Lavender Oil Reduces Depressive Mood in Healthy Individuals and Enhances the Activity of Single Oxytocin Neurons of the Hypothalamus Isolated from Mice: A Preliminary Study

BACKGROUND: The aim of the present study was to assess the effects of lavender oil inhalation on blood pressure, pulse measurements, cortisol levels, depressive mood, and anxiety in healthy male adults. The mechanism was investigated by the action on oxytocin single neurons in the hypothalamus of rodents. METHODS: The participants (n = 7) were aged 20–40 years. After randomisation, they received an inhaled dose of lavender oil or distilled water for 20 min. They received the other treatment after a washout period of one week. We assessed the outcomes using the Self-Rating Depression Scale, State-Trait Anxiety Inventory, and self-rated unidimensional Visual Analogue Scale for depression; anxiety; and hunger, thirst, and appetite, respectively. Blood pressure, pulse rate, and cortisol concentration in the peripheral blood were assessed before and after inhalation. In the rodent study (n = 4), oxytocin single neurons were isolated from the mouse hypothalamus. Intracellular Ca(2+) concentration in the oxytocin neurons isolated from the hypothalamus was measured following direct administration of lavender oil. RESULTS: Seven participants completed the study. Lavender inhalation decreased Self-Rating Depression Scale score and systolic and diastolic blood pressure. Ex vivo administration of lavender oil increased intracellular Ca(2+) concentration in the hypothalamic oxytocin neurons. CONCLUSIONS: Lavender oil might be a useful therapy for stress relief, and its mechanism of action may include activation of the central oxytocin neurons.