The Research On Diagnostic Ultrasound And Sonovue Open The Blood-brain Barrier In Rat

BackgroundThe blood-brain barrier (BBB) is a diffusion barrier consisting of endothelial cells, pericytes and astrocyte end-feet which present in almost all areas of the brain. Brain capillary endothelial cells have no fenestrations, more extensive tight junctions than the rest of the body and sparse pinocytic vesicular transport[1]. Cerebral endothelial cells have an enzymatic barrier, capable of metabolizing drug and nutrients[2]. Because of this specialized endothelial barrier, the BBB can protect the center nervous system against the nociceptive stimulus and also limits the passage of some therapeutic agents into the brain[3]. So Several methods have been investigated to increase the permeability of the BBB to help drugs, antibodies and gene transfer. There is a good deal of evidence showing that ultrasound can be used to permeate blood–tissue barriers. Large molecules and genes can cross the plasma membrane of cultured cells after application of acoustic energy[4].High-intensity focused ultrasound has been shown to allow selective and non-destructive disruption of the BBB in rats. If microbubbles are introduced to the blood stream prior to focused US exposure, the BBB can be transiently opened at the ultrasound focus without acute neuronal damage. Thus, the introduction of cavitation nuclei into the blood stream can con?ne the ultrasound effects to the vasculature and reduce the intensity needed to produce BBB opening. This can diminish the risk of tissue damage and make the technique more easily applied through the intact skull.PurposeThe primary goal of this study was to investigate the potential use of UCA SonoVue for focally increasing BBB permeability in animal models using diagnostic ultrasound. In addition to demonstrating the duration and extent of the BBB permeability change and evaluate the safety of this method by watching if there is cellular necrosis and red blood cell extravasation into tissue through histological HE stain .And determine whether the opening could affect the Arterial blood gas and cognitive ability.MethodPart I The research on DU with SonoVue open the rat BBB1.The feasibility of the DU with SonoVue open the BBBThirty two SD rats were randomly divided into four groups (n=8per group): Con, DU, SonoVue and UC. All the animal were anesthesed by Phenobarbital, the hair of the right eye to ipsilateral ear to the top of skull were removed ,venous catheters were placed .Animals in Con were just injected EB; animals in DU: diagnostic scanner was used to insonify the brain for 10mins,then injected EB; animals in SonoVue were injected SonoVue 8ml/kg,10mins later were injected EB;UC animal were injected SonoVue 8ml/kg, at the same time the diagnostic scanner was used to insonify the rats’brain for 10mins,then were injected EB. 2.The duration of the BBB open induced by the UC.Thirty two SD rats were randomly divided into four groups (n=8per group):2h、4h、6h、8h. The EB was injected at different time point after the UC.3.The effect of UC on the rat Arterial blood gas.Arterial blood gas samples were obtained at three time points: before the SonoVue injection, right at 5mins of the ultrasound exposure, after the treatment.Part II The effect of the UC on the brain neural cells.Three male SD rats were treated with UC, then get the brain and made into histological slices, HE stain and examined under the microscope.Part III The effect of UC on the rat cognitive function .Twenty four animals were randomly divided into three groups (n=8per group):Con、Shem、UC. Morris water maze was used for assessing the spatial learning and memory 24 hours after the treatment.Result:Evens blue could be detected in the local brain after the contrast imaging and the permeability’change recovered in 4 hours. Ph, PaO2, PaCO2 were no different among the three time points. The escape latency and pathlength to the platform decreased compared to the control groups.Conclusion:Blood-brain barrier could open after diagnostic ultrasound and contrast agent in rat. The cognitive function was improved after ultrasound with SonoVue. Arterial blood gas is not affected.