Lacroix M-C, Badonnel K, Meunier N, Tan F, Schlegel-Le Poupon C, Durieux D, Monnerie R, Baly C, Congar P, Salesse R, Caillol M
INRA, UMR 1197 Neurobiologie de l'Olfaction et de la Prise Alimentaire, Recepteurs et Communication Chimique, Jouy en Josas, France.
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.
食物气味是食物选择的主要决定因素；它们的检测受营养状况的影响。在不同的代谢信号中，胰岛素在食物摄入调节中起主要作用。本研究的目的是利用离体组织和体外原代培养，研究胰岛素在嗅黏膜（OM）中的潜在作用。我们首先确定了胰岛素受体（IR）在大鼠嗅黏膜中的表达。在OM提取物中检测到IR-A和IR-B亚型以及IRS-1和IRS-2的转录本。通过免疫细胞化学方法，发现IR蛋白位于嗅觉受体神经元、支持细胞和基底细胞以及固有层血管的内皮中。此外，与嗅球或肝脏相比，OM的胰岛素结合能力相当高。除了主要的胰腺胰岛素来源外，我们还证明了OM中存在低水平的胰岛素合成。有趣的是，禁食48小时导致血浆胰岛素水平下降，增加了OM中IR的数量。局部胰岛素浓度也有所提高。这些数据表明营养状况对OM胰岛素系统有调控作用。最后，在OM上应用胰岛素以模拟餐后胰岛素增加，可使对气味剂的嗅觉电图反应幅度可逆地降低约30%。这些数据首次证明胰岛素在嗅黏膜水平调节气味检测的最外周步骤。
