Tadaaki Satou

Objective/background: This study aimed to determine the effects of aromatherapy on the autonomic nervous system and stress reduction in patients with fibromyalgia. Currently, there is no established treatment for the mental anxiety and stress associated with fibromyalgia, and aromatherapy has not been used in clinical practice for this purpose. This clinical study utilized macadamia nut oil as a control to evaluate the effects of aromatherapy on the autonomic nervous system and stress reduction. Methods: Geranium (Pelargonium graveolens) essential oil (EOPG) was used in a crossover study for each treatment period of 3 months. Ten patients were enrolled and divided into two groups. In the CI group, aromatherapy using macadamia nut oil was performed first, and 1% EOPG was used later. In the IC group, we reversed the oil order used for aromatherapy. Patients were asked to answer the State-Trait Anxiety Inventory at each return, and samples were taken for stress markers (cortisol and chromogranin A). Results and discussion: Patients’ blood pressure and heart rate were measured before and after aromatherapy. Diastolic blood pressure increased significantly in the control group (P = .02), but the change was suppressed in the EOPG group ( P = .11). Heart rate significantly decreased after aromatherapy in both treatments ( P < .001). Among stress markers measured in saliva, a transient increase of cortisol in the control treatment was suppressed in the EOPG. There was no significant difference in CgA in both treatments. From these observations, we speculated that the vasodilating effects of the constituents contained in EOPG may have prevented the increase in diastolic blood pressure after aromatherapy partly due to stress-relieving effects of EOPG. Conclusion: We conclude that aromatherapy with EOPG reduced the increase in diastolic blood pressure, suggesting that the therapy reduces the stress of patients with fibromyalgia.

Objective/background: As part of a scientific study into the effects of aromatherapy, we investigated the effects of lavender essential oil (LEO) treatment on the autonomic nervous system in subjects for whom the sense of smell had been eliminated. Methods: This study used a single-blinded cross-over design for verification. Heart rate variability was measured and effects on the autonomic nervous system were investigated. Results and discussion: Although no significant differences were found, aromatherapy treatment with 1% LEO tended to increase parasympathetic nervous system activity. Further, when differences between values before and during aromatherapy treatment were compared, LEO treatment significantly increased parasympathetic nervous system activity. Given these findings, LEO appears to increase parasympathetic nervous system activity, even in the absence of a psychological effect due to an absence of olfactory stimulation. Conclusion: The present results provide a scientific method for verifying the effects of aromatherapy and will aid in further elucidation of aromatherapy.

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.

Autonomic nervous system disorders have many causes, and thus, no effective remedy for these disorders has been established. In this study, we conducted animal experiments with essential oil from Pelargonium graveolens (EOPG, geranium essential oil), which may regulate the autonomic nervous system. EOPG was administered to awake mice by inhalation. Heart rate variability (HRV) was analyzed from the pulse wave of the mice on an elevated platform, and the ratio of sympathetic to parasympathetic nerve activity was determined. The results showed that inhalation of EOPG did not affect the heart rate but made activity of the parasympathetic nervous system dominant. This effect was thought to be due to linalool, a component of EOPG that was transferred into the brain and body.

The stress response in the brain is not fully understood, although stress is one of the risk factors for developing mental disorders. On the other hand, the stimulation of the olfactory system can influence stress levels, and a certain smell has been empirically known to have a stress-suppressing effect, indeed. In this review, we first outline what stress is and previous studies on stress-responsive biomarkers (stress markers) in the brain. Subsequently, we confirm the olfactory system and review previous studies on the relationship between smell and stress response by species, such as humans, rats, and mice. Numerous studies demonstrated the stress-suppressing effects of aroma. There are also investigations showing the effects of odor that induce stress in experimental animals. In addition, we introduce recent studies on the effects of aroma of coffee beans and essential oils, such as lavender, cypress, α-pinene, and thyme linalool on the behavior and the expression of stress marker candidates in the brain. The transfer of volatile components into the brain is also discussed while using the results of thyme linalool as an example. These studies may provide a good opportunity to connect chemical research at the molecular level with neuropharmacological approaches in the future.

There is known to be a close relationship among anxiety, fatigue and stress. Here, we studied the anxiolytic‐like effects of essential oil from Thymus vulgaris (EOT), while focusing on the relationship with stress. Male ICR mice inhaled (i.h.) EOT for 90 min. Mice were placed under three different conditions; isolated, intraperitoneal (i.p.) administration of saline or polyinosinic‐polycytidylic acid (poly I:C). EOT did not show any significant anxiolytic‐like effects in isolated mice. On the other hand, in brain fatigue model mice by poly I:C, EOT showed significant anxiolytic‐like effects. EOT increased the absolute value in the elevated plus maze (EPM) tests in the brain fatigue model mice, while linalool and terpinen‐4‐ol in the brain with poly I:C were elevated when compared with isolated mice. Augmented concentrations of these components in the brain were also observed in mice with saline, i.p. These results suggest that the amount of volatile compounds transferred to the brain increased due to stress or inflammation. In the future, further investigation concerning the relationship between the blood brain barrier (BBB) and respiration is required.

Essential oil from Rosmarinus officinalis (Rosemary essential oil, EORO) may improve cognitive function by activating the central nervous system. However, no scientific basis for the effect of EORO has been described. Therefore, we investigated the effect of EORO on Alzheimer's type dementia using model mice. Mice were administered EORO by inhalation. Then, scopolamine was used to prepare Alzheimer's type dementia model mice. To evaluate cognitive function, the Y‐maze test was used for assessment of short‐term memory. EORO produced a significant improvement in the rate of spontaneous alternation behavior. Furthermore, 1,8‐cineole, α‐pinene, and β‐pinene, the main components of EORO, were detected in the brain in a concentration‐dependent manner following inhalation of EORO. Thus, inhalation of EORO may improve cognitive function in a model of Alzheimer's type dementia. Components such as 1,8‐cineole and others are likely involved in the effects on the brain. Examination of the detailed mechanism of action of EORO is necessary for future clinical application.

The main volatile components of essential oils are monoterpenes. It is known that olfactory receptors recognize monoterpenes as a fragrance, and that they can affect emotions. On the other hand, the components of essential oils may act directly on the central nervous system as well as the olfactory nerve. However, the transport of monoterpenes to the brain following inhalation, which is the main method of administration in aromatherapy, is unclear. In this study, we investigated major monoterpenes of essential oils, such as (+)‐α‐pinene, (+)‐limonene, (‐)‐linalool, and 1,8‐cineole. After the inhalation of each compound, the mice brains were dissected, and brain extracts prepared with n‐hexane. The extracts were then subjected to gas chromatography‐mass spectrometry analysis. The results revealed that α‐pinene was transported to the brain maximally with 30 min inhalation, which may be due to its high volatility. Limonene and linalool showed maximal transport to the brain with 90 min inhalation. Brain concentrations of 1,8‐cineole showed minimal level after 30 min inhalation. Moreover, 1,8‐cineole was easily transported to the brain following intraperitoneal administration. These results could be applied as one of the indices for the effective use of essential oils in aromatherapy. Copyright © 2016 John Wiley & Sons, Ltd.

We previously reported finding anxiolytic‐like activity for sandalwood oil after administration in mice. In this report, we further investigated the emotional behavior associated with inhaled or intraperitoneally administered (+)‐α‐santalol, the main component of sandalwood oil, in addition to examining whether pharmacological or neurological transfers are responsible for this behavior. After administration of (+)‐α‐santalol by inhalation or intraperitoneal injection, we assessed anxiolytic‐like and locomotor activities using elevated‐plus maze tests. We also examined the relationship between the emotional behavior and the (+)‐α‐santalol brain concentration.Anxiolytic‐like activity was not observed immediately after administration or after water‐immersion stress for 24 h for either the (+)‐α‐santalol 2 μL/L air inhalation or the (+)‐α‐santalol 0.03 mL/kg (i.p.) administration. However, mice administered (+)‐α‐santalol 0.03 mL/kg intraperitoneally exhibited a significant decrease in the locomotor activity after exposure to water‐immersion stress for 24 h. The brain (+)‐α‐santalol concentration was 2.6 µg/g tissue after (+)‐α‐santalol 0.03 mL/kg (i.p.) administration.The observed shift of (+)‐α‐santalol to the brain suggests that this component acts via pharmacological transfer and is responsible for the sedative effect but not the anxiolytic‐like activity. Copyright © 2015 John Wiley & Sons, Ltd.