Anti‐fatigue activity of essential oil from thyme (linalool chemotype) in the polyriboinosinic:polyribocytidylic acid‐induced brain fatigue mouse

Abstract While various mechanisms are suggested to be involved in overall fatigue, recent studies have begun to specifically focus on brain fatigue. It has been speculated that brain fatigue might be due to an inflammation in the brain that subsequently influences the entire body. In the current study, we attempted to scientifically elucidate the anti‐fatigue activity responsible for the empirically noted changes associated with aromatherapy. The study used the essential oil from the thyme linalool chemotype (EOT). A brain fatigue mouse model was created by an intraperitoneal injection of polyriboinosinic:polyribocytidylic acid (20 mg/kg). Our results demonstrated that after the administration of EOT, there was a significant decrease in the mRNA expression levels of inflammatory cytokines such as interleukin‐6 in the hippocampus. We also investigated the mRNA expression level of brain‐derived neurotrophic factor (BDNF) in the hippocampus. These results suggest that EOT i.h. causes the anti‐fatigue activity via both anti‐inflammatory and nerve activating activities. This anti‐fatigue activity appears to be due to the combined influence of both (+)‐terpinen‐4‐ol and other compounds. Copyright © 2016 John Wiley & Sons, Ltd.