title: Acute effects of bergamot oil on anxiety-related behaviour and corticosterone level in rats.
abstract: Bergamot essential oil (BEO), Citrus aurantium subsp. bergamia (Risso) Wright & Arn. (Rutaceae), is used widely in aromatherapy to reduce stress and anxiety despite limited scientific evidence. A previous study showed that BEO significantly increased gamma-aminobutyric acid levels in rat hippocampus, suggesting potential anxiolytic properties. The aim of this study was to investigate the effect of BEO (1.0%, 2.5% and 5.0% w/w) administered to rats on both anxiety-related behaviours (the elevated plus-maze (EPM) and hole-board tests) and stress-induced levels of plasma corticosterone in comparison with the effects of diazepam. Inhalation of BEO (1% and 2.5%) and injection of diazepam (1 mg/kg, i.p.) significantly increased the percentage of open arm entries on the EPM. The percentage time spent in the open arms was also significantly enhanced following administration of either BEO (2.5% and 5%) or diazepam. Total arm entries were significantly increased with the highest dose (5%), suggesting an increase in locomotor activity. In the hole-board test, 2.5% BEO and diazepam significantly increased the number of head dips. 2.5% BEO and diazepam attenuated the corticosterone response to acute stress caused by exposure to the EPM. In conclusion, both BEO and diazepam exhibited anxiolytic-like behaviours and attenuated HPA axis activity by reducing the corticosterone response to stress.
authors.affiliation: Department of Physiology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand. somrudee@swu.ac.th
authors.forename: Somrudee
authors.initials: S
authors.lastname: Saiyudthong
authors.forename: Charles A
authors.initials: CA
authors.lastname: Marsden
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001008:Anxiety Disorders / Q000097:blood* / Q000188:drug therapy*; D003345:Corticosterone / Q000097:blood*; D003975:Diazepam / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D009822:Oils, Volatile / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology; D010938:Plant Oils / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D014151:Anti-Anxiety Agents; D009822:Oils, Volatile; D010936:Plant Extracts; D010938:Plant Oils; C068336:bergamot oil; D003975:Diazepam; D003345:Corticosterone