Expression of insulin system in the olfactory epithelium: first approaches to its role and regulation

J Neuroendocrinol. 2008 Oct;20(10):1176-90. doi: 10.1111/j.1365-2826.2008.01777.x.


Food odours are major determinants for food choice; their detection is influenced by nutritional status. Among different metabolic signals, insulin plays a major role in food intake regulation. The aim of the present study was to investigate a potential role of insulin in the olfactory mucosa (OM), using ex vivo tissues and in vitro primary cultures. We first established the expression of insulin receptor (IR) in rat olfactory mucosa. Transcripts of IR-A and IR-B isoforms, as well as IRS-1 and IRS-2, were detected in OM extracts. Using immunocytochemistry, IR protein was located in olfactory receptor neurones, sustentacular and basal cells and in endothelium of the lamina propria vessels. Moreover, the insulin binding capacity of OM was quite high compared to that of olfactory bulb or liver. Besides the main pancreatic insulin source, we demonstrated insulin synthesis at a low level in the OM. Interestingly 48 h of fasting, leading to a decreased plasmatic insulin, increased the number of IR in the OM. Local insulin concentration was also enhanced. These data suggest a control of OM insulin system by nutritional status. Finally, an application of insulin on OM, aiming to mimic postprandial insulin increase, reversibly decreased the amplitude of electro-olfactogramme responses to odorants by approximately 30%. These data provide the first evidence that insulin modulates the most peripheral step of odour detection at the olfactory mucosa level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Eating
  • Electrophysiology
  • Fasting
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Insulin / genetics
  • Insulin / metabolism*
  • Insulin Receptor Substrate Proteins / genetics
  • Insulin Receptor Substrate Proteins / metabolism
  • Male
  • Nutritional Status
  • Odorants
  • Olfactory Mucosa / cytology
  • Olfactory Mucosa / metabolism*
  • Olfactory Receptor Neurons / cytology
  • Olfactory Receptor Neurons / metabolism
  • Protein Isoforms / metabolism
  • Radioimmunoassay
  • Rats
  • Rats, Wistar
  • Receptor, Insulin / genetics
  • Receptor, Insulin / metabolism*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism


  • Homeodomain Proteins
  • Insulin
  • Insulin Receptor Substrate Proteins
  • Protein Isoforms
  • Trans-Activators
  • pancreatic and duodenal homeobox 1 protein
  • Receptor, Insulin