Sugi (Cryptomeria japonica) fragrance improved stress-induced memory impairment via decreasing stress hormone.

Sugi (Cryptomeria japonica) wood essential oil (SEO) inhalation improved memory disorder in the novel object recognition and Barnes maze tests. Observation of Immunohistochemistry staining of brain tissues and mRNA quantification and production of brain-derived neurotrophic factor (BDNF) in the hippocampus revealed that the inhalation of SEO and δ-cadinene, α-muurolene, and β-cadinene complex fraction (CDS) was effective in neuroprotection. Additionally, SEO inhalation promoted the discharge of injected hippocampal corticosterone, indicating suppression of neuronal cell damage in the hippocampus to improve stress-related memory disorder. To the best of our knowledge, this is the first report to demonstrate a decrease in stress hormone levels in hippocampus by inhaling fragrance and identifying the active components of SEO. The study also elucidated the mechanism of memory improvement effect of inhalation of SEO and suggested its potential as medical aromatherapy for the treatment of diseases of the brain and nervous system such as depression and dementia.