Behavioral and physiological consequences of intragastric oil feeding in rats

Four experiments were conducted to examine the appropriateness of intragastric feeding of vegetable oil. The first three experiments demonstrated that pairing intragastric feeding with a taste of saccharin, reduced subsequent saccharin preference slightly. A dose of lithium chloride which did not reduce food intake, produced a very strong conditioned aversion. It is therefore difficult to argue on the basis of taste aversions, that any reduction in food intake resulting from intragastric fat feeding is due to malaise. Intragastric fat feeding did not always reduce subsequent food intake; a large reduction in food intake was observed only when non-starved animals were given at least two previous spaced exposures to fat. The effects of oral and intragastric oil feeding on blood levels of triglycerides and free glycerol were examined. Blood triglycerides and glycerol rose sooner and fell sooner following intragastric than after oral oil feeding. Emulsifying the oil did not correct the abnormality; indeed it exaggerated the early rise in blood triglycerides and glycerol. These results indicate that interpretation of studies involving intragastric fat feeding is more complicated than generally recognized.