TNF and Cognitive impairment: Moreover, vitamin D3 decreased the protein expression of TNF‐α, the p‐NF‐κB p65/NF‐κB p65 ratio and p‐IκBα/IκBα ratio in the hippocampus of mice, suggesting that the protective effect of vitamin D3 on cognitive impairment caused by diabetes might be related to the inhibition of inflammatory response.