Mild Hyperhomocysteinemia Causes Anxiety-like Behavior and Brain Hyperactivity in Rodents: Are ATPase and Excitotoxicity by NMDA Receptor Overstimulation Involved in this Effect?

Mild hyperhomocysteinemia is a risk factor for psychiatric and neurodegenerative diseases, whose mechanisms between them are not well-known. In the present study, we evaluated the emotional behavior and neurochemical pathways (ATPases, glutamate homeostasis, and cell viability) in amygdala and prefrontal cortex rats subjected to mild hyperhomocysteinemia (in vivo studies). The ex vivo effect of homocysteine on ATPases and redox status, as well as on NMDAR antagonism by MK-801 in same structures slices were also performed. Wistar male rats received a subcutaneous injection of 0.03 µmol Homocysteine/g of body weight or saline, twice a day from 30 to 60th-67th days of life. Hyperhomocysteinemia increased anxiety-like behavior and tended to alter locomotion/exploration of rats, whereas sucrose preference and forced swimming tests were not altered. Glutamate uptake was not changed, but the activities of glutamine synthetase and ATPases were increased. Cell viability was not altered. Ex vivo studies (slices) showed that homocysteine altered ATPases and redox status and that MK801, an NMDAR antagonist, protected amygdala (partially) and prefrontal cortex (totally) effects. Taken together, data showed that mild hyperhomocysteinemia impairs the emotional behavior, which may be associated with changes in ATPase and glutamate homeostasis, including glutamine synthetase and NMDAR overstimulation that could lead to excitotoxicity. These findings may be associated with the homocysteine risk factor on psychiatric disorders development and neurodegeneration.

Sulforaphane Induces Glioprotection After LPS Challenge.

Sulforaphane is a natural compound that presents anti-inflammatory and antioxidant properties, including in the central nervous system (CNS). Astroglial cells are involved in several functions to maintain brain homeostasis, actively participating in the inflammatory response and antioxidant defense systems. We, herein, investigated the potential mechanisms involved in the glioprotective effects of sulforaphane in the C6 astrocyte cell line, when challenged with the inflammogen, lipopolysaccharide (LPS). Sulforaphane prevented the LPS-induced increase in the expression and/or release of pro-inflammatory mediators, possibly due to nuclear factor κB and hypoxia-inducible factor-1α activation. Sulforaphane also modulated the expressions of the Toll-like and adenosine receptors, which often mediate inflammatory processes induced by LPS. Additionally, sulforaphane increased the mRNA levels of nuclear factor erythroid-derived 2-like 2 (Nrf2) and heme oxygenase-1 (HO1), both of which mediate several cytoprotective responses. Sulforaphane also prevented the increase in NADPH oxidase activity and the elevations of superoxide and 3-nitrotyrosine that were stimulated by LPS. In addition, sulforaphane and LPS modulated superoxide dismutase activity and glutathione metabolism. Interestingly, the anti-inflammatory and antioxidant effects of sulforaphane were blocked by HO1 pharmacological inhibition, suggesting its dependence on HO1 activity. Finally, in support of a glioprotective role, sulforaphane prevented the LPS-induced decrease in glutamate uptake, glutamine synthetase activity, and glial-derived neurotrophic factor (GDNF) levels, as well as the augmentations in S100B release and Na+, K+ ATPase activity. To our knowledge, this is the first study that has comprehensively explored the glioprotective effects of sulforaphane on astroglial cells, reinforcing the beneficial effects of sulforaphane on astroglial functionality.

Paternal exposure to excessive methionine altered behavior and neurochemical activities in zebrafish offspring.

An increase in plasma L-methionine (Met) levels, even if transitory, can cause important toxicological alterations in the affected individuals. Met is essential in the regulation of epigenetic mechanisms and its influence on the subsequent generation has been investigated. However, few studies have explored the influence of a temporary increase in Met levels in parents on their offspring. This study evaluated the behavioral and neurochemical effects of parental exposure to high Met concentration (3 mM) in zebrafish offspring. Adult zebrafish were exposed to Met for 7 days, maintained for additional 7 days in tanks that contained only water, and then used for breeding. The offspring obtained from these fish (F1) were tested in this study. During the early stages of offspring development, morphology, heart rate, survival, locomotion, and anxiety-like behavior were assessed. When these animals reached the adult stage, locomotion, anxiety, aggression, social interaction, memory, oxidative stress, and levels of amino acids and neurotransmitters were analyzed. F1 larvae Met group presented an increase in the distance and mean speed when compared to the control group. F1 adult Met group showed decreased anxiety-like behavior and locomotion. An increase in reactive oxygen species was also observed in the F1 adult Met group whereas lipid peroxidation and antioxidant enzymes did not change when compared to the control group. Dopamine, serotonin, glutamate, and glutathione levels were increased in the F1 adult Met group. Taken together, our data show that even a transient increase in Met in parents can cause behavioral and neurochemical changes in the offspring, promoting transgenerational effects.

P2X7 receptor deletion attenuates oxidative stress and liver damage in sepsis.

Sepsis is a severe disease characterized by an uncontrolled systemic inflammation and consequent organ dysfunction generated in response to an infection. Extracellular ATP acting through the P2X7 receptor induces the maturation and release of pro-inflammatory cytokines (i.e., IL-1ß) and the production of reactive nitrogen and oxygen species that lead to oxidative tissue damage. Here, we investigated the role of the P2X7 receptor in inflammation, oxidative stress, and liver injury in sepsis. Sepsis was induced by cecal ligation and puncture (CLP) in wild-type (WT) and P2X7 knockout (P2X7-/-) mice. The oxidative stress in the liver of septic mice was assessed by 2',7'-dichlorofluorescein oxidation reaction (DCF), thiobarbituric acid-reactive substances (TBARS), and nitrite levels dosage. The status of the endogenous defense system was evaluated through catalase (CAT) and superoxide dismutase (SOD) activities. The inflammation was assessed histologically and by determining the expression of inflammatory cytokines and chemokines by RT-qPCR. We observed an increase in the reactive species and lipid peroxidation in the liver of septic WT mice, but not in the liver from P2X7-/- animals. We found an imbalance SOD/CAT ratio, also only WT septic animals. The number of inflammatory cells and the gene expression of IL-1 ß, IL-6, TNF-α, IL-10, CXCL1, and CXCL2 were higher in the liver of WT septic mice in comparison to P2X7-/- septic animals. In summary, our results suggest that the P2X7 receptor might be a therapeutic target to limit oxidative stress damage and liver injury during sepsis.

Neostigmine treatment induces neuroprotection against oxidative stress in cerebral cortex of asthmatic mice.

During chronic inflammatory disease, such asthma, leukocytes can invade the central nervous system (CNS) and together with CNS-resident cells, generate excessive reactive oxygen species (ROS) production as well as disbalance in the antioxidant system, causing oxidative stress, which contributes a large part to neuroinflammation. In this sense, the aim of this study is to investigate the effects of treatment with neostigmine, known for the ability to control lung inflammation, on oxidative stress in the cerebral cortex of asthmatic mice. Female BALB/cJ mice were submitted to asthma model induced by ovalbumin (OVA). Control group received only Dulbecco's phosphate-buffered saline (DPBS). To evaluate neostigmine effects, mice received 80 µg/kg of neostigmine intraperitoneally 30 min after each OVA challenge. Our results revealed for the first time that treatment with neostigmine (an acetylcholinesterase inhibitor that no crosses the BBB) was able to revert ROS production and change anti-oxidant enzyme catalase in the cerebral cortex in asthmatic mice. These results support the communication between the peripheral immune system and the CNS and suggest that acetylcholinesterase inhibitors, such as neostigmine, should be further studied as possible therapeutic strategies for neuroprotection in asthma.

Chronic mild Hyperhomocysteinemia impairs energy metabolism, promotes DNA damage and induces a Nrf2 response to oxidative stress in rats brain.

Homocysteine (HCY) has been linked to oxidative stress and varied metabolic changes that are dependent on its concentration and affected tissues. In the present study we evaluate parameters of energy metabolism [succinate dehydrogenase (SDH), complex II and IV (cytochrome c oxidase), and ATP levels] and oxidative stress [DCFH oxidation, nitrite levels, antioxidant enzymes and lipid, protein and DNA damages, as well as nuclear factor erythroid 2-related (Nrf2) protein abundance] in amygdala and prefrontal cortex of HCY-treated rats. Wistar male rats were treated with a subcutaneous injection of HCY (0.03 µmol/g of body weight) from the 30th to 60th post-natal day, twice a day, to induce mild hyperhomocysteinemia (HHCY). The rats were euthanatized without anesthesia at 12 h after the last injection, and amygdala and prefrontal cortex were dissected for biochemical analyses. In the amygdala, mild HHCY increased activities of SDH and complex II and decreased complex IV and ATP level, as well as increased antioxidant enzymes activities (glutathione peroxidase and superoxide dismutase), nitrite levels, DNA damage, and Nrf 2 protein abundance. In the prefrontal cortex, mild HHCY did not alter energy metabolism, but increased glutathione peroxidase, catalase and DNA damage. Other analyzed parameters were not altered by HCY-treatment. Our findings suggested that chronic mild HHCY changes each brain structure, particularly and specifically. These changes may be associated with the mechanisms by which chronic mild HHCY has been linked to the risk factor of fear, mood disorders and depression, as well as in neurodegenerative diseases.

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.

A Randomized, Open-Label, Non-inferiority Clinical Trial Assessing 7 Versus 14 Days of Antimicrobial Therapy for Severe Multidrug-Resistant Gram-Negative Bacterial Infections: The OPTIMISE Trial Protocol.

INTRODUCTION: Shorter courses of antimicrobials have been shown to be non-inferior to longer, "traditional" duration of therapies, including for some severe healthcare-associated infections, with a few exceptions. However, evidence is lacking regarding shorter regimes against severe infections by multidrug-resistant Gram-negative bacteria (MDR-GNB), which are often caused by distinct strains and commonly treated with second-line antimicrobials. In the duratiOn of theraPy in severe infecTIons by MultIdrug-reSistant gram-nEgative bacteria (OPTIMISE) trial, we aim to assess the non-inferiority of 7-day versus 14-day antimicrobial therapy in critically ill patients with severe infections caused by MDR-GNB. METHODS: This is a randomized, multicenter, open-label, parallel controlled trial to assess the non-inferiority of 7-day versus 14-day of adequate antimicrobial therapy for intensive care unit (ICU)-acquired severe infections by MDR-GNB. Adult patients with severe infections by MDR-GNB initiated after 48 h of ICU admission are screened for eligibility. Patients are eligible if they proved to be hemodynamically stable and without fever for at least 48 h on the 7th day of adequate antimicrobial therapy. After consenting, patients are 1:1 randomized to discontinue antimicrobial therapy on the 7th (± 1) day or to continue for a total of 14th (± 1) days. PLANNED OUTCOMES: The primary outcome is treatment failure, defined as death or relapse of infection within 28 days after randomization. Non-inferiority will be achieved if the upper edge of the two-tailed 95% confidence interval of the difference between the clinical failure rate in the 7-day and the 14-day group is not higher than 10%. CONCLUSION: The OPTIMISE trial is the first randomized controlled trial specifically designed to assess the duration of antimicrobial therapy in patients with severe infections by MDR-GNB. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05210387. Registered on 27 January 2022. Seven Versus 14 Days of Antibiotic Therapy for Multidrug-resistant Gram-negative Bacilli Infections (OPTIMISE).

Resistance exercise was safe for the pregnancy and offspring's development and partially protected rats against early life stress-induced effects.

Promising evidence points to gestational physical exercise as the key to preventing various disorders that affect the offspring neurodevelopment, but there are no studies showing the impact of resistance exercise on offspring health. Thus, the aim of this study was to investigate whether resistance exercise during pregnancy is able to prevent or to alleviate the possible deleterious effects on offspring, caused by early life-stress (ELS). Pregnant rats performed resistance exercise throughout the gestational period:they climbed a sloping ladder with a weight attached to their tail, 3 times a week. Male and female pups, on the day of birth (P0), were divided into 4 experimental groups: 1) rats of sedentary mothers (SED group); 2) rats of exercised mothers (EXE group); 3) rats of sedentary mothers and submitted to maternal separation (ELS group) and 4) rats of exercised mothers and submitted to MS (EXE + ELS group). From P1 to P10, pups from groups 3 and 4 were separated from their mothers for 3 h/day. Maternal behavior was assessed. From P30, behavioral tests were performed and on P38 the animals were euthanized and prefrontal cortex samples were collected. Oxidative stress and tissue damage analysis by Nissl staining were performed. Our results demonstrate that male rats are more susceptible to ELS than females, showing impulsive and hyperactive behavior similar to that seen in children with ADHD. This behavior was attenuated by the gestational resistance exercise. Our results demonstrate, for the first time, that resistance exercise performed during pregnancy seems to be safe for the pregnancy and offspring's neurodevelopment and are effective in preventing ELS-induced damage only in male rats. Interestingly, resistance exercise during pregnancy improved maternal care and it is reasonable to propose that this finding may be related to the protective role on the animals neurodevelopment, observed in our study.

Homocysteine May Decrease Glucose Uptake and Alter the Akt/GSK3ß/GLUT1 Signaling Pathway in Hippocampal Slices: Neuroprotective Effects of Rivastigmine and Ibuprofen.

Homocysteine (Hcy) is a risk factor for neurodegenerative diseases, such as Alzheimer's Disease, and is related to cellular and tissue damage. In the present study, we verified the effect of Hcy on neurochemical parameters (redox homeostasis, neuronal excitability, glucose, and lactate levels) and the Serine/Threonine kinase B (Akt), Glucose synthase kinase-3ß (GSK3ß) and Glucose transporter 1 (GLUT1) signaling pathway in hippocampal slices, as well as the neuroprotective effects of ibuprofen and rivastigmine alone or in combination in such effects. Male Wistar rats (90 days old) were euthanized and the brains were dissected. The hippocampus slices were pre-treated for 30 min [saline medium or Hcy (30 µM)], then the other treatments were added to the medium for another 30 min [ibuprofen, rivastigmine, or ibuprofen + rivastigmine]. The dichlorofluorescein formed, nitrite and Na+, K+-ATPase activity was increased by Hcy at 30 µM. Ibuprofen reduced dichlorofluorescein formation and attenuated the effect of Hcy. The reduced glutathione content was reduced by Hcy. Treatments with ibuprofen and Hcy + ibuprofen increased reduced glutathione. Hcy at 30 µM caused a decrease in hippocampal glucose uptake and GLUT1 expression, and an increase in Glial Fibrillary Acidic Protein-protein expression. Phosphorylated GSK3ß and Akt levels were reduced by Hcy (30 µM) and co-treatment with Hcy + rivastigmine + ibuprofen reversed these effects. Hcy toxicity on glucose metabolism can promote neurological damage. The combination of treatment with rivastigmine + ibuprofen attenuated such effects, probably by regulating the Akt/GSK3ß/GLUT1 signaling pathway. Reversal of Hcy cellular damage by these compounds may be a potential neuroprotective strategy for brain damage.

Effect of Quinolinic Acid on Behavior, Morphology, and Expression of Inflammatory/oxidative Status in Rats' Striatum: Is Coenzyme Q10 a Good Protector?

Quinolinic acid (QUIN) is a toxic compound with pro-oxidant, pro-inflammatory, and pro-apoptotic actions found at high levels in the central nervous system (CNS) in several pathological conditions. Due to the toxicity of QUIN, it is important to evaluate strategies to protect against the damage caused by this metabolite in the brain. In this context, coenzyme Q10 (CoQ10) is a provitamin present in the mitochondria with a protective role in cells through several mechanisms of action. Based on these, the present study was aimed at evaluating the possible neuroprotective role of CoQ10 against damage caused by QUIN in the striatum of young Wistar rats. Twenty-one-day-old rats underwent a 10-day pretreatment with CoQ10 or saline (control) intraperitoneal injections and on the 30th day of life received QUIN intrastriatal or saline (control) administration. The animals were submitted to behavior tests or euthanized, and the striatum was dissected to neurochemical studies. Results showed that CoQ10 was able to prevent behavioral changes (the open field, object recognition, and pole test tasks) and neurochemical parameters (alteration in the gene expression of IL-1ß, IL-6, SOD, and GPx, as well as in the immunocontent of cytoplasmic Nrf2 and nuclear p-Nf-κß) caused by QUIN. These findings demonstrate the promising therapeutic effects of CoQ10 against QUIN toxicity.

Sub­chronic administration of lead alters markers of oxidative stress, acetylcholinesterase and Na+K+­ATPase activities in rat brain.

This study investigated the effects of sub­chronic administration of lead (Pb) acetate on thiobarbituric acid reactive substances (TBA­RS), total sulfhydryl content, protein carbonyl content, antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH­Px]), acetylcholinesterase (AChE), and Na+K+­ATPase in the cerebral structures of rats. Male Wistar rats aged 60 days were treated with saline (control group) or Pb (treatment group), at various doses, by gavage, once a day for 35 days. The animals were sacrificed twelve hours after the last administration, and the cerebellum, hippocampus and cerebral cortex were removed. The results showed that Pb did not alter the evaluated oxidative stress parameters. Furthermore, Pb (64 and/or 128 mg/kg) altered SOD in the cerebellum, cerebral cortex and hippocampus. Pb (128 mg/kg) altered CAT in the cerebellum and cerebral cortex and GSH­Px in the cerebral cortex. Also, Pb (64 mg/kg and 128 mg/kg) altered GSH­Px in the cerebellum. Moreover, Pb (128 mg/kg) increased AChE in the hippocampus and decreased Na+K+­ATPase in the cerebellum and hippocampus. In conclusion, sub­chronic exposure to Pb (occupational and environmental intoxication) altered antioxidant enzymes, AChE, and Na+K+­ATPase, contributing to cerebral dysfunction.

Quinolinic Acid Impairs Redox Homeostasis, Bioenergetic, and Cell Signaling in Rat Striatum Slices: Prevention by Coenzyme Q10.

Quinolinic acid (QUIN) is an important agonist of NMDA receptors that are found at high levels in cases of brain injury and neuroinflammation. Therefore, it is necessary to investigate neuroprotection strategies capable of neutralizing the effects of the QUIN on the brain. Coenzyme Q10 (CoQ10) is a provitamin that has an important antioxidant and anti-inflammatory action. This work aims to evaluate the possible neuroprotective effect of CoQ10 against the toxicity caused by QUIN. Striatal slices from 30-day-old Wistar rats were preincubated with CoQ10 25-100 µM for 15 min; then, QUIN 100 µM was added to the incubation medium for 30 min. A dose-response curve was used to select the CoQ10 concentration to be used in the study. Results showed that QUIN caused changes in the production of ROS, nitrite levels, activities of antioxidant enzymes, glutathione content, and damage to proteins and lipids. CoQ10 was able to prevent the effects caused by QUIN, totally or partially, except for damage to proteins. QUIN also altered the activities of electron transport chain complexes and ATP levels, and CoQ10 prevented totally and partially these effects, respectively. CoQ10 prevented the increase in acetylcholinesterase activity, but not the decrease in the activity of Na+,K+-ATPase caused by QUIN. We also observed that QUIN caused changes in the total ERK and phospho-Akt content, and these effects were partially prevented by CoQ10. These findings suggest that CoQ10 may be a promising therapeutic alternative for neuroprotection against QUIN neurotoxicity.

Rivastigmine Reverses the Decrease in Synapsin and Memory Caused by Homocysteine: Is There Relation to Inflammation?

Elevated levels of homocysteine (Hcy) in the blood, called hyperhomocysteinemia (HHcy), is a prevalent risk factor for it has been shown that Hcy induces oxidative stress and increases microglial activation and neuroinflammation, as well as causes cognitive impairment, which have been linked to the neurodegenerative process. This study aimed to evaluate the effect of mild hyperhomocysteinemia with or without ibuprofen and rivastigmine treatments on the behavior and neurochemical parameters in male rats. The chronic mild HHcy model was chemically induced in Wistar rats by subcutaneous administration of Hcy (4055 mg/kg body weight) twice daily for 30 days. Ibuprofen (40 mg/kg) and rivastigmine (0.5 mg/kg) were administered intraperitoneally once daily. Motor damage (open field, balance beam, rotarod, and vertical pole test), cognitive deficits (Y-maze), neurochemical parameters (oxidative status/antioxidant enzymatic defenses, presynaptic protein synapsin 1, inflammatory profile parameters, calcium binding adapter molecule 1 (Iba1), iNOS gene expression), and cholinergic anti-inflammatory pathway were investigated. Results showed that mild HHcy caused cognitive deficits in working memory, and impaired motor coordination reduced the amount of synapsin 1 protein, altered the neuroinflammatory picture, and caused changes in the activity of catalase and acetylcholinesterase enzymes. Both rivastigmine and ibuprofen treatments were able to mitigate this damage caused by mild HHcy. Together, these neurochemical changes may be associated with the mechanisms by which Hcy has been linked to a risk factor for AD. Treatments with rivastigmine and ibuprofen can effectively reduce the damage caused by increased Hcy levels.

Homocysteine and Gliotoxicity.

Homocysteine is a sulfur amino acid that does not occur in the diet, but it is an essential intermediate in normal mammalian metabolism of methionine. Hyperhomocysteinemia results from dietary intakes of Met, folate, and vitamin B12 and lifestyle or from the deficiency of specific enzymes, leading to tissue accumulation of this amino acid and/or its metabolites. Severe hyperhomocysteinemic patients can present neurological symptoms and structural brain abnormalities, of which the pathogenesis is poorly understood. Moreover, a possible link between homocysteine (mild hyperhomocysteinemia) and neurodegenerative/neuropsychiatric disorders has been suggested. In recent years, increasing evidence has emerged suggesting that astrocyte dysfunction is involved in the neurotoxicity of homocysteine and possibly associated with the physiopathology of hyperhomocysteinemia. This review addresses some of the findings obtained from in vivo and in vitro experimental models, indicating high homocysteine levels as an important neurotoxin determinant of the neuropathophysiology of brain damage. Recent data show that this amino acid impairs glutamate uptake, redox/mitochondrial homeostasis, inflammatory response, and cell signaling pathways. Therefore, the discussion of this review focuses on homocysteine-induced gliotoxicity, and its impacts in the brain functions. Through understanding the Hcy-induced gliotoxicity, novel preventive/therapeutic strategies might emerge for these diseases.

Hyperhomocysteinemia alters cytokine gene expression, cytochrome c oxidase activity and oxidative stress in striatum and cerebellum of rodents.

AIMS: Homocysteine has been linked to neurodegeneration and motor function impairments. In the present study, we evaluate the effect of chronic mild hyperhomocysteinemia on the motor behavior (motor coordination, functional performance, and muscular force) and biochemical parameters (oxidative stress, energy metabolism, gene expression and/or protein abundance of cytokine related to the inflammatory pathways and acetylcholinesterase) in the striatum and cerebellum of Wistar male rats. MAIN METHODS: Rodents were submitted to one injection of homocysteine (0.03 µmol Hcy/g of body weight) between 30th and 60th postnatal days twice a day. After hyperhomocysteinemia induction, rats were submitted to horizontal ladder walking, beam balance, suspension, and vertical pole tests and/or euthanized to brain dissection for biochemical and molecular assays. KEY FINDINGS: Chronic mild hyperhomocysteinemia did not alter motor function, but induced oxidative stress and impaired mitochondrial complex IV activity in both structures. In the striatum, hyperhomocysteinemia decreased TNF-α gene expression and increased IL-1ß gene expression and acetylcholinesterase activity. In the cerebellum, hyperhomocysteinemia increased gene expression of TNF-α, IL-1ß, IL-10, and TGF-ß, while the acetylcholinesterase activity was decreased. In both structures, hyperhomocysteinemia decreased acetylcholinesterase protein abundance without altering total p-NF-κB, NF-κB, Nrf-2, and cleaved caspase-3. SIGNIFICANCE: Chronic mild hyperhomocysteinemia compromises several biochemical/molecular parameters, signaling pathways, oxidative stress, and chronic inflammation in the striatum and cerebellum of rats without impairing motor function. These alterations may be related to the mechanisms in which hyperhomocysteinemia has been linked to movement disorders later in life and neurodegeneration.

Withdrawal Effects Following Methionine Exposure in Adult Zebrafish.

Methionine (Met) has important functions for homeostasis of various species, including zebrafish. However, the increased levels of this amino acid in plasma, a condition known as hypermethioninemia, can lead to cell alterations. Met is crucial for the methylation process and its excesses interfere with the cell cycle, an effect that persists even after the removal of this amino acid. Some conditions may lead to a transient increase of this amino acid with unexplored persistent effects of Met exposure. In the present study, we investigated the behavioral and neurochemical effects after the withdrawal of Met exposure. Zebrafish were divided into two groups: control and Met-treated group (3 mM) for 7 days and after maintained for 8 days in tanks containing only water. In the eighth day post-exposure, we evaluated locomotion, anxiety, aggression, social interaction, and memory, as well as oxidative stress parameters, amino acid, and neurotransmitter levels in the zebrafish brain. Our results showed that 8 days after Met exposure, the treated group showed decreased locomotion and aggressive responses, as well as impaired aversive memory. The Met withdrawal did not change thiobarbituric acid reactive substances, reactive oxygen species, and nitrite levels; however, we observed a decrease in antioxidant enzymes superoxide dismutase, catalase, and total thiols. Epinephrine and cysteine levels were decreased after the Met withdrawal whereas carnitine and creatine levels were elevated. Our findings indicate that a transient increase in Met causes persistent neurotoxicity, observed by behavioral and cognitive changes after Met withdrawal and that the mechanisms underlying these effects are related to changes in antioxidant system, amino acid, and neurotransmitter levels.

Methionine Administration in Pregnant Rats Causes Memory Deficit in the Offspring and Alters Ultrastructure in Brain Tissue.

In the present work, we evaluated the effect of gestational hypermethioninemia on locomotor activity, anxiety, memory, and exploratory behavior of rat offspring through the following behavior tests: open field, object recognition, and inhibitory avoidance. Histological analysis was also done in the brain tissue of pups. Wistar female rats received methionine (2.68 µmol/g body weight) by subcutaneous injections during pregnancy. Control rats received saline. Histological analyses were made in brain tissue from 21 and 30 days of age pups. Another group was left to recover until the 30th day of life to perform behavior tests. Results from open field task showed that pups exposed to methionine during intrauterine development spent more time in the center of the arena. In the object recognition memory task, we observed that methionine administration during pregnancy reduced total exploration time of rat offspring during training session. The test session showed that methionine reduced the recognition index. Regarding to inhibitory avoidance task, the decrease in the step-down latency at 1 and 24 h after training demonstrated that maternal hypermethioninemia impaired short-term and long-term memories of rat offspring. Electron microscopy revealed alterations in the ultrastructure of neurons at 21 and 30 days of age. Our findings suggest that the cell morphological changes caused by maternal hypermethioninemia may be, at least partially, associated to the memory deficit of rat offspring.

Vitamin D Supplementation Reverses DNA Damage and Telomeres Shortening Caused by Ovariectomy in Hippocampus of Wistar Rats.

The aim of this study was to investigate the effect of ovariectomy (OVX), a surgical model of menopause, and/or vitamin D (VIT D) supplementation on oxidative status, DNA damage, and telomere length in hippocampus of rats at two ages. Ninety-day-old (adult) or 180-day-old (older) female Wistar rats were divided into four groups: SHAM, OVX, VIT D, and OVX + VIT D. Thirty days after OVX, rats were supplemented with VIT D (500 IU/kg) by gavage, for a period of 30 days. Results showed that OVX altered antioxidant enzymes, increasing the activities of catalase in adult rats and superoxide dismutase in older rats. VIT D per se increased the activities of catalase and superoxide dismutase in older rats, but not in adult rats. VIT D supplementation to OVX (OVX + VIT D) rats did not reverse the effect of OVX on catalase in adult rats, but it partially reversed the increase in superoxide dismutase activity in older rats. OVX increased DNA damage in hippocampus of adult and older rats. VIT D per se reduced DNA damage, and when associated to OVX, it partially reversed this alteration. Additionally, OVX caused a telomere shortening in older rats, and VIT D was able to reverse such effect. Taken together, these results demonstrate that surgical menopause in rats causes hippocampal biochemical changes and VIT D appears, at least in part, to act in a beneficial way.

Vitamin D partially reverses the increase in p-NF-κB/p65 immunocontent and interleukin-6 levels, but not in acetylcholinesterase activity in hippocampus of adult female ovariectomized rats.

The aim of this study was to verify the effects of ovariectomy (OVX) and/or vitamin D supplementation (VIT D) on inflammatory and cholinergic parameters in hippocampus, as well as on serum estradiol and VIT D levels of rats. Ninety-day-old female Wistar rats were randomly divided into four groups: SHAM, OVX, VIT D or OVX + VIT D. Thirty days after OVX, VIT D (500 IU/kg/day) was supplemented by gavage, for 30 days. Approximately 12 h after the last VIT D administration, rats were euthanized and hippocampus and serum were obtained for further analyses. Results showed that OVX rats presented a decrease in estradiol levels when compared to control (SHAM). There was an increase in VIT D levels in the groups submitted to VIT D supplementation. OVX increased the immunocontent of nuclear p-NF-κB/p65, TNF-α and IL-6 levels. VIT D partially reversed the increase in p-NF-κB/p65 immunocontent and IL-6 levels. Regarding cholinergic system, OVX caused an increase in acetylcholinesterase activity without changing acetylcholinesterase and choline acetyltransferase immunocontents. VIT D did not reverse the increase in acetylcholinesterase activity caused by OVX. These results demonstrate that OVX alters inflammatory and cholinergic parameters and that VIT D supplementation, at the dose used, partially reversed the increase in immunocontent of p-NF-Kb/p65 and IL-6 levels, but it was not able to reverse other parameters studied. Our findings may help in the understanding of the brain changes that occurs in post menopause period and open perspectives for futures research involving VIT D therapies.