Effect Of GS Rb1 On The Expression Of Aβ And Related Proteins In Parietal Lobe Of AD Rats

ObjectiveAlzhemier's disease(AD)is a kind of central nervous system cataplasia disease with the highest attack rate and the most critical detriment.The main clinical manifestations of AD are progressive remembrance loss and damaging of cognition function;The pathologic hallmarks of AD are accumulation of considerable Senile Plaque(SP)among neurons,intracellular production of neurofibrillary tangles in neurons and the degeneration of regional neurons and synaptic linkage.SP is thought to be the most significant feature of AD,and probably the direct etiological factor of AD.β-amyloid is the major component of SP,and might be the initiating factor,which caused the injury of neurons and deterioration of cognition function.β-secretase andγ-secretase are the key synthetases in producingβ-amyloid,but the variations ofβ-secretase andγ-secretase in AD process is still unknown.Therefore,the experiment is designed to investigate the changes ofβ-secretase andγ-secretase in the process of AD in parietal lobe of Alzheimer's disease-like rats.There are lots of researches done on this area,but no effective drugs appear yet.Ginsengs are conventional anti-aging drugs with an active ingredient of ginsenosides,which has favourable exciting effects on central nervous system and can strengthen the ability of memory,discrimination and judgment.It has been found that monomer component Rb1 of ginsenosides has protection and trophic action on neurons, promoting the regeneration of neurite and improving the ability to anti-damage and anti-apoptosis of neurons.However,the study of Ginsenosides Rbl on Aβand related proteins in AD-like rats are very limited.In the present study,we explore the effect of Ginsenosides Rb1 on expression of proteins in the purpose of providing a reliable basis of morphological and molecular biology in AD prevention and treatment. Methods30 SD male rats were randomly divided into three groups:control group,model group and treatment group.Model group and treatment group were treated with intraperitoneal injection of D-galactose,and were fed with AlCl₃ at the same time,and control group with intraperitoneal injection of the same dose of normal saline.4 weeks of intraperitoneal injection of Ginsenosides Rb1 initiated in model group 1 d after the modeling accomplished.Congo red staining,silver staining were used to assess the model; immunohistochemistry,Western Blot test and imaging analysis,Morris water amaze system were used to contrast and observe the effect of Ginsenoside Rb1 on the expression of Aβ,β- secretase andγ-secretase.Results1.Congo red stainingPositive produces are jacinth clumping or disperse plaque.Plaques are scarce in control group,while distributed intensely and dyed thickly in model group;a few plaques dyed lightly could be seen in treatment group.2.Silver stainingPositive markers are coarsening and jumbling NFTs.Some NFTs are in the periphery of neurons,others distributed intensively,covered with kytoplasm and extend to the axis cylinder.In control group,NFTs scattered orderly and dyed lightly;in model group,lots of brownish-black NFTs could be seen with axis cylinder and cytodendrite coarsening and dispersing in a jumbled way;in treatment group,NFTs were dyed lightly,neurons damaged rarely with completely reserved neurite.Nerve fibril arranged in a relatively rule way,and no obvious thickening nerve could be seen.3.Immunohistochemistry(1)Investigation with microscopesIn parietal cortex the positive manifestation of antibodies are stained brown,and most of them expressed primarily in the intracytoplasm of neurons.Few positive neurons with anti-Aβ,β-secretase andγ-secretase could be seen in control group;In model group,the numbers of positive neurons was higher than that of control group and were dyed deeply.At the same time,lots of buffy or brown positive particles could be seen in the kytoplasm.There were also analosising and disappearing of neurons.(2)Quantitative analysisCompared with control group,the OD value in model group were significantly higher(P＜0.05),which showed an increasing expression of proteins;And in comparison with model group,the OD value in treatment group were much lower(P＜0.05),which showed that the expression of Aβand related proteins were in a reduced tendency after the treatment of GS Rb1.4.Western BlotCompared with control group,OD in model group were significantly higher(P＜0.05),which showed the increasing expression of proteins;compared with model group, OD in treatment group were lower(P＜0.05),which showed the expression of Aβand related proteins were in a reduced tendency.5.Morris water amaze systemThe average escape latent periods in each group progressively declined.From the second day on,the average escape latent period was prolonged significantly(P＜0.05) compared with control group;however,compared with model group,the average escape latent period was decurtated significantly(P＜0.05),but had statistical significance only in the second and third day(P＜0.05).Conclusions1.Aβ,β-secretase andγ-secretase expression were significantly increased in the cortex of parietal lobe of AD-like rats.2.Aβ,β-secretase andγ-secretase expression were decreased in treatment group compared with model group.3.GS Rb1 could prevent the expression of Aβthrough inhibiting the expression ofβ-secretase andγ-secretase,suggesting that GS Rb1 could protect neurons or improve their functions.