Effects of fragrance administration on stress-induced prefrontal cortex activity and sebum secretion in the facial skin

• Published in: Neuroscience letters 2008-02, Vol.432 (2), p.157-161
• Main Authors: Tanida, Masahiro, Katsuyama, Masako, Sakatani, Kaoru
• Format: Article
• Language: English
• Subjects: Acne vulgaris; Adrenal steroid hormone; Adult; Aromatherapy - methods; Aromatherapy - psychology; Biological and medical sciences; Dominance, Cerebral - physiology; Down-Regulation - drug effects; Down-Regulation - physiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Hypothalamic–pituitary–adrenal system; Hypothalamo-Hypophyseal System - metabolism; Hypothalamo-Hypophyseal System - physiopathology; Hypothalamo-Hypophyseal System - secretion; Mental stress; Neural Pathways - drug effects; Neural Pathways - physiology; NIRS; Odorants; Olfactory Pathways - drug effects; Olfactory Pathways - physiology; Pituitary-Adrenal System - physiopathology; Prefrontal cortex; Prefrontal Cortex - drug effects; Prefrontal Cortex - physiology; Sebum - secretion; Skin - physiopathology; Skin - secretion; Smell - drug effects; Smell - physiology; Stress, Psychological - physiopathology; Stress, Psychological - therapy; Treatment Outcome; Vertebrates: nervous system and sense organs
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2007.12.014

Although fragrances have long been known to influence stress-induced psychosomatic disorders, the neurophysiological mechanism remains unclear. We evaluated the effect of fragrance on the relation between the level of sebum secretion in the facial skin and the stress-induced prefrontal cortex (PFC) activity, which regulates the activity of the hypothalamic–pituitary–adrenal axis. Employing near infrared spectroscopy, we measured hemoglobin concentration changes in the bilateral PFC during a mental arithmetic task in normal adults ( n = 31), and evaluated asymmetry of the PFC activity in terms of the laterality index (i.e., [(right − left)/(right + left)]) of oxyhemoglobin concentration changes (LI-oxyHb). We measured the level of sebum secretion in the facial skin before the task performance. There was a significant positive correlation between the LI-oxyHb and the level of sebum secretion ( r = +0.44, p = 0.01). We selected the subjects who exhibited high levels of sebum secretion and right-dominant PFC activity for the study on the fragrance effect ( n = 12). Administration of fragrance for four weeks significantly reduced the level of sebum ( p = 0.02) in the fragrance group ( n = 6). In addition, the LI-oxyHb decreased significantly from 0.11 ± 0.07 to −0.10 ± 0.18 ( p = 0.01), indicating that the dominant side of the stress-induced PFC activity changed from the right to left side. In contrast, neither LI-oxyHb nor the levels of sebum secretion changed significantly in the control group ( n = 6). These results suggest that administration of fragrance reduced the level of sebum secretion by modulating the stress-induced PFC activity. The PFC may be involved in the neurophysiological mechanism of fragrance effects on systemic response to mental stress.