Neurophysiological and behavioural effects of lavender oil in rats with experimentally induced anxiety

This study examined anxiolytic effects of lavender oil on brain serotonin levels and anxiety-related behaviours of rats. The experimental rats were divided into five groups, which respectively received inhalation of saline, 1.25% lavender oil, 2.5% lavender oil, chlordiazepoxide (CDP), and 2.5% lavender oil co-administered with CDP. Anxiety was induced in rats using animal models including Elevated Plus Maze and Open Field. The levels of serotonin in the pre-frontal cortex and striatum of the rats, the anxiolytic effects of lavender oil and its augmentation effect as to co-administration with CDP were evaluated. The neurophysiological findings showed that groups receiving lavender oils, CDP, and 2.5% lavender oils co-administered with CDP had significantly higher level of serotonin in the pre-frontal cortex. However, the anxiolytic behavioural effects of lavender oil were found to have mixed results. This study provided preliminary evidence that inhalation of lavender oil paralleled effects of CDP in up-regulating synthesis of serotonin in rat pre-frontal cortex, and the co-administration of CDP with 2.5% lavender oil tended to augment effect of CDP on serotonin in their pre-frontal cortex and striatum.