Effect of Age and Elemental Diets on Gastric Emptying in Rats

Abstract

Aim: Delayed gastric emptying affects the quality of life. We previously showed that elemental tube feeding emptied more rapidly than standard tube feedings and were associated with a decreased risk of aspiration. The current aim was to develop animal model to confirm the human findings and for subsequent use to identify which components were responsible for the phenomena. Methods: Gastric emptying was assessed in young (7-11 weeks, n=8), adult (9 months, n=6) and aged (18 months, n=8) male Wistar rats using water, a low fat (0.6%) elemental diet containing glutamine or a standard liquid diet (20% fat). 13C sodium acetate breath tests were used to assess gastric emptying (i.e., as 13C excretion rate as percent of intake/min). Results: Gastric emptying of the three different diets decreased with age. The gastric emptying rate in aged rats reduced to about two thirds of adult rats and one half of young rats. In young rats and adult rats gastric emptying of the elemental diet and standard liquid diet were similar (p>0.999 at 21 min). In contrast, the elemental diet was emptied significantly more rapidly compared with the standard liquid diet in aged rats (p<0.0001 at 21 min). Conclusions: Gastric emptying in rats was age dependent. In aged rats the low fat elemental diet containing glutamine was emptied significantly more rapidly than a standard liquid diet. The animal model appears suitable for identifying which components are responsible for the differences.