Modification of Electrical Brain Wave by Citrus sp. Essential Oil Inhalation
Abstract
The essential oil of orange (Citrus sp.) has been widely used in aromatherapy according to its anxiolytic effect. Electroencephalography (EEG) is one of the reliable neurological techniques used to study the brain and behavioral functions. This method has been used to record brain waves for frequency analysis. The present study examined the effect of citrus essential oil (EO) on EEG patterns in adult male Wistar rats. Animals were anesthetized with Zoletil® (60 mg/kg i.m.). Stereotaxic apparatus was used to fix rat skull for the implantation of 4 stainless steel screw electrodes over the frontal and parietal cortices using bregma as the landmark. Ampicillin (145 mg/kg i.m.) was daily injected for 4 days after the surgery and the animals were allowed to recover for 10 days. On the day of the experiment, individual rat EEG was recorded using PowerLab®/4s system. The EEG signals were displayed on LabChart® software and processed on a personal computer. The inhalation of EO (20 and 200 μl) and distilled water as control were performed in the EEG recording chamber. Frontal EEG analysis showed that EO (20 μl) increased the percent baseline powers in low frequency bands ranging from theta (4.7-6.6 Hz), alpha1 (7-9.4 Hz), alpha2 (9.8-12.5 Hz) to beta1 (12.9-18.4 Hz) waves. However, in the parietal cortex, only alpha2 and beta1 powers were significantly increased. In addition, EO 200 μl increased the percentage of the baseline powers only in the theta and the alpha2 bands in the frontal cortex. In conclusion, this study demonstrates EEG pattern in response to inhalation of citrus EO. The data may represent EEG biomarker of the EO in the central nervous system (CNS). However, it remains unknown in terms of its CNS mechanism.
