Neuroreceptor Inhibition by Clozapine Triggers Mitohormesis and Metabolic Reprogramming in Human Blood Cells.

The antipsychotic drug clozapine demonstrates superior efficacy in treatment-resistant schizophrenia, but its intracellular mode of action is not completely understood. Here, we analysed the effects of clozapine (2.5-20 µM) on metabolic fluxes, cell respiration, and intracellular ATP in human HL60 cells. Some results were confirmed in leukocytes of clozapine-treated patients. Neuroreceptor inhibition under clozapine reduced Akt activation with decreased glucose uptake, thereby inducing ER stress and the unfolded protein response (UPR). Metabolic profiling by liquid-chromatography/mass-spectrometry revealed downregulation of glycolysis and the pentose phosphate pathway, thereby saving glucose to keep the electron transport chain working. Mitochondrial respiration was dampened by upregulation of the F0F1-ATPase inhibitory factor 1 (IF1) leading to 30-40% lower oxygen consumption in HL60 cells. Blocking IF1 expression by cotreatment with epigallocatechin-3-gallate (EGCG) increased apoptosis of HL60 cells. Upregulation of the mitochondrial citrate carrier shifted excess citrate to the cytosol for use in lipogenesis and for storage as triacylglycerol in lipid droplets (LDs). Accordingly, clozapine-treated HL60 cells and leukocytes from clozapine-treated patients contain more LDs than untreated cells. Since mitochondrial disturbances are described in the pathophysiology of schizophrenia, clozapine-induced mitohormesis is an excellent way to escape energy deficits and improve cell survival.

The Dopaminergic Cells in the Median Raphe Region Regulate Social Behavior in Male Mice.

According to previous studies, the median raphe region (MRR) is known to contribute significantly to social behavior. Besides serotonin, there have also been reports of a small population of dopaminergic neurons in this region. Dopamine is linked to reward and locomotion, but very little is known about its role in the MRR. To address that, we first confirmed the presence of dopaminergic cells in the MRR of mice (immunohistochemistry, RT-PCR), and then also in humans (RT-PCR) using healthy donor samples to prove translational relevance. Next, we used chemogenetic technology in mice containing the Cre enzyme under the promoter of the dopamine transporter. With the help of an adeno-associated virus, designer receptors exclusively activated by designer drugs (DREADDs) were expressed in the dopaminergic cells of the MRR to manipulate their activity. Four weeks later, we performed an extensive behavioral characterization 30 min after the injection of the artificial ligand (Clozapine-N-Oxide). Stimulation of the dopaminergic cells in the MRR decreased social interest without influencing aggression and with an increase in social discrimination. Additionally, inhibition of the same cells increased the friendly social behavior during social interaction test. No behavioral changes were detected in anxiety, memory or locomotion. All in all, dopaminergic cells were present in both the mouse and human samples from the MRR, and the manipulation of the dopaminergic neurons in the MRR elicited a specific social response.

Clearing the Fog: A Review of Antipsychotics for Parkinson's-Related Hallucinations: A Focus on Pimavanserin, Quetiapine and Clozapine.

Parkinson's disease is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms, including hallucinations. The use of antipsychotic medications is a common strategy to manage hallucinations associated with Parkinson's disease psychosis (PDP). However, careful consideration is necessary when selecting the most appropriate drug due to the potential risks associated with the available treatment options. Atypical antipsychotics (AAPs), such as Pimavanserin and Clozapine, have effectively controlled PDP symptoms. On the contrary, the support for utilizing quetiapine is not as substantial as other antipsychotics because research studies specifically investigating its application are still emerging and relatively recent. The broad mechanisms of action of AAPs, involving dopamine and serotonin receptors, provide improved outcomes and fewer side effects than typical antipsychotics. Conversely, other antipsychotics, including risperidone, olanzapine, aripiprazole, ziprasidone, and lurasidone, have been found to worsen motor symptoms and are generally not recommended for PDP. While AAPs offer favorable benefits, they are associated with specific adverse effects. Extrapyramidal symptoms, somnolence, hypotension, constipation, and cognitive impairment are commonly observed with AAP use. Clozapine, in particular, carries a risk of agranulocytosis, necessitating close monitoring of blood counts. Pimavanserin, a selective serotonin inverse agonist, avoids receptor-related side effects but has been linked to corrected QT (QTc) interval prolongation, while quetiapine has been reported to be associated with an increased risk of mortality. This review aims to analyze the benefits, risks, and mechanisms of action of antipsychotic medications to assist clinicians in making informed decisions and enhance patient care.

Chemogenetic Manipulation of Amygdala Kappa Opioid Receptor Neurons Modulates Amygdala Neuronal Activity and Neuropathic Pain Behaviors.

Neuroplasticity in the central nucleus of the amygdala (CeA) plays a key role in the modulation of pain and its aversive component. The dynorphin/kappa opioid receptor (KOR) system in the amygdala is critical for averse-affective behaviors in pain conditions, but its mechanisms are not well understood. Here, we used chemogenetic manipulations of amygdala KOR-expressing neurons to analyze the behavioral consequences in a chronic neuropathic pain model. For the chemogenetic inhibition or activation of KOR neurons in the CeA, a Cre-inducible viral vector encoding Gi-DREADD (hM4Di) or Gq-DREADD (hM3Dq) was injected stereotaxically into the right CeA of transgenic KOR-Cre mice. The chemogenetic inhibition of KOR neurons expressing hM4Di with a selective DREADD actuator (deschloroclozapine, DCZ) in sham control mice significantly decreased inhibitory transmission, resulting in a shift of inhibition/excitation balance to promote excitation and induced pain behaviors. The chemogenetic activation of KOR neurons expressing hM3Dq with DCZ in neuropathic mice significantly increased inhibitory transmission, decreased excitability, and decreased neuropathic pain behaviors. These data suggest that amygdala KOR neurons modulate pain behaviors by exerting an inhibitory tone on downstream CeA neurons. Therefore, activation of these interneurons or blockade of inhibitory KOR signaling in these neurons could restore control of amygdala output and mitigate pain.

Continuous oral olanzapine or clozapine treatment initiated in adolescence has differential short- and long-term impacts on antipsychotic sensitivity than those initiated in adulthood.

One of the major discoveries in recent research on antipsychotic drugs is that antipsychotic treatment in adolescence could induce robust long-term alterations in antipsychotic sensitivity that persist into adulthood. These long-term impacts are likely influenced by various factors, including the "diseased" state of animals, sex, type of drugs, mode of drug administration, and age of treatment onset. In this study we compared the short- and long-term behavioral effects of 21-day continuous oral olanzapine (7.5 mg/kg/day) or clozapine (30.0 mg/kg/day) administration in heathy or maternal immune activated adolescent (33-53 days old) or adult (80-100 days old) rats of both sexes. We used a conditioned avoidance response model to assess the drug-induced alterations in antipsychotic sensitivity. Here, we report that while under the chronic drug treatment period, olanzapine progressively increased its suppression of avoidance responding over time, especially when treatment was initiated in adulthood. Clozapine's suppression depended on the age of drug exposure, with treatment initiated in adulthood showing a suppression while that initiated in adolescent did not. After a 17-day drug-free interval, in a drug challenge test, olanzapine treatment initiated in adolescence caused a decrease in drug sensitivity, as reflected by less avoidance suppression (a tolerance effect); whereas that initiated in adulthood appeared to cause an increase (more avoidance suppression, a sensitization effect). Clozapine treatments initiated in both adolescence and adulthood caused a similar tolerance effect. Our findings indicate that the same chronic antipsychotic treatment regimen initiated in adolescence or adulthood can have differential short- and long-term impacts on drug sensitivity.

Antipsychotic drugs selectively decorrelate long-range interactions in deep cortical layers.

Psychosis is characterized by a diminished ability of the brain to distinguish externally driven activity patterns from self-generated activity patterns. Antipsychotic drugs are a class of small molecules with relatively broad binding affinity for a variety of neuromodulator receptors that, in humans, can prevent or ameliorate psychosis. How these drugs influence the function of cortical circuits, and in particular their ability to distinguish between externally and self-generated activity patterns, is still largely unclear. To have experimental control over self-generated sensory feedback, we used a virtual reality environment in which the coupling between movement and visual feedback can be altered. We then used widefield calcium imaging to determine the cell type-specific functional effects of antipsychotic drugs in mouse dorsal cortex under different conditions of visuomotor coupling. By comparing cell type-specific activation patterns between locomotion onsets that were experimentally coupled to self-generated visual feedback and locomotion onsets that were not coupled, we show that deep cortical layers were differentially activated in these two conditions. We then show that the antipsychotic drug clozapine disrupted visuomotor integration at locomotion onsets also primarily in deep cortical layers. Given that one of the key components of visuomotor integration in cortex is long-range cortico-cortical connections, we tested whether the effect of clozapine was detectable in the correlation structure of activity patterns across dorsal cortex. We found that clozapine as well as two other antipsychotic drugs, aripiprazole and haloperidol, resulted in a strong reduction in correlations of layer 5 activity between cortical areas and impaired the spread of visuomotor prediction errors generated in visual cortex. Our results are consistent with the interpretation that a major functional effect of antipsychotic drugs is a selective alteration of long-range layer 5-mediated communication.

Neurophysiological treatment effects of mesdopetam, pimavanserin and clozapine in a rodent model of Parkinson's disease psychosis.

Psychosis in Parkinson's disease is a common phenomenon associated with poor outcomes. To clarify the pathophysiology of this condition and the mechanisms of antipsychotic treatments, we have here characterized the neurophysiological brain states induced by clozapine, pimavanserin, and the novel prospective antipsychotic mesdopetam in a rodent model of Parkinson's disease psychosis, based on chronic dopaminergic denervation by 6-OHDA lesions, levodopa priming, and the acute administration of an NMDA antagonist. Parallel recordings of local field potentials from eleven cortical and sub-cortical regions revealed shared neurophysiological treatment effects for the three compounds, despite their different pharmacological profiles, involving reversal of features associated with the psychotomimetic state, such as a reduction of aberrant high-frequency oscillations in prefrontal structures together with a decrease of abnormal synchronization between different brain regions. Other drug-induced neurophysiological features were more specific to each treatment, affecting network oscillation frequencies and entropy, pointing to discrete differences in mechanisms of action. These findings indicate that neurophysiological characterization of brain states is particularly informative when evaluating therapeutic mechanisms in conditions involving symptoms that are difficult to assess in rodents such as psychosis, and that mesdopetam should be further explored as a potential novel antipsychotic treatment option for Parkinson psychosis.

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.

Modulation of neuronal morphology by antipsychotic drug: Involvement of serotonin receptor 7.

Antipsychotic drugs (APDs) are the primary pharmacological treatment for schizophrenia, a complex disorder characterized by altered neuronal connectivity. Atypical or second-generation antipsychotics, such as Risperidone (RSP) and Clozapine (CZP) predominantly block dopaminergic D2 and serotonin receptor 2A (5-HT2A) neurotransmission. Both compounds also exhibit affinity for the 5-HT7R, with RSP acting as an antagonist and CZP as an inverse agonist. Our study aimed to determine whether RSP and CZP can influence neuronal morphology through a 5-HT7R-mediated mechanism. Here, we demonstrated that CZP promotes neurite outgrowth of early postnatal cortical neurons, and the 5-HT7R mediates its effect. Conversely, RSP leads to a reduction of neurite length of early postnatal cortical neurons, in a 5-HT7R-independent way. Furthermore, we found that the effects of CZP, mediated by 5-HT7R activation, require the participation of ERK and Cdk5 kinase pathways. At the same time, the modulation of neurite length by RSP does not involve these pathways. In conclusion, our findings provide valuable insights into the morphological changes induced by these two APDs in neurons and elucidate some of the associated molecular pathways. Investigating the 5-HT7R-dependent signaling pathways underlying the neuronal morphogenic effects of APDs may contribute to the identification of novel targets for the treatment of schizophrenia.

Clozapine Induces Neuronal Activation in the Medial Prefrontal Cortex in a Projection Target-Biased Manner.

The medial prefrontal cortex (mPFC) is associated with various behavioral controls via diverse projections to cortical and subcortical areas of the brain. Dysfunctions and modulations of this circuitry are related to the pathophysiology of schizophrenia and its pharmacotherapy, respectively. Clozapine is an atypical antipsychotic drug used for treatment-resistant schizophrenia and is known to modulate neuronal activity in the mPFC. However, it remains unclear which prefrontal cortical projections are activated by clozapine among the various projection targets. To identify the anatomical characteristics of neurons activated by clozapine at the mesoscale level, we investigated the brain-wide projection patterns of neurons with clozapine-induced c-Fos expression in the mPFC. Using a whole-brain imaging and virus-mediated genetic tagging of activated neurons, we found that clozapine-responsive neurons in the mPFC had a wide range of projections to the mesolimbic, amygdala and thalamic areas, especially the mediodorsal thalamus. These results may provide key insights into the neuronal basis of the therapeutic action of clozapine.

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.

Behavioral and Molecular Characterization of Prenatal Stress Effects on the C57BL/6J Genetic Background for the Study of Autism Spectrum Disorder.

Stress-inducing events during pregnancy are associated with aberrant neurodevelopment resulting in adverse psychiatric outcomes, including autism spectrum disorder (ASD). While numerous preclinical models for the study of ASD are frequently generated using C57BL/6J mice, few studies have investigated the effects of prenatal stress on this genetic background. In the current manuscript, we stressed C57BL/6 dams during gestation and examined numerous behavioral and molecular endophenotypes in the adult male and female offspring to characterize the resultant phenotype as compared with offspring born from nonstressed (NS) dams. Adult mice born from prenatal restraint stressed (PRS) dams demonstrated reduced sociability and reciprocal social interaction along with increased marble burying behaviors relative to mice born from nonstressed control dams. Differential expression of genes related to excitatory and inhibitory neurotransmission was evaluated in the medial prefrontal cortex, amygdala, hippocampus, nucleus accumbens and caudate putamen via qRT-PCR. The male PRS mouse behavioral phenotype coincided with aberrant expression of glutamate and GABA marker genes (e.g., Grin1, Grin2b, Gls, Gat1, Reln) in neural substrates of social behavior. Rescue of the male PRS sociability deficit by a known antipsychotic with epigenetic properties (i.e., clozapine (5 mg/kg) + 18 hr washout) indicated possible epigenetic regulation of genes that govern sociability. Clozapine treatment increased the expression levels of genes involved in DNA methylation, histone methylation, and histone acetylation in the nucleus accumbens. Identification of etiology-specific mechanisms underlying clinically relevant behavioral phenotypes may ultimately provide novel therapeutic interventions for the treatment of psychiatric disorders including ASD.

Clozapine-N-oxide protects dopaminergic neurons against rotenone-induced neurotoxicity by preventing ferritinophagy-mediated ferroptosis.

Parkinson's disease (PD) is the second most common neurodegenerative disorder, yet treatment options are limited. Clozapine (CLZ), an antipsychotic used for schizophrenia, has potential as a PD treatment. CLZ and its metabolite, Clozapine-N-Oxide (CNO), show neuroprotective effects on dopaminergic neurons, with mechanisms needing further investigation. This study aimed to confirm the neuroprotective effects of CLZ and CNO in a rotenone-induced mouse model and further explore the underlying mechanisms of CNO-afforded protection. Gait pattern and rotarod activity evaluations showed motor impairments in rotenone-exposed mice, with CLZ or CNO administration ameliorating behavioral deficits. Cell counts and biochemical analysis demonstrated CLZ and CNO's effectiveness in reducing rotenone-induced neurodegeneration of dopaminergic neurons in the nigrostriatal system in mice. Mechanistic investigations revealed that CNO suppressed rotenone-induced ferroptosis of dopaminergic neurons by rectifying iron imbalances, curtailing lipid peroxidation, and mitigating mitochondrial morphological changes. CNO also reversed autolysosome and ferritinophagic activation in rotenone-exposed mice. SH-SY5Y cell cultures validated these findings, indicating ferritinophage involvement, where CNO-afforded protection was diminished by ferritinophagy enhancers. Furthermore, knockdown of NCOA4, a crucial cargo receptor for ferritin degradation in ferritinophagy, hampered rotenone-induced ferroptosis and NCOA4 overexpression countered the anti-ferroptotic effects of CNO. Whereas, iron-chelating agents and ferroptosis enhancers had no effect on the anti-ferritinophagic effects of CNO in rotenone-treated cells. In summary, CNO shielded dopaminergic neurons in the rotenone-induced PD model by modulating NCOA4-mediated ferritinophagy, highlighting a potential therapeutic pathway for PD treatment. This research provided insights into the role of NCOA4 in ferroptosis and suggested new approaches for PD therapy.

Clozapine N-oxide, compound 21, and JHU37160 do not influence effortful reward-seeking behavior in mice.

RATIONALE: Clozapine N-oxide (CNO) has been developed as a ligand to selectively activate designer receptors exclusively activated by designer drugs (DREADDs). However, previous studies have revealed that peripherally injected CNO is reverse-metabolized into clozapine, which, in addition to activating DREADDs, acts as an antagonist at various neurotransmitter receptors, suggesting potential off-target effects of CNO on animal physiology and behaviors. Recently, second-generation DREADD agonists compound 21 (C21) and JHU37160 (J60) have been developed, but their off-target effects are not fully understood. OBJECTIVES: The present studies assessed the effect of novel DREADD ligands on reward-seeking behavior. METHODS: We first tested the possible effect of acute i.p. injection of low-to-moderate (0.1, 0.3, 1, 3 mg/kg) of CNO, C21, and J60 on motivated reward-seeking behavior in wild-type mice. We then examined whether a high dose (10 mg/kg) of these drugs might be able to alter responding. RESULTS: Low-to-moderate doses of all drugs and a high dose of CNO or C21 did not alter operant lick responding for a reward under a progressive ratio schedule of reinforcement, in which the number of operant lick responses to obtain a reward increases after each reward collection. However, high-dose J60 resulted in a total lack of responding that was later observed in an open field arena to be due to a sedative effect. CONCLUSIONS: This study provides definitive evidence that commonly used doses of CNO, C21, and J60 have negligible off-target effects on motivated reward-seeking but urges caution when using high doses of J60 due to sedative effects.

Changes in immunoglobulin levels during clozapine treatment in schizophrenia.

BACKGROUND AND HYPOTHESIS: Use of clozapine in treatment-resistant schizophrenia is often limited due to risk of adverse effects. Cross-sectional associations between clozapine treatment and low immunoglobulin levels have been reported, however prospective studies are required to establish temporal relationships. We tested the hypothesis that reductions in immunoglobulin levels would occur over the first 6 months following initiation of clozapine treatment. Relationships between immunoglobulin levels and symptom severity over the course of clozapine treatment were also explored. DESIGN: This prospective observational study measured immunoglobulin (Ig) levels (A, M and G) in 56 patients with treatment-resistant schizophrenia at 6-, 12- and 24-weeks following initiation with clozapine. Clinical symptoms were also measured at 12 weeks using the positive and negative syndrome scale (PANSS). RESULTS: IgA, IgG and IgM all decreased during clozapine treatment. For IgA and IgG the reduction was significant at 24 weeks (IgA: ß = -32.66, 95% CI = -62.38, -2.93, p = 0.03; IgG: ß = -63.96, 95% CI = -118.00, -9.31, p = 0.02). For IgM the reduction was significant at 12 and 24 weeks (12 weeks: ß = -23.48, 95% CI = -39.56, -7.42, p = 0.004; 24 weeks: ß = -33.12, 95 %CI = -50.30, -15.94, p = <0.001). Reductions in IgA and IgG during clozapine treatment were correlated with reductions in PANSS-total over 12 weeks (n = 32, IgA r = 0.59, p = 0.005; IgG r = 0.48, p = 0.03). CONCLUSIONS: The observed reductions in immunoglobulin levels over six months of clozapine treatment add further evidence linking clozapine to secondary antibody deficiency. Associations between Ig reduction and symptom improvement may however indicate that immune mechanisms contribute to both desirable and undesirable effects of clozapine.

Effects of Clozapine on Cortical Inhibition: A Transcranial Magnetic Stimulation Follow-up Study.

BACKGROUND: Preclinical and clinical investigations have revealed deficits in cortical inhibition in individuals with schizophrenia. Transcranial magnetic stimulation, a commonly used noninvasive measurement technique, is used for assessing these deficits. Limited research has been conducted on the effects of antipsychotic medications on cortical inhibition. This study aimed to evaluate the effects of clozapine on cortical inhibition with transcranial magnetic stimulation longitudinally and compare it with unaffected controls. METHODS: Ten patients who started clozapine were assessed at baseline, with 8 reassessed after 4 months. Eight age- and sex-matched unaffected controls were included. Psychopathology, neurocognitive performance, formal thought disorder, and disability were assessed, and the cortical excitability parameters (resting motor threshold, cortical silent period, short-interval intracortical inhibition, intracortical facilitation, and short-latency afferent inhibition [SAI]) were measured at baseline and four months after clozapine treatment. RESULTS: Resting motor threshold, ICF, and SAI were significantly different between patients and controls at baseline, whereas resting motor threshold, SAI, and ICF became similar to controls after clozapine with only ICF having a trend for significance. Clozapine prolonged cortical silent period significantly in the patients. CONCLUSIONS: This is the first study to investigate the effect of clozapine on SAI, a potential cholinergic biomarker, and the first follow-up study to investigate the relationship between the effects of clozapine on cortical inhibition and cognition. Clozapine seems to cause an increase in cortical inhibition through GABAergic and possibly cholinergic mechanisms. However, additional follow-up studies with larger sample sizes are required to reach more robust conclusions.

Guía internacional para una dosificación más segura de la clozapina en adultos mediante el uso de 6 titulaciones personalizadas de dosis basados en la etnicidad, la proteína C reactiva y los niveles de clozapina / An international adult guideline for making clozapine titration safer by using six ancestry-based personalized dosing titrations, CRP, and clozapine levels

Esta guía internacional propone mejorar los prospectos de la clozapina en todo el mundo mediante la inclusion de información sobre la titulación del fármaco en función de la ascendencia del paciente. Las bases de datos de reacciones adversas a medicamentos (RAM) sugieren que la clozapina es el tercer fármaco más tóxico en los Estados Unidos de América (EE. UU.) y que produce una mortalidad por neumonía en todo el mundo 4 veces mayor que la correspondiente a la agranulocitosis o la miocarditis. El rango terapéutico de referencia para las concentraciones séricas estables de clozapina es estrecho, de 350 a 600 ng/ml, con potencial de toxicidad y reacciones adversas más fecuentes a medida que aumentan las concentraciones. La clozapina se metaboliza principalmente por CYP1A2 (las mujeres no fumadoras requieren la dosis más baja y los hombres fumadores la dosis más alta). A través de la conversión fenotípica, la prescripción conjunta de inhibidores del metabolismo de la clozapina (incluidos los anticonceptivos orales y el valproato), la obesidad o la inflamación con elevaciones de la proteína C reactiva (PCR), pueden convertir al paciente en un metabolizador lento/pobre (MP). Las personas de ascendencia asiática (de Pakistán a Japón) o los habitantes originarios de las Américas tienen menor actividad de CYP1A2 y requieren dosis más bajas de clozapina para alcanzar concentraciones de 350 ng/ml. En los EE. UU. se recomiendan dosis diarias de 300-600 mg/día. La dosificación personalizada lenta puede prevenir RAM tempranas (incluidos el síncope, la miocarditis y la neumonía). La esencia de esta guía se fundamenta en 6 esquemas de titulaciones personalizadas para pacientes hospitalizados...(AU)

This is the Spanish translation of an international guideline which proposes improving clozapine package inserts worldwide by using ancestry-based: 1) dosing and 2) titration. Adverse drug reaction (ADR) databases suggest clozapine: 1) is the third most toxic drug in the United States (US), and 2) produces worldwide pneumonia mortality four times greater than that of agranulocytosis or myocarditis. For trough steady-state clozapine serum concentrations, the therapeutic reference range is narrow, from 350 to 600 ng/mL with the potential for toxicity and ADRs as concentrations increase. Clozapine is mainly metabolized by CYP1A2 (female non-smokers require the lowest dose and male smokers the highest dose). Poor metabolizer (PM) status through phenotypic conversion is associated with co-prescription of inhibitors (including oral contraceptives and valproate), obesity or inflammation with C-reactive protein (CRP) elevations. People with ancestry from Asia (Pakistan to Japan) or the Americas’ original inhabitants have lower CYP1A2 activity and require lower clozapine doses to reach concentrations of 350 ng/ml. Daily doses of 300-600 mg/day are recommended in the US. Slow personalized titration may prevent early ADRs (including syncope, myocarditis and pneumonia). The core of this guideline consists of six personalized titration schedules for inpatients...(AU)

Clozapine suppresses NADPH oxidase activation, counteracts cytosolic H2O2, and triggers early onset mitochondrial dysfunction during adipogenesis of human liposarcoma SW872 cells.

Long-term treatment of schizophrenia with clozapine (CLZ), an atypical antipsychotic drug, is associated with an increased incidence of metabolic disorders mediated by poorly understood mechanisms. We herein report that CLZ, while slowing down the morphological changes and lipid accumulation occurring during SW872 cell adipogenesis, also causes an early (day 3) inhibition of the expression/nuclear translocation of CAAT/enhancer-binding protein ß and peroxisome proliferator-activated receptor γ. Under the same conditions, CLZ blunts NADPH oxidase-derived reactive oxygen species (ROS) by a dual mechanism involving enzyme inhibition and ROS scavenging. These effects were accompanied by hampered activation of the nuclear factor (erythroid-derived2)-like 2 (Nrf2)-dependent antioxidant responses compared to controls, and by an aggravated formation of mitochondrial superoxide. CLZ failed to exert ROS scavenging activities in the mitochondrial compartment but appeared to actively scavenge cytosolic H2O2 derived from mitochondrial superoxide. The early formation of mitochondrial ROS promoted by CLZ was also associated with signs of mitochondrial dysfunction. Some of the above findings were recapitulated using mouse embryonic fibroblasts. We conclude that the NADPH oxidase inhibitory and cytosolic ROS scavenging activities of CLZ slow down SW872 cell adipogenesis and suppress their Nrf2 activation, an event apparently connected with increased mitochondrial ROS formation, which is associated with insulin resistance and metabolic syndrome. Thus, the cellular events characterised herein may help to shed light on the more detailed molecular mechanisms explaining some of the adverse metabolic effects of CLZ.

Comparison of three DREADD agonists acting on Gq-DREADDs in the ventral tegmental area to alter locomotor activity in tyrosine hydroxylase:Cre male and female rats.

RATIONALE: Despite the increasingly pervasive use of chemogenetic tools in preclinical neuroscience research, the in vivo pharmacology of DREADD agonists remains poorly understood. The pharmacological effects of any ligand acting at receptors, engineered or endogenous, are influenced by numerous factors including potency, time course, and receptor selectivity. Thus, rigorous comparison of the potency and time course of available DREADD ligands may provide an empirical foundation for ligand selection. OBJECTIVES: Compare the behavioral pharmacology of three different DREADD ligands clozapine-N-oxide (CNO), compound 21 (C21), and deschloroclozapine (DCZ) in a locomotor activity assay in tyrosine hydroxylase:cre recombinase (TH:Cre) male and female rats. METHODS: Locomotor activity in nine adult TH:Cre Sprague-Dawley rats (5 female, 4 male) was monitored for two hours following administration of d-amphetamine (vehicle, 0.1-3.2 mg/kg, IP), DCZ (vehicle, 0.32-320 µg/kg, IP), CNO (vehicle, 0.32-10 mg/kg), and C21 (vehicle, 0.1-3.2 mg/kg, IP). Behavioral sessions were conducted twice per week prior to and starting three weeks after bilateral intra-VTA hM3Dq DREADD virus injection. RESULTS: d-Amphetamine significantly increased locomotor activity pre- and post-DREADD virus injection. DCZ, CNO, and C21 did not alter locomotor activity pre-DREADD virus injection. There was no significant effect of DCZ, CNO, and C21 on locomotor activity post-DREADD virus injection; however, large individual differences in both behavioral response and receptor expression were observed. CONCLUSIONS: Large individual variability was observed in both DREADD agonist behavioral effects and receptor expression. These results suggest further basic research would facilitate the utility of these chemogenetic tools for behavioral neuroscience research.

A head-to-head comparison of two DREADD agonists for suppressing operant behavior in rats via VTA dopamine neuron inhibition.

RATIONALE: Designer receptors exclusively activated by designer drugs (DREADDs) are a tool for "remote control" of defined neuronal populations during behavior. These receptors are inert unless bound by an experimenter-administered designer drug, commonly clozapine-n-oxide (CNO). However, questions have emerged about the suitability of CNO as a systemically administered DREADD agonist. OBJECTIVES: Second-generation agonists such as JHU37160 (J60) have been developed, which may have more favorable properties than CNO. Here we sought to directly compare effects of CNO (0, 1, 5, & 10 mg/kg, i.p.) and J60 (0, 0.03, 0.3, & 3 mg/kg, i.p.) on operant food pursuit. METHODS: Male and female TH:Cre + rats and their wildtype (WT) littermates received cre-dependent hM4Di-mCherry vector injections into ventral tegmental area (VTA), causing inhibitory DREADD expression in VTA dopamine neurons of TH:Cre + rats. All rats were trained to stably lever press for palatable food on a fixed ratio 10 schedule, and doses of both agonists were tested on separate days in counterbalanced order. RESULTS: All three CNO doses reduced operant rewards earned in rats with DREADDs, and no CNO dose had behavioral effects in WT controls. The highest J60 dose tested significantly reduced responding in DREADD rats, but this dose also increased responding in WTs, indicating non-specific effects. The magnitude of CNO and J60 effects in TH:Cre + rats were correlated and were present in both sexes. CONCLUSIONS: Findings demonstrate the usefulness of directly comparing DREADD agonists when optimizing behavioral chemogenetics, and highlight the importance of proper controls, regardless of the DREADD agonist employed.