Excess dietary vitamin B6 alters water maze performance in two strains of mice

Abstract

The effects of excess vitamin B6 on learning performance in a water maze were studied in progeny of two strains of mice, I strain mice which demonstrate acute sensitivity to pyridoxine depletion, and C57BL strain mice, a control strain. I strain mice fed 12 mg pyridoxine (PN)/kg diet made more errors to complete the maze than C57BL mice. When fed diets with vitamin B6 410 or 1230 times the recommended amount, water maze error scores of I strain mice decreased; but for C57BL strain mice, increased. Significant differences between dietary treatment for both strains were found, however, only when scores from third and later litters were included in the analysis. This suggests that a cumulative effect of diet was necessary in order to see an effect on water maze learning. The improvement in water maze performance demonstrated by the I strain mice with vitamin B6 intakes 410 times recommended amounts indicates that the pyridoxine requirement of the I strain is between 12 and 410 mg PN/kg diet. The detrimental effects found on learning performance of C57BL strain mice, a control strain, provides evidence of neurotoxicity with ingestion of megadose amounts of vitamin B6. In parent mice, final body weight and organ weights tended to increase in the I strain and decrease in the C57BL mice with the higher PN diets, but body weight gain was less in both strains in mice fed the higher amounts of PN. In the offspring mice, dietary PN had no effect on body weight and brain pyridoxal phosphate content.