No abstract

Oxidative stress (OS) has been implicated in the etiology of certain neurodegenerative disorders. Some of these disorders have been associated with unbalanced levels of essential fatty acids (EFA). The response of certain brain regions to OS, however, is not uniform and a selective vulnerability or resilience can occur. In our previous study on rat brains, we observed that a two-generation EFA dietary restriction reduced the number and size of dopaminergic neurons in the substantia nigra (SN) rostro-dorso-medial. To understand whether OS contributes to this effect, we assessed the status of lipid peroxidation (LP) and anti-oxidant markers in both SN and corpus striatum (CS) of rats submitted to this dietary treatment for one (F1) or two (F2) generations. Wistar rats were raised from conception on control or experimental diets containing adequate or reduced levels of linoleic and α-linolenic fatty acids, respectively. LP was measured using the thiobarbituric acid reaction method (TBARS) and the total superoxide dismutase (t-SOD) and catalase (CAT) enzymatic activities were assessed. The experimental diet significantly reduced the docosahexaenoic acid (DHA) levels of SN phospholipids in the F1 (~28%) and F2 (~50%) groups. In F1 adult animals of the experimental group there was no LP in both SN and CS. Consistently, there was a significant increase in the t-SOD activity (p < 0.01) in both regions. In EF2 young animals, degeneration in dopaminergic and non-dopaminergic neurons and a significant increase in LP (p < 0.01) and decrease in the CAT activity (p < 0.001) were detected in the SN, while no inter-group difference was found for these parameters in the CS. Conversely, a significant increase in t-SOD activity (p < 0.05) was detected in the CS of the experimental group compared to the control. The results show that unbalanced EFA dietary levels reduce the redox balance in the SN and reveal mechanisms of resilience in the CS under this stressful condition.

Many studies have shown that a maternal low-protein diet increases the susceptibility of offspring to cardiovascular disease in later-life. Moreover, a lower incidence of cardiovascular disease in females than in males is understood to be largely due to the protective effect of high levels of estrogens throughout a woman's reproductive life. However, to our knowledge, the role of estradiol in moderating the later-life susceptibility of offspring of nutrient-deprived mothers to cardiovascular disease is not fully understood. The present study is aimed at investigating whether oxidative stress in the brainstem caused by a maternal low-protein diet administered during a critical period of fetal/neonatal brain development (i.e during gestation and lactation) is affected by estradiol levels. Female Wistar rat offspring were divided into four groups according to their mothers' diets and to the serum estradiol levels of the offspring at the time of testing: (1) 22 days of age/control diet: (2) 22 days of age/low-protein diet; (3) 122 days of age/control diet: (4) 122 days of age/low-protein diet. Undernutrition in the context of low serum estradiol compared to undernutrition in a higher estradiol context resulted in increased levels of oxidative stress biomarkers and a reduction in enzymatic and non-enzymatic antioxidant defenses. Total global oxy-score showed oxidative damage in 22-day-old rats whose mothers had received a low-protein diet. In the 122-day-old group, we observed a decrease in oxidative stress biomarkers, increased enzymatic antioxidant activity, and a positive oxy-score when compared to control. We conclude from these results that following a protein deficiency in the maternal diet during early development of the offspring, estrogens present at high levels at reproductive age may confer resistance to the oxidative damage in the brainstem that is very apparent in pre-pubertal rats.

The cerebellum is vulnerable to malnutrition effects. Notwithstanding, it is able to incorporate higher amount of docosahexaenoic acid (DHA) than the cerebral cortex (Cx) when low n-6/n-3 fatty acid ratio is present in a multideficient diet. Considering importance of DHA for brain redox balance, we hypothesize that this cerebellum feature improves its antioxidant status compared to the Cx. A chronic malnutrition status was induced on dams before mating and kept until weaning or adulthood (offspring). A group nutritionally rehabilitated from weaning was also analyzed. Morphometric parameters, total-superoxide dismutase (t-SOD) and catalase activities, lipoperoxidation (LP), nitric oxide (NO), reduced (GSH) and oxidized (GSSG) glutathione, reactive oxygen species (ROS), and reduced nicotinamide adenine dinucleotide/phosphate levels were assessed. Both ROS and LP levels were increased (∼53 %) in the Cx of malnourished young animals while the opposite was seen in the cerebellum (72 and 20 % of the control, respectively). Consistently, lower (∼35 %) and higher t-SOD (∼153 %) and catalase (CAT) (∼38 %) activities were respectively detected in the Cx and cerebellum compared to the control. In malnourished adult animals, redox balance was maintained in the cerebellum and recovered in the Cx (lower ROS and LP levels and higher GSH/GSSG ratio). NO production was impaired by malnutrition at either age, mainly in the cerebellum. The findings suggest that despite a multinutrient deficiency and a modified structural development, a low dietary n-6/n-3 ratio favors early antioxidant resources in the male cerebellum and indicates an important role of astrocytes in the redox balance recovery of Cx in adulthood.

Maternal protein deficiency during the critical development period of the progeny disturbs mitochondrial metabolism in the brainstem, which increases the risk of developing cardiovascular diseases in the first-generation (F1) offspring, but is unknown if this effect persists in the second-generation (F2) offspring. The study tested whether mitochondrial health and oxidative balance will be restored in F2 rats. Male and female rats were divided into six groups according to the diet fed to their mothers throughout gestation and lactation periods. These groups were: (1) normoprotein (NP) and (2) low-protein (LP) rats of the first filial generation (F1-NP and F1-LP, respectively) and (3) NP and (4) LP rats of the second filial generation (F2-NP and F2-LP, respectively). After weaning, all groups received commercial chow and a portion of each group was sacrificed on the 30th day of life for determination of mitochondrial and oxidative parameters. The remaining portion of the F1 group was mated at adulthood and fed an NP or LP diet during the periods of gestation and lactation, to produce progeny belonging to (5) F2R-NP and (6) F2R-LP group, respectively. Our results demonstrated that male F1-LP rats suffered mitochondrial impairment associated with an 89% higher production of reactive species (RS) and 137% higher oxidative stress biomarkers, but that the oxidative stress was blunted in female F1-LP animals despite the antioxidant impairment. In the second generation following F0 malnutrition, brainstem antioxidant defenses were restored in the F2-LP group of both sexes. However, F2R-LP offspring, exposed to LP in the diets of the two preceding generations displayed a RS overproduction with a concomitant decrease in mitochondrial bioenergetics. Our findings demonstrate that nutritional stress during the reproductive life of the mother can negatively affect mitochondrial metabolism and oxidative balance in the brainstem of F1 progeny, but that restoration of a normal diet during the reproductive life of those individuals leads toward a mitochondrial recovery in their own (F2) progeny. Otherwise, if protein deprivation is continued from the F0 generation and into the F1 generation, the F2 progeny will exhibit no recovery, but instead will remain vulnerable to further oxidative damage.

No abstract

There is a strong correlation between inadequate gestational and postpartum nutrition with the occurrence of cardiovascular diseases. The present study investigates the effects of maternal low-protein and neonatal overfeeding on the oxidative balance and morphology of the renal cortex of male Wistar rats. Two independent protocols were used. First, pregnant Wistar rats received diets containing either 17% (normal protein) or 8% (low protein) casein throughout pregnancy and lactation. Second, the litter size was reduced by one-third on the third postnatal day to induce overnourishment in offspring. In experimental age, the oxidative balance and morphology of the renal cortex analyses were performed in the kidney cortex. Results showed small but significant increase in renal corpuscle area in low protein (LP, 5%) and overnutrition (ON, 8%). Glomerular tuft area also increases in LP (6%) and ON (9%), as did glomerular cellularity (LP +11% and ON, +12%). In the oxidative stress analyses, both nutritional insult significantly elevated lipid peroxidation (LP +18% and ON +135%) and protein oxidation (LP +40% and ON, +65%), while significantly reducing non-enzymatic antioxidant defenses measured by reduced glutathione (LP, -32%; ON, -45%) and total thiol content (LP, -28%; ON, -24%), respectively. In enzymatic defense we observe decrease in superoxide dismutase (LP -78% and ON -51%), catalase (LP -18% and ON -61%) and GST (only in ON -44%). Our results demonstrate that nutritional insults, even those of a very different nature, occurring during perinatal development can result in similar changes in oxidative parameters and glomerular morphology in the renal cortex.

Nutritional insults during pregnancy and/or lactation phases increase the risk in offspring for future arterial hypertension. 1-3 Maternal dyslipidaemia is a condition characterized by high levels of total cholesterol (TC), triacylglycerol (TAG), low-density lipoprotein (LDL) and decreased high-density lipoprotein (HDL). 4 Although pregnancy and/or lactation can be recognized as a period of life favourable to increased lipid profile in serum, 5 the dyslipidaemia effects on the offspring are poorly understood. We have developed a maternal diet-induced dyslipidaemic model in rats, characterized by increased serum levels of total cholesterol, LDL-cholesterol, and triacylglycerol, reduced HDL-cholesterol and compromised glucose tolerance and insulin sensitivity in dams.