Interaction between caffeine and zinc on brain in newborn rats.

The purpose of this study was to determine whether adding zinc to the caffeine-supplemented diet of dams during gestation and lactation would affect brain development in newborn rats. On day 9 of gestation, dams of group 1 were fed to a 20% protein diet as a control. Dams of group 2 were fed a 20% protein diet supplemented with caffeine. Dams of group 3 were fed a 20% protein diet supplemented with caffeine and zinc. The amount of caffeine added to the maternal diet was 2 mg/100 g of body weight. The amount of zinc chloride added to diet was 0.6 g/kg of diet. At birth, 8 randomly selected pups from each group were assigned to each dam of the respective group and were continuously fed the same diet. On day 15, the pups were killed and brains were removed. Zinc, protein, DNA, alkaline phosphatase activity and cholesterol contents were measured. Milk and maternal and neonatal blood were collected to determine caffeine levels. There was a significant correlation between the milk caffeine and brain caffeine concentrations in group 3. A significant correlation between the neonatal plasma caffeine and brain caffeine concentrations was observed in groups 2 and 3. There was no correlation between neonatal brain weight and zinc content per brain in each group. The correlation between neonatal brain weight and alkaline phosphatase activity was significant in groups 1 and 3. The neonatal zinc content and concentration of group 2 was less than that of group 1. The DNA content and concentration of group 3 was greater than that of either groups 1 or 2. Supplementation of zinc to the caffeine-added diet could restore the brain zinc levels observed in brains of newborn rats.