Resveratrol and resveratrol-hydroxypropyl-ß-cyclodextrin complex recovered the changes of creatine kinase and Na+, K+-ATPase activities found in the spleen from streptozotocin-induced diabetic rats.

Type 1 diabetes (T1D) is the result of the selective destruction of the pancreatic ß-cells by T cells of the immune system. Although spleen is a secondary lymphoid organ, it is also involved in the T1D pathogenesis. However, the alterations in a variety of cellular processes of this disease need to be further understood. We aimed to analyze the benefits of resveratrol, and its complexed form on diabetic complications in the spleen of rats. To this end, we investigated important enzymes of phosphoryl transfer network, and Na+, K+-ATPase activity. Wistar rats were divided into non-diabetic groups: Control, Ethanol, Resveratrol, Hydroxypropyl-ß-cyclodextrin, Resveratrol-hydroxypropyl-ß-cyclodextrin, and diabetic groups with the same treatments. Diabetes was induced by a single dose of 60 mg/kg of streptozocin intraperitoneally, and treatments by intragastric gavage once daily for 60 days. Hyperglycemia reduced creatine kinase activity, which was reversed by the administration of resveratrol. Na+, K+-ATPase activity was greatly affected, but it was reversed by resveratrol and resveratrol-hydroxypropyl-ß-cyclodextrin. This suggest an energetic imbalance in the spleen of diabetic rats, and in case this also occurs in the diabetic patients, it is possible that resveratrol supplementation could be beneficial to the better functioning of the spleen in diabetic patients.

Experimental neonatal hypoxia ischemia causes long lasting changes of oxidative stress parameters in the hippocampus and the spleen.

Neonatal hypoxia ischemia (HI) is the main cause of mortality and morbidity in newborns. The mechanisms involved in its progression start immediately and persist for several days. Oxidative stress and inflammation are determinant factors of the severity of the final lesion. The spleen plays a major part in the inflammatory response to HI. This study assessed the temporal progression of HI-induced alterations in oxidative stress parameters in the hippocampus, the most affected brain structure, and in the spleen. HI was induced in Wistar rat pups in post-natal day 7. Production of reactive oxygen species (ROS), and the activity of the anti oxidant enzyme superoxide dismutase and catalase were assessed 24 h, 96 h and 38 days post-HI. Interestingly, both structures showed a similar pattern, with few alterations in the production of ROS species up to 96 h often combined with an increased activity of the anti oxidant enzymes. However, 38 days after the injury, ROS were at the highest in both structures, coupled with a decrease in the activity of the enzymes. Altogether, present results suggest that HI causes long lasting alterations in the hippocampus as well as in the spleen, suggesting a possible target for delayed treatments for HI.

Forced Treadmill Exercise Prevents Spatial Memory Deficits in Aged Rats Probably Through the Activation of Na+, K+-ATPase in the Hippocampus.

Regular physical activity has shown to improve the quality of life and to prevent age-related memory deficits. Memory processing requires proper regulation of several enzymes such as sodium-potassium adenosine triphosphatase (Na+, K+-ATPase) and acetylcholinesterase (AChE), which have a pivotal role in neuronal transmission. The present study investigated the effects of a treadmill running protocol in young (3 months), mature (6 months) and aged (22 months) Wistar rats, on: (a) cognitive function, as assessed in the Water maze spatial tasks; (b) Na+, K+-ATPase and AChE activities in the hippocampus following cognitive training alone or treadmill running combined with cognitive training. Animals of all ages were assigned to naïve (with no behavioral or exercise training), sedentary (non-exercised, with cognitive training) and exercised (20 min of daily running sessions, 3 times per week for 4 weeks and with cognitive training) groups. Cognition was assessed by reference and working memory tasks run in the Morris Water maze; 24 h after last session of behavioral testing, hippocampi were collected for biochemical analysis. Results demonstrated that: (a) a moderate treadmill running exercise prevented spatial learning and memory deficits in aged rats; (b) training in the Water maze increased both Na+, K+-ATPase and AChE activities in the hippocampus of mature and aged rats; (c) aged exercised rats displayed an even further increase of Na+, K+-ATPase activity in the hippocampus, (d) enzyme activity correlated with memory performance in aged rats. It is suggested that exercise prevents spatial memory deficits in aged rats probably through the activation of Na+, K+-ATPase in the hippocampus.

Characterization of Amino Acid Profile and Enzymatic Activity in Adult Rat Astrocyte Cultures.

Astrocytes are multitasking players in brain complexity, possessing several receptors and mechanisms to detect, participate and modulate neuronal communication. The functionality of astrocytes has been mainly unraveled through the study of primary astrocyte cultures, and recently our research group characterized a model of astrocyte cultures derived from adult Wistar rats. We, herein, aim to characterize other basal functions of these cells to explore the potential of this model for studying the adult brain. To characterize the astrocytic phenotype, we determined the presence of GFAP, GLAST and GLT 1 proteins in cells by immunofluorescence. Next, we determined the concentrations of thirteen amino acids, ATP, ADP, adenosine and calcium in astrocyte cultures, as well as the activities of Na(+)/K(+)-ATPase and acetylcholine esterase. Furthermore, we assessed the presence of the GABA transporter 1 (GAT 1) and cannabinoid receptor 1 (CB 1) in the astrocytes. Cells demonstrated the presence of glutamine, consistent with their role in the glutamate-glutamine cycle, as well as glutamate and D-serine, amino acids classically known to act as gliotransmitters. ATP was produced and released by the cells and ADP was consumed. Calcium levels were in agreement with those reported in the literature, as were the enzymatic activities measured. The presence of GAT 1 was detected, but the presence of CB 1 was not, suggesting a decreased neuroprotective capacity in adult astrocytes under in vitro conditions. Taken together, our results show cellular functionality regarding the astrocytic role in gliotransmission and neurotransmitter management since they are able to produce and release gliotransmitters and to modulate the cholinergic and GABAergic systems.

Lipid, Oxidative and Inflammatory Profile and Alterations in the Enzymes Paraoxonase and Butyrylcholinesterase in Plasma of Patients with Homocystinuria Due CBS Deficiency: The Vitamin B12 and Folic Acid Importance.

Cystathionine-ß-synthase (CBS) deficiency is the main cause of homocystinuria. Homocysteine (Hcy), methionine, and other metabolites of Hcy accumulate in the body of affected patients. Despite the fact that thromboembolism represents the major cause of morbidity in CBS-deficient patients, the mechanisms of cardiovascular alterations found in homocystinuria remain unclear. In this work, we evaluated the lipid and inflammatory profile, oxidative protein damage, and the activities of the enzymes paraoxonase (PON1) and butyrylcholinesterase (BuChE) in plasma of CBS-deficient patients at diagnosis and during the treatment (protein-restricted diet supplemented with pyridoxine, folic acid, betaine, and vitamin B12). We also investigated the effect of folic acid and vitamin B12 on these parameters. We found a significant decrease in HDL cholesterol and apolipoprotein A1 (ApoA-1) levels, as well as in PON1 activity in both untreated and treated CBS-deficient patients when compared to controls. BuChE activity and IL-6 levels were significantly increased in not treated patients. Furthermore, significant positive correlations between PON1 activity and sulphydryl groups and between IL-6 levels and carbonyl content were verified. Moreover, vitamin B12 was positively correlated with PON1 and ApoA-1 levels, while folic acid was inversely correlated with total Hcy concentration, demonstrating the importance of this treatment. Our results also demonstrated that CBS-deficient patients presented important alterations in biochemical parameters, possibly caused by the metabolites of Hcy, as well as by oxidative stress, and that the adequate adherence to the treatment is essential to revert or prevent these alterations.

Effect of physical exercise on changes in activities of creatine kinase, cytochrome c oxidase and ATP levels caused by ovariectomy.

The reduction in the secretion of ovarian hormones, principally estrogen, is a consequence of menopause. Estrogens act primarily as female sex hormones, but also exert effects on different physiological systems including the central nervous system. The treatment normally used to reduce the symptoms of menopause is the hormone therapy, which seems to be effective in treating symptoms, but it may be responsible for adverse effects. Based on this, there is an increasing demand for alternative therapies that minimize signs and symptoms of menopause. In the present study we investigated the effect of ovariectomy and/or physical exercise on the activities of energy metabolism enzymes, such as creatine kinase (cytosolic and mitochondrial fractions), pyruvate kinase, succinate dehydrogenase, complex II, cytochrome c oxidase, as well as on ATP levels in the hippocampus of adult rats. Adult female Wistar rats with 90 days of age were subjected to ovariectomy (an animal model widely used to mimic the postmenopausal changes). Thirty days after the procedure, the rats were submitted to the exercise protocol, which was performed three times a week for 30 days. Twelve hours after the last training session, the rats were decapitated for subsequent biochemical analyzes. Results showed that ovariectomy did not affect the activities of pyruvate kinase, succinate dehydrogenase and complex II, but decreased the activities of creatine kinase (cytosolic and mitochondrial fractions) and cytochrome c oxidase. ATP levels were also reduced. Exercise did not produce the expected results since it was only able to partially reverse the activity of creatine kinase cytosolic fraction. The results of this study suggest that estrogen deficiency, which occurs as a result of ovariectomy, affects generation systems and energy homeostasis, reducing ATP levels in hippocampus of adult female rats.

Study of antidepressant-like activity of an enriched phloroglucinol fraction obtained from Hypericum caprifoliatum.

CONTEXT: Hypericum caprifoliatum Cham & Schlecht (Guttiferae) extracts have a potential antidepressant-like effect in rodents. However, the molecular mechanisms by which these extracts exert this effect remain unclear. OBJECTIVE: This study evaluated the effect of HC1, a fraction obtained from H. caprifoliatum enriched in phloroglucinol derivatives, on the Na⁺, K⁺ ATPase activity in mouse brain and verified the influence of veratrine on the effect of HC1 in the forced swimming test (FST). MATERIALS AND METHODS: Veratrine (0.06 mg/kg) and HC1 (360 mg/kg) were given alone or combined i.p. 60 and p.o. 30 min, respectively, before FST. The effect of single and repeated administration (once a day for 3 consecutive days) of HC1 (360 mg/kg) on Na⁺, K⁺ ATPase activity was evaluated ex vivo in the cerebral cortex and hippocampus of mice subjected or not to FST. RESULTS: HC1 reduced the immobility time (103.15 ± 18.67 s), when compared to the control group (183.6 ± 9.51 s). This effect was prevented by veratrine (151.75 ± 22.19 s). Mice repeatedly treated with HC1 presented a significant increase in Na⁺, K⁺ ATPase activity, both in cerebral cortex (46 ± 2.41 nmol Pi/min·mg protein) and hippocampus (49.83 ± 2.31 nmol Pi/min·mg protein), in relation to the respective controls (30 ± 2.66 and 29.83 ± 2.31 nmol Pi/min·mg protein respectively). DISCUSSION AND CONCLUSION: The HC1 antidepressant-like effect on FST might be related to its capacity to inhibit Na⁺ influx. HC1 increases hippocampal and cortical Na⁺, K⁺ ATPase activities possibly through long-term regulatory mechanisms.

Mild hyperhomocysteinemia reduces the activity and immunocontent, but does not alter the gene expression, of catalytic α subunits of cerebral Na+,K+-ATPase.

Na(+),K(+)-ATPase is a membrane protein which plays a key role in the maintenance of ion homeostasis that is necessary to neuronal excitability, secondary transport and neurotransmitter uptake. Mild hyperhomocysteinemia leads to several clinical manifestations and particularly cerebral diseases; however, little is known about the mechanisms of homocysteine on cerebral Na(+),K(+)-ATPase. In the present study, we investigated the effect of mild hyperhomocysteinemia on the activity, the immunocontent of catalytic subunits (α1, α2, and α3) and the gene expression of this enzyme. We used the experimental model of mild hyperhomocysteinemia that was induced by homocysteine administration (0.03 µmol/g of body weight) twice a day, from the 30th to the 60th postpartum day. Controls received saline in the same volumes. Results showed that mild hyperhomocysteinemia significantly decreased the activity and the immunocontent of the α 1 and α 2 subunits of the Na(+),K(+)-ATPase in cerebral cortex and hippocampus of adult rats. On the other hand, we did not observe any change in levels of Na(+),K(+)-ATPase mRNA transcripts in such cerebral structures of rats after chronic exposure to homocysteine. The present findings support that the homocysteine modulates the Na(+),K(+)-ATPase and this could be associated, at least in part, with the risk to the development of cerebral diseases in individuals with mild hyperhomocysteinemia.

Homocysteine induces energy imbalance in rat skeletal muscle: is creatine a protector?

Homocystinuria is a neurometabolic disease caused by a severe deficiency of cystathionine beta-synthase activity, resulting in severe hyperhomocysteinemia. Affected patients present several symptoms including a variable degree of motor dysfunction. In this study, we investigated the effect of chronic hyperhomocysteinemia on the cell viability of the mitochondrion, as well as on some parameters of energy metabolism, such as glucose oxidation and activities of pyruvate kinase, citrate synthase, isocitrate dehydrogenase, malate dehydrogenase, respiratory chain complexes and creatine kinase in gastrocnemius rat skeletal muscle. We also evaluated the effect of creatine on biochemical alterations elicited by hyperhomocysteinemia. Wistar rats received daily subcutaneous injections of homocysteine (0.3-0.6 µmol/g body weight) and/or creatine (50 mg/kg body weight) from the 6th to the 28th days of age. The animals were decapitated 12 h after the last injection. Homocysteine decreased the cell viability of the mitochondrion and the activities of pyruvate kinase and creatine kinase. Succinate dehydrogenase was increased other evaluated parameters were not changed by this amino acid. Creatine, when combined with homocysteine, prevented or caused a synergistic effect on some changes provoked by this amino acid. Creatine per se or creatine plus homocysteine altered glucose oxidation. These findings provide insights into the mechanisms by which homocysteine exerts its effects on skeletal muscle function, more studies are needed to elucidate them. Although creatine prevents some alterations caused by homocysteine, it should be used with caution, mainly in healthy individuals because it could change the homeostasis of normal physiological functions.

Folic acid prevents behavioral impairment and Na(+), K(+) -ATPase inhibition caused by neonatal hypoxia-ischemia.

Folic acid plays an important role in neuroplasticity and acts as a neuroprotective agent, as observed in experimental brain ischemia studies. The aim of this study was to investigate the effects of folic acid on locomotor activity, aversive memory and Na(+),K(+)-ATPase activity in the frontal cortex and striatum in animals subjected to neonatal hypoxia-ischemia (HI). Wistar rats of both sexes at postnatal day 7 underwent HI procedure and were treated with intraperitoneal injections of folic acid (0.011 µmol/g body weight) once a day, until the 30th postnatal day. Starting on the day after, behavioral assessment was run in the open field and in the inhibitory avoidance task. Animals were sacrificed by decapitation 24 h after testing and striatum and frontal cortex were dissected out for Na(+),K(+)-ATPase activity analysis. Results show anxiogenic effect in the open field and an impairment of aversive memory in the inhibitory avoidance test in HI rats; folic acid treatment prevented both behavioral effects. A decreased Na(+),K(+)-ATPase activity in striatum, both ipsilateral and contralateral to ischemia, was identified after HI; a total recovery was observed in animals treated with folic acid. A partial recovery of Na(+),K(+)-ATPase activity was yet seen in frontal cortex of HI animals receiving folic acid supplementation. Presented results support that folic acid treatment prevents memory deficit and anxiety-like behavior, as well as prevents Na(+),K(+)-ATPase inhibition in the striatum and frontal cortex caused by neonatal hypoxia-ischemia.

The beneficial effects of treadmill step training on activity-dependent synaptic and cellular plasticity markers after complete spinal cord injury.

Several studies have shown that treadmill training improves neurological outcomes and promotes plasticity in lumbar spinal cord of spinal animals. The morphological and biochemical mechanisms underlying these phenomena remain unclear. The purpose of this study was to provide evidence of activity-dependent plasticity in spinal cord segment (L5) below a complete spinal cord transection (SCT) at T8-9 in rats in which the lower spinal cord segments have been fully separated from supraspinal control and that subsequently underwent treadmill step training. Five days after SCT, spinal animals started a step-training program on a treadmill with partial body weight support and manual step help. Hindlimb movements were evaluated over time and scored on the basis of the open-field BBB scale and were significantly improved at post-injury weeks 8 and 10 in trained spinal animals. Treadmill training also showed normalization of withdrawal reflex in trained spinal animals, which was significantly different from the untrained animals at post-injury weeks 8 and 10. Additionally, compared to controls, spinal rats had alpha motoneuronal soma size atrophy and reduced synaptophysin protein expression and Na(+), K(+)-ATPase activity in lumbar spinal cord. Step-trained rats had motoneuronal soma size, synaptophysin expression and Na(+), K(+)-ATPase activity similar to control animals. These findings suggest that treadmill step training can promote activity-dependent neural plasticity in lumbar spinal cord, which may lead to neurological improvements without supraspinal descending control after complete spinal cord injury.

Creatine prevents the inhibition of energy metabolism and lipid peroxidation in rats subjected to GAA administration.

Guanidinoacetate methyltransferase (GAMT) deficiency is an inherited neurometabolic disorder, biochemically characterized by the tissue accumulation of guanidinoacetate (GAA). Affected patients present epilepsy and mental retardation whose etiopathogeny is unclear. Previous reports have shown that GAA alters brain energy metabolism and that creatine, which is depleted in patients with GAMT deficiency, can act as a neuroprotector; as such, in the present study we investigated the effect of creatine administration on some of the altered parameters of energy metabolism (complex II, Na(+),K(+)-ATPase and creatine kinase) and lipid peroxidation caused by intrastriatal administration of GAA in adult rats. Animals were pretreated for 7 days with daily intraperitonial administrations of creatine. Subsequently, these animals were divided into two groups: Group 1 (sham group), rats that suffered surgery and received saline; and group 2 (GAA-treated). Thirty min after GAA or saline, the animals were sacrificed and the striatum dissected out. Results showed that the administration of creatine was able to reverse the activities of complex II, Na(+),K(+)-ATPase and creatine kinase, as well as, the levels of thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation. These findings indicate that the energy metabolism deficit caused by GAA may be prevented by creatine, which probably acts as an antioxidant since it was able to prevent lipid peroxidation. These data may contribute, at least in part, to a better understanding of the mechanisms related to the energy deficit and oxidative stress observed in GAMT deficiency.

Proline impairs energy metabolism in cerebral cortex of young rats.

In the present study we investigated the effect of acute hyperprolinemia on some parameters of energy metabolism, including the activities of succinate dehydrogenase and cytocrome c oxidase and (14)CO(2) production from glucose and acetate in cerebral cortex of young rats. Lipid peroxidation determined by the levels of thiobarbituric acid-reactive substances, as well as the influence of the antioxidants alpha-tocopherol plus ascorbic acid on the effects elicited by Pro on enzyme activities and on the lipid peroxidation were also evaluated. Wistar rats of 12 and 29 days of life received one subcutaneous injection of saline or proline (12.8 or 18.2 micromol/g body weight, respectively) and were sacrificed 1 h later. In another set of experiments, 5- and 22-day-old rats were pretreated for a week with daily intraperitoneal administration of alpha-tocopherol (40 mg/kg) plus ascorbic acid (100 mg/kg) or saline. Twelve hours after the last injection, rats received one injection of proline or saline and were sacrificed 1 h later. Results showed that acute administration of proline significantly reduced cytochrome c oxidase activity and increased succinate dehydrogenase activity and (14)CO(2) production in cerebral cortex, suggesting that Pro might disrupt energy metabolism in brain of young rats. In addition, proline administration increased the thiobarbituric acid-reactive substances levels, which were prevented by antioxidants. These findings suggest that mitochondrial dysfunction and oxidative stress may be important contributors to the neurological dysfunction observed in some hyperprolinemic patients and that treatment with antioxidants may be beneficial in this pathology.

Biochemical effects of pretreatment with vitamins E and C in rats submitted to intrastriatal hypoxanthine administration.

We previously demonstrated that intrastriatal injection of hypoxanthine, the major metabolite accumulating in Lesch-Nyhan disease, inhibited Na+,K+-ATPase activity and induced oxidative stress in rat striatum. In the present study, we evaluated the action of vitamins E and C on the biochemical alteration induced by hypoxanthine administration on Na+,K+-ATPase, TBARS, TRAP, as well as on superoxide dismutase (SOD), catalase (CAT) and glutathione-peroxidase (GPx) activities in striatum of adult rats. Animals received pretreatment with vitamins E and C or saline during 7 days. Twelve hours after the last injection of vitamins or saline, animals were divided into two groups: (1) vehicle-injected group and (2) hypoxanthine-injected group. For all parameters investigated in this research, animals were sacrificed 30 min after drug infusion. Results showed that pretreatment with vitamins E and C prevented hypoxanthine-mediated effects on Na+,K+-ATPase, TBARS and antioxidant enzymes (SOD, CAT and GPx) activities; however the reduction on TRAP was not prevented by these vitamins. Although extrapolation of findings from animal experiments to humans is difficult, it is conceivable that these vitamins might serve as an adjuvant therapy in order to avoid progression of striatal damage in patients affected by Lesch-Nyhan disease.

Homocysteine Induces Glial Reactivity in Adult Rat Astrocyte Cultures.

Astrocytes are dynamic glial cells associated to neurotransmitter systems, metabolic functions, antioxidant defense, and inflammatory response, maintaining the brain homeostasis. Elevated concentrations of homocysteine (Hcy) are involved in the pathogenesis of age-related neurodegenerative disorders, such as Parkinson and Alzheimer diseases. In line with this, our hypothesis was that Hcy could promote glial reactivity in a model of cortical primary astrocyte cultures from adult Wistar rats. Thus, cortical astrocytes were incubated with different concentrations of Hcy (10, 30, and 100 µM) during 24 h. After the treatment, we analyzed cell viability, morphological parameters, antioxidant defenses, and inflammatory response. Hcy did not induce any alteration in cell viability; however, it was able to induce cytoskeleton rearrangement. The treatment with Hcy also promoted a significant decrease in the activities of Na+, K+ ATPase, superoxide dismutase (SOD), and glutathione peroxidase (GPx), as well as in the glutathione (GSH) content. Additionally, Hcy induced an increase in the pro-inflammatory cytokine release. In an attempt to elucidate the putative mechanisms involved in the Hcy-induced glial reactivity, we measured the nuclear factor kappa B (NFκB) transcriptional activity and heme oxygenase 1 (HO-1) expression, which were activated and inhibited by Hcy, respectively. In summary, our findings provide important evidences that Hcy modulates critical astrocyte parameters from adult rats, which might be associated to the aging process.

Neonatal handling impairs intradimensional shift and alters plasticity markers in the medial prefrontal cortex of adult rats.

Stress response can be modulated by neonatal/childhood events. Neonatal handling (NH) is an animal model in which the animals are subjected to brief separations from the dam during the first days of life, and it leads to lower emotionality and behavioral changes in adulthood. The aim of this study was to observe if early events, such as (NH), may program associative learning and behavioral flexibility in adult male rats and if these changes could be related to altered neurochemistry in the medial prefrontal cortex (mPFC). We evaluated proteins related to synaptic plasticity (brain-derived neurotrophic factor [BDNF] and synaptophysin [SYP]) as well as Na+/K+-ATPase activity. Additionally, we evaluated proteins related to the dopaminergic system (tyrosine hydroxylase [TH] and phosphorylated TH [pTH]), since this system appears to be affected in some neonatal interventions. Neonatally handled animals exhibited impairment in simple discrimination and intradimensional shift but not in reversal or compound discrimination; in addition, no alteration in switching from an egocentric spatial to a cued strategy was observed. These effects were accompanied by a decrease in SYP levels and Na+/K+-ATPase activity, suggesting reduced synaptic function. These results indicate that NH increases attention to irrelevant stimuli and/or impairs associative learning, and this is accompanied by neurochemical alterations in the (mPFC).

Treadmill running prevents age-related memory deficit and alters neurotrophic factors and oxidative damage in the hippocampus of Wistar rats.

Clinical and pre-clinical studies indicate that exercise is beneficial to many aspects of brain function especially during aging. The present study investigated the effects of a treadmill running protocol in young (3month-old) and aged (22month-old) male Wistar rats, on: I) cognitive function, as assessed by spatial reference memory in the Morris water maze; II) oxidative stress parameters and the expression of neurotrophic factors BDNF, NT-3, IGF-1 and VEGF in the hippocampus. Animals of both ages were assigned to sedentary (non-exercised) and exercised (20min of daily running sessions, 3 times per week for 4weeks) groups. Cognition was assessed by a reference memory task run in the Morris water maze; twenty four hours after last session of behavioral testing hippocampi were collected for biochemical analysis. Results demonstrate that the moderate treadmill running exercise: I) prevented age-related deficits in reference memory in the Morris water maze; II) prevented the age-related increase of reactive oxygen species levels and lipid peroxidation in the hippocampus; III) caused an increase of BDNF, NT-3 and IGF-1 expression in the hippocampus of aged rats. Taken together, results suggest that both exercise molecular effects, namely the reduction of oxidative stress and the increase of neurotrophic factors expression in the hippocampus, might be related to its positive effect on memory performance in aged rats.

Severe Hyperhomocysteinemia Decreases Creatine Kinase Activity and Causes Memory Impairment: Neuroprotective Role of Creatine.

In the present study, we investigate the effect of severe hyperhomocysteinemia on biochemical (creatine kinase activity), behavioral (memory tests), and histological assessments (hippocampal volume). A possible neuroprotective role of creatine on hyperhomocysteinemia effects was also evaluated. Severe hyperhomocysteinemia was induced in neonate rats (starting at 6 days of age) by treatment with homocysteine (0.3-0.6 µmol/g body weight) for 23 days. Creatine (50 mg/kg body weight) was administered concomitantly with homocysteine. Controls received saline in the same volumes. Twelve hours after the last injection, the rats were submitted to behavioral tests [(recognition task (NOR)] and inhibitory avoidance (IA)]. Following behavioral assessment, the animals were perfused and decapitated, the brain removed for subsequent morphological analysis of the hippocampus. Another group of animals was used to test creatine kinase activity in hippocampus. The results showed that rats treated with homocysteine decreased (44%) the exploration of the novel object in NOR. In the IA task, homocysteine-treated animals presented decreased latencies to step down the platform in short- (32%) and long-term (18%) testings (3 h and 7 days, respectively), evidencing aversive memory impairment. Hippocampal volume was not altered by homocysteine administration. Hyperhomocysteinemia decreased (45%) creatine kinase activity, and creatine was able to prevent such effect probably by creatine kinase/phosphocreatine/creatine homeostasis, which serves as energy circuit within of the cell. This finding may be associated, at least in part, with memory improvement, suggesting that creatine might represent an effective adjuvant to protect against the effects of high homocysteine plasma levels.

Effects of previous physical exercise to chronic stress on long-term aversive memory and oxidative stress in amygdala and hippocampus of rats.

Since stressful situations are considered risk factors for the development of depression and there are few studies evaluating prevention therapies for this disease, in the present study we evaluated the effect of previous physical exercise in animals subjected to chronic variable stress (CVS), an animal model of depression, on behavior tasks. We also investigated some parameters of oxidative stress and Na+, K+-ATPase activity, immunocontent and gene expression of alpha subunits in amygdala and hippocampus of rats. Young male rats were randomized into four study groups (control, exercised, stressed, exercised+stressed). The animals were subjected to controlled exercise treadmill for 20min,three times a week, for two months prior to submission to the CVS (40days). Results show that CVS impaired performance in inhibitory avoidance at 24h and 7days after training session. CVS induced oxidative stress, increasing reactive species, lipoperoxidation and protein damage, and decreasing the activity of antioxidant enzymes. The activity of Na+, K+-ATPase was decreased, but the immunocontents and gene expression of catalytic subunits were not altered. The previous physical exercise was able to improve performance in inhibitory avoidance at 24h after training; additionally, exercise prevented oxidative damage, but was unable to reverse completely the changes observed on the enzymatic activities. Our findings suggest that physical exercise during the developmental period may protect against aversive memory impairment and brain oxidative damage caused by chronic stress exposure later in life.

Vitamin D3 Reverses the Hippocampal Cytoskeleton Imbalance But Not Memory Deficits Caused by Ovariectomy in Adult Wistar Rats.

The objective of study was to investigate changes caused by ovariectomy (OVX) on aversive and non-aversive memories, as well as on cytoskeleton phosphorylating system and on vitamin D receptor (VDR) immunocontent in hippocampus. The neuroprotective role of vitamin D was also investigated. Ninety-day-old female Wistar rats were divided into four groups: SHAM, OVX, VITAMIN D and OVX + VITAMIN D; 30 days after the OVX, vitamin D supplementation (500 IU/kg), by gavage, for 30 days was started. Results showed that OVX impaired short-term and long-term recognition, and long-term aversive memories. OVX altered hippocampal cytoskeleton phosphorylating system, evidenced by the hyperphosphorylation of glial fibrillary acidic protein (GFAP), low molecular weight neurofilament subunit (NFL), medium molecular weight neurofilament subunit (NFM) and high molecular weight neurofilament subunit (NFH), and increased the immunocontent of c-Jun N-terminal protein kinases (JNK), Ca2+/calmodulin-dependent protein kinase II (PKCaMII) and of the sites phosphorylated lysine-serine-proline (KSP) repeats, Ser55 and Ser57. Vitamin D reversed the effects caused by OVX on cytoskeleton in hippocampus, but it was not able to reverse the effects on memory.