Disruption of dopamine D2/D3 system function impairs the human ability to understand the mental states of other people.

Difficulties in reasoning about others' mental states (i.e., mentalising/Theory of Mind) are highly prevalent among disorders featuring dopamine dysfunctions (e.g., Parkinson's disease) and significantly affect individuals' quality of life. However, due to multiple confounding factors inherent to existing patient studies, currently little is known about whether these sociocognitive symptoms originate from aberrant dopamine signalling or from psychosocial changes unrelated to dopamine. The present study, therefore, investigated the role of dopamine in modulating mentalising in a sample of healthy volunteers. We used a double-blind, placebo-controlled procedure to test the effect of the D2/D3 antagonist haloperidol on mental state attribution, using an adaptation of the Heider and Simmel (1944) animations task. On 2 separate days, once after receiving 2.5 mg haloperidol and once after receiving placebo, 33 healthy adult participants viewed and labelled short videos of 2 triangles depicting mental state (involving mentalistic interaction wherein 1 triangle intends to cause or act upon a particular mental state in the other, e.g., surprising) and non-mental state (involving reciprocal interaction without the intention to cause/act upon the other triangle's mental state, e.g., following) interactions. Using Bayesian mixed effects models, we observed that haloperidol decreased accuracy in labelling both mental and non-mental state animations. Our secondary analyses suggest that dopamine modulates inference from mental and non-mental state animations via independent mechanisms, pointing towards 2 putative pathways underlying the dopaminergic modulation of mental state attribution: action representation and a shared mechanism supporting mentalising and emotion recognition. We conclude that dopaminergic pathways impact Theory of Mind, at least indirectly. Our results have implications for the neurochemical basis of sociocognitive difficulties in patients with dopamine dysfunctions and generate new hypotheses about the specific dopamine-mediated mechanisms underlying social cognition.

Dopamine and acetylcholine have distinct roles in delay- and effort-based decision-making in humans.

In everyday life, we encounter situations that require tradeoffs between potential rewards and associated costs, such as time and (physical) effort. The literature indicates a prominent role for dopamine in discounting of both delay and effort, with mixed findings for delay discounting in humans. Moreover, the reciprocal antagonistic interaction between dopaminergic and cholinergic transmission in the striatum suggests a potential opponent role of acetylcholine in these processes. We found opposing effects of dopamine D2 (haloperidol) and acetylcholine M1 receptor (biperiden) antagonism on specific components of effort-based decision-making in healthy humans: haloperidol decreased, whereas biperiden increased the willingness to exert physical effort. In contrast, delay discounting was reduced under haloperidol, but not affected by biperiden. Together, our data suggest that dopamine, acting at D2 receptors, modulates both effort and delay discounting, while acetylcholine, acting at M1 receptors, appears to exert a more specific influence on effort discounting only.

Enhancement of Haloperidol-Induced Catalepsy by GPR143, an L-Dopa Receptor, in Striatal Cholinergic Interneurons.

Dopamine neurons play crucial roles in pleasure, reward, memory, learning, and fine motor skills and their dysfunction is associated with various neuropsychiatric diseases. Dopamine receptors are the main target of treatment for neurologic and psychiatric disorders. Antipsychotics that antagonize the dopamine D2 receptor (DRD2) are used to alleviate the symptoms of these disorders but may also sometimes cause disabling side effects such as parkinsonism (catalepsy in rodents). Here we show that GPR143, a G-protein-coupled receptor for L-3,4-dihydroxyphenylalanine (L-DOPA), expressed in striatal cholinergic interneurons enhances the DRD2-mediated side effects of haloperidol, an antipsychotic agent. Haloperidol-induced catalepsy was attenuated in male Gpr143 gene-deficient (Gpr143-/y ) mice compared with wild-type (Wt) mice. Reducing the endogenous release of L-DOPA and preventing interactions between GPR143 and DRD2 suppressed the haloperidol-induced catalepsy in Wt mice but not Gpr143-/y mice. The phenotypic defect in Gpr143-/y mice was mimicked in cholinergic interneuron-specific Gpr143-/y (Chat-cre;Gpr143flox/y ) mice. Administration of haloperidol increased the phosphorylation of ribosomal protein S6 at Ser240/244 in the dorsolateral striatum of Wt mice but not Chat-cre;Gpr143flox/y mice. In Chinese hamster ovary cells stably expressing DRD2, co-expression of GPR143 increased cell surface expression level of DRD2, and L-DOPA application further enhanced the DRD2 surface expression. Shorter pauses in cholinergic interneuron firing activity were observed after intrastriatal stimulation in striatal slice preparations from Chat-cre;Gpr143flox/y mice compared with those from Wt mice. Together, these findings provide evidence that GPR143 regulates DRD2 function in cholinergic interneurons and may be involved in parkinsonism induced by antipsychotic drugs.

N-n-butyl haloperidol iodide mediates cardioprotection via regulating AMPK/FoxO1 signalling.

Derangement of redox condition largely contributes to cardiac ischemia/reperfusion (I/R) injury. FoxO1 is a transcription factor which transcripts a series of antioxidants to antagonize I/R-induced oxidative myocardial damage. N-n-butyl haloperidol iodide (F2 ) is a derivative derived from haloperidol structural modification with potent capacity of inhibiting oxidative stress. This investigation intends to validate whether cardio-protection of F2 is dependent on FoxO1 using an in vivo mouse I/R model and if so, to further elucidate the molecular regulating mechanism. This study initially revealed that F2 preconditioning led to a profound reduction in I/R injury, which was accompanied by attenuated oxidative stress and upregulation of antioxidants (SOD2 and catalase), nuclear FoxO1 and phosphorylation of AMPK. Furthermore, inactivation of FoxO1 with AS1842856 abolished the cardio-protective effect of F2 . Importantly, we identified F2 -mediated nuclear accumulation of FoxO1 is dependent on AMPK, as blockage of AMPK with compound C induced nuclear exit of FoxO1. Collectively, our data uncover that F2 pretreatment exerts significant protection against post ischemic myocardial injury by its regulation of AMPK/FoxO1 pathway, which may provide a new avenue for treating ischemic disease.

NMDA glutamate receptor antagonist MK-801 induces proteome changes in adult human brain slices which are partially counteracted by haloperidol and clozapine.

Deciphering the molecular pathways associated with N-methyl-D-aspartate receptor (NMDAr) hypofunction and its interaction with antipsychotics is necessary to advance our understanding of the basis of schizophrenia, as well as our capacity to treat this disease. In this regard, the development of human brain-derived models that are amenable to studying the neurobiology of schizophrenia may contribute to filling the gaps left by the widely employed animal models. Here, we assessed the proteomic changes induced by the NMDA glutamate receptor antagonist MK-801 on human brain slice cultures obtained from adult donors submitted to respective neurosurgery. Initially, we demonstrated that MK-801 diminishes NMDA glutamate receptor signaling in human brain slices in culture. Next, using mass-spectrometry-based proteomics and systems biology in silico analyses, we found that MK-801 led to alterations in proteins related to several pathways previously associated with schizophrenia pathophysiology, including ephrin, opioid, melatonin, sirtuin signaling, interleukin 8, endocannabinoid, and synaptic vesicle cycle. We also evaluated the impact of both typical and atypical antipsychotics on MK-801-induced proteome changes. Interestingly, the atypical antipsychotic clozapine showed a more significant capacity to counteract the protein alterations induced by NMDAr hypofunction than haloperidol. Finally, using our dataset, we identified potential modulators of the MK-801-induced proteome changes, which may be considered promising targets to treat NMDAr hypofunction in schizophrenia. This dataset is publicly available and may be helpful in further studies aimed at evaluating the effects of MK-801 and antipsychotics in the human brain.

High-dose Agomelatine Combined with Haloperidol Decanoate Improves Cognition, Downregulates MT2, Upregulates D5, and Maintains Krüppel-like Factor 9 But Alters Cardiac Electrophysiology.

Haloperidol decanoate (HD) has been implicated in cognitive impairment. Agomelatine (AGO) has been claimed to improve cognition. We aimed at investigating the effects of HD + low- or high-dose AGO on cognition, verifying the melatonergic/dopaminergic to the cholinergic hypothesis of cognition and exploring relevant cardiovascular issues in adult male Wistar albino rats. HD + high-dose AGO prolonged the step-through latency by +61.47% (P < 0.0001), increased the time spent in bright light by +439.49% (P < 0.0001), reduced the time spent in dim light by -66.25% (P < 0.0001), and increased the percent of alternations by +71.25% (P < 0.0001), despite the reductions in brain acetylcholine level by -10.67% (P < 0.0001). Neurodegeneration was minimal, while the mean power frequency of the source wave was reduced by -23.39% (P < 0.05). Concurrently, the relative expression of brain melatonin type 2 receptors was reduced by -18.75% (P < 0.05), against increased expressions of dopamine type 5 receptors by +22.22% (P < 0.0001) and angiopoietin-like 4 by +119.18% (P < 0.0001). Meanwhile, electrocardiogram (ECG) demonstrated inverted P wave, reduced P wave duration by -36.15% (P < 0.0001) and PR interval by -19.91% (P < 0.0001), prolonged RR interval by +27.97% (P < 0.05), increased R wave amplitude by +523.15% (P < 0.0001), and a depressed ST segment and inverted T wave. In rats administered AGO, HD, or HD+ low-dose AGO, Alzheimer's disease (AD)-like neuropathologic features were more evident, accompanied by extensive ECG and neurochemical alterations. HD + high-dose AGO enhances cognition but alters cardiac electrophysiology. SIGNIFICANCE STATEMENT: Given the issue of cognitive impairment associated with HD and the claimed cognitive-enhancing activity of AGO, combined high-dose AGO with HD improved cognition of adult male rats, who exhibited minimal neurodegenerative changes. HD+ high-dose AGO was relatively safe regarding triggering epileptogenesis, while it altered cardiac electrophysiology. In the presence of low acetylcholine, the melatonergic/dopaminergic hypothesis, added to angiopoietin-like 4 and Krüppel-like factor 9, could offer some clue, thus offering novel targets for pharmacologic manipulation of cognition.

Caffeine plus haloperidol reduces fatigue in an experimental model of Parkinson's disease - a prospective to A2AR-D2R heterodimer antagonism.

Fatigue is a non-motor symptom of Parkinson's disease (PD). Adenosine 2A receptor (A2AR) and compromised dopamine neurotransmission are linked to fatigue. Studies demonstrate that A2AR antagonism potentiates dopamine transmission via dopamine receptor D2 (D2R). However, the heterodimer form of A2AR-D2R in the striatum prompted questions about the therapeutic targets for PD patients. This study investigates the effects of caffeine (A2AR non-selective antagonist) plus haloperidol (D2R selective antagonist) treatment in the fatigue induced by the reserpine model of PD. Reserpinized mice showed impaired motor control in the open field test (p < 0.05) and fatigue in the grip strength meter test (p < 0.05). L-DOPA and caffeine plus haloperidol similarly increased motor control (p < 0.05) and mitigated fatigue (p < 0.05). Our results support the A2AR-D2R heterodimer participation in the central fatigue of PD, and highlight the potential of A2AR-D2R antagonism in the management of PD.

N -N-Butyl Haloperidol Iodide Mitigates Myocardial Ischemia/Reperfusion Injury Through Activation of SIRT1-Nrf2 Signaling Loop.

ABSTRACT: N -n-butyl haloperidol iodide (F 2 ), a derivative of haloperidol developed by our group, exhibits potent antioxidative properties and confers protection against cardiac ischemia/reperfusion (I/R) injury. The protective mechanisms by which F 2 ameliorates I/R injury remain obscure. The activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor transactivating many antioxidative genes, also attenuates I/R-induced myocardial damage. The present study investigated whether the cardioprotective effect of F 2 depends on Nrf2 using a mouse heart I/R model. F 2 (0.1, 0.2 or 0.4 mg/kg) or vehicle was intravenously injected to mice 5 minutes before reperfusion. Systemic administration of 0.4 mg/kg F 2 led to a significant reduction in I/R injury, which was accompanied by enhanced activation of Nrf2 signaling. The cardioprotection conferred by F 2 was largely abrogated in Nrf2-deficient mice. Importantly, we found F 2 -induced activation of Nrf2 is silent information regulator of transcription 1 (SIRT1)-dependent, as pharmacologically inhibiting SIRT1 by the specific inhibitor EX527 blocked Nrf2 activation. Moreover, F 2 -upregulated expression of SIRT1 was also Nrf2-dependent, as Nrf2 deficiency inhibited SIRT1 upregulation. These results indicate that SIRT1-Nrf2 signaling loop activation is indispensable for the protective effect of F 2 against myocardial I/R injury and may provide new insights for the treatment of ischemic heart disease.

Interhemispheric differences of pyramidal cells in the primary motor cortices of schizophrenia patients investigated postmortem.

Motor disturbances are observed in schizophrenia patients, but the neuroanatomical background is unknown. Our aim was to investigate the pyramidal cells of the primary motor cortex (BA 4) in both hemispheres of postmortem control and schizophrenia subjects-8 subjects in each group-with 2.5-5.5 h postmortem interval. The density and size of the Sternberger monoclonal incorporated antibody 32 (SMI32)-immunostained pyramidal cells in layer 3 and 5 showed no change; however, the proportion of larger pyramidal cells is decreased in layer 5. Giant pyramidal neurons (Betz cells) were investigated distinctively with SMI32- and parvalbumin (PV) immunostainings. In the right hemisphere of schizophrenia subjects, the density of Betz cells was decreased and their PV-immunopositive perisomatic input showed impairment. Part of the Betz cells contained PV in both groups, but the proportion of PV-positive cells has declined with age. The rat model of antipsychotic treatment with haloperidol and olanzapine showed no differences in size and density of SMI32-immunopositive pyramidal cells. Our results suggest that motor impairment of schizophrenia patients may have a morphological basis involving the Betz cells in the right hemisphere. These alterations can have neurodevelopmental and neurodegenerative explanations, but antipsychotic treatment does not explain them.

Antipsychotic drugs counteract autophagy and mitophagy in multiple sclerosis.

Multiple sclerosis (MS) is a neuroinflammatory and neurodegenerative disease characterized by myelin damage followed by axonal and ultimately neuronal loss. The etiology and physiopathology of MS are still elusive, and no fully effective therapy is yet available. We investigated the role in MS of autophagy (physiologically, a controlled intracellular pathway regulating the degradation of cellular components) and of mitophagy (a specific form of autophagy that removes dysfunctional mitochondria). We found that the levels of autophagy and mitophagy markers are significantly increased in the biofluids of MS patients during the active phase of the disease, indicating activation of these processes. In keeping with this idea, in vitro and in vivo MS models (induced by proinflammatory cytokines, lysolecithin, and cuprizone) are associated with strongly impaired mitochondrial activity, inducing a lactic acid metabolism and prompting an increase in the autophagic flux and in mitophagy. Multiple structurally and mechanistically unrelated inhibitors of autophagy improved myelin production and normalized axonal myelination, and two such inhibitors, the widely used antipsychotic drugs haloperidol and clozapine, also significantly improved cuprizone-induced motor impairment. These data suggest that autophagy has a causal role in MS; its inhibition strongly attenuates behavioral signs in an experimental model of the disease. Therefore, haloperidol and clozapine may represent additional therapeutic tools against MS.

Effects of Intracerebral Aminophylline Dosing on Catalepsy and Gait in an Animal Model of Parkinson's Disease.

Parkinson's disease (PD) is a progressive disorder characterized by the apoptosis of dopaminergic neurons in the basal ganglia. This study explored the potential effects of aminophylline, a non-selective adenosine A1 and A2A receptor antagonist, on catalepsy and gait in a haloperidol-induced PD model. Sixty adult male Swiss mice were surgically implanted with guide cannulas that targeted the basal ganglia. After seven days, the mice received intraperitoneal injections of either haloperidol (experimental group, PD-induced model) or saline solution (control group, non-PD-induced model), followed by intracerebral infusions of aminophylline. The assessments included catalepsy testing on the bar and gait analysis using the Open Field Maze. A two-way repeated-measures analysis of variance (ANOVA), followed by Tukey's post hoc tests, was employed to evaluate the impact of groups (experimental × control), aminophylline (60 nM × 120 nM × saline/placebo), and interactions. Significance was set at 5%. The results revealed that the systemic administration of haloperidol in the experimental group increased catalepsy and dysfunction of gait that paralleled the observations in PD. Co-treatment with aminophylline at 60 nM and 120 nM reversed catalepsy in the experimental group but did not restore the normal gait pattern of the animals. In the non-PD induced group, which did not present any signs of catalepsy or motor dysfunctions, the intracerebral dose of aminophylline did not exert any interference on reaction time for catalepsy but increased walking distance in the Open Field Maze. Considering the results, this study highlights important adenosine interactions in the basal ganglia of animals with and without signs comparable to those of PD. These findings offer valuable insights into the neurobiology of PD and emphasize the importance of exploring novel therapeutic strategies to improve patient's catalepsy and gait.

Sex-Specific Effects of Long-Term Antipsychotic Drug Treatment on Adipocyte Tissue and the Crosstalk to Liver and Brain in Rats.

Antipsychotic drug (APD) medication can lead to metabolic dysfunctions and weight gain, which together increase morbidity and mortality. Metabolically active visceral adipose tissue (VAT) in particular plays a crucial role in the etiopathology of these metabolic dysregulations. Here, we studied the effect of 12 weeks of drug medication by daily oral feeding of clozapine and haloperidol on the perirenal fat tissue as part of VAT of male and female Sprague Dawley rats in the context of complex former investigations on brain, liver, and blood. Adipocyte area values were determined, as well as triglycerides, non-esterified fatty acids (NEFAs), glucose, glycogen, lactate, malondialdehyde equivalents, ferric iron and protein levels of Perilipin-A, hormone-sensitive-lipase (HSL), hepcidin, glucose transporter-4 (Glut-4) and insulin receptor-ß (IR-ß). We found increased adipocyte mass in males, with slightly higher adipocyte area values in both males and females under clozapine treatment. Triglycerides, NEFAs, glucose and oxidative stress in the medicated groups were unchanged or slightly decreased. In contrast to controls and haloperidol-medicated rats, perirenal adipocyte mass and serum leptin levels were not correlated under clozapine. Protein expressions of perilipin-A, Glut-4 and HSL were decreased under clozapine treatment. IR-ß expression changed sex-specifically in the clozapine-medicated groups associated with higher hepcidin levels in the perirenal adipose tissue of clozapine-treated females. Taken together, clozapine and haloperidol had a smaller effect than expected on perirenal adipose tissue. The perirenal adipose tissue shows only weak changes in lipid and glucose metabolism. The main changes can be seen in the proteins examined, and probably in their effect on liver metabolism.

Kinetic Properties and Pharmacological Modulation of High- and Low-Affinity Dopamine Transport in Striatal Astrocytes of Adult Rats.

Astrocytes actively participate in neurotransmitter homeostasis by bidirectional communication with neuronal cells, a concept named the tripartite synapse, yet their role in dopamine (DA) homeostasis remains understudied. In the present study, we investigated the kinetic and molecular mechanisms of DA transport in cultured striatal astrocytes of adult rats. Kinetic uptake experiments were performed using radiolabeled [3H]-DA, whereas mRNA expression of the dopamine, norepinephrine, organic cation and plasma membrane monoamine transporters (DAT, NET, OCTs and PMAT) and DA receptors D1 and D2 was determined by qPCR. Additionally, astrocyte cultures were subjected to a 24 h treatment with the DA receptor agonist apomorphine, the DA receptor antagonist haloperidol and the DA precursor L-DOPA. [3H]-DA uptake exhibited temperature, concentration and sodium dependence, with potent inhibition by desipramine, nortriptyline and decynium-22, suggesting the involvement of multiple transporters. qPCR revealed prominent mRNA expression of the NET, the PMAT and OCT1, alongside lower levels of mRNA for OCT2, OCT3 and the DAT. Notably, apomorphine significantly altered NET, PMAT and D1 mRNA expression, while haloperidol and L-DOPA had a modest impact. Our findings demonstrate that striatal astrocytes aid in DA clearance by multiple transporters, which are influenced by dopaminergic drugs. Our study enhances the understanding of regional DA uptake, paving the way for targeted therapeutic interventions in dopaminergic disorders.

Design, Synthesis, and Cytotoxic Assessment of New Haloperidol Analogues as Potential Anticancer Compounds Targeting Sigma Receptors.

Sigma receptors (SRs), including SR1 and SR2 subtypes, have attracted increasing interest in recent years due to their involvement in a wide range of activities, including the modulation of opioid analgesia, neuroprotection, and potential anticancer activity. In this context, haloperidol (HAL), a commonly used antipsychotic drug, also possesses SR activity and cytotoxic effects. Herein, we describe the identification of novel SR ligands, obtained by a chemical hybridization approach. There wereendowed with pan-affinity for both SR subtypes and evaluated their potential anticancer activity against SH-SY5Y and HUH-7 cancer cell lines. Through a chemical hybridization approach, we identified novel compounds (4d, 4e, 4g, and 4j) with dual affinity for SR1 and SR2 receptors. These compounds were subjected to cytotoxicity testing using a resazurin assay. The results revealed potent cytotoxic effects against both cancer cell lines, with IC50 values comparable to HAL. Interestingly, the cytotoxic potency of the novel compounds resembled that of the SR1 antagonist HAL rather than the SR2 agonist siramesine (SRM), indicating the potential role of SR1 antagonism in their mechanism of action. The further exploration of their structure-activity relationships and their evaluation in additional cancer cell lines will elucidate their therapeutic potential and may pave the way for the development of novel anticancer agents that target SRs.

Dopaminergic Modulation of Dynamic Emotion Perception.

Emotion recognition abilities are fundamental to our everyday social interaction. A large number of clinical populations show impairments in this domain, with emotion recognition atypicalities being particularly prevalent among disorders exhibiting a dopamine system disruption (e.g., Parkinson's disease). Although this suggests a role for dopamine in emotion recognition, studies employing dopamine manipulation in healthy volunteers have exhibited mixed neural findings and no behavioral modulation. Interestingly, while a dependence of dopaminergic drug effects on individual baseline dopamine function has been well established in other cognitive domains, the emotion recognition literature so far has failed to account for these possible interindividual differences. The present within-subjects study therefore tested the effects of the dopamine D2 antagonist haloperidol on emotion recognition from dynamic, whole-body stimuli while accounting for interindividual differences in baseline dopamine. A total of 33 healthy male and female adults rated emotional point-light walkers (PLWs) once after ingestion of 2.5 mg haloperidol and once after placebo. To evaluate potential mechanistic pathways of the dopaminergic modulation of emotion recognition, participants also performed motoric and counting-based indices of temporal processing. Confirming our hypotheses, effects of haloperidol on emotion recognition depended on baseline dopamine function, where individuals with low baseline dopamine showed enhanced, and those with high baseline dopamine decreased emotion recognition. Drug effects on emotion recognition were related to drug effects on movement-based and explicit timing mechanisms, indicating possible mediating effects of temporal processing. Results highlight the need for future studies to account for baseline dopamine and suggest putative mechanisms underlying the dopaminergic modulation of emotion recognition.SIGNIFICANCE STATEMENT A high prevalence of emotion recognition difficulties among clinical conditions where the dopamine system is affected suggests an involvement of dopamine in emotion recognition processes. However, previous psychopharmacological studies seeking to confirm this role in healthy volunteers thus far have failed to establish whether dopamine affects emotion recognition and lack mechanistic insights. The present study uncovered effects of dopamine on emotion recognition in healthy individuals by controlling for interindividual differences in baseline dopamine function and investigated potential mechanistic pathways via which dopamine may modulate emotion recognition. Our findings suggest that dopamine may influence emotion recognition via its effects on temporal processing, providing new directions for future research on typical and atypical emotion recognition.

Ketamine disrupts locomotion and electrolocation in a novel model of schizophrenia, Gnathonemus petersii fish.

The present study aimed to examine a weakly electric fish Gnathonemus petersii (G. petersii) as a candidate model organism of glutamatergic theory of schizophrenia. The idea of G. petersii elevating the modeling of schizophrenia symptoms is based on the fish's electrolocation and electrocommunication abilities. Fish were exposed to the NMDA antagonist ketamine in two distinct series differing in the dose of ketamine. The main finding revealed ketamine-induced disruption of the relationship between electric signaling and behavior indicating impairment of fish navigation. Moreover, lower doses of ketamine significantly increased locomotion and erratic movement and higher doses of ketamine reduced the number of electric organ discharges indicating successful induction of positive schizophrenia-like symptoms and disruption of fish navigation. Additionally, a low dose of haloperidol was used to test the normalization of the positive symptoms to suggest a predictive validity of the model. However, although successfully induced, positive symptoms were not normalized using the low dose of haloperidol; hence, more doses of the typical antipsychotic haloperidol and probably also of a representative of atypical antipsychotic drugs need to be examined to confirm the predictive validity of the model.

Antipsychotic drugs induce vascular defects in hematopoietic organs.

Antipsychotic agents are clinically utilized to treat schizophrenia and other mental disorders. These drugs induce neurological and metabolic side effects, but their influence on blood vessels remains largely unknown. Here, we show that haloperidol, one of the most frequently prescribed antipsychotic agents, induces vascular defects in bone marrow. Acute haloperidol treatment results in vascular dilation that is specific to hematopoietic organs. This vessel dilation is associated with disruption of hematopoiesis and hematopoietic stem/progenitor cells (HSPCs), both of which are reversible after haloperidol withdrawal. Mechanistically, haloperidol treatment blocked the secretion of vascular endothelial growth factor A (VEGF-A) from HSPCs. Genetic blockade of VEGF-A secretion from hematopoietic cells or inhibition of VEGFR2 in endothelial cells result in similar vessel dilation in bone marrow during regeneration after irradiation and transplantation. Conversely, VEGF-A gain of function rescues the bone marrow vascular defects induced by haloperidol treatment and irradiation. Our work reveals an unknown effect of antipsychotic agents on the vasculature and hematopoiesis with potential implications for drug application in clinic.

Gene expression changes following chronic antipsychotic exposure in single cells from mouse striatum.

Schizophrenia is an idiopathic psychiatric disorder with a high degree of polygenicity. Evidence from genetics, single-cell transcriptomics, and pharmacological studies suggest an important, but untested, overlap between genes involved in the etiology of schizophrenia and the cellular mechanisms of action of antipsychotics. To directly compare genes with antipsychotic-induced differential expression to genes involved in schizophrenia, we applied single-cell RNA-sequencing to striatal samples from male C57BL/6 J mice chronically exposed to a typical antipsychotic (haloperidol), an atypical antipsychotic (olanzapine), or placebo. We identified differentially expressed genes in three cell populations identified from the single-cell RNA-sequencing (medium spiny neurons [MSNs], microglia, and astrocytes) and applied multiple analysis pipelines to contextualize these findings, including comparison to GWAS results for schizophrenia. In MSNs in particular, differential expression analysis showed that there was a larger share of differentially expressed genes (DEGs) from mice treated with olanzapine compared with haloperidol. DEGs were enriched in loci implicated by genetic studies of schizophrenia, and we highlighted nine genes with convergent evidence. Pathway analyses of gene expression in MSNs highlighted neuron/synapse development, alternative splicing, and mitochondrial function as particularly engaged by antipsychotics. In microglia, we identified pathways involved in microglial activation and inflammation as part of the antipsychotic response. In conclusion, single-cell RNA sequencing may provide important insights into antipsychotic mechanisms of action and links to findings from psychiatric genomic studies.

The dopamine receptor antagonist haloperidol disrupts behavioral responses of sea urchins and sea stars.

Despite lacking a brain and having an apparent symmetrically pentaradial nervous system, echinoderms are capable of complex, coordinated directional behavioral responses to different sensory stimuli. However, very little is known about the molecular and cellular mechanisms underlying these behaviors. In many animals, dopaminergic systems play key roles in motivating and coordinating behavior, and although the dopamine receptor antagonist haloperidol has been shown to inhibit the righting response of the sea urchin Strongylocentrotus purpuratus, it is not known whether this is specific to this behavior, in this species, or whether dopaminergic systems are needed in general for echinoderm behaviors. We found that haloperidol inhibited multiple different behavioral responses in three different echinoderm species. Haloperidol inhibited the righting response of the sea urchin Lytechinus variegatus and of the sea star Luidia clathrata. It additionally inhibited the lantern reflex of S. purpuratus, the shell covering response of L. variegatus and the immersion response of L. variegatus, but not S. purpuratus or L. clathrata. Our results suggest that dopamine is needed for the neural processing and coordination of multiple different behavioral responses in a variety of different echinoderm species.

Rho kinase inhibitors ameliorate cognitive impairment in a male mouse model of methamphetamine-induced schizophrenia.

Schizophrenia (SCZ) is a severe psychiatric disorder characterized by positive symptoms, negative symptoms, and cognitive deficits. Current antipsychotic treatment in SCZ improves positive symptoms but has major side effects and little impact on negative symptoms and cognitive impairment. The pathoetiology of SCZ remains unclear, but is known to involve small GTPase signaling. Rho kinase, an effector of small GTPase Rho, is highly expressed in the brain and plays a major role in neurite elongation and neuronal architecture. This study used a touchscreen-based visual discrimination (VD) task to investigate the effects of Rho kinase inhibitors on cognitive impairment in a methamphetamine (METH)-treated male mouse model of SCZ. Systemic injection of the Rho kinase inhibitor fasudil dose-dependently ameliorated METH-induced VD impairment. Fasudil also significantly suppressed the increase in the number of c-Fos-positive cells in the infralimbic medial prefrontal cortex (infralimbic mPFC) and dorsomedial striatum (DMS) following METH treatment. Bilateral microinjections of Y-27632, another Rho kinase inhibitor, into the infralimbic mPFC or DMS significantly ameliorated METH-induced VD impairment. Two proteins downstream of Rho kinase, myosin phosphatase-targeting subunit 1 (MYPT1; Thr696) and myosin light chain kinase 2 (MLC2; Thr18/Ser19), exhibited increased phosphorylation in the infralimbic mPFC and DMS, respectively, after METH treatment, and fasudil inhibited these increases. Oral administration of haloperidol and fasudil ameliorated METH-induced VD impairment, while clozapine had little effect. Oral administration of haloperidol and clozapine suppressed METH-induced hyperactivity, but fasudil had no effect. These results suggest that METH activates Rho kinase in the infralimbic mPFC and DMS, which leads to cognitive impairment in male mice. Rho kinase inhibitors ameliorate METH-induced cognitive impairment, perhaps via the cortico-striatal circuit.