Selenium and zinc protect brain mitochondrial antioxidants and electron transport chain enzymes following postnatal protein malnutrition.

AIMS: Selenium (Se) and zinc (Zn) are trace elements required for optimal brain functions. Thus, the role of Se and Zn against protein malnutrition induced oxidative stress on mitochondrial antioxidants and electron transport chain (ETC) enzymes from rats' brain were investigated. MAIN METHODS: Normal protein (NP) and low protein (LP) rats were fed with diets containing 16% and 5% casein respectively for a period of 10weeks. Then the rats were supplemented with Se and Zn at a concentration of 0.15mgL(-1) and 227mgL(-1) in drinking water for 3weeks after which the rats were sacrificed. KEY FINDINGS: The results obtained from the study showed significant (p<0.05) increase in lipid peroxidation (LPO), ROS production, oxidized glutathione (GSSG) levels and mitochondrial swelling and significant (p<0.05) reductions in catalase (CAT) and Mn-superoxide dismutase (Mn-SOD) activities, glutathione (GSH) levels, GSH/GSSG ratio and MTT reduction as a result of LP ingestion. The activities of mitochondrial ETC enzymes were also significantly inhibited in both the cortex and cerebellum of LP-fed rats. Supplementation with either Se or Zn restored the alterations in all the parameters. SIGNIFICANCE: The study showed that Se and Zn might be beneficial in protecting mitochondrial antioxidants and ETC enzymes against protein malnutrition induced oxidative stress.

Reduced expressions of calmodulin genes and protein and reduced ability of calmodulin to activate plasma membrane Ca(2+)-ATPase in the brain of protein undernourished rats: modulatory roles of selenium and zinc supplementation.

The roles of protein undernutrition as well as selenium (Se) and zinc (Zn) supplementation on the ability of calmodulin (CaM) to activate erythrocyte ghost membrane (EGM) Ca(2+)-ATPase and the calmodulin genes and protein expressions in rat's cortex and cerebellum were investigated. Rats on adequate protein diet and protein-undernourished (PU) rats were fed with diet containing 16% and 5% casein, respectively, for a period of 10 weeks. The rats were then supplemented with Se and Zn at a concentration of 0.15 and 227 mg l(-1), respectively, in drinking water for 3 weeks. The results obtained from the study showed significant reductions in synaptosomal plasma membrane Ca(2+)-ATPase (PMCA) activity, Ca(2+)/CaM activated EGM Ca(2+) ATPase activity and calmodulin genes and protein expressions in PU rats. Se or Zn supplementation improved the ability of Ca(2+)/CaM to activate EGM Ca(2+)-ATPase and protein expressions. Se or Zn supplementation improved gene expression in the cerebellum but not in the cortex. Also, the activity of PMCA was significantly improved by Zn. In conclusion, it is postulated that Se and Zn might be beneficial antioxidants in protecting against neuronal dysfunction resulting from reduced level of calmodulin such as present in protein undernutrition.

Dietary Selenium or Zinc Supplementation Restores Brain Lipid Composition and Membrane Fluidity in Protein-Undernourished Rats.

Studies have shown that protein undernutrition (PU) modifies the membrane lipid composition in the intestine and liver, as well as in plasma and other areas. However, there is limited information on the effect of PU on synaptosomal membrane lipid composition and fluidity and the protective role of selenium (Se) and zinc (Zn), which is a major focus of the present study. For 10 weeks, rats were fed diets containing 16% casein, which constituted the adequate protein diet, or 5% casein, representing the PU diet. The animals were supplemented with Se and Zn at a concentration of 0.15 and 227 mg L-1, respectively, in drinking water for 3 weeks. The results showed a significant increase in total lipids, glycolipids, triglycerides, cholesterol, and the cholesterol/phospholipid (Chol/PL) ratio, and a significant reduction in phospholipids and membrane fluidity. Se and Zn supplementation to PU rats, however, significantly lowered total lipids, glycolipids, triglycerides, cholesterol, and the Chol/PL ratio, while phospholipids and membrane fluidity were significantly restored. It is concluded that a perturbed lipid composition induced by PU affects the membrane structure and fluidity, which in turn influences membrane functions. The study suggests that Se and Zn supplementation might be beneficial in restoring the lipid dyshomeostasis associated with PU.

Protective roles of selenium and zinc against postnatal protein-undernutrition-induced alterations in Ca(2+)-homeostasis leading to cognitive deficits in Wistar rats.

Postnatal protein-undernutrition impacts on mental development and cognition in children and can lead to problem with attention and unresponsiveness which compromise children's ability to learn. These behavioral disorders might be due to alteration in calcium homeostasis as calcium plays critical roles in fundamental functions of neuron. The role of low protein diet as well as Se and Zn supplementation on intracellular calcium concentration ([Ca(2+)]i), Ca(2+)-ATPase, Na(+)-K(+)-ATPase, calpain and caspase-3 activities from rat cortex and cerebellum were investigated. Well-fed (WF) and low protein diet-fed (LPDF) rats were given diets containing 16% and 5% casein, respectively, for a period of 10 weeks. Then, the rats were supplemented with Se and Zn at a concentration of 0.15 mgL(-1) and 227 mgL(-1), respectively, in drinking water for 3 weeks. The results obtained from the study showed a significant increase in [Ca(2+)]i; calpain and caspase-3 activities as well as increase transfer latency in water maze study and reductions in Ca(2+)-ATPase and Na(+)-K(+)-ATPase activities for LPDF rats compared to WF rats. Se and Zn supplementation to LPDF rats reversed the elevation in [Ca(2+)]i, calpain and caspase-3 activities and restored the cognitive deficits and the activities of Ca(2+)-ATPase and Na(+)-K(+)-ATPase. Conclusively, protein-undernutrition results in the accumulation of synaptosomal calcium and inhibition of calcium transporters presumably via free radical generations and results in cognitive impairment which also probably results from neuronal death in rats through calpain activation and the caspase cascade mechanisms. However, Se and Zn supplementations ameliorated the anomalies observed.

Postnatal protein malnutrition induces neurochemical alterations leading to behavioral deficits in rats: prevention by selenium or zinc supplementation.

BACKGROUND/OBJECTIVES: Protein malnutrition (PM) is a worldwide problem affecting brain development in a large number of children. The present study was aimed at studying the perturbations in antioxidant defense system resulting from protein deficiency and to evaluate the preventive effect of Se and Zn on cortex and cerebellum. METHODS: Well-fed (WF) and PM rats were fed on 16 and 5% protein diet, respectively. After 10 weeks, animals were supplemented with Se and Zn at a concentration of 0.15 and 227 mg/l in drinking water for 3 weeks. RESULTS: PM rats showed significant increase in lipid peroxidation, nitrite, and protein carbonyl levels. Reduction in the activity of antioxidant enzymes, thiol levels, GSH/GSSG ratio, and neurobehavioral deficits were observed in PM groups. Se and Zn supplementation reduced the levels of lipid peroxidation, nitrite, and protein carbonyl and restored the activity of antioxidant enzymes and thiol levels in the cortex and cerebellum of PM rats along with neurobehavioral deficits. DISCUSSION: The study showed that Se and Zn supplementation might be beneficial in preventing biochemical alterations and neurobehavioral deficits in PM children.

Comparative study on the influence of fluoride on lipid peroxidation and antioxidants levels in the different brain regions of well-fed and protein undernourished rats.

Effects of fluoride on the levels of Lipid peroxidation (LP) and antioxidant enzymes in the brain regions of protein undernourished (PU) and well-fed rats (WF) rats exposed to 100 ppm fluoride in drinking water were investigated. The results indicate that the mean body weights and the total brain weights of PU rats as well as those given fluoride (both WF and PU) were significantly (P < 0.05) lower than their respective controls. The weights of different brain regions were also significantly reduced (P < 0.05) in PU rats compared to WF rats except in the brain stem. Fluoride ingestion diminished the weights of WF and PU rats affecting the cerebrum only (in the case of PU rats) and the cerebellum of both WF and PU rats without an effect on the brain stem of both WF and PU. Additionally, increased LP was observed in the cerebrum and cerebellum of PU rats but after fluoride ingestion, 30% increase in LP was observed only in the cerebrum. In the brain stem however, protein undernutrition was accompanied with a significant reduction in LP but the region seems insensitive to fluoride. There were significant reductions (P < 0.05) in CAT, SOD and GSH in all the brain regions (except the GSH level in the brain stem only) of PU rats. Fluoride induced reduction in the activity of CAT in the three brain regions and on SOD activity in cerebrum only for WF rats but no effect of fluoride on all the antioxidants studied in the three brain regions for PU rats. It is concluded that WF and PU rats responded differently to fluoride toxicity. However, it seems that at the dosage used, fluoride toxicity may be a direct effect on the antioxidant enzymes.