Oral Administration of Lipopolysaccharide Prevents Cognitive Impairment in Streptozotocin-induced Diabetic Mice in a Blood Glucose-independent Manner

Abstract

Background/aim: Diabetes is a risk factor for dementia. However, no radical preventive method for diabetes-associated dementia has yet been developed. Our previous study revealed that oral administration of lipopolysaccharide (LPS) prevents high-fat diet-induced cognitive impairment. Therefore, we investigated here whether oral administration of LPS (OAL) could also prevent diabetes-associated dementia.

Materials and methods: Diabetic mice were produced by intraperitoneal administration of streptozotocin (STZ), and then mice were orally administered LPS. Cognitive ability was evaluated using the Morris water maze, and gene expression was analyzed in isolated microglia.

Results: OAL prevented STZ-induced diabetic cognitive impairment, but did not affect blood glucose levels. Moreover, OAL promoted the expression of neuroprotective genes in microglia, such as heat shock protein family 40 (HSP40) and chemokine CCL7.

Conclusion: OAL prevents diabetes-associated dementia, potentially via promotion of HSP40 and CCL7 expression in microglia.

Keywords: Lipopolysaccharide (LPS); cognitive impairment; dementia; diabetes; microglia; oral administration; streptozotocin (STZ).