Effects of Fragrance Inhalation on Sympathetic Activity in Normal Adults

Abstract

ABSTRACT-We investigated the effects of fragrance inhalation on sympathetic activity in normal adult subjects using both power spectral analysis of blood pressure fluctuations and measurement of plasma catecholamine levels. Fragrance inhalation of essential oils, such as pepper oil, estragon oil, fennel oil or grapefruit oil, resulted in 1.5-to 2.5-fold increase in relative sympathetic activity, representing low frequency amplitude of systolic blood pressure (SBP-LF amplitude), compared with inhalation of an odorless solvent, triethyl citrate (P<0.05, each). In contrast, fragrance inhalation of rose oil or patchouli oil caused a 40% decrease in relative sympathetic activity (P<0.01, each). Fragrance inhalation of pepper oil induced a 1.7-fold increase in plasma adrenaline concentration compared with the resting state (P = 0.06), while fragrance inhalation of rose oil caused a 30% decrease in adrenaline concentration (P<0.01). Our results indicate that fragrance inhalation of essential oils may modulate sympathetic activity in normal adults.Keywords: Sympathetic nerve function, Power spectral analysis, Catecholamine, Essential oil, Fragrance inhalationIt has been reported that olfactory stimulation by fragrance inhalation exerts various physiological effects on humans. Effects of fragrance on brain function have been studied by using alpha and theta activity in the electroencephalogram (EEG) (1) or contingent negative variation (CNV) (2, 3). These studies have shown that some fragrances exert stimulant or inhibitory effects on brain function. Moreover, it has been reported that human endocrine and immune systems are affected by fragrance in a study that assessed the effects of fragrance on both endocrine function, by analyzing urinary cortisol and dopamine levels, and immune function, by analyzing natural killer cell activity and CD4 /8 values (4).On the other hand, effects of fragrance on the autonomic nervous system have been studied by noninvasive recording of various autonomic parameters such as heart rate (HR), skin conductance and respiration (5), or skin temperature, skin conductance, breathing rate, pulse rate and blood pressure (6). To our knowledge, there is no study that has been designed to quantitate the separate effects of fragrances on sympathetic and parasympathetic activities.Power spectral analysis of heart rate variability or blood pressure fluctuations have been developed for the noninvasive assessment of autonomic nerve activity and utilized to assess the autonomic nerve activity in various disorders such as hypertension and diabetes mellitus (7 -9). In such analyses, it is assumed that the low frequency components (LF) of blood pressure fluctuations and the high frequency components (HF) of heart rate variability reflect sympathetic activity and parasympathetic activity, respectively (10). In general, fast Fourier transform processing has been employed for power spectral analysis of fluctuations, a new method, which provides real-time, noise-adjusted calculation of sympathetic and parasympat...

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