Protective effect and mechanisms of alternate day fasting on intestinal barrier function in Parkinson’s disease model mice

Abstract:

[Background] Parkinson’s disease is a neurodegenerative disorder accompanied by gastrointestinal dysfunction and other non-motor symptoms. Intestinal microflora disorder and increased intestinal epithelial permeability are the main factors that affect the function of intestinal barrier. Dietary restriction can improve the composition of intestinal microflora and maintain intestinal epithelial homeostasis. We hypothesize that dietary restriction might have a protective effect on intestinal barrier function in Parkinson’s disease model mice and the mechanism might be related to the correction of intestinal microflora disorder and the promotion of intestinal tight junction protein expression. [Objective] To investigate the protective effect and its mechanism of alternate day fasting on intestinal barrier in Parkinson’s disease model mice. [Methods] Thirty-two C57BL/6 mice were randomly divided into normal saline+fed libitum group (NS+AL, n=8), normal saline+alternate day fasting group (NS+ADF group, n=8), MPTP+fed libitum group (MPTP+AL group, n=8) and MPTP+alternate day fasting group (MPTP+ADF group, n=8). We took 48 h as an experimental cycle of the alternate day fasting program, 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 build Parkinson’s disease model in the 12th?14th cycles (for five consecutive days) of ADF. After the end of the 17th cycle, we collected the feces of mice and detected the changes of intestinal microflora by high-throughput 16S rRNA gene sequencing, then we detected the behavioral test of mice. After collect jejunum tissues of mice, we observed the histopathological changes of intestine by HE staining. We detected mRNA expression levels of AMPK, Occludin and ZO-1 by RT-qPCR (Prkaa1, Ocln, Tjp1), and detected protein expression levels of ZO-1 by Western blotting in tissue. [Results] The results of behavioral test showed that compared with NS+AL group, the motor ability of mice in MPTP+AL group decreased significantly (P<0.01), while the motor ability of mice in MPTP+ADF group improved (P<0.01). HE staining showed that the jejunum villi in the NS+AL group were structurally completed and closely arranged, while the jejunum villi in the MPTP+AL group were broken or even shed. Compared with the MPTP+AL group, the MPTP+ADF group showed that the jejunum villi were intact and closely arranged. Sequencing results of intestinal microflora showed that the abundance and diversity of intestinal microflora in MPTP+AL group were significantly higher than that in NS+AL group (P<0.001), while there was no significant change between MPTP+AL group and MPTP+ADF group. There were significant differences in intestinal microflora structure between four groups. The relative species abundance at family level showed that compared with NS+AL group, Akkermansiaceae abundance in MPTP+AL group was significantly increased (P<0.05), while in MPTP+ADF group this was significantly decreased (P<0.01). The results of RT-qPCR showed the expression levels of Prkaa1 (P<0.01), Ocln (P<0.01), Tjp1 (P<0.01) were significantly decreased in the MPTP+AL group, while the expression levels of Prkaa1 (P<0.01) and Tjp1 (P<0.01) were significantly increased in the MPTP+ADF group. The expression level of Ocln in the MPTP+ADF group was also higher than the MPTP+AL group, but the difference was not significant. Western blot results showed ZO-1 expression in MPTP+ADF group was significantly higher than that in MPTP+AL group (P<0.05). [Conclusion] Alternate day fasting has protective effect on intestinal barrier in Parkinson’s disease model mice and the mechanism may be related to maintaining the relative abundance at family level of Akkermansiaceae and increasing the expression of intestinal tight junctions.