SuHeXiang Wan Essential Oil Alleviates Amyloid Beta Induced Memory Impairment Through Inhibition of Tau Protein Phosphorylation in Mice

SuHeXiang Wan (SHXW), a traditional Chinese medicine, has been used orally for the treatment of seizures, infantile convulsions and stroke. Previously, we reported the effects of a modified SHXW essential oil in terms of sedative effect, anticonvulsant activity and antioxidative activity. The purpose of this study was to evaluate the potential beneficial effects of SHXW essential oil in neurodegenerative diseases such as Alzheimer's disease (AD). SHXW essential oil was extracted from nine herbs. The mouse AD model was induced by a single injection of amyloid beta protein (A beta(1-42)) into the hippocampus. The animals were divided into four groups, the negative control group injected with A beta(42-1), the A beta group injected with A beta(1-42), the SHXW group inhaled SHXW essential oil and received A beta(1-42) injection, and the positive control group administered with docosahexaenoic acid (DHA, 10 mg/kg) and with subsequent A beta(1-42) injection. Mice were analyzed by behavioral tests and immunological examination in the hippocampus. An additional in vitro investigation was performed to examine whether SHXW essential oil inhibits A beta(1-42) induced neurotoxicity in a human neuroblastoma cell line, SH-SY5Y cells. Pre-inhalation of SHXW essential oil improved the A beta(1-42) induced memory impairment and suppressed A beta(1-42) induced JNK, p38 and Tau phosphorylation in the hippocampus. SHXW essential oil suppressed A beta-induced apoptosis and ROS production via an up-regulation of HO-1 and Nrf2 expression in SH-SY5Y cells. The present study suggests that SHXW essential oil may have potential as a therapeutic inhalation drug for the prevention and treatment of AD.