Effects Of Palmatine On Aggregation Toxicity Of Aβ In Caenorhabditis Elegans

Dementia is a common clinical syndrome characterized by progressive decline in two or more cognitive domains(including memory,language,executive and visual spatial functions,personality and behavior),resulting in the loss of the ability to perform basic activities of daily living.Alzheimer’s disease(AD)is the most common cause of dementia so far.At present,the drugs that can be used for its treatment,have been proved to only delay the process of the disease,but will not decline rate or cure,and the side effects of drugs cannot be ignored,so the study of Alzheimer’s disease is still essential.Palmatine is a naturally occurring isoquinoline alkaloid,which has been reported to exhibit neuroprotective effect to alleviate the progression of Alzheimer’s disease.However,the mechanism of palmatine’s neuroprotective effect in vivo is still unclear.Therefore,this paper takes Caenorhabditis elegans as the object to explore the neuroprotective effect and mechanism mediated by palmatine.Firstly,the effective concentration range of the compound was determined by comparing the effect of palmatine on food clearance and body size of wild-type Caenorhabditis elegans.Transgenic nematodes model of Aβ expression was used to verify the influence of the compounds on the behavioral dysfunction of AD nematode model and the level of ROS in vivo.Then,combined with the results of life span,oxidative stress,mRNA sequencing and real-time PCR of wild-type nematodes,visual transgenic nematodes were selected to further explore.Finally,thioflavin S and oil red O(Sudan black B)were employed to stain and quantitatively detect the content of Aβ protein and fat in AD nematode model.Treatment with palmatine significantly delayed the paralysis induced by Aβ-toxicity in transgenic C.elegans,which also decreased Aβ-induced formation of reactive oxygen species(ROS)in Aβ-transgenic nematode and increased oxidative stress resistance but did not affect the lifespan in wildtype nematodes.mRNA sequencing analysis showed that the differentially expressed genes(DEGs)were mainly involved in aging,detoxification and lipid metabolism.At the same time,Real-time PCR indicated that the resistance-related genes such as sod-3 and shsp were significantly upregulated while lipid metabolism-related gene fat-5 was downregulated.Based on the results of sequencing and PCR,using transgenic CF1553 and CL2070 strains,studies demonstrated that the inhibition of palmatine on Aβtoxicity may be due to its ability to scavenge free radicals and up regulation of drug resistance-related genes,especially s HSP regulated by hsf-1,plays an important role in protecting cells from Aβ toxicity.Thioflavin S(TH-S)staining showed that palmatine could reduce Aβ deposition of transgenic CL2006 nematodes.In addition,we found that Aβ toxicity was accompanied by lipid metabolism disorder,which led to excessive fat accumulation in transgenic CL4176 nematodes,at the same time,oil red O(Sudan black B)staining showed that palmatine could not only reduce the fat accumulation in wild type nematodes,but also effectively inhibit lipid metabolism disorder induced by Aβ aggregation and toxicity in transgenic CL4176 nematodes,and reduce abnormal fat accumulation.Therefore,it is suggested that alleviating effect of palmatine on lipid metabolism disorder is not only related to the reduction of fat synthesis,but also related to the inhibition of Aβ aggregation and toxicity to jointly maintain metabolic homeostasis.This study provides useful information for the prevention and treatment of Alzheimer’s disease.