Mechanisms on the chemical reception of dietary fat in the oral cavity and its signaling to the brain

虽然众所周知，我们更喜欢高脂肪饮食，但我们仍然不知道是什么让饮食中的脂肪如此美味。最近的证据表明，饮食中的脂肪，特别是脂肪酸，可能在口腔中被识别。这些结果在接受脂肪酸的机制上有一些不一致，但它们至少支持了这样一种理论，即舌头脂肪的化学接收不是以能量储存形式甘油三酯为中心，而是以代谢更活跃的形式脂肪酸为中心。然而，食物中的绝大多数脂肪成分是甘油三酯，这与口腔中接受脂肪酸的日益增长的结果相矛盾。甘油三酯作为脂肪酸的接受机制尚不清楚。在本研究中，我们检测到少量但相当数量的脂肪酸被Ebner腺体开口乳头和叶乳头分泌的舌脂酶所分解。将放射性甘油三酯涂在乳突上，在1到3秒内就能产生接近芽细胞的脂肪酸，这足以让你尝到脂肪的味道。在人乳头叶中也观察到了类似的酶活性，被认为产生的脂肪酶很少。此外，提供甘油三酯和奥利司他(一种脂肪酶抑制剂)的小鼠并没有表现出任何偏好。奥利司他本身并不抑制液体的摄取。这些发现表明，舌脂酶对于品尝高脂肪食物是很重要的。

Though it is generally known that we have a preference for high fat diets, we still do not know what makes dietary fat so tasty. Recent evidence suggests that dietary fat, especially fatty acids, may be recognized in the oral cavity. These results has some inconsistency about mechanisms on, reception of fatty acids but they at least support the theory that chemical reception of fats in the tongue centers not on triglycerides, the energy storage form, but on the, more metabolically active form, fatty acids. However, vast majority of fat component in foods is triglycerides, contradicting with the growing results of being fatty acid reception in oral cavity. Mecanisms have been unclear underlying the,acception of, triglycerides as fatty acids. In the present study, we detected small but significant amount of fatty acids ~ cleaved by lingual lipase secreted from Ebner's gland opening papillae vallatae and papillae foliate. Radioactive triglycerides applied on the papillae vallatae produced fatty acids close on bud cells within 1 to 3 sec which is enough speed to taste fat. The similar enzyme activity was observed in the human papillae foliate which was, beleaved producing few lipase. Moreover, mice offered triglycerides with orlistat a lipse-inhibitor did not show any preference to it. Orlistat, itself did not inhibit the fluid intake. These findings suggest that lingual lipase is important for tasting the fatty foods.