Adolescent Risperidone treatment alters protein expression associated with protein trafficking and cellular metabolism in the adult rat prefrontal cortex

Comprehensive analysis of circRNA expression profile and circRNA-miRNA-mRNA network susceptibility to very early-onset schizophrenia

To explore the potential role of circular RNAs (circRNAs) in children developing very early-onset schizophrenia (VEOS). Total RNA was extracted from the plasma samples of 10 VEOS patients and eight healthy controls. Expression profiles of circRNAs, micro RNAs (miRNAs), and messenger RNAs (mRNAs) were analyzed using RNA-seq. The interaction networks between miRNAs and targets were predicted using the miRanda tool. A differentially expressed circRNA-miRNA-mRNA (ceRNA) network was further constructed. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of the target mRNAs in the ceRNA network were performed to predict the potential functions of their host genes. The patient group and the control group were also compared on the regulatory patterns of circRNAs on mRNAs. 1934 circRNAs were identified from the samples and reported for the first time in schizophrenia. The circRNA expression levels were lower in the VEOS group than in the healthy control group, and 1889 circRNAs were expressed only in the control group. Differential expression analysis (i.e., log2fold change > 1.5, p 0.05) identified 235 circRNAs (1 up-regulated, 234 down-regulated), 11 miRNAs (7 up-regulated, 4 down-regulated), and 2,308 mRNAs (1906 up-regulated, 402 down-regulated) respectively. In VEOS, a ceRNA network with 10 down-regulated circRNA targets, 6 up-regulated miRNAs, and 47 down-regulated mRNAs was constructed. The target genes were involved in the membrane, the signal transduction, and the cytoskeleton and transport pathways. Finally, different expression correlation patterns of circRNA and mRNA in the network were observed between the patient group and the control group. The current research is the first to reveal the differentially expressed circRNAs in the plasma of VEOS patients. A circRNA-miRNA-mRNA network was also conducted in this study. It may be implied that the circRNAs in this network are potential diagnostic biomarkers for VEOS and they play an important role in the onset and development of VEOS symptoms.

Psychiatric drugs impact mitochondrial function in brain and other tissues

Mitochondria have been linked to the etiology of schizophrenia (SZ). However, studies of mitochondria in SZ might be confounded by the effects of pharmacological treatment with antipsychotic drugs (APDs) and other common medications. This review summarizes findings on relevant mitochondria mechanisms underlying SZ, and the potential impact of psychoactive drugs including primarily APDs, but also antidepressants and anxiolytics. The summarized data suggest that APDs impair mitochondria function by decreasing Complex I activity and ATP production and dissipation of the mitochondria membrane potential. At the same time, in the brains of patients with SZ, antipsychotic drug treatment normalizes gene expression modules enriched in mitochondrial genes that are decreased in SZ. This indicates that APDs may have both positive and negative effects on mitochondria. The available evidence suggests three conclusions i) alterations in mitochondria functions in SZ exist prior to APD treatment, ii) mitochondria alterations in SZ can be reversed by APD treatment, and iii) APDs directly cause impairment of mitochondria function. Overall, the mechanisms of action of psychiatric drugs on mitochondria are both direct and indirect; we conclude the effects of APDs on mitochondria may contribute to both their therapeutic and metabolic side effects. These studies support the hypothesis that neuronal mitochondria are an etiological factor in SZ. Moreover, APDs and other drugs must be considered in the evaluation of this pathophysiological role of mitochondria in SZ. Considering these effects, pharmacological actions on mitochondria may be a worthwhile target for further APD development.

Neurobehavioral effects of chronic low-dose risperidone administration in juvenile male rats

Despite substantial increases in the use of antipsychotics to treat various psychiatric conditions in children, there is a lack of literature regarding long-term effects of early treatment. Some studies have indicated that early administration results in differential alterations to neurotransmission systems, but few studies have investigated whether there are long-term behavioral modifications. Therefore, the aim of the current study was to investigate the neurobehavioral effects of low dose risperidone (a commonly prescribed antipsychotic) treatment using juvenile rats. Twenty-four male Sprague-Dawley rats were either subcutaneously implanted with a continuous release risperidone pellet (.04 mg/day) or a placebo pellet. To encompass the peri-adolescent to adolescent timeframe (postnatal day 40-70) thought to be important for brain development, male rats began risperidone treatment at post-natal day 35. Six weeks following commencement of risperidone treatment, all rats were tested on a battery of behavioral assessments including open field, object recognition, Morris Water Maze, and Y-Maze tasks. Risperidone treatment did not affect performance on the open field, object recognition, or Morris Water maze. A significant effect was found on the Y-maze. Although all rats exhibited normal spontaneous alternation, risperidone treated rats demonstrated significantly higher same arm returns, indicative of a working memory deficit. Continued research is needed to determine whether early exposure to risperidone may lead to differences in working memory at longer time-points. These results seem to indicate that early low dose risperidone treatment during the peri-adolescent and adolescent period does not severely impair behavior.

Correlation of hair risperidone concentration and serum level among patients with schizophrenia

BACKGROUND

Risperidone (RSP) has a rapid onset in vivo, low dosage and high plasma protein binding rate, therefore therapeutic drug monitoring (TDM) is needed to ensure safety in clinical treatment. However, compared with blood, hair is non-invasive, safe, non-infectious and easy to transport and store.

AIMS

This study aims to investigate the correlations among the drug concentrations of RSP in hair and serum, which provides an experimental basis to explore hair as a novel biomaterial to meet the needs of clinical detection.

METHODS

34 patients with schizophrenia treated with RSP for more than 3 months were enrolled in this study. About 1 cm section of hair near the scalp was taken from the subjects, pretreated and detected by liquid chromatography-mass spectrometry. A correlation analysis was conducted among the drug concentrations in hair, the serum concentrations and the daily dosage. The data were analysed using SPSS 20.0 software.

RESULTS

There was significant correlation between the hair concentration of RSP (two-tailed test, r=0.440, p=0.009) with the serum concentration of RSP, and the hair concentration of 9-hydroxyrisperidone (9-HR) with the serum concentration of 9-HR had no significant correlation (two-tailed test, r=-0.217, p=0.217); the total concentration of the RSP and 9-HR had no significant correlation between hair and serum (r=0.227, p=0.196). The dosage had no statistically significant correlation with the concentration of RSP in hair (r=0.207, p=0.241), 9-HR in hair (r=-0.194, p=0.271) and the total concentration of RSP and 9-HR in hair (r=0.188, p=0.288). There was no statistical correlation between the dosage and the concentration of RSP in serum (r=-0.059, p=0.741), but significant correlation between the dosage and 9-HR in serum (r=0.581 p<0.001) was found, and the correlation between the dosage and the total concentration of the two drugs RSP and 9-HR in serum was also significant (r=0.437, p=0.01).

CONCLUSION

The correlation analysis showed that the concentration of RSP in hair was statistically significant with the serum RSP concentration. In this study, we provided some experimental basis for hair as a new biomaterial to monitor the therapeutic drug concentration.

The Effects of Prenatal Iron Deficiency and Risperidone Treatment on the Rat Frontal Cortex: A Proteomic Analysis

Prenatal iron deficiency (pID) has been described to increase the risk for neurodevelopmental disorders such as autism and schizophrenia; however, the precise molecular mechanisms are still unknown. Here, we utilized high-throughput MS to examine the proteomic effects of pID in adulthood on the rat frontal cortex area (FCA). In addition, the FCA proteome was examined in adulthood following risperidone treatment in adolescence to see if these effects could be prevented. We identified 1501 proteins of which 100 were significantly differentially expressed in the FCA at postnatal day 90. Pathway analysis of proteins affected by pID revealed changes in metabolic processes, including the tricyclic acid cycle, mitochondrial dysfunction, and P13K/Akt signaling. Interestingly, most of these protein changes were not present in the adult pID offspring who received risperidone in adolescence. Considering the link between pID and several neurodevelopmental disorders such as autism and schizophrenia these presented results bring new perspectives to understand the role of iron in metabolic pathways and provide novel biomarkers for future studies of pID.

Short- and long-term effects of risperidone on catalepsy sensitisation and acquisition of conditioned avoidance response: Adolescent vs adult rats

The effects of antipsychotic drugs (APDs) on the adolescent brain are poorly understood despite a dramatic increase in prescription of these drugs in adolescents over the past twenty years. Neuronal systems continue to be remodeled during adolescence. Therefore, when given in adolescence, antipsychotic drugs (APDs) have the potential to affect this remodeling. In this study we investigated the effects of chronic 22-day risperidone treatment (1.3mg/kg/day) in both adolescent and adult rats. We examined short- and long-term changes in behaviour (catalepsy, locomotion and conditioned avoidance response (CAR)), and dopaminergic and serotonergic neurochemistry in the striatum and the nucleus accumbens. Here, we report that, both during chronic treatment and after a lengthy drug-free interval, risperidone induced a sensitised cataleptic response regardless of the age of exposure. Selectively in adolescents, risperidone-induced catalepsy was inversely correlated with striatal dopamine turnover immediately after chronic treatment. After a drug-free interval, a significant proportion of rats with prior adolescent risperidone treatment also failed to acquire CAR to a defined criterion. Our data provide evidence that the same chronic risperidone treatment regimen can induce contrasting short- and long-term neural outcomes in the adolescent and adult brains.

Neural changes induced by antipsychotic administration in adolescence: A review of studies in laboratory rodents

Adolescence is characterized by major remodelling processes in the brain. Use of antipsychotic drugs (APDs) in adolescents has increased dramatically in the last 20 years; however, our understanding of the neurobiological consequences of APD treatment on the adolescent brain has not kept the same pace and significant concerns have been raised. In this review, we examined currently available preclinical studies of the effects of APDs on the adolescent brain. In animal models of neuropsychiatric disorders, adolescent APD treatment appears to be protective against selected structural, behavioural and neurochemical phenotypes. In "neurodevelopmentally normal" adolescent animals, a range of short- and long-term alterations in behaviour and neurochemistry have been reported. In particular, the adolescent brain appears to be sensitive to long-term locomotor/reward effects of chronic atypical APDs in contrast with the outcomes in adults. Long-lasting changes in dopaminergic, glutamatergic and gamma-amino butyric acid-ergic systems induced by adolescent APD administration have been observed in the nucleus accumbens. A detailed examination of other potential target regions such as striatum, prefrontal cortex and ventral tegmental area is still required. Through identification of specific neural pathways targeted by adolescent APD treatment, future studies will expand the current knowledge on long-term neural outcomes which are of translational value.

Early antipsychotic exposure affects serotonin and dopamine receptor binding density differently in selected brain loci of male and female juvenile rats

BACKGROUND

Antipsychotic drugs (APDs) were developed to treat schizophrenia in adults; however they have been increasingly prescribed (mostly "off-label") for children and adolescents. This study aimed to investigate the effects of aripiprazole, olanzapine and risperidone on the binding of serotonin (5-HT) and dopamine receptors in juvenile rat brain regions that are involved in antipsychotic efficacy.

METHODS

Male and female rats were treated orally with aripiprazole (1mg/kg), olanzapine (1mg/kg), risperidone (0.3mg/kg) or vehicle 3 times/day starting from postnatal day 23 (±1day) for 20 days. Quantitative autoradiography was performed to examine the receptor binding densities.

RESULTS

Olanzapine significantly decreased 5-HT2A (5-HT2AR) and 5-HT2C receptor (5-HT2CR) binding in the prefrontal cortex (PFC), cingulate cortex (Cg) and nucleus accumbens (NAc) of both male and female rats. In the caudate putamen (CPu), olanzapine attenuated 5-HT2AR binding in both genders, and reduced 5-HT2CR binding in male rats. Olanzapine increased D2 receptor (D2R) binding in the NAcS of male rats, but decreased it in females. Olanzapine increased D1 receptor (D1R) binding in the Cg, while aripiprazole decreased D1R binding in the PFC of males. Aripiprazole significantly reduced 5-HT2AR binding in the male PFC. Risperidone decreased 5-HT2AR binding in the PFC of female rats, while attenuating D1R binding in the PFC and Cg of males. However, APDs have no effects on the binding of serotonin and dopamine transporters.

CONCLUSION

This study revealed that aripiprazole, olanzapine and risperidone affected 5-HT2AR, 5-HT2CR, 5-HTT, D1R and D2R bindings differently in the brains of juvenile male and female rats.

Employing proteomics to unravel the molecular effects of antipsychotics and their role in schizophrenia

Schizophrenia is an incurable neuropsychiatric disorder managed mostly by treatment of the patients with antipsychotics. However, the efficacy of these drugs has remained only low to moderate despite intensive research efforts since the early 1950s when chlorpromazine, the first antipsychotic, was synthesized. In addition, antipsychotic treatment can produce often undesired severe side effects in the patients and addressing these remains a large unmet clinical need. One of the reasons for the low effectiveness of these drugs is the limited knowledge about the molecular mechanisms of schizophrenia, which impairs the development of new and more effective treatments. Recently, proteomic studies of clinical and preclinical samples have identified changes in the levels of specific proteins in response to antipsychotic treatment, which have converged on molecular pathways such as cell communication and signaling, inflammation and cellular growth, and maintenance. The findings of these studies are summarized and discussed in this review and we suggest that this provides validation of proteomics as a useful tool for mining drug mechanisms of action and potentially for pinpointing novel molecular targets that may enable development of more effective medications.

Proteome and pathway effects of chronic haloperidol treatment in mouse hippocampus

Proteomic exploration of the effects of psychotropic drugs on specific brain areas in rodents has the potential to uncover novel molecular networks and pathways affected by psychotropic medications, and may inform etiologic hypotheses on mental disorders. Haloperidol, a widely used first-generation antipsychotic, has been shown to produce structural and functional changes of the hippocampus, a brain region also implicated in the neuropathology of disorders such as schizophrenia and bipolar disorder. Seven adult male C57BL/6 mice were injected daily intraperitoneally with 0.5 mg/kg of haloperidol, for 28 days. A control group of six animals was injected with vehicle only (saline). Protein levels of postmortem hippocampus homogenate were determined using label-free LC/MS/MS. In the treatment group, 216 differentially expressed hippocampal proteins were identified as compared to controls. Ingenuity pathway analysis implicated oxidative phosphorylation and mitochondrial function as top canonical pathways, and local networks involved in tubulin-mediated cytoskeleton dynamics, clathrin-mediated endocytosis, and extracellular signal-regulated kinase and c-Jun N-terminal kinase signaling. The findings of this study could stimulate further research into the cellular mechanisms associated with haloperidol treatment and the pathophysiology of psychotic disorders, assisting treatment biomarker discovery. All MS data have been deposited in the ProteomeXchange with identifier PXD002250 (http://proteomecentral.proteomexchange.org/dataset/PXD002250).

Stathmin reduction and cytoskeleton rearrangement in rat nucleus accumbens in response to clozapine and risperidone treatment - Comparative proteomic study

The complex network of anatomical connections of the nucleus accumbens (NAc) makes it an interface responsible for the selection and integration of cognitive and affective information to modulate appetitive or aversively motivated behaviour. There is evidence for NAc dysfunction in schizophrenia. NAc also seems to be important for antipsychotic drug action, but the biochemical characteristics of drug-induced alterations within NAc remain incompletely characterized. In this study, a comprehensive proteomic analysis was performed to describe the differences in the mechanisms of action of clozapine (CLO) and risperidone (RIS) in the rat NAc. Both antipsychotics influenced the level of microtubule-regulating proteins, i.e., stathmin, and proteins of the collapsin response mediator protein family (CRMPs), and only CLO affected NAD-dependent protein deacetylase sirtuin-2 and septin 6. Both antipsychotics induced changes in levels of other cytoskeleton-related proteins. CLO exclusively up-regulated proteins involved in neuroprotection, such as glutathione synthetase, heat-shock 70-kDa protein 8 and mitochondrial heat-shock protein 75. RIS tuned cell function by changing the pattern of post-translational modifications of some proteins: it down-regulated the phosphorylated forms of stathmin and dopamine and the cyclic AMP-regulated phosphoprotein (DARPP-32) isoform but up-regulated cyclin-dependent kinase 5 (Cdk5). RIS modulated the level and phosphorylation state of synaptic proteins: synapsin-2, synaptotagmin-1 and adaptor-related protein-2 (AP-2) complex.

Proteome effects of antipsychotic drugs: Learning from preclinical models

Proteome-wide expression analyses are performed in the brain of schizophrenia patients to understand the biological basis of the disease and discover molecular paths for new clinical interventions. A major issue with postmortem analysis is the lack of tools to discern molecular modulation related to the disease from dysregulation due to medications. We review available proteome-wide analysis of antipsychotic treatment in rodents, highlighting shared dysregulated pathways that may contribute to an extended view of molecular processes underlying their pharmacological activity. Fourteen proteomic studies conducted with typical and atypical antipsychotic treatments were examined; hypothesis-based approaches are also briefly discussed. Treatment with antipsychotics mainly affects proteins belonging to metabolic pathways involved in energy generation, both in glycolytic and oxidative phosphorylation pathways, suggesting antipsychotics-induced impairments in metabolism. Nevertheless, schizophrenic patients show impaired glucose metabolism and mitochondrial dysfunctions independent of therapy. Other antipsychotics-induced changes shared by different studies implicate cytoskeletal and synaptic function proteins. The mechanism can be related to the reorganization of dendritic spines resulting from neural plasticity events induced by treatments affecting neurotransmitter circuitry. However, metabolic and plasticity pathways activated by antipsychotics can also play an authentic role in the etiopathological basis of schizophrenia.

Evidence of Mitochondrial Dysfunction within the Complex Genetic Etiology of Schizophrenia

Genetic evidence has supported the hypothesis that schizophrenia (SZ) is a polygenic disorder caused by the disruption in function of several or many genes. The most common and reproducible cellular phenotype associated with SZ is a reduction in dendritic spines within the neocortex, suggesting alterations in dendritic architecture may cause aberrant cortical circuitry and SZ symptoms. Here, we review evidence supporting a multifactorial model of mitochondrial dysfunction in SZ etiology and discuss how these multiple paths to mitochondrial dysfunction may contribute to dendritic spine loss and/or underdevelopment in some SZ subjects. The pathophysiological role of mitochondrial dysfunction in SZ is based upon genomic analyses of both the mitochondrial genome and nuclear genes involved in mitochondrial function. Previous studies and preliminary data suggest SZ is associated with specific alleles and haplogroups of the mitochondrial genome, and also correlates with a reduction in mitochondrial copy number and an increase in synonymous and nonsynonymous substitutions of mitochondrial DNA. Mitochondrial dysfunction has also been widely implicated in SZ by genome-wide association, exome sequencing, altered gene expression, proteomics, microscopy analyses, and induced pluripotent stem cell studies. Together, these data support the hypothesis that SZ is a polygenic disorder with an enrichment of mitochondrial targets.