Suppressive effect of glycyrrhizic acid against lipopolysaccharide-induced neuroinflammation and cognitive impairment in C57 mice via toll-like receptor 4 signaling pathway

Abstract

Background: Glycyrrhizinic acid (GA), a major active ingredient enriched in the roots of licorice, possesses well-confirmed anti-inflammatory effects. Objective: To evaluate the underlying mechanisms of GA against lipopolysaccharide (LPS)-induced chronic neuroinflammation and memory impairment. Design: We explored to investigate the effects of GA on neuroinflammation and memory impairment in an LPS-induced Alzheimer’s mouse model. Results: Data of micro-PET/CT imaging and morris water maze test suggested that GA, when administrated orally, could reverse LPS-induced abnormalized glucose intake and metabolism in the brain and alleviate LPS-induced memory loss and cognitive defects in mice. Histological and immunohistochemical staining results revealed that GA treatment suppressed overexpressions of pro-inflammatory cytokines of IL-1 β and TNF-α in the brain of C57 mice by inhibiting toll-like receptor 4 (TLR4) signaling pathway activation. Conclusion: Our findings suggest that GA may be a therapeutic agent for the treatment of neuroinflammation and cognitive impairment.

Keywords

• glycyrrhizinic acid
• LPS
• neuroinflammation
• toll-like receptor (TLR4)
• Alzheimer’s disease