Effects of Undernutrition on Glycine Metabolism in the Cerebellum of Rats

Comparison of the effects of maternal protein malnutrition and intrauterine growth restriction on redox state of central nervous system in offspring rats

Both maternal protein malnutrition and intrauterine growth restriction (IUGR) have deleterious effects on brain development, but a comparison of these effects has not been previously reported. The objectives of this study were to investigate and compare the effects of both factors on the oxidative status of the central nervous system (CNS), including the spinal cord, in offspring rats. We evaluated various parameters of oxidative status and antioxidant enzyme activities of superoxide dismutase and catalase (CAT) in different regions of the CNS from 60-day-old rats subjected to prenatal and postnatal protein restrictions [middle protein restriction 12%, severe protein restriction (SPR) 4%] or IUGR produced by uterine artery ligation. Furthermore, we compared these study groups to each other and to control rats fed an isocaloric 24% protein diet. Results were analyzed using one-way ANOVA followed by Tukey's post hoc test. Both protein restrictions and IUGR altered various parameters of oxidative status. In all evaluated structures, protein restrictions resulted in increases in thiobarbituric acid-reactive substances level and index of lipid peroxidation (P<0.001), and in decreases in antioxidant enzyme activities (P<0.005). IUGR also increased lipid peroxidation levels in the blood samples (P<0.04) and protein oxidative damage in the cerebellum and cerebral cortex (P<0.005); however, no effects were detected on the spinal cord. The greatest decrease in CAT activity was in the cerebellum of rats fed with SPR diet (P<0.001). This study suggests that not only severe but also middle protein malnutrition have deleterious effects on CNS structures, including the spinal cord. Protein restriction has a greater effect on the redox state of the CNS than IUGR.

Effects of maternal protein malnutrition on oxidative markers in the young rat cortex and cerebellum

Malnutrition affects a large number of children worldwide. Inadequate nutrition during pre- and postnatal period may alter brain development resulting in biochemical, physiological and anatomical changes which in turn could cause behavioral abnormalities. The impairment of the central nervous system following protein deficit have been extensively studied and this deprivation produces deleterious effects upon cerebral structures. The aim of this study was to identify oxidative parameters present in the developing brain as consequence of maternal protein malnutrition. Female Wistar rats were fed a normal protein diet (25% casein) or low protein diet (8% casein) from the time of conception up to 21 days after the parturition. In addition, the diets were supplemented or not with l-methionine. Cortex and cerebellum were removed from offspring to determine the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and the levels of lipoperoxidation (TBARS). Our findings demonstrated heterogeneity in response to protein restriction. The levels of lipoperoxidation were increased in the cerebellum of malnourished offspring. Methionine supplementation caused an increase in lipoperoxidation in both brain structures. CAT activity was decreased in the cerebellum of the offspring supplemented with methionine whereas the cerebellum of malnourished pups with or not methionine supplementation showed a decrease in SOD activity. The activity of SOD in the cortex did not differ among groups. CAT activity, however, was increased in the cortex of malnourished pups supplemented or not with methionine. Thus, these results provide clues to the knowledge of malnutrition effects upon the brain.

Effect of protein malnutrition on redox state of the hippocampus of rat

The protein malnutrition is a worldwide problem, affecting mainly newborns and children of developing countries. This deficiency reaches the brain in the most critical period of the development. Various consequences are related to this insult, such as memory disturbance, learning, and behavioral impairment. Protein content of the diet plays an important role on antioxidant mechanisms. This study observed the effects of protein malnutrition on rat hippocampus redox state. Wistar rats were separate in four groups, receiving different diets: first group with 25% casein, protein deficient group with 8% casein, and the same two groups supplemented with methionine (0.15%). Diets were isocaloric and were administered since the prenatal period up to the sacrifice. Rats were decapitated at 21 or 75 days old and hippocampus were isolated for measuring the lipoperoxidation by TBARS method, protein oxidative damage by carbonyl (DNPH) levels, and the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). There was significant alterations in the activities of the enzyme SOD, lipoperoxidation, and protein oxidation in hippocampus of 21 and 75 day-old rats fed with 25% of protein with methionine and the groups fed with low levels of protein (8%) both supplemented or not with methionine. Our data suggest that both the content of protein in the diet and the essential amino acid methionine may alter the antioxidant system and the redox state of the brain.