The Effect Of Estradiol On β-Amyliod And β-Secretase In Different Sections Of The Rat Brain With Alzheimer's Disease Model

OBJECTIVE To observe the effect of estradiol onβ-amyloid_1-40 andβ-secretase in different sections of the rat brain with fimbria/fornix transection andovariectomy as an Alzheimer's disease model.METHODS Healthy female rats were randomly divided into 4 groups according to2×2 ANOVA design, there were seven rats in every group:â‘ ovariectomized group(OVX);â‘¡fimbria/fornix transection of group(FF);â‘¢fimbria/fornix transection andovariectomized group(OF);â‘£control groups. The bilateral fimbria-fornix of brain wastransected in the stereotaxic apparatus and bilateral ovaries were ablated in order to erectanimal model. Immunoreactive cells of Aβ_1-40 were stained by immunohistochemical way,and the expressive varieties of Aβ_1-40 immunoreactive cell in the cerebral cortex,hippocampus CA1, almond complex and Meynert nucleus were observed. The number ofmasculine cell were noted in high times microscope at random selected 5 fields in everydetected area, and then compared the average number of Aβ_1-40 according to 2×2 ANOVAanalysis amoung the four groups.The cells of theβ-secretase were stained by immunofluorescent cell labeling andobserved with confocal laser scanning microscopy. The number of masculine cell werenoted in high times microscope at random selected 5 fields in every detected area, andthen compared the average number ofβ-secretase between the two groups.RESULTSAbout the study 1: The bilateral fimbria/fomix transection and ovariectomization hada interaction on the expression of Aβ_1-40 in all areas of the brain(p＜0.01). The expressionof Aβ_1-40 remarkably increased in hippocampus CA1, cerebral cortex, almond complexand Meynert nucleus of the brain in the OVX group, FF group(p＜0.01), The expression ofAβ_1-40 remarkably increased in hippocampus CA1, amygdala, Meynert of the basalforebrain of the brain in the OF model group with the bilateral fimbria/fornix transectionand ovariectomization(p＜0.05).About the study 2: The expression of Aβ_1-40 and theβ-secretase remarkablyincreased in in the cerebral cortex and the hippocampus CA1 of the brain in the AD modelgroup with the bilateral fimbria/fornix transection and ovariectomization. It was decreasedin the AD+E₂ group than that in the AD model group(p＜0.01).CONCLUSION fimbria/fornix transection and ovariectomization can cause the expression of Aβ_1-40 that increased in many sections of the rat's brain. Possibly it is a mainreason to the agedness cognitive disturbance and maybe as a way to set Alzheimer'sdisease model. Estrogen replacement therapy can cause the expression of Aβ_1-40 and theβ-secretase decreased and maybe affect the process of the metabolism of APP, thetherapy maybe prevented the pathologic change of Alzheimer's disease.