Ginseng Glycopeptide Ameliorates Aβ (25-35)-induced Cognitive Impairments In Rats Via Anti-inlfammatory And Anti-apoptosis

In our previous study, ginseng polysaccharides(GP-1) could improve thecognitive ability in Aβ25-35-induced AD rats. On the basis of the preliminaryresearch, GP-1was divided into GP-6, GP-7and GP-8. With the purpose of selectingthe most effective sample that is ginseng glycopeptide(GP-6), the model of AD ratswere established by injecting Aβ25-35into hippocampus, and the Morris WaterMaze(MWM) test was evaluated the improvement of cognitive ability.GP-6(160mg/kg,80mg/kg and40mg/kg) was evaluated cognitive ability by the theMWM test in Aβ25-35-induced AD rats. Meanwhile, HE staining and congo stainingwere used to test the change of pathology. Additionally, to explore the mechanism ofGP-6on AD, the expression level of inflammatory factor and NF-kB apoptoticpathways were detected by RT-PCR and immunohistochemical method.Methods:1. The methods of separation, composition and effectiveness of GP-6, GP-7andGP-8in Aβ25-35-induced AD rats(1) The extraction of GP-6, GP-7and GP-8in a flowchart: The GP-1was dialyzedfrom10kD to5kD, the retentate of dialysis(5kD) was collected as GP-6, meanwhileits filtrate was separated by the activated-charcoal column. In the process, distilledwater and60%ethanol were used to elute through the column in turn, GP-7and GP-8were obtained correspondingly. We determined the molecular weight, physical andchemical properties, monosaccharide analysis and amino acid analysis of them byHPLC, GPC and other common chemical methods.(2) The method of effectiveness study of GP-6, GP-7and GP-8was MWM test,while it was comprised of the place navigation test and the spatial probe test.2. The methods of effectiveness and pathology of GP-6in Aβ25-35-induced ADrats (1) The method of effectiveness study of GP-6was MWM test, while it wascomprised of the place navigation test and the spatial probe test.(2) The methods of pathology study of GP-6were Congo red staining and HEstaining.3. The methods of mechanism study of GP-6anti-inflammatory andanti-apoptosis in Aβ25-35-induced AD rats(1) The mRNA relative expression of TNF-α, IL-1β, IL-6, iNOS and COX-2were measured by RT-PCR in hippocampus(2) The relative expression of NF-kBp65, Caspase-3, Bcl-2and Bax weremeasured by the immunohistochemical assay in hippocampusResults:1. The results of composition and effectiveness of GP-6, GP-7and GP-8inAβ25-35-induced AD rats(1) GP-6consisted of three oligosaccharides with the molecular weight of42325Da(34%),15937Da(21%) and6001Da(39%); GP-7consisted of oneoligosaccharide with the molecular weight of287Da(100%); GP-8mainly consistedof one oligosaccharide with the molecular weight of243Da(100%). The content oftotal polysaccharides of GP-6and GP-8were about31%and73%, and glucose wasmain component. The protein content of GP-6(50%) was highest, in addition, GP-6was consisted of17amino acids.(2) GP-6and GP-8can significantly shorten the escape latency and increase thenumber of crossings over the platform position, and GP-6is better than the other,while GP-1was regarded as positive drug.2. The results of effectiveness and pathology of GP-6in Aβ25-35-induced ADrats(1) The high dose group and the middle dose group can markedly reverse theextension of the escape latency and increase the number of crossings over theplatform position.(2) HE staining results showed that the high dose group can improve arranged clutter and neuron loss on CA1region in Aβ25-35-induced AD rats. Congo redstaining results revealed that the high dose group can significantly reverse theexpression of amyloid plaques in Aβ25-35-induced AD rats.3. The results of mechanism study of GP-6anti-inflammatory and anti-apoptosisin Aβ25-35-induced AD rats(1) RT-PCR results explained that the high dose group can significantly reduce therelative expression of TNF-α, IL-1β, IL-6, iNOS and COX-2, while the middle dosegroup can signally decrease the relative expression of iNOS and COX-2.(2) Immunohistochemical results illustrated that the high dose group can markedlyameliorate the expression of NF-kBp65, Caspase-3and Bax, but has no obviouslyreduce the expression of Bcl-2.Conclusion:GP-6and GP-8could treat with the cognitive ability in Aβ25-35-induced ADrats, and the effect of GP-6is better, while according to the composition analysis, weinferred that GP-6was a type of ginseng glycopeptide. The high dose group and themiddle dose group can significantly improve the cognitive ability in Aβ25-35-inducedAD rats. According to the HE staining and Congo red staining results, the high dosegroup and the middle dose group can effectively improve the severity of Aβ25-35induced AD. The mechanism of GP-6on AD is probable by inhibiting the expansionof the inflammatory cascade reaction and prohibiting the expression of the NF-kBpathway.