Attenuation of metabolic syndrome in the ob/ob mouse model by resistant starch intervention is dose dependent†
The current study applied an ob/ob mouse model of obesity for investigating the impact of different RS doses in a high-fat (HF) diet on the attenuation of metabolic syndrome. Although a significant reduction of body weight was not achieved, RS intervention significantly decreased liver weight with suppressed lipid accumulation in the liver tissue and reduced adipocyte size in the fat tissue. All levels of RS intervention were associated with significantly enriched pathways for PPAR, NAFLD and cGMP-PKG signaling. In contrast, either a medium or a higher RS intake (MRS and HRS, respectively) led the AMPK signaling pathway to be significantly enriched but not a diet with lower RS intake. More importantly, sphingolipid biosynthesis activity was noted with MRS and HRS intervention, which is highly associated with the improvement in insulin resistance, and the pathway of type II diabetes mellitus was correspondingly significantly enriched in the HRS group, demonstrating a dose-dependent manner. Similarly, there was no significant difference in the ratio of Bacteroidetes and Firmicutes between high-fat diet and RS groups until RS reached a certain level (i.e. in the HRS group). Furthermore, increased profiles of both Prevotellaceae and Coriobacteriaceae in the HF group were noted for the first time with a revised function from RS intervention, which is consistent with the content of lipopolysaccharides in their corresponding serum. Gut microbiota functional analysis showed that primary and secondary bile acid biosynthesis was also noted to be enriched following the RS intervention, benefiting cholesterol homeostasis. This study further highlights the association of RS consumption with the attenuation of metabolic syndrome in an obesity model, and its functionality is characterized by dose-dependence.