Abstract P240: Role Of Acetic Acid Produced By Gut Microbiota In The Mechanism Of Reducing Blood Pressure By Saccharina Japonica In Renovascular Hypertensive Rats

Abstract

In a previous study, we observed that Saccharina japonica (SJ) intake reduced blood pressure (BP) in 2-clip, 1-kidney renovascular hypertension model (2K1C) rats. However, the mechanism is not clear. Dietary fibers such as alginate, fucoidan and laminaran are components of SJ and have been reported to change gut microbiota and increase short-chain fatty acids (SCFAs) in normotensive rats. SCFAs have been reported to have an antihypertensive effect when intraperitoneally or intracolonically administered, although it was reported that 2K1C rats reduce SCFAs and bacteria which produce SCFAs compared to sham operated control model (SHAM) rats. To investigate whether acetic acid (AA), one of SCFAs, is involved in the mechanism of BP reduction by an ingestion of SJ, we observed AA, in 2K1C rats fed SJ. Under anesthesia, 2K1C and SHAM were induced to Sprague Dawley rats. Both models were allowed to ingest a standard diet (C group) or a 5% (5 of 100) SJ mixed diet (SJ group) for 7 weeks, to a drinking water freely. During the breeding period, the amount of intake, body weight, and systolic BP (SBP) of each group were observed. After that, rats were euthanized, the contents of cecum were collected, and the pH was measured. The amounts of AA were measured using a commercial kit. The SBP of 2K1C-C was significantly higher than that of SHAM-C throughout the feeding (146 ± 3 vs 131 ± 1 mmHg, p<0.05), the SBP of 2K1C-SJ was significantly lower than that of 2K1C-C (136 ± 5 vs 146 ± 3 mmHg, p<0.05). The pH of the cecal contents was significantly lowered in the SJ group rats in both SHAM and 2K1C. The amounts and concentrations of AA in the cecal contents were significantly increased in both SHAM ( 46 ± 8 vs 92 ± 9 mmol, p<0.05)and 2K1C (50 ± 3 vs 87 ± 5 mmol, p<0.05) in the SJ diet group compared with the C group. On the other hand, there was no significant difference in the amounts of AA between SHAM and 2K1C animal models. These results indicated that ingestion of SJ increased AA, and decreased pH in the cecal contents in both SHAM and 2K1C of the SJ group, which may be involved in the antihypertensive effect of SJ ingestion.