[Effects of diets differing in fat content on lipid metabolism and gut microbiota in rats with high triglyceride...

To elucidate the effects of diets differing in fat content on lipid metabolism and gut microbiota composition in rats colonized with the intestinal microbiota of hypertriglyceridemic humans.

Ten-week-old germ-free SD rats were randomly assigned by body weight into three groups of six animals each. The control group was inoculated with gut microbiota from normotriglyceridemic humans and maintained on a standard sterile basal diet, whereas the other two groups received microbiota from hypertriglyceridemic humans and were fed either the same basal diet(NDG group)or a high-fat diet(HFDG group), respectively. A fecal microbial suspension was administered by gavage at 1 mL per 100 g body weight on alternate days for a total of three inoculations, followed by a 2-week period to allow microbiota engraftment and adaptation. Subsequently, the rats were maintained on their respective basal or high-fat diets for 9 weeks. Body-weight changes, serum lipid profiles, hepatic lipid accumulation, liver function indices, and gut microbiota composition were assessed.

After intestinal microbiota colonization followed by 9 weeks of continuous feeding on their respective diets, the NDG group exhibited higher body weight, liver index, epididymal fat index, and subcutaneous fat index than the control group, although none of these differences reached statistical significance. In contrast, the HFDG group was significantly elevated for all these parameters versus the control group, while its brown adipose tissue index was markedly lower. Serum lipid and hepatic function analyses revealed no significant differences between the control and NDG groups. Relative to the control group, the HFDG group displayed a 1.47-fold increase in serum total cholesterol(TC) and a 2.06-fold increase in LDL-C, both statistically significant. Serum ALT in the HFDG group was significantly higher than in controls(P<0.05), whereas AST showed an upward trend but lacked statistical significance. Histologically, the HFDG livers contained markedly more red-stained lipid droplets, and the droplet area fraction was significantly greater than in controls. Concurrently, microbial diversity in the HFDG group was lower than in the control group, and both phylum-and genus-level community structures diverged substantially from those of the NDG group. Furthermore, specific intestinal taxa were significantly correlated with circulating lipid levels, whereas no significant differences were observed between the control and NDG groups.

Dietary intervention can improve lipid metabolism and maintain normal gut microbiota composition in individuals with dyslipidemia.