(P20-020-23) Effect of Saccharina japonica Intake on Blood Pressure and Gut Microbiota Composition in Hypertensive Rats

Objectives: It was reported that hypertension is associated with dysbiosis characterized by an increase in Firmicutes/Bacteroidetes (F/B) ratio and a decrease in short-chain fatty acid (SCFA) produced by bacteria. Dietary fibers such as alginate, fucoidan and laminaran are components of Saccharina japonica (SJ) and were reported to change gut microbiota in normotensive rats. In addition, it was reported that blood pressure (BP) increase suppressed by intake of SJ in spontaneously hypertensive rats (SHRs). However, to our knowledge, the effect of SJ intake on the gut microbiota is not reported in hypertensive rats. To investigate that, we observed gut microbiota in SHRs fed SJ.

Methods: SHR and Wistar Kyoto rats (WKY) were allowed to ingest a standard diet (CTL group) or a 5% (5 of 100, w/w) SJ containing diet (SJ group), and to access a drinking water freely for 6 weeks. During the breeding, systolic BP (SBP) in consciousness of each rat were measured. At the end of the breeding, mean arterial pressure (MAP) was measured under anesthesia. After euthanasia, the cecum was removed and the contents were collected. Cecal contents of SHR were analyzed for microbiota by 16S ribosomal RNA amplicon sequencing using V3-V4 hypervariable regions. P < 0.05 was considered statistically significant.

Results: SBP of SHR-CTL was significantly higher than that of WKY-CTL (206±3 vs 131±1 mmHg). SBP of SHR-SJ (176±3 mmHg) was significantly lower than SHR-CTL (P < 0.01). There was no significant difference between WKY-SJ and WKY-CTL. Similarly, MAP of SHR-CTL was significantly higher than that of WKY-CTL (157±7 vs 108±6 mmHg). SHR-SJ (124±7 mmHg) was significantly lower than SHR-CTL (P < 0.05). There was no significance between WKY-SJ and WKY-CTL. According to Linear dicriminant analysis effect size analysis, the relative abundance of 5 bacterial taxa (phylum, class, order, family, genus and species) and decreased 19 bacterial taxa were increased in SHR-SJ compared with SHR-CTL. Based on the changes, we are going to investigate how these bacteria changes in alleviate hypertension.

Conclusions: Saccharina japonica intake suppressed the increase in blood pressure and altered the gut microbiota in SHRs.

Funding Sources: This work was supported by the Sasakawa Scientific Research Grant from The Japan Science Society.