Oat β-Glucan Attenuates Diabetic Liver Injury by Improving the Gut Microbiota

This study investigated the effects of oat β-glucan on liver injury and the gut microbiota in a rat model of a high-fat diet combined with streptozotocin (STZ)-induced type 2 diabetes.

To achieve this, specific-pathogen-free (SPF) male Sprague-Dawley (SD) rats were utilized and initially acclimated to the laboratory environment for one week. Following the stabilization period, 12 rats were randomly selected as the normal control (CON) group and fed a standard chow diet, while the remaining rats were fed a high-fat diet for 4 weeks and then were induced via intraperitoneal (i.p.) injection of multiple low doses of STZ (30 mg/kg) in freshly prepared sodium citrate-citric acid buffer (pH 4.5) once a week for two consecutive weeks. Blood glucose levels were measured using a glucometer, and rats with fasting blood glucose levels exceeding 11.1 mmol/L for 7 consecutive days were confirmed as diabetic. Subsequently, 48 confirmed diabetic rats were then randomly divided into four subgroups (n = 12 each): the diabetic model (DM) group, Oat β-Glucan Low-Dose (OGL) group, Oat β-Glucan Middle-Dose (OGM) group, and Oat β-Glucan High-Dose (OGH) group. The rats in the OGL, OGM, and OGH groups were gavaged with oat β-glucan at doses of 0.275 g/kg BW, 0.55 g/kg BW, and 1.10 g/kg BW, respectively, daily for 10 weeks, while the CON and DM groups received an equivalent volume of distilled water.

Following the 10-week intervention, the rats were sacrificed for multi-indicator assessments. Oat β-glucan treatment significantly improved hyperglycemia and alleviated hepatic injury. Histological analysis confirmed that oat β-glucan alleviated pathological liver damage. Furthermore, oat β-glucan effectively reshaped the gut microbiota by reducing the abundance of Enterococcaceae and increasing the abundance of beneficial taxa, including Ruminococcaceae, Lachnospiraceae, and Christensenellaceae. Compared with the DM group, the OGH group exhibited a significant reduction in metabolic endotoxemia (serum LPS). Meanwhile, the observed microbial shifts were closely correlated with the downregulation of pro-inflammatory cytokines (TNF-α and IL-6).

In conclusion, our findings demonstrate that oat β-glucan exerts a protective effect against diabetic liver injury by modulating gut microbiota composition and suppressing inflammation via the gut-liver axis, highlighting its potential as a functional dietary strategy for diabetes management.