The Effects Of Total Lotus Plumule Alkaloids And Pseudolaric Acid B On Alzheimer’s Disease In Mice

Alzheimer’s Disease（AD）,also known as senile dementia,is one of the neurodegenerative diseases,which mostly occurs in elderly people clinically,and seriously affects the health and quality of life of patients.At present,the number of elderly people in China is soaring,and the aging population is intensifying.The treatment and prevention of AD have been a hot issue in the field of life science.However,there is a serious shortage of drugs for the treatment of Alzheimer’s disease.Lotus plumule alkaloids（LPAs）are alkaloid mixture derived from the kernel of Nelumbo nucifera Gaertn,and the main components of LPAs are neferine,isoliensinine and liensinine;while Pseudolarix acid B is a compound isolated from the root bark of Pseudolarix kaempferi Gord.Previous cytological studies of our research group have shown that LPAs and Pseudolarix acid B have significant anti-inflammatory effects and show obvious potential for the prevention and treatment of diseases associated with inflammation,such as Alzheimer’s disease.Therefore,in this paper,AlCl₃-induced AD model mice and APP/PS1 double transgenic AD model mice were gavage administered with LPAs or subcutaneously injected with Pseudolarix acid B.And whether or not these two compounds play a prominent role in the prevention and treatment of AD were further studied.First of all,AlCl₃-induced AD model mice were successfully established by injecting AlCl₃into the hippocampus of 4-month-old Kunming mice and feeding them for another three months.Then,LPAs and Pseudolarix acid B were gavage administered or subcutaneous injected for 60 days.Morris water maze experiment was conducted to explore whether the drugs could improve the learning and spatial memory ability of AD mice to some extent.The inhibition of the drugs on the formation of tangles of nerve fibers（NFTs）was observed by silver glycine immersion staining,HE staining and Congo red staining of the paraffin sections of mouse hippocampal tissue.The immunohistochemical staining of the paraffin sections of mouse hippocampal tissue was used to observe the inhibitory effects of the drugs on the production of APP and Aβpeptide and the aggregation of microglial cells.Western blot analysis of brain tissue extracts was performed to determine whether LPAs and Pseudolarix acid B can inhibit the expression of Calmodulin,Aβ,and BACE1 in mice.Morris water maze experiment showed that the escape latency of AlCl₃-induced AD mice is significantly reduced,and the number of mice crossing the platform and the time around the platform of AD mice are significantly elevated after the administration of LPAs and Pseudolarix acid B.These showed that LPAs and Pseudolarix acid B could significantly improve the learning and spatial memory ability of AD mice.The results of the paraffin sections,Congo red staining and immunohistochemical staining of the brain tissue showed that,after the administration of LPAs and Pseudolarix acid B,Aβplaque in the brain hippocampus tissue of mice is significantly reduced and the number of activated microglial cells and the degree of activation of the cells are significantly reduced.The pathological change of hippocampal pyramidal cells in mice was significantly reduced.The number of NFTs in the hippocampal tissue of mice was significantly reduced.Western Blot analysis of brain tissue of AD mice showed that,after drug administration,the levels of Aβpeptide and BACE1 protein were significantly reduced,compared with the model group.The AD model mice of 6-month-old double transgenic APP/PS1 mice were given LPAs by gavage administration for 60 days,and the treating effects of the drug on APP/PS1 AD model mice was investigated similarly as the above experiment.Morris water maze experiment showed that the escape latency of the AD mice is significantly reduced after drug administration,while the time of the mice around the platform and the number of mice crossing the platform were significantly increased,indicating that LPAs could significantly improve the learning and spatial memory abilities of the mice.Further studies of Congo red staining and immunohistochemical staining experiments of the paraffin sections of mouse brain tissues showed that,after the administration of LPAs,the mice have significantly less Aβplaques in the hippocampus tissue compared with the model group,while no significant A plaques were observed in the brain of wild-type mice（the control group）.After drug administration,the number of activated microglial cells and degree of their aggregation in the hippocampus of mice were significantly reduced.Hematoxylin-eosin（HE）staining and silver glycine immersion staining of brain paraffin sections of AD mice showed that,after drug administration,the degree of pathological changes of hippocampal pyramidal cells is significantly improved and the degree of tangles of nerve fibers is significantly reduced.Western blot results of brain tissue of AD mice showed that,After drug administration,the expression of the selenoprotein Sel K is significantly increased and the expression of calmodulin and BACE1 are significantly decreased.In conclusion,the administration of total lotus plumule alkaloids and Pseudolarix acid B showed good therapeutic and preventive effects to both of AlCl₃-induced AD model mice and double transgenic APP/PS1 AD model mice.