Moderate offspring exercise offsets the harmful effects of maternal protein deprivation on mitochondrial function and oxidative balance by modulating sirtuins

The REDOX balance in the prefrontal cortex is positively modulated by aerobic exercise and altered by overfeeding

While obesity rates increase worldwide, physical activity levels are reduced. Obesity and physical inactivity may be inversely related to the production of reactive oxygen species (ROS) and cause oxidative stress in the central nervous system. In this study, we aimed to investigate the effects of aerobic physical exercise on the oxidative balance of the prefrontal cortex of rats subjected to overnutrition during lactation. For this, male Wistar rats were subjected to overnutrition during lactation between postnatal day 3 to 21. On postnatal day 23, the two groups of animals were subdivided into trained and untrained animals. Trained rats were subjected to a treadmill training protocol for four weeks, five days/week, 60 min/day, at 50% of maximum running capacity. Our findings demonstrate that overnutrition impairs REDOX balance in the prefrontal cortex through increased prooxidants and reduced antioxidant defenses. On the contrary, exercise tends to restore most of these measures to control levels, possibly due to the increase in mRNA levels of Sirt1 and reduction in Il-6 in the prefrontal cortex. Overnutrition causes oxidative stress in the prefrontal cortex, while exercise re-covers most of its adverse effects through activating anti-inflammatory mechanisms.

Moderate aerobic training counterbalances the deleterious effect of undernutrition on oxidative balance and mitochondrial markers

The state of Maternal Protein Malnutrition (MPM) is associated with several deleterious effects, including inflammatory processes and dysregulation in oxidative balance, which can promote neurodegeneration. On the other hand, it is known that aerobic exercise can promote systemic health benefits, combating numerous chronic diseases. Therefore, we evaluate the effect of aerobic exercise training (AET) on indicators of mitochondrial bioenergetics, oxidative balance, endoplasmic reticulum stress, and neurotrophic factor in the prefrontal cortex of malnourished juvenile Wistar rats. Pregnant Wistar rats were fed with a diet containing 17% or 8% casein during pregnancy and lactation. At 30 days of life, male offspring were divided into 4 groups: Low-Protein Control (LS), Low-Protein Trained (LT), Normoprotein Control (NS), and Normoprotein Trained (NT). The trained groups performed an AET for 4 weeks, 5 days a week, 1 h a day per session. At 60 days of life, the animals were sacrificed and the skeletal muscle, and prefrontal cortex (PFC) were removed to evaluate the oxidative metabolism markers and gene expression of ATF-6, GRP78, PERK and BDNF. Our results showed that MPM impairs oxidative metabolism associated with higher oxidative and reticulum stress. However, AET restored the levels of indicators of mitochondrial bioenergetics, in addition to promoting resilience to cellular stress. AET at moderate intensity for 4 weeks in young Wistar rats can act as a non-pharmacological intervention in fighting against the deleterious effects of a protein-restricted maternal diet.

The deleterious effects of maternal protein deprivation on the brainstem are minimized with moderate physical activity by offspring during early life

Maternal protein malnutrition during developmental periods might impair the redox state and the brain's excitatory/inhibitory neural network, increasing central sympathetic tone. Conversely, moderate physical exercise at an early age reduces the risk of chronic diseases. Thus, we hypothesized that a moderate training protocol could reduce the harmful effects of a low-protein maternal diet on the brainstem of young male offspring. We used a rat model of maternal protein restriction during the gestational and lactation period followed by an offspring's continuous treadmill exercise. Pregnant rats were divided into two groups according to the protein content in the diet: normoprotein (NP), receiving 17% of casein, and low protein (LP), receiving 8% of casein until the end of lactation. At 30 days of age, the male offspring were further subdivided into sedentary (NP-Sed and LP-Sed) or exercised (NP-Ex and LP-Ex) groups. Treadmill exercise was performed as follows: 4 weeks, 5 days/week, 60 min/day at 50% of maximal running capacity. The trained animals performed a treadmill exercise at 50% of the maximal running capacity, 60 min/day, 5 days/week, for 4 weeks. Our results indicate that a low-protein diet promotes deficits in the antioxidant system and a likely mitochondrial uncoupling. On the other hand, physical exercise restores the redox balance, which leads to decreased oxidative stress caused by the diet. In addition, it also promotes benefits to GABAergic inhibitory signaling. We conclude that regular moderate physical exercise performed in youthhood protects the brainstem against changes induced by maternal protein restriction.

Undernutrition during development modulates endoplasmic reticulum stress genes in the hippocampus of juvenile rats: Involvement of oxidative stress

To evaluate whether exercise training mitigates the deleterious effects of undernutrition during the developmental period in juvenile Wistar rats. Pregnant Wistar rats were fed with a diet containing 17 % or 8 % casein during pregnancy and lactation. At 30 days of life, male offspring were divided into 4 groups: Low-Protein non-trained (LS), Low-Protein Trained (LT), Normoprotein non-trained (NS), and Normoprotein Trained (NT). Trained rats performed aerobic exercise training (AET) for 4 weeks, 5 days a week, 1 h a day. 24 h from the last day of training, the animals were sacrificed. The tissues were removed to analyze indicators of mitochondrial metabolism, oxidative stress, and gene expression of GRP78, PERK, ATF6 ER stress markers, and BDNF. The results showed that undernutrition during development promotes deleterious effects on mitochondrial oxidative metabolism and induces reticulum stress in the hippocampus of juvenile rats. On the other hand, AET improves mitochondrial function and increases enzymatic and non-enzymatic antioxidant capacity, as well as declines ER stress. AET at moderate intensity for 4 weeks in male juvenile Wistar rats acts as a lifestyle intervention opposing the negative effects induced by a protein-restricted maternal diet.

Low Nephron Number Induced by Maternal Protein Restriction Is Prevented by Nicotinamide Riboside Supplementation Depending on Sirtuin 3 Activation

A reduced nephron number at birth, due to critical gestational conditions, including maternal malnutrition, is associated with the risk of developing hypertension and chronic kidney disease in adulthood. No interventions are currently available to augment nephron number. We have recently shown that sirtuin 3 (SIRT3) has an important role in dictating proper nephron endowment. The present study explored whether SIRT3 stimulation, by means of supplementation with nicotinamide riboside (NR), a precursor of the SIRT3 co-substrate nicotinamide adenine dinucleotide (NAD⁺), was able to improve nephron number in a murine model of a low protein (LP) diet. Our findings show that reduced nephron number in newborn mice (day 1) born to mothers fed a LP diet was associated with impaired renal SIRT3 expression, which was restored through supplementation with NR. Glomerular podocyte density, as well as the rarefaction of renal capillaries, also improved through NR administration. In mechanistic terms, the restoration of SIRT3 expression through NR was mediated by the induction of proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α). Moreover, NR restored SIRT3 activity, as shown by the reduction of the acetylation of optic atrophy 1 (OPA1) and superoxide dismutase 2 (SOD2), which resulted in improved mitochondrial morphology and protection against oxidative damage in mice born to mothers fed the LP diet. Our results provide evidence that it is feasible to prevent nephron mass shortage at birth through SIRT3 boosting during nephrogenesis, thus providing a therapeutic option to possibly limit the long-term sequelae of reduced nephron number in adulthood.

The Role of SIRT3 in Exercise and Aging

The health benefits of regular exercise are well established. Nonetheless, the molecular mechanism(s) responsible for exercise-induced health benefits remain a topic of debate. One of the key cell-signaling candidates proposed to provide exercise-induced benefits is sirtuin 3 (SIRT3). SIRT3, an NAD+ dependent mitochondrial deacetylase, positively modulates many cellular processes, including energy metabolism, mitochondrial biogenesis, and protection against oxidative stress. Although the exercise-induced change in SIRT3 signaling is a potential mechanism contributing to the health advantages of exercise on aging, studies investigating the impact of exercise on SIRT3 abundance in cells provide conflicting results. To resolve this conundrum, this narrative review provides a detailed analysis of the role that exercise-induced changes in SIRT3 play in providing the health and aging benefits associated with regular physical activity. We begin with an overview of SIRT3 function in cells followed by a comprehensive review of the impact of exercise on SIRT3 expression in humans and other mammalians. We then discuss the impact of SIRT3 on aging, followed by a thorough analysis of the cell-signaling links between SIRT3 and exercise-induced adaptation. Notably, to stimulate future research, we conclude with a discussion of key unanswered questions related to exercise, aging, and SIRT3 expression.