Oral perception of food particles is important in mastication and swallowing. However, the mechanism underlying particle perception remains poorly understood because of the lack of suitable experimental systems. We evaluated microparticle perception in rats utilizing insoluble cellulose particles of varying diameters (20-170 μm). The cellulose additives have polycrystalline morphologies and contain smaller crushed particles. The filtrate containing 20 μm particles at a concentration of 1.6% was passed through 3 μm pore-size filter paper, and numerous small particles equivalent to a 0.25 mM soluble solution were observed. In two-bottle preference tests, rats showed no innate preference or avoidance of particles of any size at concentrations ranging from 0.05-1.6%. Next, conditioned preference learning tests employing 8% glucose and fructose solutions were performed. After being repeatedly presented with glucose and fructose solutions containing particles of different sizes (170 and 20 μm particles or 20 μm filtrate) at a concentration of 1.6%, the rats preferred particles in glucose solution even without glucose presentation. Intriguingly, rats preferred the filtrate following repeated presentations of glucose-containing filtrate and water containing fructose. These results suggest that rats can distinguish microparticles in water. The preference learning test is useful for analyzing particle perception mechanisms in mammals.

中文翻译：

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大鼠纤维素微粒的辨别

口腔对食物颗粒的感知对于咀嚼和吞咽很重要。然而，由于缺乏合适的实验系统，粒子感知的机制仍然知之甚少。我们利用不同直径（20-170 μm）的不溶性纤维素颗粒评估了大鼠的微粒感知。纤维素添加剂具有多晶形态并含有较小的粉碎颗粒。将浓度为1.6%的含有20μm颗粒的滤液通过3μm孔径的滤纸，观察到许多相当于0.25mM溶解溶液的小颗粒。在两瓶偏好测试中，大鼠对浓度范围为 0.05-1.6% 的任何大小的颗粒没有表现出先天偏好或回避。接下来，使用 8% 葡萄糖和果糖溶液进行条件偏好学习测试。在反复给予浓度为1.6%的含有不同尺寸颗粒（170和20μm颗粒或20μm滤液）的葡萄糖和果糖溶液后，即使没有葡萄糖存在，大鼠也更喜欢葡萄糖溶液中的颗粒。有趣的是，在重复提供含葡萄糖的滤液和含果糖的水后，大鼠更喜欢滤液。这些结果表明老鼠可以区分水中的微粒。偏好学习测试对于分析哺乳动物的粒子感知机制很有用。