A rodent model of schizophrenia reveals increase in creatine kinase activity with associated behavior changes

The relationship between alcohol bingeing in the gestational period of wistar rats and the development of schizophrenia in the offspring adult life

The incidence of schizophrenia in young adulthood may be associated with intrauterine factors, such as gestational alcohol consumption. This study investigated the relationship between a single high dose of alcohol during pregnancy in Wistar rats and the development of schizophrenia in the adult life of the offspring. On the 11th day of gestation, pregnant rats received either water or alcohol via intragastric gavage. Male and female offspring were subjected to behavioral tests at 30 days of age according to the maternal group. At 60 days of age, offspring received intraperitoneal injections of ketamine (ket) or saline (SAL). After the final ketamine administration, the adult offspring underwent behavioral tests, and their brain structures were removed for biochemical analysis. Alcohol binge drinking during pregnancy induces hyperlocomotion in both young female and male offspring, with males of alcohol-exposed mothers showing reduced social interactions. In adult offspring, ketamine induced hyperlocomotion; however, only females in the alcohol + ket group exhibited increased locomotor activity, and a decrease in the time to first contact was observed in the alcohol group. Cognitive impairment was exclusively observed in male animals in the alcohol group. Increased serotonin and dopamine levels were observed in male rats in the alcohol + ket group. Biochemical alterations indicate the effects of intrauterine alcohol exposure associated with ketamine in adult animals. These behavioral and biochemical changes suggest that the impact of prenatal stressors such as alcohol persists throughout the animals' lives and may be exacerbated by a second stressor in adulthood, such as ketamine.

A novel mucoadhesive paliperidone-nanoemulsion developed using the ultrasonication method in the treatment of schizophrenia

Aim: To develop paliperidone mucoadhesive-nanoemulsion (PLP-NE) to enhance brain bioavailability. To evaluate comparative effects of PLP-NE and CS-PLP-NE in the treatment of schizophrenia, followed by a toxicity study of opt-NE. Material and methods: Oil: oleic acid, surfactant: Tween-80, and co-surfactant: Labrasol were chosen based on the solubility and maximum nanoemulsion area. The ultrasonication technique was applied with the aqueous micro titration method for the development of PLP-NE. The optimization of the method for the excellent PLP-NE was performed using a central composite design based on a five-factor and four-level. Oil (% v/v), S mix (v/v%), ultrasonication intensity in percentage, ultrasonication time in minutes, and temperature (°C) were optimized and used to the independent variables. Results: The parameters i.e., oil (5%), S mix (10%), ultrasonication time (5.0 min), ultrasonication intensity (25%), and temperature (38 °C) were optimized and used as independent and dependent variables for the development of novel PLP-NE. Based on experimental data, the dependent variables, i.e., globule size (53.90 ± 4.01 nm), % transmittance (92.56% ± 1.06%), PDI (0.218 ± 0.007), and zeta potential (-11.60 ± 0.031 mV), were determined. The smooth near about spherical shaped of PLP-NE globules with, refractive index i.e., 1.62 ± 0.021, viscosity: 39 ± 6 cp with the pH: 7.40 ± 0.089, and content of drug (97.98 ± 0.39%) for optimized-PLP-NE. The optimized PLP-NE with oleic acid, Tween-80, and Labrasol was used to improve brain bioavailability with good permeation via the intranasal route. CS-PLP-NE yielded good mucoadhesive property results compared to paliperidone-nanoemulsion, and PLP-S containing a 0.751 minutes retention time with their deuterated-IS (0.806 min) and m/z of 427.2/207.2 with IS (m/z: 431.2/211.2) for PLP and PLP-IS. A calibration curve was plotted with a linear range of 1-2000 ng mL-1 with inter- and intraday accuracy (97.03-99.31%) and precision (1.69-50.05%). The results of AUC(0-24) and C max for PLP were found to be highly significant (p < 0.001) as an improvement of brain bioavailability in rats via intranasal delivery of CS-PLP-NE. Furthermore, the locomotion test, social interaction, and forced swimming test (forced swimming, climbing, and immobility) of a mucoadhesive CS-PLP-NE (intranasally) provided highly significant results with the improvement of behavioral analysis when compared to the PLP-NE and PLP-S studies. Conclusion: CS-PLP-NE (i.n.) showed highly significant results, i.e., p < 0.001 for the improvement of bioavailability of the brain in the treatment of schizophrenia. Optimized-mucoadhesive-CS-based-PLP-NE is safe and shows no toxicity.

Low-dose ketamine improves animals' locomotor activity and decreases brain oxidative stress and inflammation in ammonia-induced neurotoxicity

Ammonium ion (NH4 + ) is the major suspected molecule responsible for neurological complications of hepatic encephalopathy (HE). No specific pharmacological action for NH4 + -induced brain injury exists so far. Excitotoxicity is a well-known phenomenon in the brain of hyperammonemic cases. The hyperactivation of the N-Methyl- d-aspartate (NMDA) receptors by agents such as glutamate, an NH4 + metabolite, could cause excitotoxicity. Excitotoxicity is connected with events such as oxidative stress and neuroinflammation. Hence, utilizing NMDA receptor antagonists could prevent neurological complications of NH4 + neurotoxicity. In the current study, C57BL6/J mice received acetaminophen (APAP; 800 mg/kg, i.p) to induce HE. Hyperammonemic animals were treated with ketamine (0.25, 0.5, and 1 mg/kg, s.c) as an NMDA receptor antagonist. Animals' brain and plasma levels of NH4 + were dramatically high, and animals' locomotor activities were disturbed. Moreover, several markers of oxidative stress were significantly increased in the brain. A significant increase in brain tissue levels of TNF-α, IL-6, and IL-1β was also detected in hyperammonemic animals. It was found that ketamine significantly normalized animals' locomotor activity, improved biomarkers of oxidative stress, and decreased proinflammatory cytokines. The effects of ketamine on oxidative stress biomarkers and inflammation seem to play a key role in its neuroprotective mechanisms in the current study.

Combined Low Dose of Ketamine and Social Isolation: A Possible Model of Induced Chronic Schizophrenia-Like Symptoms in Male Albino Rats

While animal models for schizophrenia, ranging from pharmacological models to lesions and genetic models, are available, they usually mimic only the positive symptoms of this disorder. Identifying a feasible model of chronic schizophrenia would be valuable for studying the possible underlying mechanism and to investigate emerging treatments. Our hypothesis starts from the observation that combining ketamine with isolation could result in long-lasting neuro-psychological deficits and schizophrenia-like features; thus, it could probably be used as the first model of chronic schizophrenia that emphasizes the characteristic of having a multifactorial etiology. By the means of this study, we investigated the effects of ketamine administration combined with isolation in inducing schizophrenia-like symptoms in male albino rats and the brain reactive oxygen species levels. Our results showed that the number of lines crossings in the open field test, the number of open arm entries in the elevated plus maze, and the spontaneous alternations percentage in the Y-maze were significantly lower in the ketamine + isolation group compared to both the control and ketamine + social housing group (p < 0.05). Furthermore, the ketamine + isolation intervention significantly increased the MDA levels and decreased the GPx levels both in the hippocampus and the cortex of the rats. In addition, our premise of creating a model capable of exhibiting both positive and negative symptoms of schizophrenia was also based on adding the aripiprazole treatment to a group of rats. Therefore, we compared the ketamine + social isolation group with the ketamine + social isolation + aripiprazole group in order to attempt to discover if the antipsychotic drug would significantly decrease the potential positive schizophrenia-like symptoms induced by social isolation and ketamine. Given that we obtained significant results, we cautiously presume that this might be an important step in developing our animal model capable of illustrating both positive and negative symptoms of schizophrenia. This study could be a first step towards the creation of a complex animal model capable of exhibiting the multifactorial origin and manifestation of schizophrenia.

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.

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.

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-1β, 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.

Changes in behavioural parameters, oxidative stress and neurotrophins in the brain of adult offspring induced to an animal model of schizophrenia: The effects of FA deficient or FA supplemented diet during the neurodevelopmental phase

A deficiency of maternal folic acid (FA) can compromise the function and development of the brain, and may produce a susceptibility to diseases such as schizophrenia (SZ) in the later life of offspring. The aim of this study was to evaluate the effects of both FA deficient and FA supplemented diets during gestation and lactation on behavioural parameters, the markers of oxidative stress and neurotrophic factors in adult offspring which had been subjected to an animal model of SZ. Female mother rats (Dam's) were separated into experimental maternal groups, which began receiving a special diet (food) consisting of the AIN-93 diet, a control diet, or an FA deficient diet during the periods of pregnancy and lactation. Dam's receiving the control diet were further subdivided into four groups: one group received only control diet, while three groups to receive supplementation with FA at different doses (5, 10 and 50 mg/kg). Adult offspring bred from the Dam's were divided into ten groups for induction of the animal model of SZ through the administration of ketamine (Ket) (25 mg/kg). After the last administration of the drug, the animals were subjected to the behavioural tests and were then euthanized. The frontal cortex (FC) and hippocampus (Hip) were then dissected for later biochemical analysis. Our data demonstrates that Ket induced the model of SZ by altering the behavioural parameters (e.g. hyperlocomotion, social impairment, deficits in the sensory-motor profile and memory damage in the adult animals); and also caused changes in the parameters of oxidative stress (lipid hydroperoxide - LPO; 8-isoprostane - 8-ISO; 4-hydroxynonenal - 4-HNE; protein carbonyl content; superoxide dismutase - SOD and catalase - CAT) as well as in the levels of neurotrophic factors (brain-derived neurotrophic factor - BDNF and nerve growth factor - NGF) particularly within the FC of adult offspring. A deficiency in maternal FA, alone or in combination with ket, was able to induce hyperlocomotion and social impairment in the offspring with increased levels of lipid and protein damage (LPO, 8-ISO, 4-HNE, carbonylation of protein) within the FC, increased activity of antioxidant enzymes (SOD and CAT) in both of the brain structures studied, and also reduced the levels of neurotrophins (BDNF and NGF), particularly within the Hip of the adult offspring. Supplementation of FA (5, 10 and 50 mg/kg) to the Dam's was mostly able to prevent the cognitive damage which was induced by Ket in the adult animals. FA (10 and 50 mg/kg) attenuated the action of Ket in the animals in relation to the biochemical parameters, proving the possible neuroprotective effect of FA in the adulthood of offspring that were subjected to the animal model of SZ. Our study indicates that the intake of maternal FA during pregnancy and lactation plays an important role, particularly in the regulation of markers of oxidative stress and neurotrophins.

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.

The inhibition of the kynurenine pathway prevents behavioral disturbances and oxidative stress in the brain of adult rats subjected to an animal model of schizophrenia

Evidence has shown that the kynurenine pathway (KP) plays a role in the onset of oxidative stress and also in the pathophysiology of schizophrenia. The aim of this study was to use a pharmacological animal model of schizophrenia induced by ketamine to investigate if KP inhibitors could protect the brains of Wistar rats against oxidative stress and behavioral changes. Ketamine, injected at the dose of 25mg/kg, increased spontaneous locomotor activity. However, the inhibitors of tryptophan 2,3-dioxygenase (TDO), indoleamine 2,3-dioxygenase (IDO) and kynurenine-3-monooxygenase (KMO) were able to reverse these changes. In addition, the IDO inhibitor prevented lipid peroxidation, and decreased the levels of protein carbonyl in the prefrontal cortex (PFC), hippocampus and striatum. It also increased the activity of superoxide dismutase (SOD) in the hippocampus, as well as increasing the levels of catalase activity in the PFC and hippocampus. The TDO inhibitor prevented lipid damage in the striatum and reduced the levels of protein carbonyl in the hippocampus and striatum. Also, the TDO inhibitor increased the levels of SOD activity in the striatum and CAT activity in the hippocampus of ketamine-induced pro-oxidant effects. Lipid damage was not reversed by the KMO inhibitor. The KMO inhibitor increased the levels of SOD activity in the hippocampus, and reduced the levels of protein carbonyl while elevating the levels of CAT activity in the striatum of rats that had been injected with ketamine. Our findings revealed that the KP pathway could be a potential mechanism by which a schizophrenia animal model induced by ketamine could cause interference by producing behavioral disturbance and inducing oxidative stress in the brain, suggesting that the inhibition of the KP pathway could be a potential target in treating schizophrenia.

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.

The preventive effects of ascorbic acid supplementation on locomotor and acetylcholinesterase activity in an animal model of schizophrenia induced by ketamine

Studies have shown that schizophrenic patients seem to have nutritional deficiencies. Ascorbic acid (AA) has an important antioxidant effect and neuromodulatory properties. The aim of this study was to evaluate the effects of AA on locomotor activity and the acetylcholinesterase activity (AChE) in an animal model of schizophrenia (SZ). Rats were supplemented with AA (0.1, 1, or 10 mg/kg), or water for 14 days (gavage). Between the 9th and 15th days, the animals received Ketamine (Ket) (25 mg/kg) or saline (i.p). After the last administration (30 min) rats were subjected to the behavioral test. Brain structures were dissected for biochemical analysis. There was a significant increase in the locomotor activity in Ket treated. AA prevented the hyperlocomotion induced by ket. Ket also showed an increase of AChE activity within the prefrontal cortex and striatum prevented by AA. Our data indicates an effect for AA in preventing alterations induced by Ket in an animal model of SZ, suggesting that it may be an adjuvant approach for the development of new therapeutic strategies within this psychiatric disorder.

Therapeutic efficacy of atypical antipsychotic drugs by targeting multiple stress-related metabolic pathways

Schizophrenia (SZ) is considered to be a multifactorial brain disorder with defects involving many biochemical pathways. Patients with SZ show variable responses to current pharmacological treatments of SZ because of the heterogeneity of this disorder. Stress has a significant role in the pathophysiological pathways and therapeutic responses of SZ. Atypical antipsychotic drugs (AAPDs) can modulate the stress response of the hypothalamic-pituitary-adrenal (HPA) axis and exert therapeutic effects on stress by targeting the prefrontal cortex (PFC) and hippocampus. To evaluate the effects of AAPDs (such as clozapine, risperidone and aripiprazole) on stress, we compared neurochemical profile variations in the PFC and hippocampus between rat models of chronic unpredictable mild stress (CUMS) for HPA axis activation and of long-term dexamethasone exposure (LTDE) for HPA axis inhibition, using an ultraperformance liquid chromatography-mass spectrometry (UPLC-MS/MS)-based metabolomic approach and a multicriteria assessment. We identified a number of stress-induced biomarkers comprising creatine, choline, inosine, hypoxanthine, uric acid, allantoic acid, lysophosphatidylcholines (LysoPCs), phosphatidylethanolamines (PEs), corticosterone and progesterone. Specifically, pathway enrichment and correlation analyses suggested that stress induces oxidative damage by disturbing the creatine-phosphocreatine circuit and purine pathway, leading to excessive membrane breakdown. Moreover, our data suggested that the AAPDs tested partially restore stress-induced deficits by increasing the levels of creatine, progesterone and PEs. Thus, the present findings provide a theoretical basis for the hypothesis that a combined therapy using adenosine triphosphate fuel, antioxidants and omega-3 fatty acids as supplements may have synergistic effects on the therapeutic outcome following AAPD treatment.

The Evaluation of Folic Acid-Deficient or Folic Acid-Supplemented Diet in the Gestational Phase of Female Rats and in Their Adult Offspring Subjected to an Animal Model of Schizophrenia

Although folic acid (FA) supplementation is known to influence numerous physiological functions, especially during pregnancy, little is known about its direct effects on the mothers' health. However, this vitamin is essential for the health of the mother and for the normal growth and development of the fetus. Thus, the aim of this study was (1) to evaluate the cognitive effects and biochemical markers produced by the AIN-93 diet (control), the AIN-93 diet supplemented with different doses of FA (5, 10, and 50 mg/kg), and a FA-deficient diet during pregnancy and lactation in female mother rats (dams) and (2) to evaluate the effect of maternal diets on inflammatory parameters in the adult offspring which were subjected to an animal model of schizophrenia (SZ) induced by ketamine (Ket). Our study demonstrated through the Y-maze test that rats subjected to the FA-deficient diet showed significant deficits in spatial memory, while animals supplemented with FA (5 and 10 mg/kg) showed no deficit in spatial memory. Our results also suggest that the rats subjected to the FA-deficient diet had increased levels of carbonylated proteins in the frontal cortex and hippocampus and also increased plasma levels of homocysteine (Hcy). Folate was able to prevent cognitive impairments in the rats supplemented with FA (5 and 10 mg/kg), data which may be attributed to the antioxidant effect of the vitamin. Moreover, FA prevented protein damage and elevations in Hcy levels in the rats subjected to different doses of this vitamin (5, 10, and 50 mg/kg). We verified a significant increase of the anti-inflammatory cytokine (interleukin-4 (IL-4)) and a reduction in the plasma levels of proinflammatory cytokines (interleukin-6 (IL-6)) and TNF-α) in the dams that were subjected to the diets supplemented with FA (5, 10, and 50 mg/kg), showing the possible anti-inflammatory effects of FA during pregnancy and lactation. In general, we also found that in the adult offspring that were subjected to an animal model of SZ, FA had a protective effect in relation to the levels of IL-4, IL-6, and TNF-α, which indicates that the action of FA persisted in the adult offspring, since FA showed a lasting effect on the inflammatory response, which was similar in both the dams and their offspring. In conclusion, the importance of supplementation with FA during pregnancy and lactation should be emphasized, not only for the benefit of the offspring but also for the health of the mother. All this is due to the considerable protective effect of this vitamin against oxidative damage, cognitive impairment, hyperhomocysteinemia, immune function, and also its ability in preventing common processes in post-pregnancy stages, as well as in reducing the risks of neurodevelopmental disorders and enhancing fetal immune development.

Evaluation of 50-kHz ultrasonic vocalizations in animal models of mania: Ketamine and lisdexamfetamine-induced hyperlocomotion in rats

Drug-induced hyperlocomotion in rodents is frequently used as a behavioral model for mania. However, the use of locomotor activity as the single parameter in these animal models of mania may pose some limitations for developing new pharmacological treatments. Thus, alternative behavioral markers are required. Fifty-kHz ultrasonic vocalizations (USV), which are thought to represent positive affect, are increased by the administration of the psychostimulant d-amphetamine, an effect that can be prevented by lithium treatment, the gold standard antimanic drug for treating bipolar disorder. The aim of this study was to evaluate 50-kHz USV in two other pharmacological-induced animal models of mania: ketamine (KET)- and lisdexamfetamine (LDX)-induced hyperlocomotion. After systemic injection of LDX (10mg/kg, ip), racemic-ketamine (25mg/kg, ip) or S-ketamine (25mg/kg, ip), locomotor activity and 50-kHz USV emission were evaluated in rats. Furthermore, the effects of an antimanic treatment, namely lithium carbonate (100mg/kg, ip), on LDX-induced 50-kHz USV and hyperlocomotion were tested. Rats treated with racemic KET and S-KET showed increased locomotor activity, but these drug treatments did not significantly affect 50-kHz USV emission rates. On the other hand, LDX administration increased both locomotor activity and 50-kHz USV with both effects being reversed by lithium administration. The present findings suggest that 50-kHz USV can differentiate between drug-induced models of mania, which may represent different types of manic episodes. Thus, measuring 50-kHz USV might serve as an additional valuable behavioral variable to assess mania-like phenotypes in rat models.

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

ABSTRACTNew 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-1β and IL6. These findings suggest that the similarity of IL-1β 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.

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.

Different effects of the NMDA receptor antagonists ketamine, MK-801, and memantine on postsynaptic density transcripts and their topography: role of Homer signaling, and implications for novel antipsychotic and pro-cognitive targets in psychosis

Administration of NMDA receptor antagonists, such as ketamine and MK-801, may induce psychotic-like behaviors in preclinical models of schizophrenia. Ketamine has also been observed to exacerbate psychotic symptoms in schizophrenia patients. However, memantine, a non-competitive NMDA receptor antagonist approved for Alzheimer's disease and proposed for antipsychotic augmentation, may challenge this view. To date, the molecular mechanisms by which these NMDA receptor antagonists cause different neurochemical, behavioral, and clinical effects are still a matter of debate. Here, we investigated by molecular imaging whether these agents could differently modulate gene expression and topographical distribution of glutamatergic postsynaptic density (PSD) proteins. We focused on Homer1a/Homer1b/PSD-95 signaling network, which may be implicated in glutamate-dependent synaptic plasticity, as well as in psychosis pathophysiology and treatment. Ketamine (25 and 50mg/kg) and MK-801 (0.8mg/kg) significantly induced the transcripts of immediate-early genes (Arc, c-fos, and Homer1a) in cortical regions compared to vehicle, whereas they reduced Homer1b and PSD-95 expression in cortical and striatal regions. Differently, memantine (5mg/kg) did not increase Homer1a signal compared to vehicle, whereas it induced c-fos in the somatosensory and in the medial agranular cortices. Moreover, memantine did not affect Homer1b and PSD-95 expression. When compared to ketamine and MK-801, memantine significantly increased the expression of c-fos, Homer1b and PSD-95. Overall, ketamine and MK-801 prominently increased Homer1a/Homer1b expression ratio, whereas memantine elicited the opposite effect. These data may support the view that ketamine, MK-801 and memantine exert divergent effects on PSD transcripts, which may contribute to their partially different behavioral and clinical effects.

Rivastigmine reverses cognitive deficit and acetylcholinesterase activity induced by ketamine in an animal model of schizophrenia

Schizophrenia is one of the most disabling mental disorders that affects up to 1 % of the population worldwide. Although the causes of this disorder remain unknown, it has been extensively characterized by a broad range of emotional, ideational and cognitive impairments. Studies indicate that schizophrenia affects neurotransmitters such as dopamine, glutamate and acetylcholine. Recent studies suggest that rivastigmine (an acetylcholinesterase inhibitor) is important to improve the cognitive symptoms of schizophrenia. Therefore, the present study evaluated the protective effect of rivastigmine against the ketamine-induced behavioral (hyperlocomotion and cognitive deficit) and biochemical (increase of acetylcholinesterase activity) changes which characterize an animal model of schizophrenia in rats. Our results indicated that rivastigmine was effective to improve the cognitive deficit in different task (immediate memory, long term memory and short term memory) induced by ketamine in rats. Moreover, we observed that rivastigmina reversed the increase of acetylcholinesterase activity induced by ketamine in the cerebral cortex, hippocampus and striatum. However, rivastigmine was not able to prevent the ketamine-induced hyperlocomotion. In conslusion, ours results indicate that cholinergic system might be an important therapeutic target in the physiopathology of schizophrenia, mainly in the cognition, but additional studies should be carried.

Effect of maternal deprivation on acetylcholinesterase activity and behavioral changes on the ketamine-induced animal model of schizophrenia

Maternal deprivation has been associated with physiological and developmental changes that may be related to an increased risk for childhood and adult neuropsychiatric diseases. A growing number of studies demonstrated the importance of childhood experiences in the development of psychosis and schizophrenia in adulthood. Therefore, the present study investigated different behavior responses in rats following maternal deprivation and/or ketamine treatment in adulthood. Male rats were subjected to maternal deprivation for 180 min from postnatal day-01 to postnatal day-10. We evaluated locomotor activity, avoidance task and social interaction of adult male rats deprived or not deprived that were administered with saline or acute subanesthetic doses of ketamine (5, 15 and 25 mg/kg, i.p.). Our results show that only ketamine (25 mg/kg, i.p.) treatment in the adult rats lead to hyperlocomotion but not ketamine (5 and 15 mg/kg) and maternal deprivation alone. However, maternally deprived rats treated with ketamine (5 mg/kg) induced hyperlocomotion. Additionally, ketamine (25 mg/kg) and maternal deprivation alone induced cognitive deficit in the avoidance task. Rats deprived of and treated with ketamine (5, 15 and 25 mg/kg) also lead to memory deficit. Moreover, ketamine (25 mg/kg) and maternal deprivation alone increased latency to start social behavior. However, ketamine (5 mg/kg) and maternal deprivation lead to an increase of latency to start social behavior. Biochemistry data showed that all doses of ketamine and ketamine plus maternal deprivation increased the acetylcholinesterase (AChE) activity in the prefrontal cortex, hippocampus and striatum. The major doses of ketamine associated with maternal deprivation induced a major increase of AChE activity. Together, our results suggest that animals subjected to maternal deprivation had an increased risk for schizophrenia-like behavior and cholinergic alteration.

Evaluation of behavioral and neurochemical changes induced by ketamine in rats: implications as an animal model of mania

Bipolar disorder (BD) is a chronic, prevalent, and highly debilitating psychiatric illness characterized by recurrent manic and depressive episodes. Mood stabilizing agents such as lithium and valproate are two primary drugs used to treat BD. To develop a novel animal model of mania (hallmark of BD), it is important to assess the therapeutic and prophylactic effect of these mood stabilizers on the new candidate target animal model. The present work investigates the therapeutic and prophylactic value of lithium and valproate in a novel preclinical animal model of mania, induced by ketamine. In the prevention protocol, wistar rats were pretreated with lithium (47.5 mg/kg, i.p., twice a day), valproate (200 mg/kg, i.p., twice a day), or saline (i.p., twice a day) for 14 days. Between days 8 and 14, the rats were treated with ketamine (25 mg/kg, i.p.) or saline. In the reversal protocol, rats first received ketamine (25 mg/kg, i.p.) or saline. After, the administration of lithium, valproate, or saline was carried out for seven days. Our results indicated that lithium and valproate reversed and prevented ketamine-induced hyperlocomotion. Moreover, lithium and valproate reversed (prefrontal cortex, hippocampus, and striatum) and prevented (prefrontal cortex, hippocampus, striatum, and amygdala) the increase of the TBARS level induced by ketamine. The protein carbonyl formation, induced by ketamine, was reversed by lithium and valproate in the prefrontal cortex, hippocampus, and striatum, and prevented only in the amygdala. These findings support the notion that the administration of ketamine might be a promising pharmacological animal model of mania, which could play a role in the pathophysiology of BD.

Na+,K+-ATPase activity is increased in rats subjected to chronic administration of ketamine

De Luca RD, Fraga DB, Ghedim FV, Kolling J, Ferreira AGK, Cunha AA, Wyse ATS, Zugno AI. Na+,K+-ATPase activity is increased in rats subjected to chronic administration of ketamine.

Objective: Schizophrenia is a devastating psychiatric disorder. Symptoms of schizophrenia can be divided into positive, negative and cognitive, and the physiopathology is still been unknown. Na+,K+-ATPase is a protein in its role as a maintainer of fluid balance in all mammals and alterations in this enzyme could cause brain abnormalities. The aim of our study was to investigate the activity of this enzyme in rats submitted to chronic administration of ketamine.

Methods: Adult male Wistar rats were submitted to sub-anaesthetic doses of the 25 mg/kg ketamine by seven consecutive days and the Na+,K+-ATPase activity was analysed in prefrontal and hippocampus of rats.

Results: We observed an increase in Na+,K+-ATPase activity in prefrontal cortex administration of 25 mg/kg ketamine. However, ketamine has no effect in hippocampus.

Conclusion: This evidence indicates that the alteration in Na+,K+-ATPase may be related with glutamatergic system and consequently could be related to the development of schizophrenia.