Masaki Yamaguchi* and Naoko Hanawa, Kei Hamazaki, Kimiharu Sato and Kimihiro Nakano,

Abstract: The purpose of this study is to evaluate the usefulness of a biomarker, salivary amylase, as an indicator of the acute psychological sedative effects of four different types of fragrances. Twenty healthy female subjects in their late 30s were enrolled (36.3 ± 2.5 yr, mean ± SD). In order to induct the subjects a pre-stress, a cold pressor test was conducted as an uncomfortable distress task, prior to the inhalation of test samples. The salivary amylase activity was analyzed before, during and after the inhalation of the fragrance, using a hand-held salivary amylase activity monitor previously fabricated by the authors. Our results indicated that (i) fragrances containing no chemical materials which could directly activate the central nervous system, significantly induced a sedative effect in women, as assessed by both analysis of the biomarker and subjective evaluation; (ii) salivary amylase activity can be an excellent indicator for the evaluation of an acute, psychological sedative effect; and (iii) feel relaxed and refreshed might be a appropriate question to precisely describe the sedative state, rather than the questions fun, stressed or uplifted.

It is thought that there are two pathways for physiological effects of inhaled chemical materials; (i) a chemical material directly activates the central nervous system through mucus and blood circulation, regardless of whether it can be recognized as a fragrance or not; (ii) a signal sensed by olfaction is transmitted to brain and acts on the memory and emotions. When a person inhales certain narcotics such as cannabis or cocaine, through the nostril, the chemical materials are transported to brain via blood circulation and exert a potent analgesic sedative action. On the other hand, olfactory perception includes diverse phenomena from chemistry to physiology, commencing with a chemical signal as a molecule of a certain fragrance, which is then converted into electrical signals that can be recognized in the brain. Buck and Axel (1) identified the genes for olfactory receptors and suggested that there might be approximately 1,000 different types of the olfactory receptor in mammalians. It has been considered that the olfactory information induced by chemosignals, such as a fragrance molecule (2) or pheromone (3,4), is transmitted to the brain through the nervous and endocrine systems, and this signal finally acts directly on the emotions. It has been observed that exposure to the components of plants and flowers by mice directly influenced their motility, either stimulating or sedating the mouse movement, suggesting a direct correlation between olfactory perception and voluntary movement (5,6).