Center for Molecular Nutrition and Sensory Disorders, The Taste and Smell Clinic, Washington, DC, USA.
Nutrition. 2010 Jun;26(6):624-33. doi: 10.1016/j.nut.2009.08.003. Epub 2009 Dec 22.
Intranasal insulin has proven useful to control hyperglycemia in diabetics but its mechanism of action has not been well defined. We attempted to understand several aspects of human insulin metabolism by measurement of and interaction of insulin and its associated moieties in nasal mucus, saliva and blood plasma under various physiological and pathological conditions.
Insulin, insulin receptors, insulin-like growth factor 1 (IGF1) and insulin-like growth receptor 3 (IGFR3) were measured in nasal mucus, saliva and blood plasma in normal subjects, in thin and obese subjects and in diabetics under fasting and fed conditions.
There are complex relationships among each of these moieties in each biological fluid. Insulin and its associated moieties are present in both nasal mucus and saliva. These moieties in nasal mucus and saliva report on physiological and pathological changes in glucose metabolism as do these moieties in plasma. Indeed, insulin and its associated moieties in nasal mucus may offer specific data on how insulin enters the brain and thereby play essential roles in control of insulin metabolism.
These data support the concept that insulin is synthesized not only in parotid glands but also in nasal serous glands. They also support the concept that insulin enters the brain following intranasal administration either 1) by direct entry through the cribriform plate, along the olfactory nerves and into brain parenchyma, 2) by entry through specific receptors in blood-brain barrier and thereby into the brain or 3) some combination of 1) and 2). Conversely, data also show that insulin introduced directly into the brain is secreted out of brain into the peripheral circulation. Data in this study demonstrate for the first time that insulin and its associated moieties are present not only in saliva but also in nasal mucus. How these complex relationships among nasal mucus, saliva and plasma occur are unclear but results demonstrate these relationships play separate yet interrelated roles in physiology and pathology of human insulin metabolism.
鼻内胰岛素已被证明可有效控制糖尿病患者的高血糖，但它的作用机制尚未得到很好的定义。我们试图通过测量和研究胰岛素及其相关物质在各种生理和病理条件下在鼻黏液、唾液和血浆中的相互作用，来了解人类胰岛素代谢的几个方面。
在正常受试者、消瘦和肥胖受试者以及空腹和进食状态下的糖尿病患者中，测量鼻黏液、唾液和血浆中的胰岛素、胰岛素受体、胰岛素样生长因子 1（IGF1）和胰岛素样生长因子受体 3（IGFR3）。
在每种生物液中，这些物质之间存在复杂的关系。胰岛素及其相关物质存在于鼻黏液和唾液中。这些物质在鼻黏液和唾液中的存在反映了葡萄糖代谢的生理和病理变化，就像在血浆中一样。事实上，鼻黏液中的胰岛素及其相关物质可能提供了关于胰岛素如何进入大脑的具体数据，并因此在控制胰岛素代谢中发挥重要作用。
这些数据支持胰岛素不仅在腮腺中合成，而且在鼻浆液腺中合成的概念。它们还支持胰岛素在经鼻给药后进入大脑的概念，无论是 1）通过筛板直接进入，沿着嗅神经进入脑实质，2）通过血脑屏障中的特定受体进入大脑，还是 3）1）和 2）的某种组合。相反，数据还表明，直接引入大脑的胰岛素会从大脑分泌到外周循环中。本研究首次表明，胰岛素及其相关物质不仅存在于唾液中，也存在于鼻黏液中。鼻黏液、唾液和血浆之间的这些复杂关系是如何发生的尚不清楚，但结果表明，这些关系在人类胰岛素代谢的生理和病理中发挥着独立但相互关联的作用。
