Using mitochondrial respiration inhibitors to design a novel model of bipolar disorder-like phenotype with construct, face and predictive validity.

We mimicked mild mitochondrial-distress robustly reported in bipolar-disorder (BD) by chronic exposure to uniquely low doses of inhibitors of mitochondrial-respiration complexes in vitro and in vivo. Exposure of the neuronal-originating SH-SY5Y cells to very low dose (10 pM) rotenone, a mitochondrial-respiration complex (Co)I inhibitor, for 72 or 96 h did not affect cell viability and reactive oxygen species (ROS) levels. Yet, it induced a dual effect on mitochondrial-respiration: overshooting statistically significant several-fold increase of most oxygen-consumption-rate (OCR) parameters vs. significantly decreased all OCR parameters, respectively. Chronic low doses of 3-nitropropionic acid (3-NP) (CoII inhibitor) did not induce long-lasting changes in the cells' mitochondria-related parameters. Intraperitoneal administration of 0.75 mg/kg/day rotenone to male mice for 4 or 8 weeks did not affect spontaneous and motor activity, caused behaviors associated with mania and depression following 4 and 8 weeks, respectively, accompanied by relevant changes in mitochondrial basal OCR and in levels of mitochondrial-respiration proteins. Our model is among the very few BD-like animal models exhibiting construct (mild mitochondrial dysfunction), face (decreased/increased immobility time in the forced-swim test, increased/decreased consumption of sweet solution, increased/decreased time spent in the open arms of the elevated plus maze) and predictive (reversal of rotenone-induced behavioral changes by lithium treatment) validity. Our rotenone regime, employing doses that, to the best of our knowledge, have never been used before, differs from those inducing Parkinson's-like models by not affecting ROS-levels and cell-viability in vitro nor motor activity in vivo.

The circadian syndrome predicts cardiovascular disease better than metabolic syndrome in Chinese adults.

BACKGROUND: To compare the predictive value of the circadian syndrome (CircS) and Metabolic syndrome (MetS) for cardiovascular disease. METHOD: We used the data of 9360 Chinese adults aged ≥40 years from the 2011 China Health and Retirement Longitudinal Study (CHARLS). Of the participants, 8253 people were followed in the 2015 survey. MetS was defined using the harmonized criteria. CircS was based on the components of the International Diabetes Federation (IDF) MetS plus short sleep and depression. The cut-off for CircS was set as ≥4. Multivariable logistic regression analysis was used to examine the associations. RESULTS: The prevalence of CircS and MetS was 39.0% and 44.7%. Both MetS and CircS were directly associated with prevalent CVD. The odds ratios for prevalent CVD comparing CircS with MetS, respectively, were 2.83 (95%CI 2.33-3.43) and 2.34 (1.93-2.83) in men, and 2.33 (1.98-2.73) and 1.79 (1.53-2.10) in women. Similar associations were found for incident CVD. The five-year incidence of CVD was 15.1% in CircS and 14.0% in MetS. The number of CircS components has a better predictive power for both prevalent and incident CVD than those of Mets components as indicated by the area under the ROC (AUC). AUC values for CVD in 2011 were higher for CircS than MetS in both men (0.659 (95%CI 0.634-0.684) vs 0.635 (95%CI 0.610-0.661)) and women (0.652 (95%CI 0.632-0.672) vs 0.619 (95%CI 0.599-0.640)). CONCLUSION: The circadian syndrome is a strong and better predictor for CVD than the metabolic syndrome in Chinese adults.

Designed proteinoid polymers and nanoparticles encapsulating risperidone for enhanced antipsychotic activity.

BACKGROUND: Nanoparticles (NPs) incorporating drug formulations can be used to facilitate passage through biological barriers including the blood-brain barrier (BBB) and increase drug delivery and bioavailability. Hence, NP-based administration may enhance the efficiency of current antipsychotics. Encapsulation within NPs can resolve aqueous solubility problems that not only reduce permeability through the BBB but also affect targeting. The present study describes a new drug delivery system based on proteinoid NPs to explore the possibility of improving drug efficacy. Risperidone (RSP) is a commonly used atypical antipsychotic medication, and was therefore selected for encapsulation by proteinoid NPs. RESULTS: Proteinoid polymers with high molecular weight and low polydispersity were synthesized from L-amino acids and poly-L-lactic acid (PLLA) by thermal step-growth polymerization mechanism. RSP-loaded proteinoid NPs were then prepared using a self-assembly process in the presence of RSP, followed by PEGylation. The optimal PEGylated RSP-loaded NPs were characterized in terms of diameter and size distribution, drug loading, ζ-potential, cytotoxicity, biodistribution, and psychopharmacological effects. The findings indicate significantly higher antipsychotic activity of drug-loaded proteinoid NPs compared to free RSP. CONCLUSIONS: Proteinoid NPs enhance RSP delivery and may potentially increase drug efficiency by reducing dosage and side effects.

The Circadian Syndrome: is the Metabolic Syndrome and much more!

The Metabolic Syndrome is a cluster of cardio-metabolic risk factors and comorbidities conveying high risk of both cardiovascular disease and type 2 diabetes. It is responsible for huge socio-economic costs with its resulting morbidity and mortality in most countries. The underlying aetiology of this clustering has been the subject of much debate. More recently, significant interest has focussed on the involvement of the circadian system, a major regulator of almost every aspect of human health and metabolism. The Circadian Syndrome has now been implicated in several chronic diseases including type 2 diabetes and cardiovascular disease. There is now increasing evidence connecting disturbances in circadian rhythm with not only the key components of the Metabolic Syndrome but also its main comorbidities including sleep disturbances, depression, steatohepatitis and cognitive dysfunction. Based on this, we now propose that circadian disruption may be an important underlying aetiological factor for the Metabolic Syndrome and we suggest that it be renamed the 'Circadian Syndrome'. With the increased recognition of the 'Circadian Syndrome', circadian medicine, through the timing of exercise, light exposure, food consumption, dispensing of medications and sleep, is likely to play a much greater role in the maintenance of both individual and population health in the future.

Revisiting the validity of the mouse forced swim test: Systematic review and meta-analysis of the effects of prototypic antidepressants.

One problem area regarding animal models for affective disorders is unclear reproducibility, including external validity or generalizability. One way to evaluate external validity is with systematic reviews and meta-analyses. The current study presents a meta-analysis of the effects of prototypic antidepressants in the mouse forced swim test (FST). We identified studies that examined effects of antidepressants in the FST in mice and used standard protocol, male mice and acute drug administration. We calculated Effect sizes using Cohen's d, homogeneity using Q statistic and correlations using Pearson's correlation. Results indicate that all drugs reduce immobility in the FST. However, effect sizes for most drugs are heterogeneous and do not show a consistent dose/response relationship across variability factors. Reducing variability by examining only one strain or data from individual laboratories partially increases dose response relationship. These findings suggest that whereas the FST is a valid tool to qualitatively screen antidepressant effects its validity in the context of hierarchical comparison between doses or compounds might be relevant only to single experiments.

Lack of effect of chronic ketamine administration on depression-like behavior and frontal cortex autophagy in female and male ICR mice.

The acute antidepressant effects of ketamine provide hope for the development of a fast acting approach to treat depression but the consequences of chronic treatment with ketamine are still unclear. One theory regarding the acute effect is that ketamine acts through activation of mTOR but chronic activation of mTOR may lead to reduced autophagy and reduced autophagy could have negative consequences on neuronal plasticity and survival and on affect. To study the interaction between chronic ketamine administration, autophagy and depression the present study tested the effects of 3 weeks daily administration of 5 or 10mg/kg ketamine in both female and male ICR mice on behavior in the open field and the forced swim test and on frontal cortex levels of beclin-1 and p62, two proteins that serve as markers of autophagy. The results show that acute administration of ketamine results in an antidepressant-like effect in the FST, chronic ketamine had no effects in the behavioral tests. There was no difference in the acute or chronic groups between female and male mice. Additionally, chronic ketamine did not alter frontal cortex levels of autophagy markers. The present study suggests that in ICR mice, chronic ketamine does not have the same clear effects that are seen after acute treatment. The lack of difference between females and males and the lack of effects on autophagy after chronic treatment is discussed.

IP3 accumulation and/or inositol depletion: two downstream lithium's effects that may mediate its behavioral and cellular changes.

Lithium is the prototype mood stabilizer but its mechanism is still unresolved. Two hypotheses dominate-the consequences of lithium's inhibition of inositol monophosphatase at therapeutically relevant concentrations (the 'inositol depletion' hypothesis), and of glycogen-synthase kinase-3. To further elaborate the inositol depletion hypothesis that did not decisively determine whether inositol depletion per se, or phosphoinositols accumulation induces the beneficial effects, we utilized knockout mice of either of two inositol metabolism-related genes-IMPA1 or SMIT1, both mimic several lithium's behavioral and biochemical effects. We assessed in vivo, under non-agonist-stimulated conditions, 3H-inositol incorporation into brain phosphoinositols and phosphoinositides in wild-type, lithium-treated, IMPA1 and SMIT1 knockout mice. Lithium treatment increased frontal cortex and hippocampal phosphoinositols labeling by several fold, but decreased phosphoinositides labeling in the frontal cortex of the wild-type mice of the IMPA1 colony strain by ~50%. Inositol metabolites were differently affected by IMPA1 and SMIT1 knockout. Inositoltrisphosphate administered intracerebroventricularly affected bipolar-related behaviors and autophagy markers in a lithium-like manner. Namely, IP3 but not IP1 reduced the immobility time of wild-type mice in the forced swim test model of antidepressant action by 30%, an effect that was reversed by an antagonist of all three IP3 receptors; amphetamine-induced hyperlocomotion of wild-type mice (distance traveled) was 35% reduced by IP3 administration; IP3 administration increased hippocampal messenger RNA levels of Beclin-1 (required for autophagy execution) and hippocampal and frontal cortex protein levels ratio of Beclin-1/p62 by about threefold (p62 is degraded by autophagy). To conclude, lithium affects the phosphatidylinositol signaling system in two ways: depleting inositol, consequently decreasing phosphoinositides; elevating inositol monophosphate levels followed by phosphoinositols accumulation. Each or both may mediate lithium-induced behavior.

Chronic Lithium Treatment Enhances the Number of Quiescent Neural Progenitors but Not the Number of DCX-Positive Immature Neurons.

BACKGROUND: The term adult neurogenesis constitutes a series of developmental steps including the birth, survival, differentiation, maturation, and even death of newborn progenitor cells within neurogenic niches. Within the hippocampus progenitors reside in the neurogenic niche of the subgranular zone in the dentate gyrus subfield. At the different stages, designated type-I, type-IIa, type-IIb, type-III, and granule cell neurons, the cells express a series of markers enabling their identification and visualization. Lithium has been shown to increase hippocampal cell proliferation in the subgranular zone of the hippocampal dentate gyrus subfield of adult rodents and to stimulate the proliferation of hippocampal progenitor cells in vitro, but data regarding lithium's ability to increase neuronal differentiation and survival is equivocal. METHODS: To clarify the effect of lithium on adult hippocampal neurogenesis, we identified the effect of chronic lithium treatment on distinct stages of hippocampal progenitor development using adult Nestin-green fluorescent protein transgenic mice and immunofluorescent techniques. RESULTS: The present observations confirm that lithium targets the initial stages of progenitor development enhancing the turnover of quiescent neural progenitors/putative stem-cells, corroborating previous reports. However, the enhanced quiescent neural progenitor-turnover does not translate into an increased number of immature neurons. We also observed a steep decline in the number of type-III immature neurons with complex tertiary-dendrites, suggesting that lithium alters the morphological maturation of newborn neurons. CONCLUSIONS: Our results do not corroborate previous reports of lithium-induced enhanced numbers of newly generated neurons.

Acute intracerebroventricular inositol does not reverse the effect of chronic lithium treatment in the forced swim test.

BACKGROUND: Lithium has numerous biochemical effects but it is difficult to dissect which of these is responsible for its therapeutic action in bipolar disorder. In the current study we aimed to address one of the major hypotheses, the inositol depletion hypothesis. This hypothesis postulates that lithium's mood-stabilizing effect is mediated by the depletion of brain inositol levels and the subsequent effect on cellular signaling. METHODS: We studied whether acute intracerebroventricular (ICV) administration of myo-inositol could reverse the antidepressant-like effect of chronic lithium treatment in the forced swim test (FST). RESULTS: In contrast with our prediction, acute myo-inositol administration did not reverse the effect of chronic lithium to decrease immobility in the FST. CONCLUSIONS: The results of the present study are limited due to the following: (1) inositol was given acutely while possible events downstream of inositol depletion might require a longer period and (2) ICV inositol may not have reached those areas of the brain involved in the FST.

Trehalose induced antidepressant-like effects and autophagy enhancement in mice.

RATIONALE: The disaccharide trehalose protects cells from hypoxic and anoxic injury and suppresses protein aggregation. In vivo studies with trehalose show cellular and behavioral beneficial effects in animal models of neurodegenerative diseases. Moreover, trehalose was shown to enhance autophagy, a process that had been recently suggested to be involved in the therapeutic action of antidepressant and mood-stabilizing drugs. OBJECTIVE: The present study was therefore designed to explore antidepressant and mood-stabilizing activity of trehalose in animal models for depression and mania. METHODS: Trehalose 1 or 2% was administered for 3 weeks as a drinking solution to Black Swiss mice (a model of manic-like behaviors) or 2% to ICR mice and their behavior evaluated in a number of tests related to depression or mania. The effects of trehalose were compared with similar chronic administration of the disaccharide maltose as well as with a vehicle (water) control. RESULTS: Chronic administration of trehalose resulted in a reduction of frontal cortex p62/beclin-1 ratio suggesting enhancement of autophagy. Trehalose had no mood-stabilizing effects on manic-like behavior in Black Swiss mice but instead augmented amphetamine-induced hyperactivity, an effect similar to antidepressant drugs. In ICR mice, trehalose did not alter spontaneous activity or amphetamine-induced hyperactivity but in two separate experiments had a significant effect to reduce immobility in the forced swim test, a standard screening test for antidepressant-like effects. CONCLUSIONS: The results suggest that trehalose may have antidepressant-like properties. It is hypothesized that these behavioral changes could be related to trehalose effects to enhance autophagy.

Rodent models for mania: practical approaches.

The scarcity of good animal models for bipolar disorder (BPD) and especially for mania is repeatedly mentioned as one of the rate-limiting factors in the process of gaining a better understanding into its pathophysiology and of developing better treatments. Standard models of BPD have some value but usually represent only one facet of the disease and have partial validity. A number of new approaches for modeling BPD and specifically mania have been suggested in the last few years and can be combined to improve models. These approaches include targeted mutation models representing reverse translation, the identification of advantageous strains for components of the disorder, a search for the most homologous species to address specific human pathology, and the exploration of individual differences of response including the separation between susceptible and resilient animals. Additionally, recent efforts have identified and developed new tests to distinguish between "normal" and "BPD-like" animals including the different utilization of known tests and novel tests such as the female-urine-sniffing test and behavior pattern monitor analysis. Additional tests relating to further domains of BPD are still needed. An ideal model for BPD that will encompass the entire disease and be useful for every demand will probably not become available until we have a full understanding of the pathophysiology of the disorder. However, the current advances in modeling should lead to better comprehension of the disorder and therefore to the gradual development of increasingly improved models.

Antidepressive-like effects of rapamycin in animal models: Implications for mTOR inhibition as a new target for treatment of affective disorders.

Lithium, the prototypic mood stabilizer, was recently demonstrated to enhance autophagy in cells. Recent hypotheses regarding the source of therapeutic effects of lithium as well as other mood stabilizers and antidepressants suggest that they may stem from increased neuroprotection, cellular plasticity and resilience. Hence it is clearly a possibility that enhanced autophagy may be involved in the therapeutic action by contributing to increased cellular resilience. A well-documented mechanism to induce autophagy is by inhibition of mTOR, a negative modulator of autophagy and rapamycin (sirolimus) is a commonly used inhibitor of mTOR. Accordingly, the present study was designed to evaluate the effects of rapamycin in animal models of antidepressant activity. A dose-response experiment in the mice forced swim test was performed and followed by additional testing of mice and rats in an open field, the forced swim test and the tail suspension test. Results show that sub-chronic, but not acute, administration of rapamycin doses of 10mg/kg and above, have an antidepressant-like effect in both mice and rats and in both the forced swim and the tail suspension tests with no effects on the amount or distribution of activity in the open field. Whereas it is tempting to conclude that the antidepressant-like effects are related to mTOR inhibition, they may also be the consequences of interactions with other intracellular pathways. Additional studies are now planned to further explore the behavioral range of rapamycin's effects as well as the biological mechanisms underlying these effects.

Myo-inositol-1-phosphate (MIP) synthase inhibition: in-vivo study in rats.

Lithium and valproate are the prototypic mood stabilizers and have diverse structures and targets. Both drugs influence inositol metabolism. Lithium inhibits IMPase and valproate inhibits MIP synthase. This study shows that MIP synthase inhibition does not replicate or augment the effects of lithium in the inositol sensitive pilocarpine-induced seizures model. This lack of effects may stem from the low contribution of de-novo synthesis to cellular inositol supply or to the inhibition of the de-novo synthesis by lithium itself.

Possible involvement of the ERK signaling cascade in bipolar disorder: behavioral leads from the study of mutant mice.

Despite the devastating impact that bipolar disorder has on the lives of millions worldwide, little is known for certain about its etiology or pathophysiology. Whereas research has traditionally focused on biogenic amines, it is becoming increasingly more apparent that intracellular pathways are involved in the etiology and treatment of the disease and that a true understanding of the pathophysiology of bipolar disorder must address its neurobiology at different physiological levels, that is, molecular, cellular, systems and behavioral levels. There is now considerable biochemical evidence that the antimanic agents lithium and valproate robustly activate the ERK signaling cascade in therapeutically relevant paradigms. This raises the possibility that this pathway may play a role in the antimanic effects of these agents. The present paper reviews behavioral studies that may shed light on the involvement of the ERK pathway in affective-like behaviors in animals. The available literature suggests that genetic manipulations of the brain-derived neurotrophic factor (BDNF)-ERK kinase pathway produces a variety of changes in affective-like behaviors, with most changes consistent with manic-like behavior. Thus, overall, mice with targeted mutation of the BDNF gene exhibited increased spontaneous locomotion and increased response to acute amphetamine, altered response to chronic cocaine, increased aggression, increase in risk-taking behavior, as demonstrated by time spent in the center of an open field, and changes in eating patterns. Although it has to be acknowledged that the currently available behavioral data from the BDNF-ERK pathway mutants is less than ideal to offer real substantiation relating this pathway to bipolar disorder, the data still supports the possibility that this pathway modulates manic-like behavior in animals, and perhaps mania in humans.

Preliminary evaluation of oral anticonvulsant treatment in the quinpirole model of bipolar disorder.

A potential model for bipolar disorder, quinpirole-induced biphasic locomotion, was used for a preliminary evaluation of behavioral effects of oral anticonvulsant treatment. Quinpirole, a D2/D3 agonist, induces a biphasic locomotor response starting with inhibition and followed by excitation, resembling the oscillating nature of bipolar disorder. The present study developed a paradigm for oral administration of anticonvulsants that resulted in therapeutic blood levels and tested the effects of treatment on the quinpirole-induced response. Eleven days treatment with valproate (12 g/liter water), phenytoin (6 g/kg food), and carbamazepine (8 g/kg food) resulted in therapeutic blood levels and in a borderline significant reduction in quinpirole-induced hyperactivity without effects on the hypoactive phase. Valproate effects became more significant at the height of the hyperactivity response. Eleven days treatment with topiramate (30 mg/kg) resulted in a significant attenuation of quinpirole-induced hyperactivity, qualitatively similar to the effects of the other anticonvulsants. The results suggest that mood-stabilizing anticonvulsant drugs including topiramate may attenuate quinpirole-induced hyperactivity.

[Animal models of psychiatric diseases: possibilities, limitations, examples and demonstration of use].

Animal models of psychopathology serve as a central tool for psychopharmacologists in their attempts to develop new, more efficient medications for psychiatric disorders, and in the efforts to explore the mechanisms of conventional and novel drugs. The development of efficient models for psychiatric diseases is complicated since the mechanisms of the disorders are not clear, major parts of the diagnosis depend on verbal communication with the patient and many of the symptoms are expressed mainly through the subjective experiences of the afflicted individual. Inspite of these difficulties, effective models were developed for most psychiatric diseases. The development of such models is based on their validation in three different dimensions: face validity--behavioral similarities between the model and the disorder; construct validity--similarities between the mechanisms related to the model and a mechanistic theory of the disease; predictive validity--that the model response to the conventional medications that are effective in the disease and will not respond to drugs that are not effective in the disease. The present paper presents three known models of depression; each induced in a different way and therefore represents a group of models: Reserpine-induced hypoactivity--represents the group of pharmacologically induced models. Forced swim test--represents the group of behaviorally induced models. Flinders Sensitive Line--represents the group of genetically induced models. The use of these models in an attempt to examine the range of action of a new potential antidepressant and its mechanisms of action is demonstrated with a recent set of experiments with inositol.

Smoking habits in bipolar and schizophrenic outpatients in southern Israel.

BACKGROUND: Although rates of cigarette smoking have been found to be higher in schizophrenic and depressed patients than in the general population, data regarding rates in bipolar patients are limited. This study further examines the relationship between bipolar disorder and smoking and compares the rate of smoking in bipolar disorder patients with rates in schizophrenic patients and in the general population. METHOD: Seventy bipolar patients and 64 schizophrenic patients (diagnosed using DSM-IV criteria) treated at the largest specialized public bipolar and schizophrenia clinics in southern Israel were interviewed regarding their smoking habits. The interview included a questionnaire relating to personal information, past and present smoking, and drug abuse and the Fagerstrom scale for nicotine dependence. Data from these patients were also compared with data from the general Israeli population. RESULTS: Data indicate that the rate of smoking does not appear to differ between bipolar (43.0%) and schizophrenic (45.0%) patients, whereas the rate for both patient groups is higher than that for the general Israeli population (27.5%). Smoking intensity was not found to be different between the 2 groups of patients. CONCLUSION: Smoking in patients with schizophrenia was suggested to be related to nicotine cholinergic dysfunction, but this suggestion cannot explain the equally high rates of smoking in bipolar patients. Schizophrenia, bipolar disorder, and smoking may all be related to dopamine transmission, and, therefore, dopaminergic interactions may provide a better explanation for the results.

Transcranial magnetic stimulation in an amphetamine hyperactivity model of mania.

OBJECTIVES: Transcranial magnetic stimulation (TMS) of the brain has been reported to have therapeutic effects in mania, as well as depression. TMS has previously been reported to have effects similar to those of electroconvulsive shock in rat models of depression. METHODS: We, therefore, studied TMS in amphetamine-induced hyperactivity as a rat model of mania. RESULTS: While two and seven daily TMS sessions significantly reduced activity after amphetamine, twice-daily TMS for 7 days enhanced activity after amphetamine. CONCLUSIONS: The results suggest that TMS treatment to rats interacts with the effects of amphetamine; the specific effects may be dependent on the schedule of treatment.

The antidepressant activity of inositol in the forced swim test involves 5-HT(2) receptors.

The effect of inositol as an antidepressant was previously demonstrated in both animal models of depression-like behavior and in clinical trials. Unlike most antidepressant drugs, inositol does not have a clear target in the synapse and was not demonstrated to alter monoamine levels in the brain. The present study attempted to draw a psychopharmacological profile of inositol's behavioral effects by exploring the interactions between the drug and specific receptor agonists and antagonists in the forced swim test. Rats received inositol treatment (or control) in combination with the serotonergic metabolism inhibitor PCPA or with the noradrenergic neurotoxin DSP-4. Results indicated that PCPA but not DSP-4 abolished the ability of inositol to cause a reduction in immobility time in the forced swim test. In mice, the specific 5-HT(2A)/5-HT(2C) antagonist ritanserin, but not the 5-HT(1A)/5-HT(1B)/beta adrenergic antagonist pindolol, abolished inositol's effect in the forced swim test. The 5-HT(2A)/5-HT(2C) agonist DOI and the 5-HT(1A) agonist 8-OH-DPAT did not have any significant effects on inositol's activity. The present data indicates that the antidepressant effect of inositol may involve 5-HT(2) receptors. It is thus possible that the effects of reuptake antidepressant drugs and the effects of inositol may have a common final pathway.