactic surgery. At the same time, brain tissue around hematoma was sucted as biopsy specimen.Control group is composed of patients who died from non brain diseases. Consistent with the experimental study, Activities of GLUT1 in brain capillary endothelial cell were detected with immunohistochemistry while morphological change of blood-brain barrier was watched by microscope.4. Minimally invasive surgery on hypertensive intracerebral hemorrhage56 cases with hypertensive intracerebral hemorrhage were randomly divided intotwo groups: medical treatment group and minimally invasive treatment groups. Difference of the BBB index was assessed .Meanwhile, the clinical neurological deficient scale was evaluated. Result1. Injection collagenaselV/heparin saline lmm after anterior fontanel achieved the highest neurological deficit score; Heparin could accelebrated the formation of hematoma.2. In experimental study, Expression of GLUTl upregulated within 48 hours after intracerebral hemorrhage, afterwards expression of GLUTl downregulated Damage of blood-brain barrier appeared 12 hours after cerebral hemorrhage, and gradually deteriorated till the seventh day after cerebral hemorrhage.3. Consistent with experimental rat model, expression of GLUTl upregulated within 48 hours after cerebral hemorrhage, afterwards expression of GLUTl downregulated. Damage of blood-brain barrier appeared 12 hours after cerebral hemorrhage, and gradually deteriorated till the third day after cerebral hemorrhage.4. The BBB index of minimally invasive surgery group is significantly lower than medical treatment, and the BBB index of the two groups are significantly lower than control group. The clinical neurological deficient scale showed remarkably significant difference between minimally invasive surgery group and medical treatment group.Conclusion1. Constant rat model with cerebral hemorrhage could be established within 24hrs for experimental research.2. Protective reactive to supply glucose for neuron can be triggered agaist injury of cerebral hemorrhage by blood-brain barrier 12h after intracerebral hemorrhage around hematoma.3. Prevention of blood-brain barrier damage plays an important role in curing cerebral hemorrhage.4. Consistent result has been achieved between experimental study and clinical study in present research.5. Minimally invasive surgery can reduce the lesion of cytotoxicity to blood-brain barrier in patients with hypertensive intracerebral hemorrhage and improved the prognosis.