Plasma and brain ammonia and amino acids in rats measured after feeding 75% casein or 28% egg white

Male rats were trained to consume their daily food intake in 3 h. When rats were fed 6% casein for 14 d and were then fed either the 6 or 75% casein diet for 1 d, the plasma and brain ammonia concentrations of rats fed 75% casein were higher (P < 0.05) at 23 h after test meal initiation compared to those of rats fed 6% casein. When rats were fed 6% casein for 13 d and then fed the same 6% casein diet with or without an addition 15% ammonium acetate for an additional 7 d before feeding 75% casein for 1 d, the plasma ammonia concentration of each group was not different, but plasma and brain amino acid concentrations were lower in rats prefed 15% ammonium acetate before the 75% casein diet. When rats were fed 6.8% egg white for 9 d and then fed 27.9% egg white for an additional 7 d, food intake of rats fed the 27.9% egg white diet was lower (P < 0.05, paired t-test) for 4 d compared with that during the 3-d pretest period. When rats were meal-fed the 6.8% egg white diet for 13 d and then fed either the same 6.8% egg white diet or the 27.9% egg white diet for 1 d, plasma ammonia and plasma and brain amino acid concentrations were higher at 5 h after test meal initiation (P < 0.05) in rats fed 27.9% egg white compared to those of rats fed 6.8% egg white. At 23 h after test meal initiation, plasma ammonia, plasma amino acid and most brain amino acid concentrations were lower than they were at 5 h after test meal initiation in rats fed 27.9% egg white.