Effects of Olfactory Stimulation with Scents, Foods and Music on Autonomic Nerves and Physiological Functions

Abstract

Authors recently found that olfactory stimulation with scents of grapefruit oil (GFO) and lavender oil (LVO) inversely affect activities of autonomic nerves innervating the white adipose tissue, brown adipose tissue, adrenal gland, kidney and stomach, which was measured by electrophysiological method under urethane-anesthesia, then cause changes in physiological functions such as lipolysis, heat production (energy expenditure), blood pressure, blood glucose and appetite in rats and mice. Moreover, authors obtained evidence that the biological clock located in the hypothalamic suprachiasmatic nucleus (SCN) and histaminergic neurons are involved in these changes elicited by these oils. That is, olfactory stimulation with scent of GFO elevated activities of sympathetic nerves innervating the white and brown adipose tissues, adrenal gland and kidney, lowered the gastric parasympathetic (vagus) nerve activity and increased lipolysis, heat production (thus body temperature), blood pressure and blood glucose, and suppressed appetite. While, olfactory stimulation with scent of LVO lowered activities of sympathetic nerves innervating the white and brown adipose tissues, adrenal gland and kidney, elevated the gastric parasympathetic nerve activity, and decreased lipolysis, heat production (thus body temperature), blood pressure and blood glucose, and increased appetite. Moreover, all of these changes, which induced by GFO and LVO, were eliminated by either electrolytic lesion of the SCN or histaminergic blockers. Changes in auotnomic nerve activities and physiological functions were also induced by intestinal administration of a kind of lactobacillus and music. Intraduodenal injection of Lactobacillus johnsonii La1 suppressed activities of sympathetic nerves innervating the adrenal gland and kidney and reduced the blood pressure and blood glucose. Repeated sound application of the music, Traeumerai composed by Schuman, to ears caused suppression of the renal sympathetic nerve and reduced the blood pressure. These changes were also eliminated by the SCN-lesions or histaminergic blockers. Furthermore, authors and others found evidence that the SCN is a control center of autonomic nerves using pseudorabies virus (PRV), which is reptrogradely and polysynaptically transported into the brain.These findings suggest that the SCN and histaminergic neurons are involved in the mechanisms of effects of GFO, LVO, the lactobacillus and music on autonomic nerve activities, thus physiological functions.