Gastric distension is a physiologic satiety signal in the dog

Gastric distension is thought to produce satiety, but whether this effect is seen during physiologic distension by food is unknown. The purpose of this study was to determine whether levels of gastric distension seen during a meal have a satiety effect and whether the nutrient value of the meal was important. Four dogs were prepared with gastric, duodenal, and esophageal fistulas. Physiologic distension was determined by allowing the animals to eat liquid nutrient diet until sated and measuring the volume consumed and the time it took to consume it (means 2000 ml in 4 min). To test the effect of gastric distension on satiety, distension was produced during sham feeding by infusions of either liquid nutrient, inert liquid (Karaya), or by a water-filled balloon. Lower degrees of distension were also tested to determine if a dose-response relationship existed. Balloon, inert, and nutrient distension all inhibited sham feeding dose-dependently. Peak inhibitions of sham feeding caused by physiologic gastric distension (balloon, inert, nutrient) were 69 +/- 5%, 67 +/- 12%, and 61 +/- 6%, respectively. In all cases, maximal distension terminated sham feeding before the end of the feeding period. The effect of gastric distension on feeding was not blocked by pretreatment with atropine (50 micrograms/kg). Thus, graded degrees of gastric distension, comparable to those seen during ingestion of a normal meal, produced graded inhibition of food intake by a noncholinergic mechanism and independent of the nutrient properties of the food.