Effects of Inhaled Linalool on the Autonomic Nervous System in Awake Mice

Objective/background A previous study showed that geranium essential oil predominantly affects the parasympathetic nervous system. This article examined the effects on the autonomic nervous system of linalool, one of the main components of geranium essential oil. Methods Mice were placed on a narrow elevated open platform and pulse wave measurements were taken while they were awake, with behaviors restricted. Heart rate and heart rate variability were analyzed from the pulse waves obtained and the effects on the parasympathetic and sympathetic nerves were examined. Results The results showed that linalool (5 μL/L air, inhaled) resulted in parasympathetic dominance before and after administration. Conversely, a tendency toward sympathetic dominance was observed with fluoxetine (1 mg/kg, intraperitoneal) as the positive control in the elevated open-platform test. Conclusion These results suggest that linalool and essential oils containing linalool regulate the autonomic nervous system by promoting dominance of the parasympathetic nervous system.