Effects of Inhalation of Geranium Essential Oil on Blood Pressure and Heart Rate in Mice

For a better scientific understanding of the basics of aromatherapy, our research group attempted to clarify the effectiveness of the essential oil from Pelargonium graveolens (EOPG, geranium essential oil), which is used to try and balance the mind-body connection. In order to eliminate any possible placebo effect, we used animal experiments that are considered to be insensitive to the placebo effect. Measurements of blood pressure and heart rate in the mouse tail artery were used as a reflection of the mind-body balance. Thirty minutes after inhalation of EOPG (5 µL/L air) for 90 minutes, blood pressure and heart rate of the mice were measured. EOPG significantly reduced blood pressure and heart rate. To further clarify the factors responsible for these effects, gas chromatography analysis was performed in order to determine the components transferred into the brain after the EOPG inhalation. Linalool, citronellol, and geraniol were detected at concentrations around 0.1 nL/L tissue from the brain after 10 µL/L air inhalation of EOPG. However, these were not detected after a 5 µL/L air inhalation of EOPG, as the levels were below the detection limit. These results suggest EOPG inhalation might lower blood pressure and heart rate, with the expressed effects associated with the transfer of components such as linalool into the brain.