Digestive Endocrine Cell Numbers Contribute to Contraction/Relaxation of the Lower Esophageal Sphincter

It is often recommended that patients at risk for gastroesophageal reflux (GER) should remain in a seated or upright position for 30 to 60 min after eating. However, there is no scientific justification for this time frame. The lower esophageal sphincter (LES) is important for preventing GER, and some gastrointestinal hormones are known to regulate the LES. To obtain morpho-functional evidence for the time during which one should assume such a position, we used a rat model to focus on gastrin and cholecystokinin (CCK), the hormones that contract and relax the LES, respectively, and examined the changes in the number of cells immunoreactive to these hormones before and after eating. The present study is based on the deduction that vigorous secretion decreases the intracellular contents of hormones to a level lower than that detectable by immunohistochemistry. After 23 h of fasting (PC-0), rats were fed for 3 min and sacrificed 10 min (PC-10) and 60 min (PC-60) later. The number of gastrin cells was decreased in the PC-10 group; however, in the PC-60 group, the number had recovered to that of the PC-0 group. The number of CCK cells was unchanged in the PC-10 group but was decreased in the PC-60 group. Residual gastric contents were found in all groups, indicating that the LES is relaxed despite these contents and suggesting that there are some risks of gastroesophageal reflux even 60 min after eating