Effects of environmental stimulation on brain N-acetylneuraminic acid content and behavior

A study was conducted in which the nutritional and early stimulation conditions of rat pups were manipulated during the first 3 weeks of life. Early stimulation reduced the change in open-field behavior caused by malnutrition at 21 days postnatally. The cerebrum and cerebellum were analyzed for ganglioside and glycoprotein N-acetylneuraminic acid (NANA), DNA and protein content. The improved behavioral performance was associated with a significantly higher ganglioside and glycoprotein NANA content in both brain areas analyzed. The remaining rats from each litter were weaned onto a standard laboratory stock diet at 21 days of age and housed individually until age 6 months. At this time, their performance in a Y maze was tested. Once again early stimulation was associated with an improved ability to learn the maze. The biochemical changes persisted into adulthood in the stimulated groups with the exception that the difference in cerebellar ganglioside content had disappeared by this time. The results are discussed with respect to the possible role of NANA in behavior.