Protective Effect Of Alternate Day Fasting On Intestinal Barrier And Brain In Parkinson’s Disease Mice

Parkinson’s disease(PD)is the second most common neurodegenerative disease in the world.The classical motor symptoms are static tremor and bradykinesia,due to degeneration and death of dopaminergic neurons in substantia nigra pars compacta and the decrease of dopamine level in striatum.However,there is also present gastrointestinal dysfunction such as gastroparesis and constipation,which may promote the occurrence of motor symptoms.Although many studies proved that not only genetic and environmental factors,but also mitochondrial dysfunction,oxidative stress,and apoptosis were involved in PD,the exact pathogenesis is not exhaustively understood.Drug therapy and surgical treatment are the main therapeutic methods for PD in current clinic.Drug therapy will cause adverse effects in the later stage,while surgical treatments apply only to terminal stage patients.Recent studies have proved that dietary restriction has neuroprotective effects on PD.Here we report alternate day fasting(ADF),a form of dietary restriction,which has been studied extensively on improving metabolic diseases such as obesity,diabetes and neurodegenerative diseases.Otherwise,the rhythm of ADF prevents intestinal barrier dysfunction,which results from intestinal microflora disorder and intestinal epithelial injury,is closely associated with the occurrence of PD.In this study,6-week-old male C57BL/6 mice were randomly divided into 4 groups: normal saline+fed ad libitum group(NS+AL group,n=8),normal saline+alternate day fasting group(NS+ADF group,n=8),MPTP+fed ad libitum group(MPTP+AL group,n=8)and MPTP+alternate day fasting group(MPTP+ADF group,n=8).The ADF program takes 48 h as an experimental cycle,with fasting in the first 24 h and free feeding in the second 24 h.We injected 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine(MPTP)into mice intraperitoneally to induce subacute Parkinson’s disease model in the 12th-14 th cycles(for five consecutive days)of ADF.After cycle,we collected the feces of mice and detected the changes of intestinal microflora by high-throughput sequencing and detected SCFAs by GC-MS.After behavioral tests in mice,the striatum was collected and the levels of neurotransmitters such as Dopamine(DA),5-hydroxytryptamine(5-HT)and their metabolites were detected by high performance liquid chromatography(HPLC).We detected the expression of Tyrosine Hydroxylase(TH)in striatum in each group by western blot.We collected the jejunal tissues of mice,and observed the histopathological changes of intestinal by HE staining.The changes of mRNA expression levels of AMPK,Occludin and ZO-1(Prakk1,Ocln,Tjp1)were detected by RT-qPCR,and those of protein expression levels of ZO-1 were detected by western blot.The results showed that ADF can significantly alleviate the motor dysfunction in PD mice,reverse the loss of dopaminergic neurons in the substantia nigra,inhibit the loss of DA and 5-HT in the striatum of PD mice and increase the level of TH in the striatum.Besides,ADF not only alleviate the jejunal villi pathological morphology in PD mice,but also enhance the expression of intestinal epithelium tight junction.The sequencing results of 16 S rRNA showed that ADF impact intestinal microflora composition,especially lower abundance of Akkermansiaceae at the family level in PD mice.Result of GC-MS proved that ADF higher SCFAs from fecal such as acetic acid,propionic acid and isobutyric acid in PD mice.In summary,ADF plays a protective role in both intestinal barrier and brain in PD mice.The changes of intestinal microflora composition and its metabolites content and promote expression of intestinal tight junction protein may be important factors for ADF protecting the intestinal barrier of PD mice.