Results of simulated mastication suggest existence of a periodontogastric motility reflex

Various reflexes inhibit gastric motor activity. Might a contrary one permi t the oral region to increase gastric motility? Ten fasted rats were allowe d to feed for 15 min. Following anesthesia and cannula insertion, antral pr essure was recorded during three consecutive 5-min intervals: the baseline, procedure, and postprocedure periods. The procedure involved manually lowe ring and raising the mandible about once per second, causing repetitive mol ar occlusion. Doing this when food is in the stomach resembles conditions a s the latter part of a meal is consumed. Gastric motor events increased fro m 1.10 +/- 1.67 (mean +/- SD) to 5.50 +/- 4.12 per 5 min during the procedu re (p < 0.05) and 5.80 +/- 3.97 in the ensuing period (p < 0.05). The findi ngs suggest an excitatory reflex following stimulation of mechanoreceptors in one or more sites related to mastication: the periodontium, temporomandi bular joints, or masticatory muscles. Because rubbing the maxillary molars while the mouth remained constantly open also increased motor events, the p eriodontium is the most likely location of the receptors. They and associat ed trigeminal neurons would comprise the reflex's afferent arm. The vagi, p erhaps with intermediaries, are its likely efferent arm. In these recently fed rats this reflex acts despite receptive relaxation and enterogastric re flexes to increase distal gastric motor activity.