A rat model for determining the postprandial response to foods.

Background: The use of small animal models for studying postprandial changes in circulating nutrients, hormones and metabolic biomarkers is hampered by the limited quantity of blood that can be withdrawn for analysis. Here, we describe the development of an unrestrained, meal-fed rat model, having a permanent or temporary vascular cannula that permits repeated blood sampling. The applicability and performance of the model were evaluated in a series of experiments on acute glycaemic and insulinaemic responses to carbohydrate-based test meals.

Results: A test food containing 0.4 g carbohydrate raised blood glucose by 1.5 mmol L . Postprandial blood glucose levels peaked at 15 min and returned to baseline at 180 min, whereas they remained elevated for longer when the test meal contained 1.25 g carbohydrate. The glycaemic response tended (P = 0.063) to be higher when the meal tolerance test was conducted at the start rather than the end of the dark period, but the insulinaemic response was unaffected. The magnitude of the glycaemic response was less for blood collected from the caudal vein compared to that from the jugular vein. Both cannulation strategies were equally effective in enabling return of red blood cells, thus preserving blood volume.

Conclusion: This improved small animal model affords new opportunities to screen foods for nutrient bioavailability and explore metabolic mechanisms mediating responses to food consumption. © 2016 Society of Chemical Industry.