Min Chen, Shun Huang, Yuan-Yuan Chang, Xi Zheng, Ren-Ping Zhou, Dong-Li Li and Kun Zhang
Current Research in Neuroscience, 2018, 8(1), 1-9.
Background and Objective: Curcumin is a bioactive natural polyphenol, but the poor bioavailability has limited its application. To be effective as a therapeutic drug, curcumin must be combined with other drugs to improve bioavailability. The aim of the present study was to investigate the effects and mechanisms of curcumin and piperine administered individually or in combination on lipopolysaccharide (LPS)-induced neuroinflammation. Materials and Methods: Mice were treated with curcumin (100 and 200 mg kg1, p.o.) and piperine (20 mg kg1, p.o.) for 21 days followed by LPS (250 μg kg1, i.p.) administration for 7 days. Results: It is found that repeat injections of LPS induced neuronal damage and increased inflammatory cytokines release, while pretreatment with curcumin reversed these changes. In addition, co-administration of piperine with curcumin potentiated their neuroprotective effects as compared to the treatment with curcumin alone. It is further examined that the molecular mechanisms by which curcumin exerts its neuroprotective effects and inhibited the Toll-like receptor 4 (TLR4)-mediated downstream signaling and effectively lowered the production of inflammatory mediators. Conclusion: These findings led us to the conclusion that the effects of curcumin on LPS-induced neuroinflammation is mediated by modulating TLR4 pathway, which is enhanced by an adjuvant, piperine.