Neonatal Immune Activation May Provoke Long-term Depressive Attributes.

BACKGROUND: Studies have shown the relationship between neuroinflammation and depressive- like parameters. However, research still has not been carried out to evaluate neuroinflammation in the neonatal period and psychiatric disorders in adulthood. OBJECTIVE: To verify the association between neonatal immune activation and depressive-like parameters in adulthood using an animal model. METHODS: Two days old C57BL/6 animals were exposed to lipopolysaccharides (LPS) or phosphate- buffered saline (PBS). When the animals were 46 days old, they received PBS or Imipramine at 14 days. At 60 days, the consumption of sucrose; immobility time; adrenal gland and the hippocampus weight; levels of plasma corticosterone and hippocampal Brain-derived neurotrophic factor (BDNF) were evaluated. RESULTS: It was observed that the animals exposed to LPS in the neonatal period and evaluated in adulthood decreased the consumption of sucrose and had reducted hippocampus weight. Also, the exposed animals presented an increase of immobility time, adrenal gland weight and plasma levels of corticosteroids. The use of imipramine did not only modify the decreased hippocampal weight. On the other hand, there were no alterations in the BDNF levels in the hippocampus with or without the use of imipramine. CONCLUSION: These results suggest that neonatal immune activation may be associated with depressive- like parameters in adulthood. It is believed that endotoxemia may trigger physiological and behavioral alterations, increasing vulnerability for the development of depression in adulthood.

Experimental Neonatal Sepsis Causes Long-Term Cognitive Impairment.

Neonatal sepsis is a major cause of morbidity and mortality in neonatal intensive care units. Treatment with antibiotics reduces mortality and morbidity, but neonatal sepsis remains a serious life-threatening condition. The objective of this study was to evaluate cognitive impairment in adult mice submitted to sepsis in the neonatal period. To this aim, 2-day-old male C57BL/6 mice were submitted to sepsis by injection of 25 µg of LPS. Sixty days after, the learning and memory were evaluated. It was observed that the mice submitted to neonatal sepsis presented impairment of habituation, aversive, and object recognition memories, and had an increase of immobility time in forced swimming test in adulthood. In conclusion, this study shows that the neonatal sepsis causes long-term brain alterations. These alterations can persist to adulthood in an animal model due to a vulnerability of the developing brain.

Effect of sepsis on behavioral changes on the ketamine-induced animal model of schizophrenia.

This study aimed to evaluate the effect of sepsis on behavioral changes on the ketamine-induced animal model of schizophrenia. Male Wistar rats underwent Cecal Ligation and Perporation (CLP) with "basic support" or were sham-operated. After 30 days, the animals were submitted to a model of schizophrenia by injection of Ketamine. The behavior tests were performed after 30 min of the injection of Ketamine or saline. Ketamine in doses of 15 and 25mg/kg increased locomotor activity, latency to first contact in the social interaction and stereotyped behavior. Some changes caused by sepsis may be associated with a predisposition to develop schizophrenia in the animal model.

Il1-ß involvement in cognitive impairment after sepsis.

Sepsis is defined as the host's reaction to infection and characterised by a systemic inflammatory response with important clinical implications. Central nervous system dysfunction secondary to sepsis is associated with local generation of pro- and anti-inflammatory cytokines, impaired cerebral microcirculation, an imbalance of neurotransmitters, apoptosis and cognitive impairment. It's known that the IL-1ß is one of the first cytokines to be altered. Thus, the objective of this study was to evaluate the role of IL-1ß in cognitive parameters in brain tissue through the use of an IL-1ß (IL-1ra) receptor antagonist up to 10 days and to assess blood-brain barrier permeability, cytokine levels, oxidative parameters and energetic metabolism up to 24 h, after sepsis induction. To this aim, we used sham-operated Wistar rats or submitted to the cecal ligation and perforation (CLP) procedure. Immediately after, the animals received one dose of 10 µg of IL-1ra. After 24 h, the rats were killed and were evaluated for biochemical parameters in the pre-frontal cortex, hippocampus and striatum. After 10 days, the animals were submitted to the habituation to the open field and step-down inhibitory avoidance task. We observed that the use of IL-1ra reverted the increase of blood-brain barrier permeability in the pre-frontal cortex, hippocampus and striatum; the increase of IL-1ß, IL1-6 and TNF-α levels in the pre-frontal cortex and striatum; the decrease of complex I activity in the pre-frontal, hippocampus and striatum; the increase of oxidative parameters in pre-frontal cortex, hippocampus and striatum; and cognitive impairment. In conclusion, the results observed in this study reinforce the role of acute brain inflammatory response, in particular, the IL1ß response, in the cognitive impairment associated with sepsis.

Erythropoietin reverts cognitive impairment and alters the oxidative parameters and energetic metabolism in sepsis animal model.

Sepsis is characterized by systemic biochemical alterations including the central nervous system in the early times and cognitive impairment at later times after sepsis induction in the animal model. Recent studies have shown that, besides its hematological activity, erythropoietin (EPO) has cytoprotective effects on various cells and tissues. In order to corroborate elucidating the effects of alternative drugs for sepsis treatment, we evaluated the effects of both acute and chronic EPO treatment on oxidative stress and energetic metabolism in the hippocampus, and cognitive impairment, respectively, after sepsis induction by cecal ligation and perforation (CLP). To this aim, male Wistar rats underwent CLP with "basic support" or sham operation. In the acute treatment, EPO was administered once immediately after CLP induction. The rats were then killed after 6 and 24 h, and the hippocampus was removed for analysis of oxidative stress and energetic metabolism, respectively. Regarding the chronic treatment, EPO was administered once daily until the 4th day after induction. Aversive memory was tested on the 10th day after surgery. It was observed that the acute use of EPO (a single dose) alters the oxidative parameters and energetic metabolism. Chronic use (4 days) reversed cognitive impairment in the sepsis animal model. Mortality rates were attenuated only during chronic treatment.

Acute low dose of MK-801 prevents memory deficits without altering hippocampal DARPP-32 expression and BDNF levels in sepsis survivor rats.

Sepsis is characterized by an intense inflammatory reaction with potential neurotoxic effects in the central nervous system and damage to memory and learning ability. We assessed the effects of acute low dose of MK-801 on the memory impairment, hippocampal BDNF levels and DARPP-32 expression ten days after sepsis. Under anesthesia, male Wistar rats underwent either cecal ligation and perforation (CLP) or sham. Then, the animals received either a single systemic injection of MK-801 (0.025 mg/kg) or saline solution. Ten days after CLP, the animals were submitted to the step-down inhibitory avoidance and object recognition tests. Also, the hippocampal BDNF protein levels and DARPP-32 expression were evaluated. MK-801 prevented cognitive impairment, but did not affect the hippocampal BDNF levels. DARPP-32 expression was significantly different only in the animals submitted to sepsis that received MK-801 treatment. Thus, we demonstrated that a single low dose of MK-801 prevented memory impairment without altering hippocampal DARPP-32 expression and BDNF levels.

Alterations in inflammatory mediators, oxidative stress parameters and energetic metabolism in the brain of sepsis survivor rats.

Sepsis is characterized by biochemical alterations in the central nervous system at early times and cognitive impairment at late times after induction in sepsis animal model. In order to understand at least in part the mechanism of disease, we have evaluated the effects of sepsis on cytokine levels in the cerebrospinal fluid (CSF); oxidative parameters; the activity of the electron transport chain enzymes; and creatine kinase (CK) activity in the brain of sepsis survivor rats 10 days after cecal ligation and perforation (CLP). Male Wistar rats underwent CLP with "basic support" or sham-operated. Ten days after surgery, the animals were killed and prefrontal cortex, cortex, hippocampus, striatum, cerebellum, and CSF were obtained. It was found a decrease in the levels of TNF-α (P = 0.001), IL-1ß (P = 0.008), IL-6 (P = 0.038), and IL-10 (P = 0.022) in the CSF; an increase in the TBARS only hippocampus (0.027); an up-regulation in the activity of complex II (P = 0.024), III (P = 0.018), and IV (P = 0.047) only in the prefrontal cortex; a decrease in the CK activity in the cerebellum (P = 0.001) and striatum (P = 0.0001), and an increase in the hippocampus (P = 0.0001) and cortex (P = 0.0001). Oxidative stress and mitochondrial alterations observed during early times in sepsis, persisted up to 10 days after surgery. The cytokines levels during the early times were found at high levels, decreasing to low levels after 10 days. In conclusion, these findings may contribute for a better comprehension of the cognitive damage in sepsis survivor rats.

Treatment with cannabidiol reverses oxidative stress parameters, cognitive impairment and mortality in rats submitted to sepsis by cecal ligation and puncture.

Oxidative stress plays an important role in the development of cognitive impairment in sepsis. Here we assess the effects of acute and extended administration of cannabidiol (CBD) on oxidative stress parameters in peripheral organs and in the brain, cognitive impairment, and mortality in rats submitted to sepsis by cecal ligation and perforation (CLP). To this aim, male Wistar rats underwent either sham operation or CLP. Rats subjected to CLP were treated by intraperitoneal injection with "basic support" and CBD (at 2.5, 5, or 10mg/kg once or daily for 9days after CLP) or vehicle. Six hours after CLP (early times), the rats were killed and samples from lung, liver, kidney, heart, spleen, and brain (hippocampus, striatum, and cortex) were obtained and assayed for thiobarbituric acid reactive species (TBARS) formation and protein carbonyls. On the 10th day (late times), the rats were submitted to the inhibitory avoidance task. After the test, the animals were killed and samples from lung, liver, kidney, heart, spleen, and brain (hippocampus) were obtained and assayed for TBARS formation and protein carbonyls. The acute and extended administration of CBD at different doses reduced TBARS and carbonyl levels in some organs and had no effects in others, ameliorated cognitive impairment, and significantly reduced mortality in rats submitted to CLP. Our data provide the first experimental demonstration that CBD reduces the consequences of sepsis induced by CLP in rats, by decreasing oxidative stress in peripheral organs and in the brain, improving impaired cognitive function, and decreasing mortality.

Effects of N-acetylcysteine/deferoxamine, taurine and RC-3095 on respiratory chain complexes and creatine kinase activities in rat brain after sepsis.

The pathogenesis of sepsis is characterized by an overwhelming systemic inflammatory response that can lead to multiple organ failure. Considering that we have recently demonstrated that mitochondrial respiratory chain and creatine kinase (CK) are altered in the brain of rats after cecal ligation and perforation (CLP) and that a combination of N-acetylcysteine/deferoxamine (NAC/DFX), taurine and RC-3095 were shown to be an effective treatment of sepsis, we investigated whether the alterations of these enzymes may be reversed by these drugs. The results demonstrated that CLP inhibited complexes I and II, and that all the treatments were able to reverse this inhibition in all brain areas studied in the present work. On the other hand, complexes III and IV were not affected by sepsis neither by any of the treatments. An increase in CK activity in brain of rats 12 h after CLP was also verified; the administration of NAC/DFX and taurine reversed the increase in CK activity in hippocampus, cerebral cortex, cerebellum and striatum. On the other hand, RC-3095 significantly decreased CK activity, when compared to sham group in all brain areas studied. This is a preliminary study which showed beneficial effects of the treatments we proposed.

Low dose dexamethasone reverses depressive-like parameters and memory impairment in rats submitted to sepsis.

Sepsis is characterized by a systemic inflammatory response of the immune system against an infection, presenting with hypothalamic-pituitary-adrenal (HPA) axis dysfunction, behavior alterations, and high mortality. In this study, we aimed to evaluate the effects of dexamethasone on mortality, anhedonia, circulating corticosterone and adrenocorticotropin hormone (ACTH) levels, body and adrenal gland weight, and aversive memory in sepsis survivor rats. Male Wistar rats underwent sham operation or cecal ligation and perforation (CLP) procedure. Rats subjected to CLP were treated with "basic support" and dexamethasone (at 0.2 and 2mg/kg daily for 7 days after CLP, intraperitonially) or saline. After 10 days of sepsis procedure, it was evaluated aversive memory, sweet food consumption, and body and adrenal gland weight. Serum and plasma were also obtained. It was observed that low dose dexamethasone reverted anhedonia, normalized adrenal gland and body weight, corticosterone and ACTH levels, and decreased mortality and avoidance memory impairment, demonstrating that low doses of dexamethasone for moderate periods may be beneficial for sepsis treatment and its sequelae-depressive-like parameters and memory impairment.

Depressive-like parameters in sepsis survivor rats.

The inflammatory and immune responses evoked in sepsis may create not only an acute brain dysfunction, which occurs in the majority of septic patients, but also long-term deficits such as memory impairment. In this context, we evaluated depressive-like parameters in sepsis survivor rats. For this purpose, male Wistar rats, weighing 300-350 g, underwent cecal ligation and perforation (CLP) (sepsis group) followed by "basic support", or were sham-operated (control group). After 3 days of the sepsis procedure, the animals were treated with imipramine at 10 mg/kg or saline during 14 days (days 3-17). The consumption of sweet food was measured for 7 days (days 10-17) and the body weight was measured before CLP, 10, and 17 days after CLP. Seventeen days after sepsis (immediately after sweet food consumption measurement), the animals were anesthetized and blood was withdrawn for the analyses of corticosterone and adrenocorticotropic hormone (ACTH) levels, and immediately killed by decapitation. The adrenal gland and hippocampus were immediately isolated and weighed, and the hippocampus was utilized for determining brain-derived neurotrophic factor (BDNF) levels. It was observed that animals subjected to CLP presented decreased sucrose intake. Septic rats did not increase body weight and presented an increase in the weight of adrenal gland. Both corticosterone and ACTH levels were increased, while hippocampus weight and BDNF levels in the hippocampus decreased. The treatment with imipramine reversed all the parameters described above. Our results supported the hypothesis that rats that survive sepsis show depressive-like behavior, alterations in the hypothalamus-pituitary-adrenal axis, and decreased BDNF levels in the hippocampus.

Oxidative mechanisms of brain dysfunction during sepsis.

Oxidative stress has drawn a lot of attention in the past few decades, since it has been reported to participate in the mechanism of many diseases. Therefore, it seemed to be a good rationale to aim oxidative stress on therapeutic research. Sepsis is a complex systemic syndrome characterized by an imbalance between pro- and anti-inflammatory responses to a pathogen; its pathophysiology is a dynamic process which involves components of the immune system, the coagulation pathway, parenchymal cells, and the endocrine and metabolic pathways. It is well characterized that oxidative stress plays a crucial role in sepsis development, but the relation between central nervous system dysfunction and oxidative stress during sepsis is not well understood. Thus, we here summarize the current knowledge on the role of free radicals in the development of brain dysfunction in sepsis focusing on oxidative damage and the redox control of brain inflammatory pathways.

Oxidative variables and antioxidant enzymes activities in the mdx mouse brain.

Dystrophin is a protein found at the plasmatic membrane in muscle and postsynaptic membrane of some neurons, where it plays an important role on synaptic transmission and plasticity. Its absence is associated with Duchenne's muscular dystrophy (DMD), in which cognitive impairment is found. Oxidative stress appears to be involved in the physiopathology of DMD and its cognitive dysfunction. In this regard, the present study investigated oxidative parameters (lipid and protein peroxidation) and antioxidant enzymes activities (superoxide dismutase and catalase) in prefrontal cortex, cerebellum, hippocampus, striatum and cortex tissues from male dystrophic mdx and normal C57BL10 mice. We observed (1) reduced lipid peroxidation in striatum and protein peroxidation in cerebellum and prefrontal cortex; (2) increased superoxide dismutase activity in cerebellum, prefrontal cortex, hippocampus and striatum; and (3) reduced catalase activity in striatum. It seems by our results, that the superoxide dismutase antioxidant mechanism is playing a protective role against lipid and protein peroxidation in mdx mouse brain.