TangNaiKang, herbal formulation, alleviates obesity in diabetic SHR/cp rats through modulation of gut microbiota and related metabolic functions

CONTEXT: Tangnaikang (TNK) is a Chinese herbal formulation that has lipid-lowering effects, but its effect on reducing obesity has not been studied. OBJECTIVE: To observe the effect of TNK on obesity and explore its effect on gut microbiota of obese rats. MATERIALS AND METHODS: The SHR/NDmcr-cp rats were divided into three groups: (1) 3.24 g/kg TNK (High TNK), (2) 1.62 g/kg TNK (Low TNK), and (3) an untreated control (CON). Wistar-Kyoto rats were used as normal controls (WKY). After 8 weeks of TNK oral administration, body weight, abdominal circumference, triglycerides (TC) and total cholesterol (CHO) were measured. Gut microbiota diversity was studied by 16S rDNA sequencing, and metagenomes analysis was conducted to determine alteration in functional gene expression. RESULTS: The body weight (496.60 ± 6.0 g vs. 523.40 ± 5.6 g), abdomen circumference (24.00 ± 0.11 cm vs. 24.87 ± 0.25 cm), TC (3.04 ± 0.16 mmol/L vs. 4.97 ± 0.21 mmol/L), CHO (2.42 ± 0.15 mmol/L vs. 2.84 ± 0.09 mmol/L) of rats in the High TNK group were decreased significantly (all p < 0.05). TNK administration regulates intestinal flora, up-regulates Eisenbergiella and down-regulates Clostridium_sensu_stricto_1, which is beneficial to the production of short-chain fatty acids (SCFAs). Metagenomes analysis shows that TNK is closely related to the fatty acid synthesis pathway. DISCUSSION AND CONCLUSIONS: TNK can regulate gut microbiota to reduce obesity, which may be related to fatty acid metabolism. Our research supports the clinical application of TNK preparation and provides a new perspective for the treatment of obesity.