Olfactory stimulation with scent of lavender oil affects autonomic neurotransmission and blood pressure in rats

Previously, we observed that olfactory stimulation with scent of lavender oil (SLVO) suppressed sympathetic nerve activities and elevated gastric vagal (parasympathetic) nerve activity (GVNA), decreased plasma glycerol concentration and body temperature, and enhanced appetite in rats. Here, we further showed that olfactory stimulation with SLVO lowered renal sympathetic nerve activity (RSNA) and blood pressure (BP) and elevated GVNA in urethane-anesthetized rats. Olfactory stimulation with linalool, a component of lavender oil, also elicited decreases in RSNA and BP and an increase in GVNA in urethane-anesthetized rats. Anosmia induced by pretreatment of the nasal cavity by application of ZnSO4 eliminated the effects of both SLVO and scent of linalool on RSNA, GVNA and BP. Furthermore, intracerebroventricular administration of thioperamide, a histaminergic H3-antagonist, abolished the suppression of RSNA and BP as well as the elevation of GVNA mediated by both SLVO and scent of linalool. Finally, bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) eliminated RSNA and BP suppression and the elevation of GVNA due to SLVO or linalool. Thus, it was concluded that scent of lavender oil and its active component, linalool, affects autonomic neurotransmission and reduces blood pressure through the central histaminergic nervous system and the SCN.