Reduced tLESR elicitation in response to gastric distension in fundoplication patients

Transient lower esophageal sphincter relaxations (tLESRs) are vagally mediated in response to gastric cardiac distension. Nine volunteers, eight gastroesophageal reflux disease (GERD) patients, and eight fundoplication patients were studied. Manometry with an assembly that included a barostat bag was done for 1 h with and 1 h without barostat distension to 8 mmHg. Recordings were scored for tLESRs and barostat bag volume. Fundoplication patients had fewer tLESRs (0.4 ± 0.3/h) than either normal subjects (2.4 ± 0.5/h) or GERD patients (2.0 ± 0.3/h). The tLESRs rate increased significantly in normal subjects (5.8 ± 0.9/h) and GERD patients (5.4 ± 0.8/h) during distension but not in the fundoplication group. All groups exhibited similar gastric accommodation (change in volume/change in pressure) in response to distension. Fundoplication patients exhibit a lower tLESR rate at rest and a marked attenuation of the response to gastric distension compared with either controls or GERD patients. Gastric accommodation was not impaired with fundoplication. This suggests that the receptive field for triggering tLESRs is contained within a wider field for elicitation of gastric receptive relaxation and that only the first is affected by fundoplication.

Results of simulated mastication suggest existence of a periodontogastric motility reflex

Various reflexes inhibit gastric motor activity. Might a contrary one permit the oral region to increase gastric motility? Ten fasted rats were allowed to feed for 15 min. Following anesthesia and cannula insertion, antral pressure was recorded during three consecutive 5-min intervals: the baseline, procedure, and postprocedure periods. The procedure involved manually lowering and raising the mandible about once per second, causing repetitive molar occlusion. Doing this when food is in the stomach resembles conditions as the latter part of a meal is consumed. Gastric motor events increased from 1.10 ± 1.67 (mean ± SD) to 5.50 ± 4.12 per 5 min during the procedure (p < 0.05) and 5.80 ± 3.97 in the ensuing period (p < 0.05). The findings suggest an excitatory reflex following stimulation of mechanoreceptors in one or more sites related to mastication: the periodontium, temporomandibular joints, or masticatory muscles. Because rubbing the maxillary molars while the mouth remained constantly open also increased motor events, the periodontium is the most likely location of the receptors. They and associated trigeminal neurons would comprise the reflex's afferent arm. The vagi, perhaps with intermediaries, are its likely efferent arm. In these recently fed rats this reflex acts despite receptive relaxation and enterogastric reflexes to increase distal gastric motor activity.Key words: gastrointestinal motility, mastication, periodontal ligament.