Perspectives for the development of animal models of bipolar disorder

The emerging neuroimmune hypothesis of bipolar disorder: An updated overview of neuroimmune and microglial findings

Bipolar disorder (BD) is a severe and multifactorial disease, with onset usually in young adulthood, which follows a progressive course throughout life. Replicated epidemiological studies have suggested inflammatory mechanisms and neuroimmune risk factors as primary contributors to the onset and development of BD. While not all patients display overt markers of inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease and seems to be mood phase dependent, likely explaining the heterogeneity of findings observed in this population. As the brain's immune cells, microglia orchestrate the brain's immune response and play a critical role in maintaining the brain's health across the lifespan. Microglia are also highly sensitive to environmental changes and respond to physiological and pathological events by adapting their functions, structure, and molecular expression. Recently, it has been highlighted that instead of a single population of cells, microglia comprise a heterogeneous community with specialized states adjusted according to the local molecular cues and intercellular interactions. Early evidence has highlighted the contribution of microglia to BD neuropathology, notably for severe outcomes, such as suicidality. However, the roles and diversity of microglial states in this disease are still largely undermined. This review brings an updated overview of current literature on the contribution of neuroimmune risk factors for the onset and progression of BD, the most prominent neuroimmune abnormalities (including biomarker, neuroimaging, ex vivo studies) and the most recent findings of microglial involvement in BD neuropathology. Combining these different shreds of evidence, we aim to propose a unifying hypothesis for BD pathophysiology centered on neuroimmune abnormalities and microglia. Also, we highlight the urgent need to apply novel multi-system biology approaches to characterize the diversity of microglial states and functions involved in this enigmatic disorder, which can open bright perspectives for novel biomarkers and therapeutic discoveries.

Antimanic-like effect of dipyridamole in the methylphenidate-induced hyperlocomotion

BACKGROUND

Adenosinergic system has been implicated in the pathophysiology of bipolar disorder and drugs that affect adenosine neurotransmission have shown some efficacy as add-on therapy in manic patients.

OBJECTIVE

Thus, the aim of the present study was to screen adenosinergic drugs for antimanic-like effect in methylphenidate (MPH)-induced hyperlocomotion in mice.

METHODS

Male and female Swiss mice received a single allopurinol (50 and 200 mg/kg, ip), dipyridamole (20 mg/kg, ip), or inosine (50 mg/kg, ip) administration before an acute MPH challenge (5 mg/kg, sc). In experiments with repeated treatment, male mice received a daily administration of allopurinol (25 and 50 mg/kg, ip), dipyridamole (20 mg/kg, ip), or inosine (50 mg/kg, ip) for 14 days. Finally, pretreatment with aminophylline (2 mg/kg, sc), an unspecific adenosine receptor antagonist, was used to evaluate a putative adenosinergic mediation. Locomotor activity was measured in the automated activity chamber for 20 min.

RESULTS

Acute and repeated dipyridamole reduced the increase in locomotor activity induced by MPH, while allopurinol and inosine had no effect. Aminophylline blocked the effect of dipyridamole in MPH-induced hyperlocomotion.

CONCLUSION

The present results suggest that dipyridamole may have an antimanic-like effect through adenosine receptors and reinforce the proposal that the adenosine system may be an interesting target for new antimanic drugs.

Zebrafish as a potential non-traditional model organism in translational bipolar disorder research: Genetic and behavioral insights

Bipolar disorder (BD) is a severe and debilitating illness that affects 1-2% of the population worldwide. BD is characterized by recurrent and extreme mood swings, including mania/hypomania and depression. Animal experimental models have been used to elucidate the mechanisms underlying BD and different strategies have been proposed to assess BD-like symptoms. The zebrafish (Danio rerio) has been considered a suitable vertebrate system for modeling BD-like responses, due to the genetic tractability, molecular/physiological conservation, and well-characterized behavioral responses. In this review, we discuss how zebrafish-based models can be successfully used to understand molecular, biochemical, and behavioral alterations paralleling those found in BD. We also outline some advantages and limitations of this aquatic species to examine BD-like phenotypes in translational neurobehavioral research. Overall, we reinforce the use of zebrafish as a promising tool to investigate the neural basis associated with BD-like behaviors, which may foster the discovery of novel pharmacological therapies.

Substance use as a risk factor for bipolar disorder: A systematic review

Detecting substance use as a predictor of bipolar disorder (BD) is important for clinicians to perform accurate and early diagnosis, as well as better manage the treatment of individuals with BD. The aim of this systematic review was to describe whether substance use is a predictor of BD. A literature search was conducted using the following databases: PubMed, PsycINFO, and Embase. All eligible studies published up to February 9, 2021 were included. This systematic review included 22 studies. We found that 66.7% of the studies assessing overall substance use found that overall substance use was a risk factor for BD. Regarding the specific substances assessed, cannabis use was described as a risk factor for BD in 55.6% of the studies, nonmedical use of prescription medications was a risk factor for BD in 50% of the studies, nicotine was found as a risk factor for BD in 50% of the studies, and alcohol use was described as a risk factor for BD in 42.9% of the studies assessing it. Only one study assessed whether cocaine use was a risk factor for BD and found a significant association. Interestingly, some studies suggested that the greater frequency of cannabis use was associated with greater risk to develop BD or hypomanic/manic symptoms. In conclusion, there is evidence supporting that substance use is a risk factor for BD. Importantly, when assessing the risk factors for BD related to psychoactive substance use, special attention should be given for the frequency of cannabis use.

Glutathione peroxidase-1 and neuromodulation: Novel potentials of an old enzyme

Glutathione peroxidase (GPx) acts in co-ordination with other signaling molecules to exert its own antioxidant role. We have demonstrated the protective effects of GPx,/GPx-1, a selenium-dependent enzyme, on various neurodegenerative disorders (i.e., Parkinson's disease, Alzheimer's disease, cerebral ischemia, and convulsive disorders). In addition, we summarized the recent findings indicating that GPx-1 might play a role as a neuromodulator in neuropsychiatric conditions, such as, stress, bipolar disorder, schizophrenia, and drug intoxication. In this review, we attempted to highlight the mechanistic scenarios mediated by the GPx/GPx-1 gene in impacting these neurodegenerative and neuropsychiatric disorders, and hope to provide new insights on the therapeutic interventions against these disorders.

Disrupted circadian rhythms and mental health

During the evolution of life, the temporal rhythm of our rotating planet was internalized in the form of circadian rhythms. Circadian rhythms are ~24h internal manifestations that drive daily patterns of physiology and behavior. These rhythms are entrained (synchronized) to the external environment, primarily by the light-dark cycle, and precisely controlled via molecular clocks located within the suprachiasmatic nucleus of the hypothalamus. Misalignment and/or disruption of circadian rhythms can have detrimental consequences for human health. Indeed, studies suggest strong associations between mental health and circadian rhythms. However, direct interactions between mood regulation and the circadian system are just beginning to be uncovered and appreciated. This chapter examines the relationship between disruption of circadian rhythms and mental health. The primary focus will be outlining the association between circadian disruption, in the form of night shift work, exposure to light at night, jet lag, and social jet lag, and psychiatric illness (i.e., anxiety, major depressive disorder, bipolar disorder, and schizophrenia). Additionally, we review animal models of disrupted circadian rhythms, which provide further evidence in support of a strong association between circadian disruption and affective responses. Finally, we discuss future directions for the field and suggest areas of study that require further investigation.

NQO1 regulates pharmaco-behavioral effects of d-amphetamine in striatal dopaminergic system in mice

The NAD(P)H:quinone oxidoreductase 1 (NQO1) gene encodes a cytosolic flavoenzyme that catalyzes the two-electron reduction of quinones to hydroquinones. A polymorphic form of NQO1 is associated with mood disorders such as schizophrenia. However, the role of NQO1 in dopaminergic system has not yet been elucidated. To determine the role of NQO1 in the dopaminergic system, we investigated pharmaco-behavioral effects of d-amphetamine using NQO1-deficienct mice. According to our comparative study involving NQO1^+/+ and NQO1^-/- mice, NQO1 deficiency increased d-amphetamine-induced psychomotor activity and psychological dependency compared to wild-type mice. Basal and d-amphetamine-induced dopamine levels were also enhanced by NQO1 deficiency. In NQO1^-/- mice, neural activation induced by d-amphetamine was higher in dorsolateral striatum, but not in dorsomedial and ventral striata. Although protein level of CaMKIIα, which is a key player in amphetamine-induced dopamine efflux, was decreased in striata of NQO1^-/- mice, phosphorylation of CaMKIIα was markedly enhanced in NQO1^-/- mice compared to wild-type mice. Interestingly, experiments with pharmacological antagonist showed that D2 antagonist-induced suppression of locomotion required activation of NQO1. Moreover, the rewarding effect in response to D1 agonist was increased by NQO1 deficiency. These results suggest that striatal NQO1 is of considerable interest to understand the mechanism of dopaminergic regulation of psychiatric disorders.

Lithium attenuates d-amphetamine-induced hyperlocomotor activity in mice via inhibition of interaction between cyclooxygenase-2 and indoleamine-2,3-dioxygenase

In the present study, we investigated whether mood stabilizer lithium (Li) protects against d-amphetamine (AMP)-induced mania-like behaviours via modulating the novel proinflammatory potential. Repeated treatment with AMP resulted in significant increases in proinflammatory cyclooxygenase-2 (COX-2) and indolemaine-2,3-dioxygenase-1 (IDO)-1 expression in the prefrontal cortex (PFC) of mice. However, AMP treatment did not significantly change IDO-2 and 5-lipoxygenase (5-LOX) expression, suggesting that proinflammatory parameters such as COX-2 and IDO-1 are specific for AMP-induced behaviours. AMP-induced initial expression of COX-2 (15 minutes post-AMP) was earlier than that of IDO-1 (1 hour post-AMP). Mood stabilizer Li and COX-2 inhibitor meloxicam significantly attenuated COX-2 expression 15 minutes post-AMP, whereas IDO-1 inhibitor 1-methyl-DL-tryptophan (1-MT) did not affect COX-2 expression. However, AMP-induced IDO-1 expression was significantly attenuated by Li, meloxicam or 1-MT, suggesting that COX-2 is an upstream molecule for the induction of IDO-1 caused by AMP. Consistently, co-immunoprecipitation between COX-2 and IDO-1 was observed at 30 minutes, 1, 3, and 6 hours after the final AMP treatment. This interaction was also significantly inhibited by Li, meloxicam or 1-MT. Furthermore, AMP-induced hyperlocomotion was significantly attenuated by Li, meloxicam or 1-MT. We report, for the first time, that mood stabilizer Li attenuates AMP-induced mania-like behaviour via attenuation of interaction between COX-2 and IDO-1, and that the interaction of COX-2 and IDO-1 may be critical for the therapeutic intervention mediated by mood stabilizer.

Circadian rhythm disruption and mental health

Circadian rhythms are internal manifestations of the solar day that permit adaptations to predictable environmental temporal changes. These ~24-h rhythms are controlled by molecular clockworks within the brain that are reset daily to precisely 24 h by exposure to the light-dark cycle. Information from the master clock in the mammalian hypothalamus conveys temporal information to the entire body via humoral and neural communication. A bidirectional relationship exists between mood disorders and circadian rhythms. Mood disorders are often associated with disrupted circadian clock-controlled responses, such as sleep and cortisol secretion, whereas disruption of circadian rhythms via jet lag, night-shift work, or exposure to artificial light at night, can precipitate or exacerbate affective symptoms in susceptible individuals. Evidence suggests strong associations between circadian rhythms and mental health, but only recently have studies begun to discover the direct interactions between the circadian system and mood regulation. This review provides an overview of disrupted circadian rhythms and the relationship to behavioral health and psychiatry. The focus of this review is delineating the role of disruption of circadian rhythms on mood disorders using human night shift studies, as well as jet lag studies to identify links. We also review animal models of disrupted circadian rhythms on affective responses. Lastly, we propose low-cost behavioral and lifestyle changes to improve circadian rhythms and presumably behavioral health.

Indoleamine-2,3-dioxygenase-1 is a molecular target for the protective activity of mood stabilizers against mania-like behavior induced by d-amphetamine

It is recognized that d-amphetamine (AMPH)-induced hyperactivity is thought to be a valid animal model of mania. In the present study, we investigated whether a proinflammatory oxidative gene indoleamine-2,3-dioxygenase (IDO) is involved in AMPH-induced mitochondrial burden, and whether mood stabilizers (i.e., lithium and valproate) modulate IDO to protect against AMPH-induced mania-like behaviors. AMPH-induced IDO-1 expression was significantly greater than IDO-2 expression in the prefrontal cortex of wild type mice. IDO-1 expression was more pronounced in the mitochondria than in the cytosol. AMPH treatment activated intra-mitochondrial Ca²⁺ accumulation and mitochondrial oxidative burden, while inhibited mitochondrial membrane potential and activity of the mitochondrial complex (I > II), mitochondrial glutathione peroxidase, and superoxide dismutase, indicating that mitochondrial burden might be contributable to mania-like behaviors induced by AMPH. The behaviors were significantly attenuated by lithium, valproate, or IDO-1 knockout, but not in IDO-2 knockout mice. Lithium, valproate administration, or IDO-1 knockout significantly attenuated mitochondrial burden. Neither lithium nor valproate produced additive effects above the protective effects observed in IDO-1 KO in mice. Collectively, our results suggest that mood stabilizers attenuate AMPH-induced mania-like behaviors via attenuation of IDO-1-dependent mitochondrial stress, highlighting IDO-1 as a novel molecular target for the protective potential of mood stabilizers.

Validation of the animal model of bipolar disorder induced by Ouabain: face, construct and predictive perspectives

A particular challenge in the development of a bipolar disorder (BD) model in animals is the complicated clinical course of the condition, characterized by manic, depressive and mixed mood episodes. Ouabain (OUA) is an inhibitor of Na⁺/K⁺-ATPase enzyme. Intracerebroventricular (ICV) injection of this drug in rats has been regarded a proper model to study BD by mimic specific manic symptoms, which are reversed by lithium (Li), an important mood stabilizer drug. However, further validation of this experimental approach is required to characterize it as an animal model of BD, including depressive-like behaviors. The present study aimed to assess manic- and depressive-like behaviors, potential alteration in the hypothalamic-pituitary-adrenal (HPA) system and oxidative stress parameters after a single OUA ICV administration in adult male Wistar rats. Moreover, we evaluated Li effects in this experimental setting. Data show that OUA ICV administration could constitute a suitable model for BD since the injection of the drug triggered manic- and depressive-like behaviors in the same animal. Additionally, the OUA model mimics significant physiological and neurochemical alterations detected in BD patients, including an increase in oxidative stress and change in HPA axis. Our findings suggest that decreased Na⁺/K⁺-ATPase activity detected in bipolar patients may be linked to increased secretion of glucocorticoid hormones and oxidative damage, leading to the marked behavioral swings. The Li administration mitigated these pathological changes in the rats. The proposed OUA model is regarded as suitable to simulate BD by complying with all validities required to a proper animal model of the psychiatric disorder.

Evaluation of Neurotransmitter Alterations in Four Distinct Brain Regions After Rapid Eye Movement Sleep Deprivation (REMSD) Induced Mania-Like Behaviour in Swiss Albino Mice

A number of neurotransmitter systems have been implicated in contributing to the pathology of mood disorders, including those of dopamine (DA), serotonin (5-HT), norepinephrine (NE) and γ-aminobutyric acid (GABA). Rapid eye movement sleep deprivation (REMSD) alters most of the neurotransmitters, which may have adverse behavioural changes and other health consequences like mania and other psychiatric disorders. The exact role of REMSD altered neurotransmitter levels and the manner in which emerging consequences lead to mania-like behaviour is poorly understood. Thus, we sought to verify the levels of neurotransmitter changes after 48, 72 and 96 h of REMSD induced mania-like behaviour in mice. We performed modified multiple platform (MMP) method of depriving the REM sleep and one group maintained as a control. To measure the hyperactivity through locomotion, exploration and behavioural despair, we performed the Open Field Test (OFT) and the Forced Swim Test (FST). Quantitative determinations of DA, 5-HT, NE and GABA concentrations in four distinct brain regions (cerebral cortex, hippocampus, midbrain, and pons) were determined by the spectrofluorimetric method. These experiments showed higher locomotion and increased swimming, struggling/climbing and decreased mobility among REMSD animals as well as disrupted concentrations of the majority of the studied neurotransmitters during REMSD. Our study indicated that REMSD results in mania-like behaviour in mice and associated disruption to neurotransmitter levels, although the exact mechanisms by which these take place remain to be determined.

Lithium and Tamoxifen Modulate Behavior and Protein Kinase C Activity in the Animal Model of Mania Induced by Ouabain

BACKGROUND

The intracerebroventricular injection of ouabain, a specific inhibitor of the Na+/K+-adenosine-triphosphatase (Na+/K+-ATPase) enzyme, induces hyperactivity in rats in a putative animal model of mania. Several evidences have suggested that the protein kinase C signaling pathway is involved in bipolar disorder. In addition, it is known that protein kinase C inhibitors, such as lithium and tamoxifen, are effective in treating acute mania.

METHODS

In the present study, we investigated the effects of lithium and tamoxifen on the protein kinase C signaling pathway in the frontal cortex and hippocampus of rats submitted to the animal model of mania induced by ouabain. We showed that ouabain induced hyperlocomotion in the rats.

RESULTS

Ouabain increased the protein kinase C activity and the protein kinase C and MARCKS phosphorylation in frontal cortex and hippocampus of rats. Lithium and tamoxifen reversed the behavioral and protein kinase C pathway changes induced by ouabain. These findings indicate that the Na+/K+-ATPase inhibition can lead to protein kinase C alteration.

CONCLUSIONS

The present study showed that lithium and tamoxifen modulate changes in the behavior and protein kinase C signalling pathway alterations induced by ouabain, underlining the need for more studies of protein kinase C as a possible target for treatment of bipolar disorder.

Lithium and valproate prevent methylphenidate-induced mania-like behaviors in the hole board test

Manic bipolar is diagnosed by psychomotor agitation, increased goal-directed activity, insomnia, grandiosity, excessive speech, and risky behavior. Animal studies aimed to modeling mania are commonly based in psychostimulants-induced hyperlocomotion. The exploration of other behaviors related with mania is mandatory to investigate this phase of bipolar disorder in animals. In this study, the hole board apparatus was suggested for evaluating mania-like behaviors induced by the psychostimulant methylphenidate. The treatment with methylphenidate (10mg/kg, ip) increased locomotion in the open field test. The pretreatment with lithium (50mg/kg, ip) and valproate (400mg/kg, ip) significantly prevented the hyperlocomotion. In the hole-board test, methylphenidate increased interactions with the central and peripheral holes and the exploration of central areas. Lithium was more effective than valproate in preventing all the behavioral manifestations induced by the psychostimulant. These findings were discussed based on the ability of methylphenidate-treated mice mimicking two symptoms of mania in the hole board test: goal-directed action and risk-taking behavior. In conclusion, the results point to a new approach to study mania through the hole board apparatus. The hole board test appears to be a sensitive assay to detect the efficacy of antimanic drugs.

Modeling mania in preclinical settings: A comprehensive review

The current pathophysiological understanding of mechanisms leading to onset and progression of bipolar manic episodes remains limited. At the same time, available animal models for mania have limited face, construct, and predictive validities. Additionally, these models fail to encompass recent pathophysiological frameworks of bipolar disorder (BD), e.g. neuroprogression. Therefore, there is a need to search for novel preclinical models for mania that could comprehensively address these limitations. Herein we review the history, validity, and caveats of currently available animal models for mania. We also review new genetic models for mania, namely knockout mice for genes involved in neurotransmission, synapse formation, and intracellular signaling pathways. Furthermore, we review recent trends in preclinical models for mania that may aid in the comprehension of mechanisms underlying the neuroprogressive and recurring nature of BD. In conclusion, the validity of animal models for mania remains limited. Nevertheless, novel (e.g. genetic) animal models as well as adaptation of existing paradigms hold promise.

Antimanic-like effects of (R)-(-)-carvone and (S)-(+)-carvone in mice

Carvone is a monoterpene that is present in spearmint (Mentha spicata) and caraway (Carum carvi) essential oils and has been shown to have anticonvulsant effects, likely through the blockade of voltage-gated sodium channels, and anxiolytic-like effects. Considering that some anticonvulsants that blocked voltage-gated sodium channels (e.g., sodium valproate and carbamazepine) exert clinical antimanic effects, the aim of the present study was to evaluate (R)-(-)-carvone and (S)-(+)-carvone in animal models of mania (i.e., hyperlocomotion induced by methylphenidate and sleep deprivation). Mice that were treated with methylphenidate (5mg/kg) or sleep-deprived for 24h using a multiple-platform protocol exhibited an increase in locomotor activity in an automated activity box. This effect was blocked by pretreatment with acute (R)-(-)-carvone (50-100mg/kg), (S)-(+)-carvone (50-100mg/kg), and lithium (100mg/kg, positive control). These doses did not alter spontaneous locomotor activity in the methylphenidate-induced experiments while (S)-(+)-carvone decreased spontaneous locomotor activity in sleep deprivation experiment, indicating a sedative effect. Chronic 21-day treatment with (R)-(-)-carvone (100mg/kg), (S)-(+)-carvone (100mg/kg), and lithium also prevented methylphenidate-induced hyperactivity. The present results suggest that carvone may have an antimanic-like effect.

Antipsychotic-like effects of a neurotensin receptor type 1 agonist

Although neurotensin (NT) analogs are known to produce antipsychotic-like effects, the therapeutic possibility of a brain penetrant NTS1 agonist in treating psychiatric disorders has not been well studied. Here, we examined whether PD149163, a brain-penetrant NTS1-specific agonist, displays antipsychotic-like effects in C57BL/6J mice by investigating the effect of PD149163 on amphetamine-mediated hyperactivity and amphetamine-induced disruption of prepulse inhibition. In addition, we assessed the effect of PD149163 on glycogen synthase kinase-3 (GSK-3) activity, a downstream molecular target of antipsychotics and mood stabilizers, using phospho-specific antibodies. PD149163 (0.1 and 0.5mg/kg) inhibited amphetamine-induced hyperactivity in mice, indicating that NTS1 activation inhibits psychomotor agitation. PD149163 (0.5mg/kg) also increased prepulse inhibition, suggesting that NTS1 activation reduces prepulse inhibition deficits which often co-occur with psychosis in humans. Interestingly, PD149163 increased the inhibitory serine phosphorylation on both GSK-3α and GSK-3β in a dose- and time-dependent manner in the nucleus accumbens and medial prefrontal cortex of the mice. Moreover, PD149163 inhibited GSK-3 activity in the nucleus accumbens and medial prefrontal cortex in the presence of amphetamine. Thus, like most current antipsychotics and mood stabilizers, PD149163 inhibited GSK-3 activity in cortico-striatal circuitry. Together, our findings indicate that PD149163 may be a novel antipsychotic.

Sodium butyrate has an antimanic effect and protects the brain against oxidative stress in an animal model of mania induced by ouabain

Studies have consistently reported the participation of oxidative stress in bipolar disorder (BD). Evidence indicates that epigenetic regulations have been implicated in the pathophysiology of mood disorders. Considering these evidences, the present study aimed to investigate the effects of sodium butyrate (SB), a histone deacetylase (HDAC)inhibitor, on manic-like behavior and oxidative stress parameters (TBARS and protein carbonyl content and SOD and CAT activities) in frontal cortex and hippocampus of rats subjected to the animal model of mania induced by intracerebroventricular (ICV) ouabain administration.The results showed that SB reversed ouabain-induced hyperactivity, which represents a manic-like behavior in rats. In addition, the ouabain ICV administration induced oxidative damage to lipid and protein and alters antioxidant enzymes activity in all brain structures analyzed. The treatment with SB was able to reversesboth behavioral and oxidative stress parameters alteration induced by ouabain.In conclusion, we suggest that SB can be considered a potential new mood stabilizer by acts on manic-like behavior and regulatesthe antioxidant enzyme activities, protecting the brain against oxidative damage.

Amphetamine increases activity but not exploration in humans and mice

RATIONALE

Cross-species quantification of physiological behavior enables a better understanding of the biological systems underlying neuropsychiatric diseases such as bipolar disorder (BD). Cardinal symptoms of manic BD include increased motor activity and goal-directed behavior, thought to be related to increased catecholamine activity, potentially selective to dopamine homeostatic dysregulation.

OBJECTIVES

The objective of this study was to test whether acute administration of amphetamine, a norepinephrine/dopamine transporter inhibitor and dopamine releaser, would replicate the profile of activity and exploration observed in both humans with manic BD and mouse models of mania.

METHODS

Healthy volunteers with no psychiatric history were randomized to a one-time dose of placebo (n = 25), 10 mg d-amphetamine (n = 18), or 20 mg amphetamine (n = 23). Eighty mice were administered one of four doses of d-amphetamine or vehicle. Humans and mice were tested in the behavioral pattern monitor (BPM), which quantifies motor activity, exploratory behavior, and spatial patterns of behavior.

RESULTS

In humans, the 20-mg dose of amphetamine increased motor activity as measured by acceleration without marked effects on exploration or spatial patterns of activity. In mice, amphetamine increased activity, decreased specific exploration, and caused straighter, one-dimensional movements in a dose-dependent manner.

CONCLUSIONS

Consistent with mice, amphetamine increased motoric activity in humans without increasing exploration. Given that BD patients exhibit heightened exploration, these data further emphasize the limitation of amphetamine-induced hyperactivity as a suitable model for BD. Further, these studies highlight the utility of cross-species physiological paradigms in validating biological mechanisms of psychiatric diseases.

Management of bipolar depression with lamotrigine: an antiepileptic mood stabilizer

The efficacy of lamotrigine in the treatment of focal epilepsies have already been reported in several case reports and open studies, which is thought to act by inhibiting glutamate release through voltage-sensitive sodium channels blockade and neuronal membrane stabilization. However, recent findings have also illustrated the importance of lamotrigine in alleviating the depressive symptoms of bipolar disorder, without causing mood destabilization or precipitating mania. Currently, no mood stabilizers are available having equal efficacy in the treatment of both mania and depression, two of which forms the extreme sides of the bipolar disorder. Lamotrigine, a well established anticonvulsant has received regulatory approval for the treatment and prevention of bipolar depression in more than 30 countries worldwide. Lamotrigine, acts through several molecular targets and overcomes the major limitation of other conventional antidepressants by stabilizing mood from “below baseline” thereby preventing switches to mania or episode acceleration, thus being effective for bipolar I disorder. Recent studies have also suggested that these observations could also be extended to patients with bipolar II disorder. Thus, lamotrigine may supposedly fulfill the unmet requirement for an effective depression mood stabilizer.

Memory and brain-derived neurotrophic factor after subchronic or chronic amphetamine treatment in an animal model of mania

Progression of bipolar disorder (BD) has been associated with cognitive impairment and changes in neuroplasticity, including a decrease in serum brain-derived neurotrophic factor (BDNF). However, no study could examine BDNF levels directly in different brain regions after repeated mood episodes to date. The proposed animal model was designed to mimic several manic episodes and evaluate whether the performance in memory tasks and BDNF levels in hippocampus, prefrontal cortex, and amygdala would change after repeated amphetamine (AMPH) exposure. Adult male Wistar rats were divided into subchronic (AMPH for 7 days) and chronic groups (35 days), mimicking manic episodes at early and late stages of BD, respectively. After open field habituation or inhibitory avoidance test, rats were killed, brain regions were isolated, and BDNF mRNA and protein levels were measured by quantitative real-time PCR and ELISA, respectively. AMPH impaired habituation memory in both subchronic and chronic groups, and the impairment was worse in the chronic group. This was accompanied by increased Bdnf mRNA levels in the prefrontal cortex and amygdala region, as well as reduced BDNF protein in the hippocampus. In the inhibitory avoidance, AMPH significantly decreased the change from training to test when compared to saline. No difference was observed between subchronic and chronic groups, although chronically AMPH-treated rats presented increased Bdnf mRNA levels and decreased protein levels in hippocampus when compared to the subchronic group. Our results suggest that the cognitive impairment related to BD neuroprogression may be associated with BDNF alterations in hippocampus, prefrontal cortex, and amygdala.

Modeling bipolar disorder in mice by increasing acetylcholine or dopamine: chronic lithium treats most, but not all features

RATIONALE

Bipolar disorder (BD) is a disabling and life-threatening disease characterized by states of depression and mania. New and efficacious treatments have not been forthcoming partly due to a lack of well-validated models representing both facets of BD.

OBJECTIVES

We hypothesized that cholinergic- and dopaminergic-pharmacological manipulations would model depression and mania respectively, each attenuated by lithium treatment.

METHODS

C57BL/6 J mice received the acetylcholinesterase inhibitor physostigmine or saline before testing for "behavioral despair" (immobility) in the tail suspension test (TST) and forced swim test (FST). Physostigmine effects on exploration and sensorimotor gating were assessed using the cross-species behavioral pattern monitor (BPM) and prepulse inhibition (PPI) paradigms. Other C57BL/6 J mice received chronic lithium drinking water (300, 600, or 1200 mg/l) before assessing their effects alone in the BPM or with physostigmine on FST performance. Another group was tested with acute GBR12909 (dopamine transporter inhibitor) and chronic lithium (1000 mg/l) in the BPM.

RESULTS

Physostigmine (0.03 mg/kg) increased immobility in the TST and FST without affecting activity, exploration, or PPI. Lithium (600 mg/l) resulted in low therapeutic serum concentrations and normalized the physostigmine-increased immobility in the FST. GBR12909 induced mania-like behavior in the BPM of which hyper-exploration was attenuated, though not reversed, after chronic lithium (1000 mg/ml).

CONCLUSIONS

Increased cholinergic levels induced depression-like behavior and hyperdopaminergia induced mania-like behavior in mice, while chronic lithium treated some, but not all, facets of these effects. These data support a cholinergic-monoaminergic mechanism for modeling BD aspects and provide a way to assess novel therapeutics.

Lithium modulates the production of peripheral and cerebral cytokines in an animal model of mania induced by dextroamphetamine

OBJECTIVES

Several recent studies have suggested that the physiopathology of bipolar disorder (BD) is related to immune system alterations and inflammation. Lithium (Li) is a mood stabilizer that is considered the first-line treatment for this mood disorder. The goal of the present study was to investigate the effects of Li administration on behavior and cytokine levels [interleukin (IL)-1β, IL-4, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α)] in the periphery and brains of rats subjected to an animal model of mania induced by amphetamine (d-AMPH).

METHODS

Male Wistar rats were treated with d-AMPH or saline (Sal) for 14 days; on Day 8 of treatment, the rats were administered Li or Sal for the final seven days. Cytokine (IL-1β, IL-4, IL-6, IL-10, and TNF-α) levels were evaluated in the cerebrospinal fluid (CSF), serum, frontal cortex, striatum, and hippocampus.

RESULTS

The present study showed that d-AMPH induced hyperactivity in rats (p < 0.001), and Li treatment reversed this behavioral alteration (p < 0.001). In addition, d-AMPH increased the levels of IL-4, IL-6, IL-10, and TNF-α in the frontal cortex (p < 0.001), striatum (p < 0.001), and serum (p < 0.001), and treatment with Li reversed these cytokine alterations (p < 0.001).

CONCLUSIONS

Li modulates peripheral and cerebral cytokine production in an animal model of mania induced by d-AMPH, suggesting that its action on the inflammatory system may contribute to its therapeutic efficacy.

Effects of mood stabilizers on oxidative stress-induced cell death signaling pathways in the brains of rats subjected to the ouabain-induced animal model of mania: Mood stabilizers exert protective effects against ouabain-induced activation of the cell death pathway

The present study aimed to investigate the effects of mood stabilizers, specifically lithium (Li) and valproate (VPA), on mitochondrial superoxide, lipid peroxidation, and proteins involved in cell death signaling pathways in the brains of rats subjected to the ouabain-induced animal model of mania. Wistar rats received Li, VPA, or saline twice a day for 13 days. On the 7th day of treatment, the animals received a single intracerebroventricular injection of ouabain or aCSF. After the ICV injection, the treatment with mood stabilizers continued for 6 additional days. The locomotor activity of rats was measured using the open-field test. In addition, we analyzed oxidative stress parameters, specifically levels of phosphorylated p53 (pp53), BAX and Bcl-2 in the brain of rats by immunoblot. Li and VPA reversed ouabain-related hyperactivity. Ouabain decreased Bcl-2 levels and increased the oxidative stress parameters BAX and pp53 in the brains of rats. Li and VPA improved these ouabain-induced cellular dysfunctions; however, the effects of the mood stabilizers were dependent on the protein and brain region analyzed. These findings suggest that the Na(+)/K(+)-ATPase can be an important link between oxidative damage and the consequent reduction of neuronal and glial density, which are both observed in BD, and that Li and VPA exert protective effects against ouabain-induced activation of the apoptosis pathway.

Valproate Inhibits Methamphetamine Induced Hyperactivity via Glycogen Synthase Kinase 3β Signaling in the Nucleus Accumbens Core

Valproate (VPA) has recently been shown to influence the behavioral effects of psycho-stimulants. Although glycogen synthase kinase 3β (GSK3β) signaling in the nucleus accumbens (NAc) plays a key role in mediating dopamine (DA)-dependent behaviors, there is less direct evidence that how VPA acts on the GSK3β signaling in the functionally distinct sub-regions of the NAc, the NAc core (NAcC) and the NAc shell (NAcSh), during psycho-stimulant-induced hyperactivity. In the present study, we applied locomotion test after acute methamphetamine (MA) (2 mg/kg) injection to identify the locomotor activity of rats received repeated VPA (300 mg/kg) pretreatment. We next measured phosphor-GSK3β at serine 9 and total GSK3β levels in NAcC and NAcSh respectively to determine the relationship between the effect of VPA on MA-induced hyperlocomotor and changes in GSK3β activity. We further investigated whether microinjection of VPA (300 μg/0.5 μl/side, once daily for 7 consecutive days) into NAcC or NAcSh could affect hyperactivity induced by MA. Our data indicated that repeated VPA treatment attenuated MA-induced hyperlocomotor, and the effect was associated with decreased levels of phosphorylated GSK3β at Ser 9 in the NAcC. Moreover, repeated bilateral intra-NAcC, but not intra-NAcSh VPA treatment, significantly attenuated MA-induced hyperactivity. Our results suggested that GSK3β activity in NAcC contributes to the inhibitory effects of VPA on MA-induced hyperactivity.

The effects of n-acetylcysteine and/or deferoxamine on manic-like behavior and brain oxidative damage in mice submitted to the paradoxal sleep deprivation model of mania

Bipolar disorder (BD) is a severe psychiatric disorder associated with social and functional impairment. Some studies have strongly suggested the involvement of oxidative stress in the pathophysiology of BD. Paradoxal sleep deprivation (PSD) in mice has been considered a good animal model of mania because it induces similar manic-like behavior, as well as producing the neurochemical alterations which have been observed in bipolar patients. Thus, the objective of the present study was to evaluate the effects of the antioxidant agent's n-acetylcysteine (Nac) and/or deferoxamine (DFX) on behavior and the oxidative stress parameters in the brains of mice submitted to the animal model of mania induced by PSD. The mice were treated for a period of seven days with saline solution (SAL), Nac, DFX or Nac plus DFX. The animals were subject to the PSD protocol for 36 h. Locomotor activity was then evaluated using the open-field test, and the oxidative stress parameters were subsequently evaluated in the hippocampus and frontal cortex of mice. The results showed PSD induced hyperactivity in mice, which is considered a manic-like behavior. In addition to this, PSD increased lipid peroxidation and oxidative damage to proteins, as well as causing alterations to antioxidant enzymes in the frontal cortex and hippocampus of mice. The Nac plus DFX adjunctive treatment prevented both the manic-like behavior and oxidative damage induced by PSD. Improving our understanding relating to oxidative damage in biomolecules, and the antioxidant mechanisms presented in the animal models of mania are important in helping to improve our knowledge concerning the pathophysiology and development of new therapeutical treatments for BD.

Investigating the mechanism(s) underlying switching between states in bipolar disorder

Bipolar disorder (BD) is a unique disorder that transcends domains of function since the same patient can exhibit depression or mania, states with polar opposite mood symptoms. During depression, people feel helplessness, reduced energy, and risk aversion, while with mania behaviors include grandiosity, increased energy, less sleep, and risk preference. The neural mechanism(s) underlying each state are gaining clarity, with catecholaminergic disruption seen during mania, and cholinergic dysfunction during depression. The fact that the same patient cycles/switches between these states is the defining characteristic of BD however. Of greater importance therefore, is the mechanism(s) underlying cycling from one state - and its associated neural changes - to another, considered the 'holy grail' of BD research. Herein, we review studies investigating triggers that induce switching to these states. By identifying such triggers, researchers can study neural mechanisms underlying each state and importantly how such mechanistic changes can occur in the same subject. Current animal models of this switch are also discussed, from submissive- and dominant-behaviors to kindling effects. Focus however, is placed on how seasonal changes can induce manic and depressive states in BD sufferers. Importantly, changing photoperiod lengths can induce local switches in neurotransmitter expression in normal animals, from increased catecholaminergic expression during periods of high activity, to increased somatostatin and corticotrophin releasing factor during periods of low activity. Identifying susceptibilities to this switch would enable the development of targeted animal models. From animal models, targeted treatments could be developed and tested that would minimize the likelihood of switching.

Sodium butyrate and mood stabilizers block ouabain-induced hyperlocomotion and increase BDNF, NGF and GDNF levels in brain of Wistar rats

Bipolar Disorder (BD) is one of the most severe psychiatric disorders. Despite adequate treatment, patients continue to have recurrent mood episodes, residual symptoms, and functional impairment. Some preclinical studies have shown that histone deacetylase inhibitors may act on manic-like behaviors. Neurotrophins have been considered important mediators in the pathophysiology of BD. The present study aims to investigate the effects of lithium (Li), valproate (VPA), and sodium butyrate (SB), an HDAC inhibitor, on BDNF, NGF and GDNF in the brain of rats subjected to an animal model of mania induced by ouabain. Wistar rats received a single ICV injection of ouabain or artificial cerebrospinal fluid. From the day following ICV injection, the rats were treated for 6 days with intraperitoneal injections of saline, Li, VPA or SB twice a day. In the 7th day after ouabain injection, locomotor activity was measured using the open-field test. The BDNF, NGF and GDNF levels were measured in the hippocampus and frontal cortex by sandwich-ELISA. Li, VPA or SB treatments reversed ouabain-related manic-like behavior. Ouabain decreased BDNF, NGF and GDNF levels in hippocampus and frontal cortex of rats. The treatment with Li, VPA or SB reversed these impairment induced by ouabain. In addition, Li, VPA and SB per se increased NGF and GDNF levels in hippocampus of rats. Our data support the notion that neurotrophic factors play a role in BD and in the mechanisms of the action of Li, VPA and SB.

MAPK signaling correlates with the antidepressant effects of ketamine

Studies have pointed to a relationship between MAPK kinase (MEK) signaling and the behavioral effects of antidepressant drugs. So, in the present study we examined the behavioral and molecular effects of ketamine, an antagonist of the N-methyl-d-aspartate receptor (NMDA), which has been shown to have an antidepressant effect after the inhibition of MEK signaling in Wistar rats. Our results showed that acute administration of the MEK inhibitor PD184161, produced depressive-like behavior and stopped antidepressant-like effects of ketamine in the forced swimming test. The phosphorylation of extracellular signal-regulated kinase 1/2 (pERK 1/2) was decreased by PD184161 in the amygdala and nucleus accumbens, and the effects of ketamine on pERK 1/2 in the prefrontal cortex and hippocampus were inhibited by PD184161. The ERK 2 levels were decreased by PD184161 in the nucleus accumbens; and the effects of ketamine were blocked in this brain area. The p38 protein kinase (p38MAPK) and proBDNF were inhibited by PD184161, and the MEK inhibitor prevented the effects of ketamine in the nucleus accumbens. In addition, ketamine increased pro-BDNF levels in the hippocampus. In conclusion, our findings demonstrated that an acute blockade of MAPK signaling lead to depressive-like behavior and stopped the antidepressant response of ketamine, suggesting that the effects of ketamine could be mediated, at least in part, by the regulation of MAPK signaling in these specific brain areas.

Sex differences in animal models of psychiatric disorders

Psychiatric disorders are characterized by sex differences in their prevalence, symptomatology and treatment response. Animal models have been widely employed for the investigation of the neurobiology of such disorders and the discovery of new treatments. However, mostly male animals have been used in preclinical pharmacological studies. In this review, we highlight the need for the inclusion of both male and female animals in experimental studies aiming at gender-oriented prevention, diagnosis and treatment of psychiatric disorders. We present behavioural findings on sex differences from animal models of depression, anxiety, post-traumatic stress disorder, substance-related disorders, obsessive-compulsive disorder, schizophrenia, bipolar disorder and autism. Moreover, when available, we include studies conducted across different stages of the oestrous cycle. By inspection of the relevant literature, it is obvious that robust sex differences exist in models of all psychiatric disorders. However, many times results are conflicting, and no clear conclusion regarding the direction of sex differences and the effect of the oestrous cycle is drawn. Moreover, there is a lack of considerable amount of studies using psychiatric drugs in both male and female animals, in order to evaluate the differential response between the two sexes. Notably, while in most cases animal models successfully mimic drug response in both sexes, test parameters and treatment-sensitive behavioural indices are not always the same for male and female rodents. Thus, there is an increasing need to validate animal models for both sexes and use standard procedures across different laboratories.

Omega-3 fatty acids alter behavioral and oxidative stress parameters in animals subjected to fenproporex administration

Studies have consistently reported the participation of oxidative stress in bipolar disorder (BD). Evidences indicate that omega-3 (ω3) fatty acids play several important roles in brain development and functioning. Moreover, preclinical and clinical evidence suggests roles for ω3 fatty acids in BD. Considering these evidences, the present study aimed to investigate the effects of ω3 fatty acids on locomotor behavior and oxidative stress parameters (TBARS and protein carbonyl content) in brain of rats subjected to an animal model of mania induced by fenproporex. The fenproporex treatment increased locomotor behavior in saline-treated rats under reversion and prevention model, and ω3 fatty acids prevented fenproporex-related hyperactivity. Moreover, fenproporex increased protein carbonyls in the prefrontal cortex and cerebral cortex, and the administration of ω3 fatty acids reversed this effect. Lipid peroxidation products also are increased in prefrontal cortex, striatum, hippocampus and cerebral after fenproporex administration, but ω3 fatty acids reversed this damage only in the hippocampus. On the other hand, in the prevention model, fenproporex increased carbonyl content only in the cerebral cortex, and administration of ω3 fatty acids prevented this damage. Additionally, the administration of fenproporex resulted in a marked increased of TBARS in the prefrontal cortex, hippocampus, striatum and cerebral cortex, and prevent this damage in the prefrontal cortex, hippocampus and striatum. In conclusion, we are able to demonstrate that fenproporex-induced hyperlocomotion and damage through oxidative stress were prevented by ω3 fatty acids. Thus, the ω3 fatty acids may be important adjuvant therapy of bipolar disorder.

Tamoxifen use for the management of mania: a review of current preclinical evidence

RATIONALE

Preliminary data on the efficacy of tamoxifen in reducing manic symptoms of bipolar disorder (BD) suggest that this agent may be a potential treatment for the management of this psychiatric disorder. However, the antimanic properties of tamoxifen have not been fully elucidated, hampering the development and/or use of mood-stabilising drugs that may share its same therapeutic mechanisms of action. Notably, we may gain a greater understanding of the neurobiological and therapeutic properties of tamoxifen by using suitable animal models of mania.

OBJECTIVES

Here, we review the preclinical studies that have evaluated the effects of tamoxifen to provide an overview of the current progress in our understanding of its antimanic actions, highlighting the critical role of protein kinase C (PKC) as a therapeutic target for the treatment of BD.

CONCLUSIONS

To date, this field has struggled to make significant progress, and the organisation of an explicit battery of tests is a valuable tool for assessing a number of prominent facets of BD, which may provide a greater understanding of the entire scope of this disease.

Guidelines for the recording and evaluation of pharmaco-sleep studies in man: the International Pharmaco-EEG Society (IPEG)

The International Pharmaco-EEG Society (IPEG) presents guidelines summarising the requirements for the recording and computerised evaluation of pharmaco-sleep data in man. Over the past years, technical and data-processing methods have advanced steadily, thus enhancing data quality and expanding the palette of sleep assessment tools that can be used to investigate the activity of drugs on the central nervous system (CNS), determine the time course of effects and pharmacodynamic properties of novel therapeutics, hence enabling the study of the pharmacokinetic/pharmacodynamic relationship, and evaluate the CNS penetration or toxicity of compounds. However, despite the presence of robust guidelines on the scoring of polysomnography -recordings, a review of the literature reveals inconsistent -aspects in the operating procedures from one study to another. While this fact does not invalidate results, the lack of standardisation constitutes a regrettable shortcoming, especially in the context of drug development programmes. The present guidelines are intended to assist investigators, who are using pharmaco-sleep measures in clinical research, in an effort to provide clear and concise recommendations and thereby to standardise methodology and facilitate comparability of data across laboratories.

Neuroprotective and antioxidant effects of curcumin in a ketamine-induced model of mania in rats

Bipolar disorder (BD) is a chronic and debilitating illness characterized by recurrent manic and depressive episodes. Our research investigates the protective effects of curcumin, the main curcuminoid of the Indian spice turmeric, in a model of mania induced by ketamine administration in rats. Our results indicated that ketamine treatment (25 mg/kg, for 8 days) induced hyperlocomotion in the open-field test and oxidative damage in prefrontal cortex (PFC) and hippocampus (HP), evaluated by increased lipid peroxidation and decreased total thiol content. Moreover, ketamine treatment reduced the activity of the antioxidant enzymes superoxide dismutase and catalase in the HP. Pretreatment of rats with curcumin (20 and 50 mg/kg, for 14 days) or with lithium chloride (45 mg/kg, positive control) prevented behavioral and pro-oxidant effects induced by ketamine. These findings suggest that curcumin might be a good compound for preventive intervention in BD, reducing the episode relapse and the oxidative damage associated with the manic phase of this disorder.

Fenproporex increases locomotor activity and alters energy metabolism, and mood stabilizers reverse these changes: a proposal for a new animal model of mania

Fenproporex (Fen) is converted in vivo into amphetamine, which is used to induce mania-like behaviors in animals. In the present study, we intend to present a new animal model of mania. In order to prove through face, construct, and predictive validities, we evaluated behavioral parameters (locomotor activity, stereotypy activity, and fecal boli amount) and brain energy metabolism (enzymes citrate synthase; malate dehydrogenase; succinate dehydrogenase; complexes I, II, II-III, and IV of the mitochondrial respiratory chain; and creatine kinase) in rats submitted to acute and chronic administration of fenproporex, treated with lithium (Li) and valproate (VPA). The administration of Fen increased locomotor activity and decreased the activity of Krebs cycle enzymes, mitochondrial respiratory chain complexes, and creatine kinase, in most brain structures evaluated. In addition, treatment with mood stabilizers prevented and reversed this effect. Our results are consistent with the literature that demonstrates behavioral changes and mitochondrial dysfunction caused by psychostimulants. These findings suggest that chronic administration of Fen may be a potential animal model of mania.

Sexually dimorphic, developmental, and chronobiological behavioral profiles of a mouse mania model

Bipolar disorders are heritable psychiatric conditions often abstracted by separate animal models for mania and depression. The principal mania models involve transgenic manipulations or treatment with stimulants. An additional approach involves analysis of naturally occurring mania models including an inbred strain our lab has recently characterized, the Madison (MSN) mouse strain. These mice show a suite of behavioral and neural genetic alterations analogous to manic aspects of bipolar disorders. In the current study, we extended the MSN strain's behavioral phenotype in new directions by examining in-cage locomotor activity. We found that MSN activity presentation is sexually dimorphic, with MSN females showing higher in-cage activity than MSN males. When investigating development, we found that MSN mice display stable locomotor hyperactivity already observable when first assayed at 28 days postnatal. Using continuous monitoring and analysis for 1 month, we did not find evidence of spontaneous bipolarism in MSN mice. However, we did find that the MSN strain displayed an altered diurnal activity profile, getting up earlier and going to sleep earlier than control mice. Long photoperiods were associated with increased in-cage activity in MSN, but not in the control strain. The results of these experiments reinforce the face validity of the MSN strain as a complex mania model, adding sexual dimorphism, an altered diurnal activity profile, and seasonality to the suite of interesting dispositional phenomena related to mania seen in MSN mice.

Influence of lifelong dietary fats on the brain fatty acids and amphetamine-induced behavioral responses in adult rat

The influence of dietary fatty acids (FA) on mania-like behavior and brain oxidative damage were evaluated in rats. First generation of rats born and maintained under supplementation with soybean-oil (SO), fish-oil (FO) or hydrogenated-vegetable-fat (HVF), which are rich in n-6, n-3 and trans (TFA) FA, respectively, until adulthood, were exposed to an amphetamine (AMPH)-induced mania animal model to behavioral and biochemical evaluations. While AMPH caused hyperlocomotion in HVF and, to a less extent, in SO- and FO-groups, a better memory performance was observed in FO group. Among vehicle-groups, HVF increased reactive species (RS) generation and protein-carbonyl (PC) levels in cortex; FO reduced RS generation in hippocampus and decreased PC levels in hippocampus and striatum. Among AMPH-treated animals, HVF exacerbated RS generation in all evaluated brain areas and increased PC levels in cortex and striatum; FO reduced RS generation in hippocampus and decreased PC levels in hippocampus and striatum. FO was related to higher percentage of polyunsaturated fatty acids (PUFA) and docosahexaenoic acid (DHA) in cortex and striatum, while HVF was associated to higher incorporation of TFA in cortex, hippocampus and striatum, besides increased n-6/n-3 FA ratio in striatum. While a continuous exposure to TFA may intensify oxidative events in brain, a prolonged FO consumption may prevent mania-like-behavior; enhance memory besides decreasing brain oxidative markers. A substantial inclusion of processed foods, instead of foods rich in omega-3, in the long term is able to influence the functionality of brain structures related to behavioral disturbances and weaker neuroprotection, whose impact should be considered by food safety authorities and psychiatry experts.

Gating of a novel brain potential is associated with perceptual anomalies in bipolar disorder

OBJECTIVES

Our laboratory recently identified the P85 gating ratio as a candidate biomarker for bipolar disorder. In order to evaluate the phenomenological significance of P85 gating, the current study examined reports of perceptual anomalies and their relationship to the P50 and P85 physiological measures of sensory gating.

METHODS

Reports of perceptual anomalies on the Structured Clinical Interview to Assess Perceptual Anomalies were compared in patients meeting DSM-IV criteria for paranoid schizophrenia (n = 66), schizoaffective disorder (n = 45), or bipolar I disorder (n = 42), and controls (n = 56), as well as their relationship with P85 and P50 gating.

RESULTS

The bipolar disorder group reported significantly more auditory, visual, and total anomalies than both the schizophrenia and control groups. The schizophrenia group also had more anomalies than the control group. Comparison of psychiatric subgroups revealed that the bipolar depressed, bipolar disorder with psychosis, and schizoaffective bipolar type groups reported the most anomalies compared to the other patient groups (bipolar disorder without psychosis, schizoaffective, bipolar manic). The total perceptual anomalies score and the P85 ratio significantly differentiated the bipolar disorder, schizoaffective, and paranoid schizophrenia groups from each other.

CONCLUSIONS

These findings provide evidence of the phenomenological significance of P85. The results also yield further support not only for the P85 ratio, but also for increased reports of perceptual anomalies as possible markers for bipolar disorder.