Abstract
Citrus fruits contain several bioactive components. Among them, one of the major components is 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF), which has previously shown protective effects in the brain in some disease models; moreover, HMF has been shown to penetrate the brain. In recent years, inflammation has been identified as a defense response in the body; however, a chronic inflammatory response may trigger several diseases. Inflammation in the peripheral tissues spreads to the brain and is suggested to be closely associated with diseases of the central nervous system. HMF has shown anti-inflammatory effects in the hippocampus following global cerebral ischemia; however, its effects on acute and chronic inflammation in the brain remain unclear. Therefore, in the present study, we examined the effects of HMF in a mouse model of systemic inflammation induced by lipopolysaccharide (LPS) administration. In this study, HMF suppressed LPS-induced microglial activation in the brains of acute inflammation model mice two days after LPS administration. In addition, 24 days after the administration of LPS in a chronic inflammation model, HMF promoted BDNF production and neurogenesis in the brain, which also tended to suppress tau protein phosphorylation at Ser396. These results suggest that HMF has anti-inflammatory and neurotrophic effects in the brains of model mice with lipopolysaccharide-induced systemic inflammation.