Increased oxidative stress in the mitochondria isolated from lymphocytes of bipolar disorder patients during depressive episodes

The present study aims to investigate the oxidative stress parameters in isolated mitochondria, as well as looking at mitochondrial complex activity in patients with Bipolar Disorder (BD) during depressive or euthymic episodes. This study evaluated the levels of mitochondrial complex (I, II, II-III and IV) activity in lymphocytes from BD patients. We evaluated the following oxidative stress parameters: superoxide, thiobarbituric acid reactive species (TBARS) and carbonyl levels in submitochondrial particles of lymphocytes from bipolar patients. 51 bipolar patients were recruited into this study: 34 in the euthymic phase, and 17 in the depressive phase. Our results indicated that the depressive phase could increase the levels of mitochondrial superoxide, carbonyl and TBARS, and superoxide dismutase, and could decrease the levels of mitochondrial complex II activity in the lymphocytes of bipolar patients. It was also observed that there was a negative correlation between the Hamilton Depression Rating Scale (HDRS) and complex II activity in the lymphocytes of depressive bipolar patients. In addition, there was a positive correlation between HDRS and superoxide, superoxide dismutase, TBARS and carbonyl. Additionally, there was a negative correlation between complex II activity and oxidative stress parameters. In conclusion, our results suggest that mitochondrial oxidative stress and mitochondrial complex II dysfunction play important roles in the depressive phase of BD.

Matrix metalloproteinase-2 and metalloproteinase-9 activities are associated with blood-brain barrier dysfunction in an animal model of severe sepsis

There is no description on the mechanisms associated with blood-brain barrier (BBB) disruption during sepsis development. Thus, we here determined changes in permeability of the BBB in an animal model of severe sepsis and the role of matrix metalloproteinase (MMP)-2 and MMP-9 in the dysfunction of the BBB. Sepsis was induced in Wistar rats by cecal ligation and perforation. BBB permeability was assessed using the Evans blue dye method. The content of MMP-2 and MMP-9 in the cerebral microvessels was determined by western blot. The activity of MMP-2 and MMP-9 was determined using zymography. An inhibitor of MMP-2 and MMP-9 or specific inhibitors of MMP-2 or MMP-9 were administered to define the role of MMPs on BBB permeability, brain inflammatory response, and sepsis-induced cognitive alterations. The increase of BBB permeability is time-related to the increase of MMP-9 and MMP-2 in the microvessels, both in cortex and hippocampus. Using an MMP-2 and MMP-9 inhibitor, or specific MMP-2 or MMP-9 inhibitors, the increase in the permeability of the BBB was reversed. This was associated with lower brain levels of interleukin (IL)-6 and lower oxidative damage. In contrast, only the inhibition of both MMP-9 and MMP-2 was able to improve acute cognitive alterations associated with sepsis. In conclusion, MMP-2 and MMP-9 activation seems to be a major step in BBB dysfunction, but BBB dysfunction seems not to be associated with acute cognitive dysfunction during sepsis development.

Effects of maintenance electroshock on mitochondrial respiratory chain and creatine kinase activities in the rat brain

Réus GZ, Stringari RB, Rezin GT, Pezente DP, Scaini G, Maggi DD, De-Nês BT, Streck EL, Quevedo J, Feier G. Effects of maintenance electroshock on mitochondrial respiratory chain and creatine kinase activities in the rat brain.

Objective:Electroconvulsive therapy is used efficacious treatment for a variety of complicated psychiatric disorders and evidences have indicated that energy metabolism impairment may be involved in pathophysiology and treatment of mood disorders. This work was performed to determine creatine kinase and mitochondrial respiratory chain activities at different times after the maintenance electroconvulsive shock (ECS).

Methods:Male Wistar rats received a protocol mimicking therapeutic of maintenance or simulated ECS (sham) and were subsequently sacrificed immediately after, 48 h and 7 days after the last maintenance ECS. We measured creatine kinase and mitochondrial respiratory chain activities in the prefrontal cortex, hippocampus, cortex, cerebellum and striatum.

Results:Our results showed that maintenance ECS alter respiratory chain complexes and creatine kinase activities in the rat brain, but these effects were related to brain area and time after the ECS, in which the animal were killed.

Conclusion:Finally, these findings further support the hypothesis that alteration on the energy metabolism could be involved in the therapeutic or adverse effects of ECS.

Behavioral changes and brain energy metabolism dysfunction in rats treated with methamphetamine or dextroamphetamine

Studies have demonstrated that AMPHs produce long-term damage to the brain dopaminergic, serotoninergic and glutamatergic regions. Prefrontal cortex, amygdala, hippocampus and striatum appear to be involved in the toxicity and behavioral changes induced by AMPHs. A single dose of AMPH causes mitochondrial dysfunction and oxidative stress in rat brain. The goal of the present study was thus to investigate the potency of two amphetamines, dextroamphetamine (d-AMPH) and methamphetamine (m-AMPH), on the behavior and energetic dysfunction in the brain of rats. d-AMPH and m-AMPH increased the crossing and rearing behaviors. The numbers of visits to the center were increased by d-AMPH and m-AMPH only at 2mg/kg. Likewise, at a high dose (2 mg/kg), the injection of m-AMPH increased the amount of sniffing. The AMPHs significantly decreased the activities of Krebs cycle enzymes (citrate synthase and succinate dehydrogenase) and mitochondrial respiratory chain complexes (I-IV); nevertheless, this effect varied depending on the brain region evaluated. In summary, this study demonstrated that at high doses, m-AMPH, increased stereotyped (sniffing) behavior in rats, but d-AMPH did not. However, this study shows that d-AMPH and m-AMPH seem to have similar effects on the brains energetic metabolism.

Creatine kinase levels in patients with bipolar disorder: depressive, manic, and euthymic phases

OBJECTIVE: Bipolar disorder is a severe, recurrent, and often chronic psychiatric illness associated with significant functional impairment, morbidity, and mortality. Creatine kinase is an important enzyme, particularly for cells with high and fluctuating energy requirements, such as neurons, and is a potential marker of brain injury. The aim of the present study was to compare serum creatine kinase levels between bipolar disorder patients, in the various phases (depressive, manic, and euthymic), and healthy volunteers. METHOD: Forty-eight bipolar patients were recruited: 18 in the euthymic phase; 17 in the manic phase; and 13 in the depressive phase. The control group comprised 41 healthy volunteers. The phases of bipolar disorder were defined as follows: euthymic-not meeting the DSM-IV criteria for a mood episode and scoring < 8 on the Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS); manic-scoring < 7 on the HDRS and > 7 on the YMRS; depressive-scoring > 7 on the HDRS and < 7 on the YMRS. Patients in mixed phases were excluded. Blood samples were collected from all participants. RESULTS: Creatine kinase levels were higher in the manic patients than in the controls. However, we observed no significant difference between euthymic and depressive patients in terms of the creatine kinase level. CONCLUSION: Our results suggest that the clinical differences among the depressive, manic, and euthymic phases of bipolar disorder are paralleled by contrasting levels of creatine kinase. However, further studies are needed in order to understand the state-dependent differences observed in serum creatine kinase activity.

Antibiotic therapy prevents, in part, the oxidative stress in the rat brain after meningitis induced by Streptococcus pneumoniae

Bacterial meningitis is associated with intense inflammation and also linked to the production of reactive oxygen species. To this aim, animals underwent a magna cistern tap and received either sterile saline as a placebo or an equivalent volume of a Streptococcus pneumoniae suspension. The animals began antibiotic therapy 16h after induction. The animals were sacrificed at 24 or 48h post-infection and the hippocampus and cortex were harvested. The activity of the enzymes superoxide dismutase, catalase, and thiobarbituric acid reactive species, protein carbonyls, and free sulphydryl groups were altered, but reversed, in part, by the antibiotic treatment. Our results support the hypothesis that antibiotic treatment prevents, in part, the oxidative stress in the bacterial meningitis induced by Streptococcus pneumoniae.

Tumor necrosis factor alpha (TNF-alpha) levels in the brain and cerebrospinal fluid after meningitis induced by Streptococcus pneumoniae

Bacterial meningitis due to Streptococcus pneumoniae is associated with a significant mortality rate and persisting neurologic sequelae including sensory-motor deficits, seizures, and impairments of learning and memory. The presence of proliferating bacteria within the subarachnoid and ventricular space compartments triggers an intense inflammatory host response at killing the invading microorganism. Proinflammatory mediators released in the process include tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-1beta, IL-6. TNF-alpha have several effects, including cytotoxicity, antiviral activity, transcription factor activation, and immune response regulation. Thus, the aim of this study was to verify the levels of the TNF-alpha after pneumococcal meningitis in male Wistar rats. The animals underwent a magna cistern tap receiving either 10 microL sterile saline as a placebo or an equivalent volume of a S. pneumoniae suspension at the concentration 5 x 10(9)cfu/mL. The animals were killed at 0, 6, 12, 24, 48 and 96 h after induction. The brain was removed and hippocampus, cortex, prefrontal and cerebrospinal fluid (CSF) were isolated and used for the determination of TNF-alpha levels. We found an increase in TNF-alpha levels at 6h after induction of the meningitis in the hippocampus (p<0.01), frontal cortex (p<0.05), and cerebrospinal fluid (p<0.001).There was no alteration in the cortex. Our data suggest that TNF-alpha is involved in the pathophysiology of the pneumococcal meningitis and could be investigated as a putative biomarker for brain damage in the first hours.

Oxidative stress in brain according to traumatic brain injury intensity

BACKGROUND

The mechanisms of brain damage and neuroplasticity following traumatic brain injury (TBI) are complex and not completely understood. Thus, we investigated markers of oxidative stress in the central nervous system after mild and severe TBI in rats.

MATERIAL AND METHODS

Adult male wistar rats (five animals per group) submitted to mild (mTBI group) or severe TBI (sTBI Group) were sacrificed 30 min, 3, 6, or 12 h after the injury to quantify markers of oxidative damage in different brain regions. Levels of thiobarbituric acid reactive species and protein carbonyl in the cortex, hippocampus, striatum, and cerebellum of mTBI and sTBI groups were compared with the control group.

RESULTS

After mTBI, levels of protein oxidation were increased in all analyzed structures in several different times after injury. The increase in TBARS levels was not so consistent in mTBI. In contrast, sTBI did not induce a sustainable increase in oxidative damage markers in all analyzed structures.

CONCLUSIONS

Oxidative damage seemed to be inversely proportional to severity of traumatic brain injury.

Peripheral nucleotide hydrolysis in rats submitted to a model of electroconvulsive therapy

Electroconvulsive therapy (ECT) is an efficacious and safe method for the treatment of mood disorders. Its utilization is accompanied by a myriad of biochemical and cellular changes, which are far from fully understood. The present work investigates in rat serum the effects of seizures induced by electroconvulsive shocks (ECS), an animal model of ECT, on enzymes that hydrolyze ATP, ADP and AMP to adenosine. Two different models of ECS were used, consisting in the application of one or eight ECS sessions, and respectively named acute or chronic. Serum samples were collected at several time points after the single shock in the acute and after the eighth and last shock in the chronic model. A single shock produced a sudden and short-lived inhibition of enzymatic activity (P<0.01 for ADP and AMP), whereas in the chronic model significant increases were noticed starting as early as 12 h after the last shock, remaining significantly elevated until the last measurement 7 days later for ATP and ADP. Analysis of hydrolysis was assessed at the selected time point of 7 days in cerebrospinal fluid samples, also demonstrating a significant activation in the chronic model (P<0.0001 for ATP and ADP). These results support the idea that adenosine nucleotides may be involved in the biochemical mechanisms underlying longer lasting therapeutic effects associated with ECT, and suggest that peripheral markers can possibly contribute to the evaluation of activity in the central nervous system.

Effects of maintenance electroshock on the oxidative damage parameters in the rat brain

Although several advances have occurred over the past 20 years concerning refining the use and administration of electroconvulsive therapy to minimize side effects of this treatment, little progress has been made in understanding the mechanisms underlying its therapeutic or adverse effects. This work was performed in order to determine the level of oxidative damage at different times after the maintenance electroconvulsive shock (ECS). Male Wistar rats (250-300 g) received a protocol mimicking therapeutic of maintenance or simulated ECS (Sham) and were subsequently sacrificed immediately after, 48 h and 7 days after the last maintenance electroconvulsive shock. We measured oxidative damage parameters (thiobarbituric acid reactive species for lipid peroxidation and protein carbonyls for protein damage, respectively) in hippocampus, cortex, cerebellum and striatum. We demonstrated no alteration in the lipid peroxidation and protein damage in the four structures studied immediately after, 48 h and 7 days after a last maintenance electroconvulsive shock. Our findings, for the first time, demonstrated that after ECS maintenance we did protocol minimal oxidative damage in the brain regions, predominating absence of damage on the findings.

Oxidative stress after acute and sub-chronic malathion intoxication in Wistar rats

Malathion is an insecticide of the group of organophosphate pesticides (OPs), which shows strong insecticidal effects. However, it possesses mutagenic and carcinogenic properties and shows organ-specific toxicity in relation to the heart, kidney and other vertebrate organs. The exact mechanism of the genotoxic effects of malathion is not yet known. Free radical damage is an important direct or indirect factor in several pathological and toxicological processes, including malathion poisoning. The aim of the present study was the evaluation of oxidative damage in different tissues of Wistar rats, administered intra peritoneally at doses of 25, 50, 100 and 150mgmalathion/kg, after acute and sub-chronic malathion exposure. Oxidative stress evaluation was based on lipid peroxidation by levels of thiobarbituric acid reactive substances (TBARS), protein oxidation by levels of carbonyl groups, and also on the activities of superoxide dismutase and catalase, two antioxidant enzymes that detoxity superoxide radical (O(2)(-)) and hydrogen peroxide, respectively. The results showed that the most sensitive targets of oxidative damage were kidney, lung and diaphragm after acute treatment, and liver, quadriceps and serum after sub-chronic treatment. Also, in general, increased lipid peroxidation measured as TBARS levels seems to be a better biomarker of oxidative stress compared to the contents of protein carbonyls after acute and sub-chronic malathion treatments. The present findings reinforce the concept that oxidative stress and particularly lipoperoxidation, are involved in OPs toxicity.

NCS-1 Expression in Rat Brain after Electroconvulsive Stimulation

Although electroconvulsive therapy (ECT) has been used as a treatment for mental disorder since 1930s, little progress has been made towards understanding the mechanisms underlying its therapeutic and adverse effects. The aim of this work was to analyze the expression of NCS-1 (neuronal calcium sensor 1, a protein that was found to be altered in post-mortem prefrontal cortex of schizophrenic patients) in striatum, cortex, hippocampus and cerebellum of Wistar rats after acute or chronic electroconvulsive stimulation (ECS). Rats were submitted to a single stimulation (acute) or to a series of eight stimulations, applied one every 48 h (chronic). Animals were killed for collection of tissue samples at time zero, 30 min, 3, 12, 24 and 48 h after stimulation in the acute model and at the same time intervals after the last stimulation in the chronic model. Our results indicated that chronic ECS increased the expression of NCS-1 only in cerebellum. Such results on the expression of proteins involved in signaling pathways that are relevant for neuropsychiatric disorders and treatment, in particular ECT, can contribute to shed light on the mechanisms related to therapeutic and adverse effects.

Effect of Electroconvulsive Shock on Mitochondrial Respiratory Chain in Rat Brain

It is well described that impairment of energy production has been implicated in the pathogenesis of a number of diseases. Although several advances have occurred over the past 20 years concerning the use and administration of electroconvulsive therapy (ECT) to minimize its side effects, little progress has been made in understanding its mechanism of action. In this work, our aim was to measure the activities of mitochondrial respiratory chain complexes II and IV and succinate dehydrogenase from rat brain after acute and chronic electroconvulsive shock (ECS). Our results showed that mitochondrial respiratory chain enzymes activities were increased after acute ECS in hippocampus, striatum and cortex of rats. Besides, we also demonstrated that complex II activity was increased after chronic ECS in cortex, while hippocampus and striatum were not affected. Succinate dehydrogenase, however, was inhibited after chronic ECS in striatum, activated in cortex and not affected in hippocampus. Finally, complex IV was not affected by chronic ECS in hippocampus, striatum and cortex. Our findings demonstrated that brain metabolism is altered by ECS.

Effects of electroconvulsive seizures on Na+,K+-ATPase activity in the rat hippocampus

Although several advances have occurred concerning the use of electroconvulsive therapy, little progress has been made in understanding the mechanisms underlying its therapeutic or side effects. Na(+),K(+)-ATPase is an important enzyme of central nervous system, responsible for ionic gradient maintenance and consumption of approximately 40-50% of brain ATP. This work was performed in order to determine Na(+),K(+)-ATPase activity after acute and chronic electroconvulsive shock. Results showed an inhibition of Na(+),K(+)-ATPase activity in the hippocampus 48 h, 7, 30, 60 and 90 days after a single electroconvulsive shock. Chronic treatment diminished the enzyme activity in the hippocampus 7 and 30 days after electroconvulsive (ECS) sessions. Our findings demonstrated that Na(+),K(+)-ATPase activity is altered by ECS.

Decreased Creatine Kinase Activity Caused by Electroconvulsive Shock

Although several advances have occurred over the past 20 years concerning the use and administration of electroconvulsive therapy to minimize side effects of this treatment, little progress has been made in understanding its mechanism of action. Creatine kinase is a crucial enzyme for brain energy homeostasis, and a decrease of its activity has been associated with neuronal death. This work was performed in order to evaluate creatine kinase activity from rat brain after acute and chronic electroconvulsive shock. Results showed an inhibition of creatine kinase activity in hippocampus, striatum and cortex, after acute and chronic electroconvulsive shock. Our findings demonstrated that creatine kinase activity is altered by electroconvulsive shock.

Glial fibrillary acidic protein expression after electroconvulsive shocks in rat brain

OBJECTIVE

The aim of the present study was to assess the effect of electroconvulsive shock (ECS) in glial fibrillary acidic protein (GFAP) expression in rat brain.

METHODS

Rats were given either a single (acute) or a series of eight (chronic) ECS. Brain regions were isolated and levels of glial fibrillary acidic protein (GFAP) in the brain tissue (cortex, hippocampus, and cerebellum) were assessed using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

We showed that GFAP expression is reduced in the hippocampus within 48 h and 7 days after acute ECS. GFAP levels are increased in the cerebellum immediately after acute and chronic ECS. No changes were observed in the cortex.

CONCLUSIONS

Our findings showed a differential effect of acute and chronic ECS in the astroglial response in the brain of rats.

Long Lasting Effects of Electroconvulsive Seizures on Brain Oxidative Parameters

This work was performed in order to determine the level of oxidative damage and antioxidant enzymes activities late after acute and chronic electroconvulsive shock (ECS) in rats. We measured oxidative parameters in hippocampus, cortex, and striatum, at 45, 60, 90 and 120 days after a single or multiple ECS. We demonstrated an increase in lipid peroxidation after multiple ECS in the hippocampus and striatum. This was also the case for protein carbonyls in the single or multiple protocols. In this way, we demonstrated an increase in catalase in cortex in contrast to striatum and hippocampus, were there were decreases sometimes in chronic ECS. The superoxide dismutase activities decrease in different times after single and multiple ECS in the hippocampus. Our findings demonstrated that there is a delayed increase after ECS in oxidative damage and decrease in antioxidant enzymes activities in hippocampus and striatum.

Malathion-induced Oxidative Stress in Rat Brain Regions

Malathion is a pesticide with high potential for human exposure. However, it is possible that during the malathion metabolism, there is generation of reactive oxygen species (ROS) and malathion may produce oxidative stress in intoxicated rats. The present study was therefore undertaken to determine malathion-induced lipid peroxidation (LPO), protein carbonylation and to determine whether malathion intoxication alters the antioxidant system in brain rats. Malathion was administered intraperitoneally in the acute and chronic protocols in the doses of 25, 50, 100 and 150 mg malathion/kg. The results showed that LPO in brain increased in both protocols. The increased oxidative stress resulted in an increased in the activity of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT), observed in cortex, striatum in the acute malathion protocol and hippocampus in the chronic malathion protocol. Our results demonstrated that malathion induced oxidative stress and modulated SOD and CAT activity in selective brain regions.

Effects of Milnacipran in Animal Models of Anxiety and Memory

Serotonin (5-HT) and noradrenaline (NA) are involved in both pathogenesis and recovery from depression and anxiety. We examined the effects of acute and chronic treatment with milnacipran, a serotonin/noradrenaline reuptake inhibitors (SNRIs) antidepressant, on anxiety and memory retention in rats. Male Wistar rats received acute or chronic administration of milnacipran (12.5, 25 or 50 mg/kg) or saline (control group). The animals were separately submitted to elevated plus-maze, inhibitory avoidance and open-field tasks 1 h after injection, in the acute group, or 23 h after last injection, in the chronic group. Our results showed an anxiolytic-like effect after chronic administration of milnacipran at doses of 25 and 50 mg/kg. The treatment does not interfere in memory retention and habituation to a novel environment at any doses studied. These findings support that milnacipran, an established SNRIs antidepressant, can also be useful in the treatment of anxiety disorders.

Acute and chronic electroconvulsive shock in rats: Effects on peripheral markers of neuronal injury and glial activity

Electroconvulsive therapy is considered one of the most effective treatments of major depression, but controversy still exists on whether it may be brain damaging. The aim of this work was to evaluate the cerebrospinal fluid (CSF) levels of neuron specific enolase (NSE), protein S100B and lactate of rats submitted to acute and chronic models of ECS. Rats were submitted to either one shock (acute) or a series of eight shocks, applied one at every 48 h (chronic). CSF samples were collected at 0, 3, 6, 12, 24, 48 and 72 h after the shock in the acute model and at these same time intervals after the last shock in the chronic model. Both models did not produce significant alterations in the levels of NSE. S100B levels were significantly increased at 6 h in the chronic model (p<0.0001). There was a significant increase in the levels of lactate at 0 h in both models (p<0.001). These results support the proposition that ECS does not produce neural damage, and suggest that the alterations in the levels of S100B and lactate may reflect an astrocytic activity of a protective nature.

Oxidative variables in the rat brain after sepsis induced by cecal ligation and perforation

OBJECTIVE

The underlying mechanisms of the changes in mental status, septic encephalopathy, and long-term cognitive symptoms in sepsis survivors have only been defined in part. The present study was undertaken to assess different variables of oxidative stress in several brain structures after cecal ligation and perforation in the rat.

DESIGN

Prospective animal study.

SETTING

Animal basic science laboratory.

SUBJECTS

Male Wistar rats, weighing 250-350 g.

INTERVENTIONS

Rats were subjected to cecal ligation and perforation (sepsis group) with saline resuscitation (at 50 mL/kg immediately and 12 hrs after cecal ligation and perforation) or sham operation (control group).

MEASUREMENTS AND MAIN RESULTS

Oxidative damage, assessed by the thiobarbituric acid reactive species and the protein carbonyl assays, occurred early (after 6 hrs) in the course of sepsis development in the hippocampus, cerebellum, and cortex. At longer times after sepsis induction (12-96 hrs), there was no evidence of oxidative damage in all analyzed structures. Except for the striatum, earlier in sepsis development (6 hrs) we demonstrated an increase in superoxide dismutase activity without a proportional increase in catalase activity with a consequent increase in the relation of superoxide dismutase/catalase. The balance between these enzymes was restored in the studied structures 12-96 hrs after sepsis induction.

CONCLUSIONS

The short-term oxidative damage demonstrated here could participate in the development of central nervous system symptoms during sepsis development, or even septic encephalopathy. The alterations in the superoxide dismutase/catalase relation were temporally related to the occurrence or not of oxidative damage in the central nervous system.

Cognitive impairment in sepsis survivors from cecal ligation and perforation*

OBJECTIVE

Critical illness survivors present long-term cognitive impairment, including problems with memory and learning. We evaluated cognitive performance in rats that survived from sepsis induced by cecal ligation and puncture (CLP).

DESIGN

Prospective, controlled experiment.

SETTING

Animal basic science laboratory.

SUBJECTS

Male Wistar rats, weighing 300-350 g.

INTERVENTIONS

The rats underwent CLP (sepsis group) with "basic support" (saline at 50 mL/kg immediately and 12 hrs after CLP plus ceftriaxone at 30 mg/kg and clindamycin at 25 mg/kg 6, 12, and 18 hrs after CLP) or sham-operated (control group).

MEASUREMENTS AND MAIN RESULTS

Ten days after surgery, the animals underwent three behavioral tasks: a) inhibitory avoidance task; b) habituation to an open field; and c) continuous multiple-trials step-down inhibitory avoidance task (CMSIA). In the habituation to an open-field task, there were no differences in the number of crossings and rearings. The sepsis group showed significantly decreased performance in latency retention compared with the sham group in inhibitory avoidance. Furthermore, when tested by the habituation to an open-field task, the sepsis group did not show any difference between training and test, indicating memory impairment. In the CMSIA, the sepsis group showed a significant increase in the number of training trials required to reach the acquisition criterion.

CONCLUSION

Our data provide the first experimental demonstration that survivors from CLP show learning and memory impairment after complete physical recovery from sepsis.

No evidence for oxidative damage in the hippocampus after acute and chronic electroshock in rats

Although several advances has occurred over the past 20 years concerning the use of electroconvulsive therapy (ECT), little progress has been made in the mechanisms underlying its therapeutic or adverse effects. Thus, this work was performed in order to determine the level of oxidative damage and antioxidant enzyme activities early and late after acute and chronic electroconvulsive shock (ECS). We demonstrated a decrease in lipid peroxidation in the hippocampus immediately after and up to 30 days after a single or multiple electroconvulsive shock. This was also true for protein carbonyls in the acute protocol. We demonstrated an increase in catalase (CAT) and superoxide dismutase (SOD) activities at different time points after single and multiple electroconvulsive shock. Our findings, for the first time, demonstrated that after electroconvulsive shock, there is an increase in antioxidant enzyme activities and we cannot demonstrate oxidative damage in the hippocampus.

[Memory consolidation and posttraumatic stress disorder]

Extensive evidence from animal and human studies has shown that memory formation is enhanced by an endogenous modulatory system mediated by stress hormones and activation of the amygdala. This system is an evolutionarily adaptive method of enhancing important memories. Under emotional stress, this system is activated promoting the formation of vivid, long lasting traumatic memories, which are the hallmark of PTSD. The understanding of the mechanisms underlying memory modulation might lead to an improved ability to assess and treat PTSD.