Christiano Spindler

Treadmill exercise induces age-related changes in aversive memory, neuroinflammatory and epigenetic processes in the rat hippocampus.

It has been described that exercise can modulate both inflammatory response and epigenetic modifications, although the effect of exercise on these parameters during the normal brain aging process yet remains poorly understood. Here, we investigated the effect of aging and treadmill exercise on inflammatory and epigenetic parameters specifically pro and anti-inflammatory cytokines levels, activation of NF-kB and histone H4 acetylation levels in hippocampus from Wistar rats. Additionally, we evaluated aversive memory through inhibitory avoidance task. Rats of 3 and 20 months of age were assigned to non-exercised (sedentary) and exercised (running daily for 20 min for 2 weeks) groups. The effect of daily forced exercise in the treadmill was assessed. The levels of inflammatory and epigenetic parameters were determined 1h, 18 h, 3 days or 7 days after the last training session of exercise. It was observed an age-related decline on aversive memory, as well as aged rats showed increased hippocampal levels of inflammatory markers, such as TNFα, IL1-β and NF-kB and decreased IL-4 levels, an anti-inflammatory cytokine. Moreover, lower levels of global histone H4 acetylation were also observed in hippocampi from aged rats. Interestingly, there was a significant correlation between the biochemical markers and the inhibitory avoidance test performance. The forced exercise protocol ameliorated aging-related memory decline, decreased pro-inflammatory markers and increased histone H4 acetylation levels in hippocampi 20-months-old rats, while increased acutely IL-4 levels in hippocampi from young adult rats. Together, these results suggest that an imbalance of inflammatory markers might be involved to the aging-related aversive memory impairment. Additionally, our exercise protocol may reverse aging-related memory decline through improving cytokine profile.

Exercise induces age-dependent changes on epigenetic parameters in rat hippocampus: a preliminary study.

Regular exercise improves learning and memory, including during aging process. Interestingly, the imbalance of epigenetic mechanisms has been linked to age-related cognitive deficits. However, studies about epigenetic alterations after exercise during the aging process are rare. In this preliminary study we investigated the effect of aging and exercise on DNA methyltransferases (DNMT1 and DNMT3b) and H3-K9 methylation levels in hippocampus from 3 and 20-months aged Wistar rats. The animals were submitted to two exercise protocols: single session or chronic treadmill protocol. DNMT1 and H3-K9 methylation levels were decreased in hippocampus from aged rats. The single exercise session decreased both DNMT3b and DNMT1 levels in young adult rats, without any effect in the aged group. Both exercise protocols reduced H3-K9 methylation levels in young adult rats, while the single session reversed the changes on H3-K9 methylation levels induced by aging. Together, these results suggest that an imbalance on DNMTs and H3-K9 methylation levels might be linked to the brain aging process and that the outcome to exercise seems to vary through lifespan.

Effects of pre- and postnatal protein malnutrition in hypoxic-ischemic rats.

Neonatal hypoxic-ischemic encephalopathy (HI) is a major cause of nervous system damage and neurological morbidity. Perinatal malnutrition affects morphological, biochemical and behavioral aspects of neural development, including pathophysiological cascades of cell death triggered by ischemic events, so modifying resulting brain damage. Female Wistar rats were subjected to protein restriction during pregnancy and lactation (control group: 25% soybean protein; malnourished group: 7%). Seven days after delivery (PND7), their offspring were submitted to unilateral cerebral HI; rats were then tested for sensorimotor (PND7 and PND60) and memory (PND60) functions. Offspring of malnourished mothers showed marked reduction in body weight starting in lactation and persisting during the entire period of observation. There was a greater sensorimotor deficit after HI in malnourished (M) animals, in righting reflex and in home bedding task, indicating an interaction between diet and hypoxia-ischemia. At PND60, HI rats showed impaired performance when compared to controls in training and test sessions of rota-rod task, however there was no effect of malnutrition per se. In the open field, nourished HI (HI-N) presented an increase in crossings number; this effect was not present in HI-M group. Surprisingly, HI-M rats presented a better performance in inhibitory avoidance task and a smaller hemispheric brain damage as compared to HI-N animals. Our data points to a possible metabolic adaptation in hypoxic-ischemic animals receiving protein malnutrition during pregnancy and lactation; apparently we observed a neuroprotective effect of diet, possibly decreasing the brain energy demand, under a hypoxic-ischemic situation.

Exposition to tannery wastewater did not alter behavioral and biochemical parameters in Wistar rats.

There are scarce data on the neurotoxicity in mammalian induced by tannery wastewaters. Previously, the anxiogenic effect of tannery wastewater was demonstrated in mice, while wastewater submitted to photoelectrooxidation (PEO) process treatment did not affect the anxiety state. Considering that species may response differently to xenobiotics, the aim of the present work was to study the effects of exposure to tannery wastewaters (non-PEO or PEO-treated) on behavioral and neurochemical markers in another species of laboratory animals, specifically Wistar rats. Male Wistar rats were given free access to water bottles containing non-PEO or PEO-treated tannery wastewaters (0.1, 1 and 5% in drinking water). During the exposure, behavioral tests of anxiety (elevated plus-maze, neophobia, open field and light-dark box), depression (forced swimming) and memory (inhibitory avoidance, novel object and discriminative avoidance) were performed. On the 30th day, brain structures were dissected out to evaluate cellular oxidative state (hippocampus, cerebellum and striatum) and acetylcholinesterase activity (hippocampus and striatum). Exposure to tannery effluent with or without photoelectrochemical treatment did not alter any behavioral and neurochemical parameters evaluated. Our data indicate that Wistar rats may not be an adequate species for ecotoxicological studies involving tannery effluents and that POE treatment did not generate other toxic compounds.

Time-dependent effects of treadmill exercise on aversive memory and cyclooxygenase pathway function

Exercise induces brain function adaptations and improves learning and memory; however the time window of exercise effects has been poorly investigated. Studies demonstrate an important role for cyclooxygenase-2 (COX-2) pathway function in the mechanisms underlying memory formation. The aim of present work was to investigate the effects of treadmill exercise on aversive memory and COX-2, PGE(2) and E-prostanoid receptors contents in the rat hippocampus at different time points after exercise has ended. Adult male Wistar rats were assigned to non-exercised (sedentary) and exercised (running daily for 20min, for 2weeks) groups. The inhibitory avoidance task was used to assess aversive memory and the COX-2, PGE(2) and E-prostanoid receptors (EP1, EP2, EP3 and EP4) levels were determined 1h, 18h, 3days or 7days after the last training session of treadmill exercise. The step down latency in the inhibitory avoidance, COX-2 and EP4 receptors levels were acutely increased by exercise, with a significant positive correlation between aversive memory performance and COX-2 levels. Increased EP2 content decreased PGE(2) levels were observed 7days after the last running session. The treadmill exercise protocol facilitates inhibitory avoidance memory and induces time-dependent changes on COX-2 pathways function (COX-2, PGE(2) and EP receptors).

Association of environmental enrichment and locomotor stimulation in a rodent model of cerebral palsy: Insights of biological mechanisms

Several physiotherapy approaches are used with different aims in the treatment of cerebral palsy (CP), such as the early stimulation and the locomotor training, but their biological effects, isolated or combined, are not completely known. In animals models, these strategies can be compared, with due translational restrictions, to the environmental enrichment (EE), that involves the enhancement of animals physical and social environment, and locomotor stimulation (LS), that can be performed using the treadmill adapted for rats. This study was designed to describe which biological and functional mechanisms underlying rehabilitative process in clinical practice. Male rat pups were initially divided in two groups: control (healthy) and submitted to a CP model. Then, pups were divided in eight groups: CP, CPEE, CPLS, CPEELS and its respectively control groups. Functional outcomes were assessed at the postnatal day (P) 31 and P52. The tibialis anterior and soleus muscles, tibia bone parameters, the expression of synaptophysin in the primary motor cortex (M1) and ventral horn (VH) of the spinal cord, were evaluated. The association of therapies was able to improve the functional assessments and musculoskeletal parameters. Isolated therapies presented complementary benefits in CP, but the association of therapies proved to be a fundamental and effective strategy to functional recovery, besides alter positively all biological tissues evaluated in this study.

Ascorbate uptake is decreased in the hippocampus of ageing rats

Ascorbate, an intracellular antioxidant, has been considered critical for neuronal protection against oxidant stress, which is supported especially by in vitro studies. Besides, it has been demonstrated an age-related decrease in brain ascorbate levels. The aims of the present study were to investigate ascorbate uptake in hippocampal slices from old Wistar rats, as well as its neuroprotective effects in in vitro and in vivo assays. Hippocampal slices from male Wistar rats aged 4, 11 and 24 months were incubated with radiolabeled ascorbate and incorporated radioactivity was measured. Hippocampal slices from rats were incubated with different concentrations of ascorbate and submitted to H(2)O(2)-induced injury, cellular damage and S100B protein levels were evaluated. The effect of chronic administration of ascorbate on cellular oxidative state and astrocyte biochemical parameters in the hippocampus from 18-months-old Wistar rats was also studied. The ascorbate uptake was decreased in hippocampal slices from old-aged rats, while supplementation with ascorbate (2 weeks) did not modify any tested oxidative status in the hippocampus and the incubation was unable to protect hippocampal slices submitted to oxidative damage (H(2)O(2)) from old rats. Our data suggest that the decline of ascorbate uptake might be involved in the brain greater susceptibility to oxidative damage with advancing age and both in vitro and vivo assays suggest that ascorbate supplementation did not protect hippocampal cells.

Paternal physical exercise demethylates the hippocampal DNA of male pups without modifying the cognitive and physical development

Abstract Maternal exercise is known to have beneficial effects in progeny development, but the influence of paternal exercise on the offspring still unclear. Since spermatogenesis is a continuous process, the father’s life experiences can reprogram epigenetic content of the sperm and somehow interfere on offspring phenotype. This study was designed to evaluate the effects of paternal physical exercise on cognitive and physical development and on hippocampal DNA methylation levels of the offspring. Adult male Wistar rats were divided into two groups: sedentary and exercised. The exercise protocol occurred before mating and consisted of treadmill running, 5 consecutive days/week for 8 weeks (20 min/day). The mothers were not trained. The following developmental parameters were examined in male offspring: body growth, physical and cognitive performance, weights of adrenal glands, gonadal fat and hindlimb muscles, BDNF expression and global DNA methylation at the hippocampus. The progeny of trained and sedentary fathers did not differ in relation to physical parameters and performance, spatial memory and BDNF expression. However, paternal exercise promoted a decrease in offsprings relative gonadal fat weight and a lower percentage of global hippocampal DNA methylation compared to offspring of sedentary fathers. These results pointed to interference of male physical activity at the time of conception on adiposity and hippocampal epigenetic reprogramming of male offspring. The data reinforces that exercise does not harm the descendant’s development and emphasize the benefits to include the practice of physical exercise in a healthier lifestyle of the parents. Nevertheless, future studies are necessary and should investigate further the long‐effects of epigenetic mechanisms in order to elucidate the father’s contribution in fetal programming.