Behavioral and inflammatory changes in rats induced by a three-hit stress model: Implications for psychiatric disorders.

Many aspects of the impact of childhood trauma remain unknown, such as the age at which individuals are most vulnerable to trauma, whether traumatic experiences have more severe and lasting effects when experienced early in life, and whether early life trauma causes psychiatric conditions such as anxiety and major depressive disorder (MDD) that persist over time or evolve into other disorders. Thus, this study aimed to investigate the impact of traumatic experiences in childhood on susceptibility to mood disorders in adulthood, particularly MDD. Animal models were used to address these questions, and different stressor protocols at various stages of the offspring's life were used. Three-hit starting with injections of Poly: IC was performed on the 9th day of gestation and then considered the first stressor. After birth, the animals were exposed to the maternal deprivation (MD) protocol, which separated the pups from the mother 3 h a day during the first ten days of life. From the 60th day of life, the animals were divided to receive the chronic mild stress (CMS) protocol over 21 days. The stressors can induce anxiety-like behaviors, such as increased locomotor activity through a maternal immune activation protocol using Poly: IC and demonstrating depressive-like behaviors through the MD and CMS protocols. It also showed changes in brain structures for pro-inflammatory parameters, IL-1ß and TNF-α, and alterations in anti-inflammatory parameters, IL-4 and IL-10, at different ages of life. The study also found that regulating pro- and anti-inflammatory cytokines is necessary for appropriate neuronal behavior, and stress responses can be both friendly and enemy, with costs and benefits balanced to provide the best-fit result. In conclusion, phenotypic characteristics of animals' life history are shaped by signals transmitted directly or indirectly to developing animals, known as "predictive adaptive responses."

Haloperidol alters neurotrophic factors and epigenetic parameters in an animal model of schizophrenia induced by ketamine.

This study aimed to evaluate Haloperidol's (Hal) effects on the behavioral, neurotrophic factors, and epigenetic parameters in an animal model of schizophrenia (SCZ) induced by ketamine (Ket). Injections of Ket or saline were administered intraperitoneal (once a day) between the 1st and 14th days of the experiment. Water or Hal was administered via gavage between the 8th and 14th experimental days. Thirty minutes after the last injection, the animals were subjected to behavioral analysis. The activity of DNA methyltransferase (DNMT), histone deacetylase (HDAC), and histone acetyltransferase and levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3), and glial-derived neurotrophic factor (GDNF) were evaluated in the frontal cortex, hippocampus, and striatum. Ket increased the covered distance and time spent in the central area of the open field, and Hal did not reverse these behavioral alterations. Significant increases in the DNMT and HDAC activities were detected in the frontal cortex and striatum from rats that received Ket, Hal, or a combination thereof. Besides, Hal per se increased the activity of DNMT and HDAC in the hippocampus of rats. Hal per se or the association of Ket plus Hal decreased BDNF, NGF, NT-3, and GDNF, depending on the brain region and treatment regimen. The administration of Hal can alter the levels of neurotrophic factors and the activity of epigenetic enzymes, which can be a factor in the development of effect collateral in SCZ patients. However, the precise mechanisms involved in these alterations are still unclear.

Effects of maternal folic acid supplementation on nuclear methyltransferase activity of adult rats subjected to an animal model of schizophrenia.

INTRODUCTION: Schizophrenia is considered one of the most disabling and severe human diseases worldwide. The etiology of schizophrenia is thought to be multifactorial and evidence suggests that DNA methylation can play an important role in underlying pivotal neurobiological alterations of this disorder. Some studies have demonstrated the effects of dietary supplementation as an alternative approach to the prevention of schizophrenia, including folic acid. However, no study has ever investigated the role of such supplementation in altering the DNA methylation system in the context of schizophrenia. OBJECTIVES: The present study aims to investigate the effects of maternal folic acid supplementation at different doses on nuclear methyltransferase activity of adult rat offspring subjected to an animal model schizophrenia induced by ketamine. METHODS: Adult female Wistar rats, (60 days old) received folic acid-deficient diet, control diet, or control diet plus folic acid supplementation (at 5, 10, or 50 mg/kg) during pregnancy and lactation. After reaching adulthood (60 days), the male offspring of these dams were subjected to the animal model of schizophrenia induced by 7 days of ketamine intraperitoneal injection (25 mg/kg). After the 7-day protocol, the activity of nuclear methyltransferase was evaluated in the brains of the offspring. RESULTS: Maternal folic acid supplementation at 50 mg/kg increased methyltransferase activity in the frontal cortex, while 10 mg/kg increased methyltransferase activity in the hippocampus. In the striatum of offspring treated with ketamine, maternal deficient diet, control diet, and folic acid supplementation at 5 mg/kg decreased methyltransferase activity compared to the control group. The folic acid supplementation at 10 and 50 mg/kg reversed this ketamine effect. CONCLUSIONS: Maternal FA deficiency could be related to schizophrenia pathophysiology, while FA supplementation could present a protective effect since it demonstrated persistent effects in epigenetic parameters in adult offspring.

Haloperidol elicits oxidative damage in the brain of rats submitted to the ketamine-induced model of schizophrenia.

The present study aims to evaluate the effects of haloperidol, an important first-generation antipsychotic, on the antioxidant system parameters in the brain of animals subjected to a model of schizophrenia induced by ketamine. Adult rats intraperitoneally received saline (1 mL/kg) or ketamine (25 mg/kg body weight) for 15 days, and saline or haloperidol (0.1 mg/kg body weight) via gavage once a day, between the 9th and 14th days. In the frontal cortex, hippocampus, and striatum, assessments of lipid (4-hydroxy-2-nonenal and 8-isoprostane levels) and protein (protein carbonyl content) oxidative damage were conducted. It was also measured the glutathione peroxidase and glutathione reductase activities in the same cerebral structures. Increases in the 4-hydroxy-2-nonenal and 8-isoprostane levels were detected in rats receiving haloperidol and ketamine. An increase in the carbonyl content was also observed in animals receiving ketamine, haloperidol, or a combination thereof. In animals receiving the antipsychotic, there was a decrease in the activity of the enzymes. Therefore, both ketamine and haloperidol induced oxidative damage. A possible energy dysfunction or a haloperidol effect targeting the glutathione enzymes, and then disrupting the redox homeostasis in neurons, could not be ruled out, although further studies are required to confirm or refute a direct interaction.

Ascorbic acid supplementation attenuates schizophrenia-like symptoms in an animal model induced by ketamine.

Schizophrenia is a chronic neuropsychiatric disorder with a poorly understood pathophysiology. The theories about the disorder are mainly about dysregulation in one or more systems of neurotransmitters, and the progression triggers the presence of inflammatory markers indicates the possibility that the disorder is initially an inflammatory disease. The objective was to evaluate the ascorbic acid supplementation in an animal model of schizophrenia, on behavioral parameters, and cytokines involved in inflammation IL-1ß, IL-10. Wistar rats with 60 days of age were used which were supplemented with ascorbic acid at 0.1, 1, and 10 mg/kg or saline for 14 days via orogastric gavage. Subsequently, four groups were given ketamine (25 mg/kg) and four groups received intraperitoneal saline from the 9th-15th day of the experiment. After 30 min of the last administration of ketamine/saline, and behavioral test, rats were killed by guillotine decapitation and the brain structures were carefully dissected for biochemical analysis. Results showed that ascorbic acid supplementation prevented motor sensory loss but nor alter other parameters evaluated. We concluded that ascorbic acid may be used as a therapeutic adjuvant in schizophrenia and may help to improve the schizophrenic patient's life quality.

Schizophrenia-like behavior is not altered by melatonin supplementation in rodents.

An emerging area in schizophrenia research focuses on the impact of immunomodulatory drugs such as melatonin, which have played important roles in many biological systems and functions, and appears to be promising. The objective was to evaluate the effect of melatonin on behavioral parameters in an animal model of schizophrenia. For this, Wistar rats were divided and used in two different protocols. In the prevention protocol, the animals received 1 or 10mg/kg of melatonin or water for 14 days, and between the 8th and 14th day they received ketamine or saline. In the reversal protocol, the opposite occurred. On the 14th day, the animals underwent behavioral tests: locomotor activity and prepulse inhibition task. In both protocols, the results revealed that ketamine had effects on locomotor activity and prepulse inhibition, confirming the validity of ketamine construction as a good animal model of schizophrenia. However, at least at the doses used, melatonin was not able to reverse/prevent ketamine damage. More studies are necessary to evaluate the role of melatonin as an adjuvant treatment in psychiatric disorders.

Pulmonary oxidative stress in wild bats exposed to coal dust: A model to evaluate the impact of coal mining on health.

This study aimed to verify possible alterations involving histological and oxidative stress parameters in the lungs of wild bats in the Carboniferous Basin of Santa Catarina (CBSC) state, Southern Brazil, as a means to evaluate the impact of coal dust on the health of wildlife. Specimens of frugivorous bat species Artibeus lituratus and Sturnira lilium were collected from an area free of coal dust contamination and from coal mining areas. Chemical composition, histological parameters, synthesis of oxidants and antioxidant enzymes, and oxidative damage in the lungs of bats were analyzed. Levels of Na, Cl, Cu, and Br were higher in both species collected in the CBSC than in the controls. Levels of K and Rb were higher in A. lituratus, and levels of Si, Ca, and Fe were higher in S. lilium collected in the carboniferous basin. Both bat species inhabiting the CBSC areas exhibited an increase in the degree of pulmonary emphysema compared to their counterparts collected from control areas. Sturnira lilium showed increased reactive oxygen species (ROS) and 2',7'-dichlorofluorescein (DCF) levels, while A. lituratus showed a significant decrease in nitrite levels in the CBSC samples. Superoxide dismutase (SOD) activity did not change significantly; however, the activity of catalase (CAT) and levels of glutathione (GSH) decreased in the A. lituratus group from CBSC compared to those in the controls. There were no differences in NAD(P)H quinone dehydrogenase 1 protein (NQO1) abundance or nitrotyrosine expression among the different groups of bats. Total thiol levels showed a significant reduction in A. lituratus from CBSC, while the amount of malondialdehyde (MDA) was higher in both A. lituratus and S. lilium groups from coal mining areas. Our results suggested that bats, especially A. lituratus, living in the CBSC could be used as sentinel species for harmful effects of coal dust on the lungs.

Effects of ketamine on prepubertal Wistar rats: Implications on behavioral parameters for Childhood-Onset Schizophrenia.

Early childhood schizophrenia (COS) is a rare condition and has no established animal model to test new treatments. Previous studies have shown that repeated doses of 25 mg/kg ketamine produce schizophrenia-like changes in adult male Wistar rats, but adequate doses of ketamine in animal COS studies are not yet known. Male and female Wistar rats, 23 days old, received an injection of ketamine or intraperitoneal saline (i.p.) for 8 days. The animals underwent different behavioral tests: open field, social interaction, pre-pulse startle inhibition (PPI). Female rats showed behavioral changes at all ketamine doses (5, 15, 25 and 50 mg/kg), in contrast to males that only at 50 mg/kg dose had interrupted PPI and higher stereotypy in the open field test. The present study demonstrated that ketamine at a dose of 50 mg/kg once daily from 23 to 31 days postnatal reproduced changes similar to schizophrenia in pre-pubertal male and female Wistar rats and could be used, with other interventions, in future studies with animals in COS.

Maternal immune activation induced by lipopolysaccharide triggers immune response in pregnant mother and fetus, and induces behavioral impairment in adult rats.

Evidence suggest that prenatal immune system disturbance contributes largely to the pathophysiology of neuropsychiatric disorders. We investigated if maternal immune activation (MIA) could induce inflammatory alterations in fetal brain and pregnant rats. Adult rats subjected to MIA also were investigated to evaluate if ketamine potentiates the effects of infection. On gestational day 15, Wistar pregnant rats received lipopolysaccharide (LPS) to induce MIA. After 6, 12 and 24 h, fetus brain, placenta, and amniotic fluid were collected to evaluate early effects of LPS. MIA increased oxidative stress and expression of metalloproteinase in the amniotic fluid and fetal brain. The blood brain barrier (BBB) integrity in the hippocampus and cortex as well integrity of placental barrier (PB) in the placenta and fetus brain were dysregulated after LPS induction. We observed elevated pro- and anti-inflammatory cytokines after LPS in fetal brain. Other group of rats from postnatal day (PND) 54 after LPS received injection of ketamine at the doses of 5, 15, and 25 mg/kg. On PND 60 rats were subjected to the memories tests, spontaneous locomotor activity, and pre-pulse inhibition test (PPI). Rats that receive MIA plus ketamine had memory impairment and a deficit in the PPI. Neurotrophins were increased in the hippocampus and reduced in the prefrontal cortex in the LPS plus ketamine group. MIA induced oxidative stress and inflammatory changes that could be, at least in part, related to the dysfunction in the BBB and PB permeability of pregnant rats and offspring. Besides, this also generates behavioral deficits in the rat adulthood's that are potentiated by ketamine.

Pre-clinical investigation of Diabetes Mellitus as a risk factor for schizophrenia.

This study investigated the behavioral and biochemical parameters of DM1 as a risk factor in an animal model of schizophrenia (SZ). All groups: 1 Control (saline+saline); 2 Alloxan (alloxan+saline); 3 Ketamine (saline+ketamine); 4 (Alloxan+Ketamine) were fasted for a period of 18h before the subsequent induction of DM via a single intraperitoneal (i.p) injection of alloxan (150mg/kg). From the 4th to the 10th days, the animals were injected i.p with ketamine (25mg/kg) or saline, once a day, to induce a model of SZ and 30min after the last administration were subjected to behavioral testing. After, the animals were decapitated and the brain structures were removed. Ketamine induced hyperactivity and in the social interaction, ketamine, alloxan and the association of alloxan+ketamine increased the latency and decreased the number of contacts between animals. The animals from the ketamine, alloxan and alloxan+ketamine groups showed a prepulse startle reflex (PPI) deficit at the three intensities (65, 70 and 75dB). Ketamine was shown to be capable of increasing the activity of acetylcholinesterase (AChE) in the brain structures. Combination of alloxan+ketamine seems to have an exacerbated effect within the cholinergic system. For lipid peroxidation and protein carbonyls, alloxan+ketamine appear to have intensified lipid and protein damage in the three structures. Ketamine and the combination of ketamine+alloxan induced DNA damage in both frequency and damage index. This research found a relationship between DM1 and SZ.

Increased risk of developing schizophrenia in animals exposed to cigarette smoke during the gestational period.

Cigarette smoking during the prenatal period has been investigated as a causative factor of obstetric abnormalities, which lead to cognitive and behavioural changes associated with schizophrenia. The aim of this study was to investigate behaviour and AChE activity in brain structures in adult rats exposed to cigarette smoke during the prenatal period. Pregnant rats were divided into non-PCSE (non-prenatal cigarette smoke exposure) and PCSE (prenatal cigarette smoke exposure) groups. On post-natal day 60, the rats received saline or ketamine for 7days and were subjected to behavioural tasks. In the locomotor activity task, the non-PCSE+ketamine and PCSE+ketamine groups exhibited increased locomotor activity compared with the saline group. In the social interaction task, the non-PCSE+ketamine and PCSE+ketamine groups exhibited an increased latency compared with the control groups. However, the PCSE+ketamine group exhibited a decreased latency compared with the non-PCSE+ketamine group, which indicates that the cigarette exposure appeared to decrease, the social deficits generated by ketamine. In the inhibitory avoidance task, the non-PCSE+ketamine, PCSE, and PCSE+ketamine groups exhibited impairments in working memory, short-term memory, and long-term memory. In the pre-pulse inhibition (PPI) test, cigarette smoke associated with ketamine resulted in impaired PPI in 3 pre-pulse (PP) intensity groups compared with the control groups. In the biochemical analysis, the AChE activity in brain structures increased in the ketamine groups; however, the PCSE+ketamine group exhibited an exacerbated effect in all brain structures. The present study indicates that exposure to cigarette smoke during the prenatal period may affect behaviour and cerebral cholinergic structures during adulthood.

Effect of folic acid on oxidative stress and behavioral changes in the animal model of schizophrenia induced by ketamine.

Recent studies have shown benefits for the supplementation of folic acid in schizophrenic patients. The aim of this study was to evaluate the effects of folic acid addition on adult rats, over a period of 7 or 14 days. It also sets out to verify any potential protective action using an animal model of schizophrenia induced by ketamine, in behavioral and biochemical parameters. This study used two protocols (acute and chronic) for the administration of ketamine at a dose of 25 mg/kg (i.p.). The folic acid was given by oral route in doses of 5, 10 and 50 mg/kg, once daily, for 7 and/or 14 days in order to compare the protective effects of folic acid. Thirty minutes after the last administration of ketamine, the locomotor and social interaction activities were evaluated, and immediately the brain structure were removed for biochemical analysis. In this study, ketamine was administered in a single dose or in doses over the course of 7 days increasing the animal's locomotion. This study showed that the administration of folic acid over 7 days was unable to prevent hyper locomotion. In contrast, folic acid (10 and 50 mg/kg) administrated over a period of 14 days, was able to partially prevent the hyper locomotion. Our data indicates that both acute and chronic administrations of ketamine increased the time to first contact between the animals, while the increased latency for social contact was completely prevented by folic acid (5, 10 and 50 mg/kg). Chronic and acute administrations of ketamine also increased lipid peroxidation and protein carbonylation in brain. Folic acid (10 and 50 mg/kg) supplements showed protective effects on the oxidative damage found in the different brain structures evaluated. All together, the results indicate that nutritional supplementation with folic acid provides promising results in an animal model of schizophrenia induced by ketamine.

Effects of omega-3 supplementation on interleukin and neurotrophin levels in an animal model of schizophrenia.

New studies suggest that polyunsaturated fatty acids, such as omega-3, may reduce the symptoms of schizophrenia. The present study evaluated the preventive effect of omega-3 on interleukines (IL) and neurotrophin brain-derived neurotrophic factor (BDNF) levels in the brains of young rats subjected to a model of schizophrenia. Treatment was performed over 21 days, starting on the 30th day of rat's life. After 14 days of treatment with omega-3 or vehicle, a concomitant treatment with saline or ketamine (25 mg/kg) was started and maintained until the last day of the experiment. BDNF levels in the rat's prefrontal cortex were decreased at 1 h and 24 h after the last administration of ketamine, whereas the group administered with ketamine and omega-3 showed a decrease in BDNF levels only after 24 h. In contrast, both interventions induced similar responses in levels of IL-1ß and IL6. These findings suggest that the similarity of IL-1ß and IL6 levels in our experimental groups is due to the mechanism of action of ketamine on the immune system. More studies have to be carried out to explain this pathology. In conclusion, according to previous studies and considering the current study, we could suggest a prophylactic role of omega-3 against the outcome of symptoms associated with schizophrenia.

Maternal deprivation disrupts mitochondrial energy homeostasis in the brain of rats subjected to ketamine-induced schizophrenia.

Maternal deprivation (MD) appears to be one of the environmental factors involved in the pathophysiology of schizophrenia. A widely used animal model of the schizophrenia involves the administration of ketamine, a dissociative anesthetic, NMDA receptors noncompetitive antagonist, that induce symptoms such as schizophrenia. To clarify the molecular mechanism of schizophrenia induced by MD, we investigated alterations in energetic metabolism, oxidative stress and neurotrophic factor levels in the brain of rats following MD and/or a single administration of ketamine during adulthood. Male Wistar rats were subjected to MD for 10 days. Additionally, these animals received acute ketamine (5, 15 or 25 mg/kg by intraperitoneal route, i.p.) during adulthood, and 30 min later, they were killed and the prefrontal cortex (PFC), the hippocampus and the striatum were removed for molecular analyses. Ketamine 25 mg/kg and/or MD and Ketamine 15 and 5 mg/kg with MD decreased the creatine kinase (CK) activity in the hippocampus. The enzyme activity of succinate dehydrogenase (SDH) in the Krebs cycle had increased in the striatum following the administration of ketamine 25 mg/kg, MD per se or MD plus ketamine 5 and 15 mg/kg. MD per se or MD combined with ketamine in different doses increased the activity of mitochondrial complexes. The PFC of animals subjected to MD and administered with ketamine 5 mg/kg exhibited increased protein carbonyl content. In the hippocampus, ketamine 15 mg/kg, ketamine 25 mg/kg and MD each increased the carbonyl content. In the striatum, the TBARS levels were increased by the administration of ketamine 25 mg/kg. Finally, in the hippocampus, MD alone or in combination with ketamine reduced the Nerve Growth Factor (NGF) levels; however, the Brain-derived Neurotrophic Factor (BDNF) levels were unaltered. In the present study, we suggest that MD increased the risk of psychotic symptoms in adulthood, altering different parameters of energy and oxidative stress. Our results suggest that adverse experiences occurring early in life may sensitize specific neurocircuits to subsequent stressors, inducing vulnerability, and may help us understand the pathophysiological mechanisms involved in this disorder.

Omega-3 fatty acids prevent the ketamine-induced increase in acetylcholinesterase activity in an animal model of schizophrenia.

AIMS: Schizophrenia is a debilitating neurodevelopmental disorder that is associated with dysfunction in the cholinergic system. Early prevention is a target of treatment to improve long-term outcomes. Therefore, we evaluated the preventive effects of omega-3 fatty acids on AChE activity in the prefrontal cortex, hippocampus and striatum in an animal model of schizophrenia. MAIN METHODS: Young Wistar rats (30 days old) were initially treated with omega-3 fatty acids or vehicle alone. Animals received ketamine to induce an animal model of schizophrenia or saline plus omega-3 fatty acids or vehicle alone for 7 consecutive days beginning on day 15. A total of 22 days elapsed between the treatment and intervention. Animals were sacrificed, and brain structures were dissected to evaluate AChE activity and gene expression. KEY FINDINGS: Our results demonstrate that ketamine increased AChE activity in these three structures, and omega-3 fatty acids plus ketamine showed lower values for the studied parameters, which indicate a partial preventive mechanism of omega-3 fatty acid supplementation. We observed no effect on AChE expression. Together, these results indicate that omega-3 fatty acid supplementation effectively reduced AChE activity in an animal model of schizophrenia in all studied structures. In conclusion, the present study provides evidence that ketamine and omega-3 fatty acids affect the cholinergic system, and this effect may be associated with the physiopathology of schizophrenia. Further studies are required to investigate the mechanisms that are associated with this effect.