Olfactory stimulation with scent of essential oil of grapefruit affects autonomic neurotransmission and blood pressure

Brain Res. 2005 Oct 5;1058(1-2):44-55. doi: 10.1016/j.brainres.2005.07.048. Epub 2005 Oct 5.


Previously, we observed that olfactory stimulation with scent of grapefruit oil (SGFO) enhances sympathetic nerve activities and suppresses gastric vagal (parasympathetic) nerve activity (GVNA), increases plasma glycerol concentration and body temperature, and decreases appetite in rats. Here, we show that olfactory stimulation with SGFO for 10 min elevates renal sympathetic nerve activity (RSNA) and blood pressure (BP) and lowers GVNA in urethane-anesthetized rats. Olfactory stimulation with limonene, a major component of grapefruit oil, also elicited increases in RSNA and BP in urethane-anesthetized rats. Anosmic treatment with ZnSO(4) eliminated both the effects of SGFO and scent of limonene on RSNA and BP. Intracerebral administration of diphenhydramine, a histaminergic H1-antagonist, abolished SGFO- or scent of limonene-mediated increases in RSNA and BP as well as the decrease in GVNA. Moreover, bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) eliminated the SGFO- and limonene-mediated increases in RSNA and BP and decrease in GVNA, but bilateral lesions of the cerebral cortex did not have any affect on these parameters. These findings suggest that scent of grapefruit oil and its active component, limonene, affect autonomic neurotransmission and blood pressure through central histaminergic nerves and the suprachiasmatic nucleus.

MeSH terms

  • Animals
  • Autonomic Nervous System / drug effects*
  • Autonomic Nervous System / physiology
  • Blood Pressure / drug effects*
  • Blood Pressure / physiology
  • Cardiovascular Physiological Phenomena / drug effects*
  • Citrus paradisi / chemistry
  • Cyclohexenes / pharmacology
  • Denervation
  • Diphenhydramine / pharmacology
  • Histamine H1 Antagonists / pharmacology
  • Limonene
  • Male
  • Plant Extracts / pharmacology*
  • Rats
  • Rats, Wistar
  • Receptors, Histamine H1 / drug effects
  • Receptors, Histamine H1 / metabolism
  • Smell / drug effects*
  • Smell / physiology
  • Suprachiasmatic Nucleus / drug effects
  • Suprachiasmatic Nucleus / physiology
  • Sympathetic Nervous System / drug effects
  • Sympathetic Nervous System / physiology
  • Synaptic Transmission / drug effects*
  • Synaptic Transmission / physiology
  • Terpenes / pharmacology
  • Vagus Nerve / drug effects
  • Vagus Nerve / physiology
  • Zinc Sulfate / pharmacology


  • Cyclohexenes
  • Histamine H1 Antagonists
  • Plant Extracts
  • Receptors, Histamine H1
  • Terpenes
  • Zinc Sulfate
  • Diphenhydramine
  • Limonene