The Neuroprotective Effect Of BBB-permeable Tripeptide In Ischemia Brain Injury

ObjectiveThe penetrating tripeptide composed of certain neuroprotective amino acids have the ability to penetrate the blood-brain barrier in the middle cerebral artery occulation model and can carry amino acids into the brain,but most clinical patients who are admitted to the hospital are in a state of thrombus occlusion,so we design different cases of ischemia-reperfusion model and administrate the tripeptide immediate after ischemia,to test whether the tripeptide could penetrate the blood-brain barrier and reach the ischemic injury area.We will research whether nasal injected the drug can penetrate the blood-brain barrier and reach the brain.MethodsThe levels of glycine in normal and ischemic brain tissues were detected by high performance liquid chromatography(HPLC).We determinated the intracellular glycine levels in neurons.The effect of GCF on the survival of cortical neurons after OGD insult was researched by LDH assay and MTT assay in vitro.Immunofluorescence method was used to determine wtether FITC-GCF can enter into brain after ischemia-reperfusion.MCAO model was used to test the survival rate of rats at different time points after ischemia.TTC staining was used to detect the effect of GCF on the survival rate of rats after ischemia and reperfusion and the protection on the survival of rats.FITC-GCF was injected intravenously after ischemia to detect whether it entered into the brain.The effects of same kinds of tripeptides on the ischemic brain were deternated by TTC staining,and the survival of neurons were investigated by using LDH and MTT assay.Results1.The glycine was increased in core after ischemia brain injury but decreased in neurons2.Gly confers neuroprotective effects3.Gly has low membrane-permeability3.1 Gly has low BBB-permeability;3.2 Gly has a very low cell membrane permeability.4.The tripeptide plays neuroprotection by delivering Gly4.1 The tripeptide confers neuroprotection to ischemia-reperfusion injury;4.2 The tripeptide confers neuroprotection in different infarcted conditions;1)FITC-GCF was injected intravenously immediately after ischemia for 2h,4h,6h and located in the ischemic area;2)GCF intravenous administrated before ischemia can play a neuroprotective effect;Immediately administration of GCF at 2 h,4 h,6 h after ischemia decreased infarct area;3)GCF intravenous administrated in continuous ischemia model can confer neuroprotection to 12 or 24h ischemic infarct;5.Nasal administration of FITC-GCF can go through the blood-brain barrier and reach the brain.Conclusions1.The tripeptide GCF intravenous administrated immediately after ischemia confers neuroprotection;2.The tripeptide GCF intravenous administrated confers neuroprotection for long time ischemia;3.GCF nasally administrated can enter into the brain by penetrating the blood-brain barrier.