Antral Motor Effects of Simulated Mastication in Fed and Sated Rats

In rats that fed for 15 minutes antral motility increased after simulated mastication (Lorber, Can J Physiol Pharmacol 78:29–35, 2000). Would massive gastric distention alter this response? After overnight fasts, 8 adult females ate until sated, ingesting 4.74 ± 1.17 g (mean ± s.d.) in 48 ± 14 min. Satiety was inferred when they paused five min. Eight others fed for 5 min, ingesting 1.43 ± 0.46 g. After laparotomy, visible antral movements were noted for three consecutive five min periods. After the baseline the mandible was elevated every sec, the molars of both jaws contacting briefly before lowering the mandible. Repetitions were done for 12 sec followed by a 3 sec rest. This sequence was done 20 times. Observations continued for the next 5 min. Analysis was by unpaired t‐ tests; significance being P < 0.05. For antral motor events see the table.Unlike the fed rats, due to their prolonged antecedent mastication sated rats had a tenfold higher baseline which appears to have disproportionately limited the extent of later antral increases in motility. The fed group developed a tenfold mean increase during the procedure period and an almost ninefold increase during the postprocedure period. Thus, manifestation of the periodontogastric motility reflex in part depends on its modulation by the degree of gastric distention; excessive distention markedly interfering with it. Support: Personal.