Effects of mechanical loads of feeding on the physiological development of a central nervous system.

我们研究了咀嚼功的减少是否从电生理上影响了中枢神经系统的生理特征。将3周龄断奶的雄性大鼠分别饲喂皮下(SL)和粉状(PW)饲料，直到4月龄和10月龄，每组均进行电生理实验。在体外制备的海马片上，对Schaffer侧支(SC)-CA1通路的长时程增强(LTP)和突触电位进行了研究。用离子电泳法研究了GABA、谷氨酸等递质对CA1锥体顶端树突的敏感性。实验结果如下：(1)SL组和PW组锥体细胞膜电位无明显变化。(2)SL组记录到的突触电位较PW组更复杂。(3)与PW组相比，SL组GABA和谷氨酸的树突受体定位较广。(4)PW组记录到的LTP波幅明显大于SL组。这些结果可能表明，强烈的咀嚼作用促进了中枢神经系统的功能发育。

We have investigated whether a decrease in masticatory work affected the physiological characteristics of the central nervous system electrophysiologically. Male rats, weaned at 3 weeks of age, were fed either pelted (SL) or powdered (PW) chow until 4 and 10 months of age and electrophysiological experiments were performed on each of feeding groups. Long-term potentiation (LTP) to be believed as learning and memory and synaptic potential were studied in the Schaffer collateral (Sc) -CA1 pathway in an in vitro slice preparation of hippocampus. The sensitivity of transmitters (GABA,glutamate) on the apical dendrites of a pyramidal sell in CA1 was investigated iontophoretically. Experimental results were as follows : (1) Significant change of membrane potentials of the pyramidal cells was not observed between the SL and PW groups. (2) Synaptic potentials recorded from the SL.groups showed more complicated feature than the PW.(3) Dendritic receptor site for GABA and glutamate was localized in the SL group compared to the PW.(4) The amplitude of LTP recorded from the PW group was significantly bigger than from the SL.Results of 2 and 3 mean that in the SL group, neuronal networks develop normally. These results may suggest that strong masticatory works promote the functional development of the central nervous systems.