Electrophysiological analysis of the lateral reticular formation controlling orofacial autonomic and motor functions

点击翻译按钮获取中文摘要

Neural network in the brainstem subserving autonomic and motor oral functions was investigated by anatomical, electrophysiological and behavioral studies. In the anatomical study, FTTC and Rhodamine were injected into the anterior part of the tongue or the secretory nerve of the subamndibular gland, respectively, and the superior salivatory (SS) neurons innervating the tongue and those innervating the submandibular salivary glands were identified in rats. The two groups of SS neurons were similar in shape and intermingled in the lateral reticular formation. In the electrophysiological study, biophysical properties of the SS neurons were analyzed by the whole-cell patch clamp technique in sliced brainstem preparations. The SS neurons innervating the tongue displayed a prominent transient outward current (A-current), and fired up to 70 Hz. Those innervating the salivary glands expressed A current lasting longer period, and fired up to 30 Hz. Post-natal development of the A-currents was observed when we compared between A- currents of one-week and two-week old rats. In behavioral study, salivary flow from the submandibular gland and activity of the masseter muscle were chronically recorded from the freely moving rats, During chewing, the amount of saliva and muscle activity were not always parallel, suggesting different centrifugal effects on autonomic and motor functions.Through these studies, we conclude that the autonomic and motor oral functions are under control from the higher central nervous system, but there is a contact point between the two functions in the lower brainstem especially the lateral reticular formation. A further study is needed to clarify relationship between feeding behavior and blood flow rate of the tongue.