The Study of Food Preferences Controled by Nutritional Factors

为了解决营养与食物偏好之间的关系机制，我们研究了蛋白质、锌的营养平衡通过改变味觉神经反应来决定食物偏好的作用。对盐和酒精的偏好随膳食蛋白质的来源和水平而改变。低水平的饮食蛋白质会导致5种基本味觉的味觉神经反应减少，老鼠开始接受它们通常不喜欢的咸和苦的溶液，因为它们的味觉变得不敏感。相反，低蛋白质饮食的老鼠对酒精的偏好降低了，因为酒精的神经反应增加了。此外，辣椒素，红辣椒的刺激性成分，通过改变饮食中的蛋白质水平来减少对盐的偏好。这些结果表明，食物偏好的变化是由于蛋白质营养对味觉神经反应的影响。锌也是影响味觉的重要因素，因为锌对维持味觉受体的结构至关重要，锌作为辅酶的摄入很重要。我们发现，缺锌大鼠对NaCl溶液和碳酸水的偏好更大。锌缺乏大鼠舌上皮及颌下腺需锌酶、碳酸酐酶活性降低。此外，碱磷酸酶（也是一种需要锌的酶）活性降低的大鼠对苦味溶液的偏好增加了近50%。另一方面，锌缺乏大鼠舌三叉神经对碳酸水的敏感性明显降低，说明锌缺乏可能通过碳酸酐酶活性改变舌三叉神经对碳酸水的敏感性。

In order to solve the mechanism of the relationship between nutrition and food preference we have studied on the effects of protein, zinc nutrition balance which determines food preference by changing the gustation nerve responses.The preference to salt and to alcohol were changed by source and levels of dietary protein. Low levels of dietary protein induces reduction of gustation nerve responses in 5 basic tastes and rats become to take in salty and bitter solutions which they do not prefer usually, since their gustation became insensitive. In contrary, preference of alcohol was reduced in rats fed low protein level diets, since the nerve response of alcohol was increased. Also capsaicin, the pungent component of red pepper, reduced preference to salt by changing protein level in diet. These results suggest that the changes of food preference is due to the gustation nerve responses affected by protein nutrition.It has been said that zinc is also an important factor which affects gustation, since it is essential to maintain structure of gustational receptor and it is important to take in zinc as a coenzyme. We have found that the preference of NaCl solution and carbonated water becomes greater in zinc deficient rats. The activity of zinc requiring enzyme, carbonic anhydrase of tongue epithelium and glandula submandibulare was reduced in zinc deficient rats. Also, the preference of bitter solution rose nearly to 50% in rats which activity of alkaliphosphatase (also a zinc requiring enzyme) was reduced. Since the chorda tympani nerve sensitivity to NaCl solutions did not change at all, on the other hand, a remarkable decrease of lingual trigeminal nerve sensitivity to carbonated water was seen in zinc deficient rats, zinc deficiency might change the lingual trigeminal nerve sensitivity to carbonated water possibly via carbonic anhydrase activity.