Olfactory Stimulation With Scent of Grapefruit Oil Affects Autonomic Nerves, Lipolysis and Appetite in Rats

Neurosci Lett. 2005 Jun 3;380(3):289-94. doi: 10.1016/j.neulet.2005.01.058. Epub 2005 Feb 5.

Abstract

In a previous study, we found that olfactory stimulation with scent of grapefruit oil (SGFO) excites the sympathetic nerve innervating the white adipose tissue in rats. Here we further examined the effects of SGFO in rats and observed that olfactory stimulation with SGFO excited the sympathetic nerves innervating the brown adipose tissue and adrenal gland and inhibited the parasympathetic gastric nerve. Local anesthesia of the nasal mucosa with xylocaine or anosmic treatment using ZnSO4 eliminated the autonomic changes caused by SGFO. Moreover, stimulation with SGFO elevated the plasma glycerol level, and treatment with either ZnSO4 or an intraperitoneal injection of diphenhydramine, a histamine H1 receptor-antagonist, abolished the glycerol elevation by SGFO. Furthermore, a 15-min exposure to SGFO three times a week reduced food intake and body weight. Finally, limonene, a component of grapefruit oil, induced responses similar to those caused by SGFO, and diphenhydramine eliminated the glycerol response to limonene. Thus, the scent of grapefruit oil, and particularly its primary component limonene, affects autonomic nerves, enhances lipolysis through a histaminergic response, and reduces appetite and body weight.

MeSH terms

  • Adipose Tissue / innervation
  • Adipose Tissue / physiology
  • Adrenal Glands / innervation
  • Adrenal Glands / physiology
  • Animals
  • Appetite / drug effects*
  • Appetite / physiology
  • Body Weight / drug effects
  • Body Weight / physiology
  • Citrus paradisi / chemistry
  • Cyclohexenes
  • Glycerol / blood
  • Histamine H1 Antagonists / pharmacology
  • Limonene
  • Lipolysis / drug effects*
  • Lipolysis / physiology
  • Male
  • Nasal Mucosa / drug effects
  • Nasal Mucosa / physiology
  • Nasal Mucosa / physiopathology
  • Olfactory Pathways / drug effects*
  • Olfactory Pathways / physiology
  • Plant Extracts / pharmacology*
  • Rats
  • Rats, Wistar
  • Stomach / innervation
  • Stomach / physiology
  • Sympathetic Fibers, Postganglionic / drug effects
  • Sympathetic Fibers, Postganglionic / physiology
  • Sympathetic Nervous System / drug effects*
  • Sympathetic Nervous System / physiology
  • Terpenes / pharmacology
  • Vagus Nerve / drug effects*
  • Vagus Nerve / physiology
  • Zinc Sulfate / pharmacology

Substances

  • Cyclohexenes
  • Histamine H1 Antagonists
  • Plant Extracts
  • Terpenes
  • Zinc Sulfate
  • Limonene
  • Glycerol