Omega-3 polyunsaturated fatty acids attenuate cognitive impairment via the gut-brain axis in diabetes-associated cognitive dysfunction rats.

Diabetes-related cognitive dysfunction (DACD) is a comorbidity of type 2 diabetes that has a negative effect on patients' quality of life. Research has indicated that disruption of the gut microbiota (GM) may be linked to dementia with altered cognitive performance. Conversely, omega-3 polyunsaturated fatty acids (n-3 PUFAs) may reverse DACD. The present study aimed to assess the effects of an n-3 PUFA intervention and fecal microbiota transplantation (FMT) on high-fat and streptozotocin-induced DACD model rats. In DACD rats, n-3 PUFA treatment restored fasting blood glucose (FBG) levels and cognitive function, increased the expression of anti-inflammatory cytokines and downregulated the expression of proinflammatory cytokines in the cortex and colon. Additionally, the expression of the postsynaptic density protein-95 mRNA and protein varied with n-3 PUFA treatment. Treatment with n-3 PUFAs also increased the expression of tight junction proteins. Beneficial and short-chain fatty acid-producing bacteria were more abundant when rats were exposed to n-3 PUFAs. After FMT from the rats with DACD symptoms that were improved by the n-3 PUFA dietary intervention into another batch of DACD rats, we observed recovery in recipient DACD rats. These results indicated that the alleviation of DACD symptoms by n-3 PUFAs was attributed to gut microbiota remodeling.