Experimental Studies Of ?-sheet Breaker Peptide In Pharmacology,Pharmacokinetics And Toxicology

Objective:To study the effects of H102-BD and HPYD on behavior and the expression of APP and A? in brain through intranasal administration of APP/PS1 double transgenic mice;to investigate the acute toxicity,the pharmacokinetic and tissue distribution of H102-BD after intranasal administration.Methods:1.The APP/PS1 double transgenic mice were randomly divided into model group,H102-BD group,HPYD group and a group of C57BL/6J mice with the same age and background was set as normal control group.The treatment groups were intranasal administrated with H102-BD or HPYD solution 5?l/d,while the model group and normal control group were treated with normal saline solution 5?l/d.After four weeks,the ability of spatial reference memory was tested by Morris Water Maze.2.Immunohistochemical stain and western blot were used to detect the expression of APP and A? in the brain.3.The SD rats were randomly divided into five treatment groups and one blank group.On day 1,each teatment rats received a single intranasal administration dose of specific concentrations solution.Mental status and behaviors of the rats were observed daily.Body weights were measured on sepecified days before killing.After necropsy,the mein tissues and organs from blank group and the largest dose group were weighed,and compare the organ coefficient in the two groups.Parts of these organs were kept in 4%paraformaldehyde for histopathological evaluation to investigate the histological changes of each group.4.The SD rats were randomly divided into blank group and the treatment groups.After administration,the radioactivity of blood and major organs was measured at different time points.Results:1.The Morris water maze test:(1)In place Navigation Training test:the escape latency of the model group was much longer than the nomal group(P<0.01).H102-BD and HPYD had significantly reduced the escape latency in AD mice(P<0.01).There was no significant difference between the drug groups and the normal group(P>0.05).(2)In Spatial Probe Test:compared with normal group,the time pasting the position of the platform of the model group was significantly less(P<0.01),and the initial angles were significantly larger(P<0.01).Compared with the model group,the time pasting the position of the platform of the drug groups was significantly increased(P<0.01),and the initial angles were much smaller(P<0.01).There was no significant difference between the drug groups and the normal group(P>0.05).2.Expression of APP and A?.in the brain:(1)Immunohistochemistry test:There were much higer APP and A? level in the brain of the model mice than in the nomal group(P<0.01),and compared with model group,there were lower level of APP and A? in the H102-BD group and HPYD group(P<0.01).There was no significant difference between the drug groups and the normal group(P>0.05).(2)Western blot test:The A? level in the brain of the model group mice was higer than that of the nomal group(P<0.01).Compared with the model group,the exprssion of A(3 in the H102-BD group and HPYD group were decreased significantly(P<0.01).And there was no significant difference between the drug groups and the normal group(P>0.05).3.There was no non-normal condition such as listlessness in all drug groups.It had indicated that there were no signigicant difference between the blank group and the largest dose group in body weight and organ coefficient(P>0.05).The HE staining showed that there were no obvious pathological changes in the largest dose group organs.4.H102-BD degraded quickly in blood and brain,and reached the peak concentration 4h after intranasal administration.H102-BD and its metabolites mainly distributed in kidney,liver,lung and lymph nodes.This study provided basis for further toxicokinetic sutdies.Conclusions:H102-BD and HPYD could improve the ablility of learning and reduce the expression of APP and A? in AD mice brain,so they have therapeutic effect on AD.H102-BD degraded quickly in blood and brain.H102-BD and its metabolites mainly distributed in kidney,liver,lung and lymph nodes.Acute toxicity test indicated that H102-BD was safety for treatment of AD.