Background/Aims: Rodent models for investigating postprandial plasma nutrient responses are limited by blood collection volume. We aimed to develop a rat model that overcomes that shortcoming and evaluate its performance in an acute metabolic study.
Methods: Rats trained to eat meals had a temporary or permanent indwelling catheter inserted in the jugular or caudal (tail) vein, respectively. Multiple blood samples were collected before and after consumption of a white bread test meal (containing 0.4 or 1.25 g carbohydrate) and analysed for glucose and insulin. Effects of meal timing (start or end of the dark period), anaesthesia recovery time and portion size were evaluated.
Results: Both meals raised blood glucose concentration and the level remained above baseline at the end of the sampling period (3 h) in rats fed the larger (1.25 g) but not smaller (0.4 g) carbohydrate load. The glycemic response tended to be higher when the meal test was conducted at the start rather than the end of the dark period (P=0.063) whereas the insulinemic response was unaffected. The postprandial glycemic response was consistently less for caudal vein blood than jugular (P<0.05).
Conclusions: This model enabled multiple blood samples to be taken from unrestrained animals to assess the glycemic response to a standardised meal. The shape of the glucose response curve is consistent with that observed in people. This model provides a new opportunity to investigate postprandial nutrient bioavailability and metabolic responses to food consumption in unrestrained rats.Funding source: Food and Nutrition Flagship