Comparison of the effects of lab chow and casein diets based on body and brain development of rats

1. In order to study the effects of protein quantity and quality on development, Wistar rats were submitted to four different diets during lactation and post-lactation periods. Three isocaloric diets were utilized with 6 per cent (M), 16 per cent (W16) and 20 per cent (W20) of protein (casein), and the fourth diet (C) consisted of a commercial lab chow containing 22 per cent protein. 2. During the lactation and post-lactation periods the body weights of dams and pups were recorded weekly. On the 49th day of age (21 days of suckling and 28 days of ad libitum chow), all animals were sacrificed and the brains removed and weighed. 3. Dams from all groups increased food intake during the lactation period, but dams of the M group consumed a lower amount of diet as compared with other groups. Only the body weight of M dams was affected by diet during the lactation period, but the body weight of pups from the M and C groups was lower than in the other two groups. At 49 days of age C and M pups showed a significantly lower brain weight compared with W16 and W20 pups. 4. Thus, a commercial lab chow diet does not promote normal body and brain development as compared with balanced diets containing 16 or 20 per cent protein. These results emphasize the need for further studies in order to evaluate other biological and behavioral parameters that might be altered by a lab chow diet

Glomerular permeability to macromolecules in gentamicin-treated rats

To determine the effect of gentamicin on the functional properties of the glomerular barrier, 44 Wistar rats received daily doses of 80 mg/kg body weight for 6 days. Glomerular permeability to neural dextrans and albumin was evaluated by day 6 and albuminuria was determined on the 1st, 3rd and 5th days of treatment. Treatment induced an intense increase in albuminuria from 74 ug/24 h to 11.5 mg/24 h on the 5th day of treatment (N=11). This increase was associated with the presence of large amounts of albumin in elements of the glomerular filter and in the apical region of the proximal tubular cells (N=4). Fractional clearances of neutral dextrans having molecular radii in the range of 18-41 A were not significantly different in control (N=5) and gentamicin-treated rats (N=7). These results show that gentamicin, a polycation at pH 7.4, produces an increase in the glomerular permeability to negatively charged macromolecules in rats, probably due to interaction of the polycation with negative charges in the glomerular filter