Behavior and oxidative stress parameters in rats subjected to the animal's models induced by chronic mild stress and 6-hydroxydopamine.

Major depressive disorder (MDD) is one of the most prevalent forms of mental illness also affecting older adults. Recent evidence suggests a relationship between MDD and neurodegenerative diseases, including Parkinson's disease (PD). Individuals with PD have a predisposition to developing MDD, and both neurobiological conditions are associated with oxidative stress. Thus, we conducted this study to investigate depressive-like behavior and oxidative stress parameters using both animal models of PD and stress. Adult Wistar rats were subjected to chronic mild stress (CMS) protocol by 40 days and then it was used 6-hydroxydopamine (6-OHDA) as a model of PD, into the striatum. The experimental groups were: Control + Sham, Stress + Sham, Control+6-OHDA, and Stress+6-OHDA. Depressive like-behavior was evaluated by the forced swimming test (FST) and spontaneous locomotor activity by open-field test. Oxidative stress parameters were measured in the striatum, hippocampus, and prefrontal cortex (PFC). The results showed effects to increase immobility and decrease climbing times in the FST in Stress + Sham, Control+6-OHDA, and Stress+6-OHDA groups. The number of crossings and rearings were decreased in the Stress+6-OHDA group. The lipid peroxidation was increased in the PFC of Stress + Sham, and the hippocampus and striatum of Stress + Sham and Control+6-OHDA groups. Carbonyl protein levels increased in the PFC of Stress + Sham and striatum in Control+6-OHDA. Nitrite/Nitrate concentration was elevated in the PFC of Stress + Sham, in the hippocampus of Control+6-OHDA, the striatum of Stress + Sham, and Control+6-OHDA groups. Myeloperoxidase (MPO) activity was increased in the PFC and hippocampus of Stress + Sham and Control+6-OHDA groups. The activity of catalase decreased in the PFC of the Stress + Sham group. The activity of the superoxide dismutase (SOD) was decreased in the PFC of the Stress + Sham group, in the hippocampus of Stress + Sham and Control+6-OHDA groups, and the striatum of Control+6-OHDA group. These findings suggest that both stress and 6-OHDA induce depressive-like behavior and oxidative stress in the brain. The joining models have little evidence of the effects. Thus these findings suggest that other pathways are involved in the common point of the pathophysiology of PD and MDD.

Ketamine treatment protects against oxidative damage and the immunological response induced by electroconvulsive therapy.

BACKGROUND: Electroconvulsive therapy (ECT) is often recommended for major depressive disorder (MDD) for those who do not respond to the first and second antidepressant trials. A combination of two therapies could improve antidepressant efficacy. Thus, this study aimed to investigate the synergistic effects of ECT combined to antidepressants with a different mechanism of action. METHODS: Rats were treated once a day, for five days with ketamine (5 mg/kg), fluoxetine (1 mg/kg), and bupropion (4 mg/kg) alone or in combination with ECT (1 mA; 100 V). After, oxidative damage and antioxidant capacity were assessed in the prefrontal cortex (PFC) and hippocampus, and pro-inflammatory cytokines levels were evaluated in the serum. RESULTS: ECT alone increased lipid peroxidation in the PFC and hippocampus. In the PFC of rats treated with ECT in combination with fluoxetine and bupropion, and in the hippocampus of rats treated with ECT combined with ketamine and bupropion there was a reduction in the lipid peroxidation. The nitrite/nitrate was increased by ECT alone but reverted by combination with ketamine in the hippocampus. Superoxide dismutase (SOD) was increased by ECT and maintained by fluoxetine and bupropion in the PFC. ECT alone increased interleukin-1ß (IL-1ß) and the administration of ketamine was able to revert this increase showing a neuroprotective effect of this drug when in combination with ECT. CONCLUSION: The treatment with ECT leads to an increase in oxidative damage and alters the immunological system. The combination with ketamine was able to protect against oxidative damage and the immunological response induced by ECT.

Stanniocalcin 1 Inhibits the Inflammatory Response in Microglia and Protects Against Sepsis-Associated Encephalopathy.

Sepsis-associated encephalopathy is a serious consequence of sepsis, triggered by the host response against an infectious agent, that can lead to brain damage and cognitive impairment. Several mechanisms have been proposed in this bidirectional communication between the immune system and the brain after sepsis as neuroinflammation, oxidative stress, and mitochondrial dysfunction. Stanniocalcin-1 (STC-1), an endogen neuroprotective protein, acts as an anti-inflammatory and suppresses superoxide generation through induction of uncoupling proteins (UCPs) in the mitochondria. Here, we demonstrated a protective role of STC-1 on inflammatory responses in vitro, in activated microglia stimulated with LPS, and on neuroinflammation, oxidative stress, and mitochondrial function in the hippocampus of rats subjected to an animal model of sepsis by cecal ligation and puncture (CLP), as well the consequences on long-term memory. Recombinant human STC-1 (rhSTC1) suppressed the pro-inflammatory cytokine production in LPS-stimulated microglia without changing the UCP-2 expression. Besides, rhSTC1 injected into the cisterna magna decreased acute hippocampal inflammation and oxidative stress and increased the activity of complex I and II activity of mitochondrial respiratory chain and creatine kinase at 24 h after sepsis. rhSTC1 was effective in preventing long-term cognitive impairment after CLP. In conclusion, rhSTC1 confers significant neuroprotection by inhibiting the inflammatory response in microglia and protecting against sepsis-associated encephalopathy in rats.

Sickness Behavior Score Is Associated with Neuroinflammation and Late Behavioral Changes in Polymicrobial Sepsis Animal Model.

The use of reliable scores is a constant development in critical illness. According to Sepsis-3 consensus, the use of Sequential Organ Failure Assessment (SOFA) score of 2 or more is associated with a higher mortality of sepsis patients. In experimental research, due murine animal model limitations, the use of a score systems can be an alternative to assess sepsis severity. In this work, we suggest a sickness behavior score (SBS) that uses physiological variables to assess sepsis severity and mortality. Animals were evaluated daily by the presence of six indicators of sickness behavior: temperature alteration, preference of water/sucrose, liquid intake, food intake, body weight, and movimentation. Male adult Wistar rats were evaluated daily after sepsis induction by cecal ligation and puncture (CLP) or laparotomy only (sham) for determination of SBS. Oxidative stress, IL-6, and HPA axis markers (corticosterone and adrenal gland weight) were evaluated 24 h after CLP to determine the correlation with the acute SBS and neuroinflammation. Also, BDNF and four cognitive behavioral tests were correlated with the chronic SBS, i.e., sum of 8 days after surgery. In result, septic rats presented higher SBS than sham animals. Sepsis severity markers were associated with acute and chronic SBS. Also, SBS was negative correlated with the cognitive tests. In conclusion, SBS shows to be reliable score to predict sepsis severity and mortality. The use of score system provides the analysis of global sickness behavior, beyond evaluation of each parameter individually.

Fish oil-rich lipid emulsion modulates neuroinflammation and prevents long-term cognitive dysfunction after sepsis.

OBJECTIVES: Sepsis is a severe organic dysfunction caused by an infection that affects the normal regulation of several organ systems, including the central nervous system. Inflammation and oxidative stress play crucial roles in the development of brain dysfunction in sepsis. The aim of this study was to determine the effect of a fish oil (FO)-55-enriched lipid emulsion as an important anti-inflammatory compound on brain dysfunction in septic rats. METHODS: Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) or sham (control) and treated orally with FO (600 µL/kg after CLP) or vehicle (saline; sal). Animals were divided into sham+sal, sham+FO, CLP+sal and CLP+FO groups. At 24 h and 10 d after surgery, the hippocampus, prefrontal cortex, and total cortex were obtained and assayed for levels of interleukin (IL)-1ß and IL-10, blood-brain barrier permeability, nitrite/nitrate concentration, myeloperoxidase activity, thiobarbituric acid reactive species formation, protein carbonyls, superoxide dismutase and catalase activity, and brain-derived neurotrophic factor levels. Behavioral tasks were performed 10 d after surgery. RESULTS: FO reduced BBB permeability in the prefrontal cortex and total cortex of septic rats, decreased IL-1ß levels and protein carbonylation in all brain structures, and diminished myeloperoxidase activity in the hippocampus and prefrontal cortex. FO enhanced brain-derived neurotrophic factor levels in the hippocampus and prefrontal cortex and prevented cognitive impairment. CONCLUSIONS: FO diminishes the negative effect of polymicrobial sepsis in the rat brain by reducing inflammatory and oxidative stress markers.

Oxidative stress and mitochondrial dysfunction contributes to postoperative cognitive dysfunction in elderly rats.

Postoperative cognitive dysfunction (POCD) is defined by cognitive impairment determined by neuropsychological tests from before to after surgery. Several mechanisms have been proposed in this bidirectional communication between the immune system and the brain after surgery. We aimed at understanding the mechanisms underlying POCD elderly rats in an experimental tibial fracture model. Elderly male Wistar rats were subjected to tibial fracture (TF) model. Control (sham) and fracture (TF) groups were followed to determine nitrite/nitrate concentration; oxidative damage to lipids and proteins; the activity of antioxidant enzymes (superoxide dismutase-SOD and catalase-CAT), mitochondrial respiratory chain enzymes, and creatine kinase (CK); and BDNF levels in the hippocampus and prefrontal cortex (at 24 h and at seven days) and cognitive function through habituation to the open field task and novel object recognition task (only at seven days). TF group presented increased concentration of nitrite/nitrate, hippocampal lipid peroxidation at seven days, protein oxidative damage in the prefrontal cortex and hippocampus at 24 h, decreased antioxidant activity in both structures on the first postoperative day and compromised function of the mitochondrial respiratory chain complexes as well as the CK enzyme. In addition, the levels of BDNF were reduced and memory function was impaired in the TF group. In conclusion, elderly rats submitted to an experimental model of tibial fracture displayed memory impairment accompanied by an increase in oxidative stress, mitochondrial dysfunction and reduced neurotrophin level.

Dimethyl Fumarate Modulates Oxidative Stress and Inflammation in Organs After Sepsis in Rats.

Sepsis is defined as life-threatening organ dysfunction induced by a disrupted host response to infecting pathogens. Evidences suggest that oxidative stress is intrinsically related to sepsis progression. Dimethyl fumarate (DMF) is a novel oral therapeutic agent with anti-oxidant properties which exerts protective effects through activation of nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2). Thus, the aim of this study is to evaluate the effect of DMF in different organs of rats submitted to an animal model of sepsis. Adult male Wistar rats were subjected to sepsis by cecal ligation and puncture (CLP) procedure and sham-operated rats was considered control group. The experimental groups were divided into sham + vehicle, sham + DMF, sham + NAC, CLP + vehicle, CLP + DMF, and CLP + NAC. Rats were treated by oral gavage with DMF immediately after and 12 h after surgery, or NAC (s.c.) at 3, 6, and 12 h after surgery. Twenty-four hours after sepsis induction, neutrophil infiltration, nitrite/nitrate concentrations, oxidative damage to lipids and proteins, superoxide dismutase (SOD), and catalase (CAT) activities were evaluated in the heart, liver, lung, and kidney. Septic animals presented increased neutrophil infiltration, NO metabolism, oxidative damage to lipids and proteins, and decreases of SOD and CAT activities, mainly in the heart, liver, and lung, while DMF-treated animals showed significant reduction in neutrophil infiltration, NO metabolism, and oxidative damage followed by increased SOD and CAT activities. DMF is effective in preventing oxidative stress and inflammation in rats 24 h after sepsis induction.

Acute treatment with ketamine and chronic treatment with minocycline exert antidepressant-like effects and antioxidant properties in rats subjected different stressful events.

Despite decades of research, the fundamental neurochemical and molecular mechanisms underlying the major depressive disorder (MDD) are still poorly understood, and current antidepressant treatments have limited clinical efficacy. In clinical conditions, the rapprochement between the disease and the corrective actions of drugs in laboratory animals is essential for developing effective therapies. Thus, the aim of this study was to evaluate the antidepressant effects of ketamine (N-metil-d-asparte (NMDA) receptor antagonist), minocycline (tetracycline antibiotic), and amitriptyline (classical antidepressant), on behavior and oxidative stress parameters in animals submitted to the chronic mild stress (CMS) and maternal deprivation protocols. For this aim, male Wistar rats were submitted to maternal deprivation or CMS. To induce maternal deprivation, Wistar rats were deprived of maternal care during the first 10 days of life. To induce CMS, Wistar rats were submitted to the CMS for 40 days. To reverse the effects of stress, treatment was done intraperitoneally with a single dose of ketamine (15 mg/kg), and minocycline (25 mg/kg) and amitriptyline (10 mg/kg) by 20 days. After treatment, the animals were submitted to the forced swimming test and then analyzed oxidative stress parameters in the prefrontal cortex (PFC), hippocampus, amygdala and nucleus accumbens (NAc). Treatment with ketamine, minocycline and amitriptyline were able to exert antidepressant effects in the forced swimming test. However, these antidepressant effects were dependent on the stress model by which the animals were exposed. In certain brain regions some treatment strategies had a pro-oxidant effect. Though, most of the strategies used in this study had antioxidant effects, as reported by a decrease on protein and lipid damage, nitrite/nitrate concentration and myeloperoxidase activity. In addition, an increase in the antioxidant superoxide dismutase (SOD) and catalase (CAT) enzymes activities were also evident after treatments. In conclusion, the antidepressant effects of ketamine and minocycline, in the present study, may be associated, at least in part, with its antioxidant and neuroprotective effects in animals subjected to maternal deprivation or CMS.

Alpha-lipoic acid attenuates acute neuroinflammation and long-term cognitive impairment after polymicrobial sepsis.

Sepsis is a complication of an infection which imbalance the normal regulation of several organ systems, including the central nervous system (CNS). Evidence points towards inflammation and oxidative stress as major steps associated with brain dysfunction in sepsis. Thus, we investigated the α-lipoic acid (ALA) effect as an important antioxidant compound on brain dysfunction in rats. Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) or sham (control) and treated orally with ALA (200 mg/kg after CLP) or vehicle. Animals were divided into sham + saline, sham + ALA, CLP + saline and CLP + ALA groups. Twelve, 24 h and 10 days after surgery, the hippocampus, prefrontal cortex and cortex were obtained and assayed for levels of TNF-α and IL-1ß, blood brain barrier (BBB) permeability, nitrite/nitrate concentration, myeloperoxidase (MPO) activity, thiobarbituric acid reactive species (TBARS) formation, protein carbonyls, superoxide dismutase (SOD) and catalase (CAT) activity and neurotrophins levels. Behavioral tasks were performed 10 days after surgery. ALA reduced BBB permeability and TNF-α levels in hippocampus in 24 h and IL-1ß levels and MPO activity in hippocampus and prefrontal cortex in 24 h. ALA reduced nitrite/nitrate concentration and lipid peroxidation in 24 h in all structures and protein carbonylation in 12 and 24 h in hippocampus and cortex. CAT activity increased in the hippocampus and cortex in all times. ALA enhanced NGF levels in hippocampus and cortex and prevented cognitive impairment. Our data demonstrates that ALA reduces the consequences of polymicrobial sepsis in rats by decreasing inflammatory and oxidative stress parameters in the brain.