Effect of grapefruit and lavender essential oil scents on pancreatic sympathetic nerve activity and plasma glucose in rats

We previously found that olfactory stimulation of rats with the scent of grapefruit oil (SGFO) elevated the activity of the sympathetic nerves innervating the adrenal glands, kidneys and white adipose tissue, blood pressure and the plasma glycerol level, whereas olfactory stimulation with the scent of lavender oil (SLVO) suppressed these same physiological values. In this study, we examined the effects of olfactory stimulation with SGFO and SLVO on the efferent pancreatic sympathetic nerve activity (pancreatic-SNA) in urethane-anaesthetized rats, hyperglycemia induced by intracranial injection of 2-deoxy-D-glucose (2DG) in rats and hyperglycemia in streptozotocin (STZ) diabetic rats which had been administered oral glucose. Olfactory stimulation with SGFO markedly elevated pancreatic-SNA and significantly increased the plasma glucose level after the 2DG injection, whereas olfactory stimulation with SLVO markedly inhibited pancreatic-SNA and significantly reduced the plasma glucose level after the 2DG injection. Furthermore, olfactory stimulation with SLVO suppressed the increase in the plasma glucose level after oral glucose loading in STZ-diabetic rats. These findings suggest that scent stimulation with SGFO and SLVO may affect the plasma glucose level via changes in the autonomic nervous system in rats. Copyright (c) 2015 John Wiley & Sons, Ltd.