The effect of the chewing reduction on the cerebral functions of the mouse

[目的]探讨咀嚼频率的差异是否影响小鼠脑功能的发育。[方法]将小鼠分为3组，分别给予普通颗粒饲料（对照组）、粉末饲料和散装饲料喂养1个月（短期）和4个月（长期）。以记忆力和学习能力为脑功能指标，采用三种不同的迷宫装置进行测定。在所有行为学测试结束后，采用HPLC-ECD法测定大脑皮层和海马中几种中枢神经递质及其相关代谢物的含量。[结果] 1.短期粉末组的记忆提取力低于对照组。这一结果表明，小鼠的记忆提取能力的发展已经固定在大脑中.短期大量饮食组的学习能力优于对照组的学习能力上级。这一结果表明，咀嚼频率增加的小鼠的跛行能力高于对照组.另一方面，长期粉末组的记忆提取力与对照组没有差异。这一结果表明，在发育期识别的小鼠记忆提取能力的差异在成熟后消失.咀嚼频率的差异不影响几种中枢神经递质和相关代谢化合物的水平。[讨论]这项研究不是对人类进行外推的结果，因为它是使用小鼠完成的。但本研究提示，生长期咀嚼频率对中枢神经系统功能发育有重要作用。将来可能需要进一步的实验。

[Purpose] The present study was carried out to clarity whether the differences of chewing frequency affected the development of cerebral functions of the mouse.[Method] Mice were divided into three groups and each was feded by normal pellet diet (control), powdered diet or bulk diet for one month (short period) and four months (long period). As indexes forcerebral functions, mneme force and learning capability of the mouse were measured by three different maze apparatuses. Furthermore, after the end of the all behavioral testing, the levels of several central neurotransmitters and related metabolites were measured by HPLC-ECD methods in cerebral cortex and hippocampus.[Results] 1. The memory retrieval force of a short-term powdered group was less than the in a control group. This result suggests that the development of memory retrieval ability of the mouse already fixed in the brain is inferior.2. The learning ability of a short-term bulk diet group was superior to that ability of the control. This result suggests that laming ability of the mouse which is increased the chewing frequency is higher than the control.3. On the other hand, the memory retrieval force of a long-term powdered group did not differ from the control group. This result suggests that the difference of the memory retrieval ability of the mouse recognized in the growth period disappears after the maturation.4. The differences in tile chewing frequency did not influence the levels of the several central neurotransmitters and the related metabolic compounds.[Discussion] This study is not a result of extrapolating for the human, because it was done using the mouse. However, the present study suggest a possibility that the chewing frequency in the growth period is important for the functions development of the central nervous system. Further experiments may be needed in a future.