Voluntary exercise in pregnant rats positively influences fetal growth without initiating a maternal physiological stress response

The role of enriched environment in neural development and repair

In addition to genetic information, environmental factors play an important role in the structure and function of nervous system and the occurrence and development of some nervous system diseases. Enriched environment (EE) can not only promote normal neural development through enhancing neuroplasticity but also play a nerve repair role in restoring functional activities during CNS injury by morphological and cellular and molecular adaptations in the brain. Different stages of development after birth respond to the environment to varying degrees. Therefore, we systematically review the pro-developmental and anti-stress value of EE during pregnancy, pre-weaning, and “adolescence” and analyze the difference in the effects of EE and its sub-components, especially with physical exercise. In our exploration of potential mechanisms that promote neurodevelopment, we have found that not all sub-components exert maximum value throughout the developmental phase, such as animals that do not respond to physical activity before weaning, and that EE is not superior to its sub-components in all respects. EE affects the developing and adult brain, resulting in some neuroplastic changes in the microscopic and macroscopic anatomy, finally contributing to enhanced learning and memory capacity. These positive promoting influences are particularly prominent regarding neural repair after neurobiological disorders. Taking cerebral ischemia as an example, we analyzed the molecular mediators of EE promoting repair from various dimensions. We found that EE does not always lead to positive effects on nerve repair, such as infarct size. In view of the classic issues such as standardization and relativity of EE have been thoroughly discussed, we finally focus on analyzing the essentiality of the time window of EE action and clinical translation in order to devote to the future research direction of EE and rapid and reasonable clinical application.

Maternal resistance exercise promotes changes in neuroplastic and epigenetic marks of offspring's hippocampus during adult life

Studies indicate that gestational exercise practice positively impacts the offspring's cognition. Nevertheless, the influence of maternal resistance exercise, different periods of exercise practice, and the inter- and transgenerational effects involved in these responses are not known. This study sought to report the influence of the maternal practice of resistance exercise on offspring's cognitive function, exploring behavior, and neuroplastic and epigenetic marks in the hippocampus. Female Wistar rats were divided into four groups: sedentary (SS), exercised during pregnancy (SE), exercised before pregnancy (ES), and exercised before and during pregnancy (EE). Exercised rats were submitted to a resistance exercise protocol (vertical ladder climbing). Between postnatal days (P)81 and P85, male offspring were submitted to the Morris water maze test. At P85, the following analyses were performed in offspring's hippocampus: expression of IGF-1 and BrdU+ cells, global DNA methylation, H3/H4 acetylation, and HDAC2 amount. Only the offspring of SE mothers presented subtly better performance on learning and memory tasks, associated with lower HDAC2 amount. Offspring from ES mothers presented an overexpression of hippocampal neuroplastic marks (BrdU+ and IGF-1), as well as a decrease of DNA methylation and an increase in H4 acetylation. Offspring from EE mothers (continuously exercised) did not present modifications in plasticity or epigenetic parameters. This is the first study to observe the influence of maternal resistance exercise on offspring's brains. The findings provide evidence that offspring's hippocampus plasticity is influenced by exercise performed in isolated periods (pre- or gestationally) more than that performed continually.

Maternal physical activity-induced adaptive transcriptional response in brain and placenta of mothers and rat offspring

Maternal physical activity induces brain functional changes and neuroplasticity, leading to an improvement of cognitive functions, such as learning and memory in the offspring. This study investigated the effects of voluntary maternal physical activity on the gene expression of the neurotrophic factors (NTFs): BDNF, NTF4, NTRK2, IGF-1 and IGF-1r in the different areas of mother's brain, placenta and foetus brain of rats. Female Wistar rats (n = 15) were individually housed in voluntary physical activity cages, containing a running wheel, for 4 weeks (period of adaptation) before gestation. Rats were classified as inactive (I, n = 6); active (A, n = 4) and very active (VA, n = 5) according to daily distance spontaneously travelled. During gestation, the dams continued to have access to the running wheel. At the 20th day of gestation, gene expression of NTFs was analysed in different areas of mother's brain (cerebellum, hypothalamus, hippocampus and cortex), placenta and the offspring's brain. NTFs gene expression was evaluated using quantitative PCR. Very active mothers showed upregulation of IGF-1 mRNA in the cerebellum (36.8%) and NTF4 mRNA expression in the placenta (24.3%). In the cortex, there was a tendency of up-regulation of NTRK2 mRNA (p = 0.06) in the A and VA groups when compared to I group. There were no noticeable changes in the gene expression of NTFs in the offspring's brain. Our findings suggest the existence of a developmental plasticity induced by maternal physical activity in specific areas of the brain and placenta representing the first investment for offspring during development.

Effects of High Intensity Interval Training on Pregnant Rats, and the Placenta, Heart and Liver of Their Fetuses

OBJECTIVE

To investigate the effects of high intensity interval training (HIIT) on the maternal heart, fetuses and placentas of pregnant rats.

METHODS

Female Sprague-Dawley rats were randomly assigned to HIIT or sedentary control groups. The HIIT group was trained for 6 weeks with 10 bouts of high intensity uphill running on a treadmill for four minutes (at 85-90% of maximal oxygen consumption) for five days/week. After three weeks of HIIT, rats were mated. After six weeks (gestational day 20 in pregnant rats), echocardiography was performed to evaluate maternal cardiac function. Real-time PCR was performed for the quantification of gene expression, and oxidative stress and total antioxidant capacity was assessed in the tissue samples.

RESULTS

Maternal heart weight and systolic function were not affected by HIIT or pregnancy. In the maternal heart, expression of 11 of 22 genes related to cardiac remodeling was influenced by pregnancy but none by HIIT. Litter size, fetal weight and placental weight were not affected by HIIT. Total antioxidant capacity, malondialdehyde content, peroxidase and superoxide dismutase activity measured in the placenta, fetal heart and liver were not influenced by HIIT. HIIT reduced the expression of eNOS (p = 0.03), hypoxia-inducible factor 1α (p = 0.04) and glutathione peroxidase 4.2 (p = 0.02) in the fetal liver and increased the expression of vascular endothelial growth factor-β (p = 0.014), superoxide dismutase 1 (p = 0.001) and tissue inhibitor of metallopeptidase 3 (p = 0.049) in the fetal heart.

CONCLUSIONS

Maternal cardiac function and gene expression was not affected by HIIT. Although HIIT did not affect fetal growth, level of oxidative stress and total antioxidant capacity in the fetal tissues, some genes related to oxidative stress were altered in the fetal heart and liver indicating that protective mechanisms may be activated.

Oxidative stress status and placental implications in diabetic rats undergoing swimming exercise after embryonic implantation

The potential benefits and risks of physical exercise on fetal development during pregnancy remain unclear. The aim was to analyze maternal oxidative stress status and the placental morphometry to relate to intrauterine growth restriction (IUGR) from diabetic female rats submitted to swimming program after embryonic implantation. Pregnant Wistar rats were distributed into 4 groups (11 animals/group): control-nondiabetic sedentary rats, control exercised-nondiabetic exercised rats, diabetic-diabetic sedentary rats, and diabetic exercised-diabetic exercised rats. A swimming program was used as an exercise model. At the end of pregnancy, the maternal oxidative stress status, placental morphology, and fetal weight were analyzed. The swimming program was not efficient to reduce the hyperglycemia-induced oxidative stress. This fact impaired placental development, resulting in altered blood flow and energy reserves, which contributed to a deficient exchange of nutrients and oxygen for the fetal development, leading to IUGR.

Environment and Brain Plasticity: Towards an Endogenous Pharmacotherapy

Brain plasticity refers to the remarkable property of cerebral neurons to change their structure and function in response to experience, a fundamental theoretical theme in the field of basic research and a major focus for neural rehabilitation following brain disease. While much of the early work on this topic was based on deprivation approaches relying on sensory experience reduction procedures, major advances have been recently obtained using the conceptually opposite paradigm of environmental enrichment, whereby an enhanced stimulation is provided at multiple cognitive, sensory, social, and motor levels. In this survey, we aim to review past and recent work concerning the influence exerted by the environment on brain plasticity processes, with special emphasis on the underlying cellular and molecular mechanisms and starting from experimental work on animal models to move to highly relevant work performed in humans. We will initiate introducing the concept of brain plasticity and describing classic paradigmatic examples to illustrate how changes at the level of neuronal properties can ultimately affect and direct key perceptual and behavioral outputs. Then, we describe the remarkable effects elicited by early stressful conditions, maternal care, and preweaning enrichment on central nervous system development, with a separate section focusing on neurodevelopmental disorders. A specific section is dedicated to the striking ability of environmental enrichment and physical exercise to empower adult brain plasticity. Finally, we analyze in the last section the ever-increasing available knowledge on the effects elicited by enriched living conditions on physiological and pathological aging brain processes.

Moderate exercise during pregnancy in Wistar rats alters bone and body composition of the adult offspring in a sex-dependent manner

Exercise during pregnancy may have long-lasting effects on offspring health. Musculoskeletal growth and development, metabolism, and later-life disease risk can all be impacted by the maternal environment during pregnancy. The skeleton influences glucose handling through the actions of the bone-derived hormone osteocalcin. The purpose of this study was to test the effects of moderate maternal exercise during pregnancy on the bone and body composition of the offspring in adult life, and to investigate the role of osteocalcin in these effects. Groups of pregnant Wistar rats either performed bipedal standing exercise to obtain food/water throughout gestation but not lactation, or were fed conventionally. Litters were reduced to 8/dam and pups were raised to maturity under control conditions. Whole body dual-energy x-ray absorptiometry, and ex vivo peripheral quantitative computed tomography scans of the right tibia were performed. At study termination blood and tissue samples were collected. Serum concentrations of fully and undercarboxylated osteocalcin were measured, and the relative expression levels of osteocalcin, insulin receptor, Forkhead box transcription factor O1, and osteotesticular protein tyrosine phosphatase mRNA were quantified. Body mass did not differ between the offspring of exercised and control dams, but the male offspring of exercised dams had a greater % fat and lower % lean than controls (p=0.001 and p=0.0008, respectively). At the mid-tibial diaphysis, offspring of exercised dams had a lower volumetric bone mineral density than controls (p=0.01) and in the male offspring of exercised dams the bone: muscle relationship was fundamentally altered. Serum concentrations of undercarboxylated osteocalcin were significantly greater in the male offspring of exercised dams than in controls (p=0.02); however, the relative expression of the measured genes did not differ between groups. These results suggest that moderate exercise during pregnancy can result in lasting changes to the musculoskeletal system and adiposity in offspring, in a sex-specific manner.

Can exercise training rescue the adverse cardiometabolic effects of low birth weight and prematurity?

Being born preterm and/or small for gestational age are well-established risk factors for cardiometabolic disease in adulthood. Physical activity has the potential to mitigate against the detrimental cardiometabolic effects of low birth weight from two perspectives: (i) maternal exercise prior to and during pregnancy; and (ii) exercise during childhood or adulthood for those born small or prematurely. Evidence from epidemiological birth cohort studies suggests that the effects of moderate-intensity physical activity during pregnancy on mean birth weight are small, but reduce the risk of either high or low birth weight infants. In contrast, vigorous and/or high-intensity exercise during pregnancy has been associated with reduced birth weight. In childhood and adolescence, exercise ability is compromised in extremely low birth weight individuals (< 1000 g), but only marginally reduced in those of very low to low birth weight (1000-2500 g). Epidemiological studies show that the association between birth weight and metabolic disease is lost in physically fit individuals and, consistently, that the association between low birth weight and metabolic syndrome is accentuated in unfit individuals. Physical activity intervention studies indicate that most cardiometabolic risk factors respond to exercise in a protective manner, independent of birth weight. The mechanisms by which exercise may protect low birth weight individuals include restoration of muscle mass, reduced adiposity and enhanced β-cell mass and function, as well as effects on both aerobic and anaerobic muscle metabolism, including substrate utilization and mitochondrial function. Vascular and cardiac adaptations are also likely important, but are less well studied.

Maternal exercise during pregnancy ameliorates the postnatal neuronal impairments induced by prenatal restraint stress in mice

Clinical and preclinical studies have demonstrated that prenatal stress (PS) induces neuronal and behavioral disturbances in the offspring. In the present study, we determined whether maternal voluntary wheel running (VWR) during pregnancy could reverse the putative deleterious effects of PS on the neurodevelopment and behavior of the offspring. Pregnant CF-1 mice were randomly assigned to control, restraint stressed or restraint stressed+VWR groups. Dams of the stressed group were subjected to restraint stress between gestational days 14 and delivery, while control pregnant dams remained undisturbed in their home cages. Dams of the restraint stressed+VWR group were subjected to exercise between gestational days 1 and 17. On postnatal day 23 (P23), male pups were assigned to one of the following experimental groups: mice born from control dams, stressed dams or stressed+VWR dams. Locomotor behavior and pyramidal neuronal morphology were evaluated at P23. Animals were then sacrificed, and Golgi-impregnated pyramidal neurons of the parietal cortex were morphometrically analyzed. Here, we present two major findings: first, PS produced significantly diminished dendritic growth of parietal neurons without altered locomotor behavior of the offspring; and second, maternal VWR significantly offset morphological impairments.