Factorial Supplementation with Arginine and Glycine on Nitrogen Retention and Body Weight Gain in the Traumatized Rat

Abstract

It has been reported (Sitren & Fisher (1977), Br. J. Nutr. 37, 195–208) that diets supplemented with both arginine and glycine increased the nitrogen retention of rats following ether anesthesia and femur fracture. The purpose of this investigation was to determine whether arginine, glycine, or both are required to improve nitrogen retention following trauma. Four groups of 12 adult, male albino rats, each weighing around 220 g, were given one of four diets: a control diet containing 25% casein, the control diet supplemented with 2% arginine plus 1% glycine, the control diet supplemented with 2% arginine alone, and the control diet supplemented with 1% glycine alone. When the rats reached a body weight of about 250 g, they were subjected to the trauma of ether anesthesia plus hind leg fracture. The effect of the diets on body weight and nitrogen balance before and after trauma was studied. Food consumption was controlled by moderately restricting the intake of all animals. The diet supplemented with arginine and glycine improved growth before and after trauma, and nitrogen retention after trauma. The arginine-supplemented diet did not promote better nitrogen retention but improved growth posttrauma. The diet supplemented with glycine alone depressed nitrogen retention before and after trauma. The results demonstrated the need for the simultaneous addition of arginine and glycine to a relatively high protein diet to improve nitrogen retention in traumatized rats; adverse effects resulted from glycine as the sole supplement. Possible reasons for these observations are discussed.