Pharmacological effects of mTORC1/C2 inhibitor in a preclinical model of NASH progression.

Knowledge of the benefits of mTOR inhibition concerning adipogenesis and inflammation has recently encouraged the investigation of a new generation of mTOR inhibitors for non-alcoholic steatohepatitis (NASH). We investigated whether treatment with a specific mTORC1/C2 inhibitor (Ku-0063794; KU) exerted any beneficial impacts on experimentally-induced NASH in vitro and in vivo. The results indicated that KU decreases palmitic acid-induced lipotoxicity in cultivated primary hepatocytes, thus emerging as a successful candidate for testing in an in vivo NASH dietary model, which adopted the intraperitoneal KU dosing route rather than oral application due to its significantly greater bioavailability in mice. The pharmacodynamics experiments commenced with the feeding of male C57BL/6 mice with a high-fat atherogenic western-type diet (WD) for differing intervals over several weeks aimed at inducing various phases of NASH. In addition to the WD, the mice were treated with KU for 3 weeks or 4 months. Acute and chronic KU treatments were observed to be safe at the given concentrations with no toxicity indications in the mice. KU was found to alleviate NASH-related hepatotoxicity, mitochondrial and oxidative stress, and decrease the liver triglyceride content and TNF-α mRNA in at least one set of in vivo experiments. The KU modulated liver expression of selected metabolic and oxidative stress-related genes depended upon the length and severity of the disease. Although KU failed to completely reverse the histological progression of NASH in the mice, we demonstrated the complexity of mTORC1/C2 signaling regulation and suggest a stratified therapeutic management approach throughout the disease course.

Different Effects of SSRIs, Bupropion, and Trazodone on Mitochondrial Functions and Monoamine Oxidase Isoform Activity.

Mitochondrial dysfunction is involved in the pathophysiology of psychiatric and neurodegenerative disorders and can be used as a modulator and/or predictor of treatment responsiveness. Understanding the mitochondrial effects of antidepressants is important to connect mitochondria with their therapeutic and/or adverse effects. Pig brain-isolated mitochondria were used to evaluate antidepressant-induced changes in the activity of electron transport chain (ETC) complexes, monoamine oxidase (MAO), mitochondrial respiratory rate, and ATP. Bupropion, escitalopram, fluvoxamine, sertraline, paroxetine, and trazodone were tested. All tested antidepressants showed significant inhibition of complex I and IV activities at high concentrations (50 and 100 µmol/L); complex II + III activity was reduced by all antidepressants except bupropion. Complex I-linked respiration was reduced by escitalopram >> trazodone >> sertraline. Complex II-linked respiration was reduced only by bupropion. Significant positive correlations were confirmed between complex I-linked respiration and the activities of individual ETC complexes. MAO activity was inhibited by all tested antidepressants, with SSRIs causing a greater effect than trazodone and bupropion. The results indicate a probable association between the adverse effects of high doses of antidepressants and drug-induced changes in the activity of ETC complexes and the respiratory rate of mitochondria. In contrast, MAO inhibition could be linked to the antidepressant, procognitive, and neuroprotective effects of the tested antidepressants.

Agomelatine, Ketamine and Vortioxetine Attenuate Energy Cell Metabolism-In Vitro Study.

This determination of the mitochondrial effect of pharmacologically different antidepressants (agomelatine, ketamine and vortioxetine) was evaluated and quantified in vitro in pig brain-isolated mitochondria. We measured the activity of mitochondrial complexes, citrate synthase, malate dehydrogenase and monoamine oxidase, and the mitochondrial respiratory rate. Total hydrogen peroxide production and ATP production were assayed. The most potent inhibitor of all mitochondrial complexes and complex I-linked respiration was vortioxetine. Agomelatine and ketamine inhibited only complex IV activity. None of the drugs affected complex II-linked respiration, citrate synthase or malate dehydrogenase activity. Hydrogen peroxide production was mildly increased by agomelatine, which might contribute to increased oxidative damage and adverse effects at high drug concentrations. Vortioxetine significantly reduced hydrogen peroxide concentrations, which might suggest antioxidant mechanism activation. All tested antidepressants were partial MAO-A inhibitors, which might contribute to their antidepressant effect. We observed vortioxetine-induced MAO-B inhibition, which might be linked to decreased hydrogen peroxide formation and contribute to its procognitive and neuroprotective effects. Mitochondrial dysfunction could be linked to the adverse effects of vortioxetine, as vortioxetine is the most potent inhibitor of mitochondrial complexes and complex I-linked respiration. Clarifying the molecular interaction between drugs and mitochondria is important to fully understand their mechanism of action and the connection between their mechanisms and their therapeutic and/or adverse effects.

Effect of Novel Antipsychotics on Energy Metabolism - In Vitro Study in Pig Brain Mitochondria.

The identification and quantification of mitochondrial effects of novel antipsychotics (brexpiprazole, cariprazine, loxapine, and lurasidone) were studied in vitro in pig brain mitochondria. Selected parameters of mitochondrial metabolism, electron transport chain (ETC) complexes, citrate synthase (CS), malate dehydrogenase (MDH), monoamine oxidase (MAO), mitochondrial respiration, and total ATP and reactive oxygen species (ROS) production were evaluated and associated with possible adverse effects of drugs. All tested antipsychotics decreased the ETC activities (except for complex IV, which increased in activity after brexpiprazole and loxapine addition). Both complex I- and complex II-linked respiration were dose-dependently inhibited, and significant correlations were found between complex I-linked respiration and both complex I activity (positive correlation) and complex IV activity (negative correlation). All drugs significantly decreased mitochondrial ATP production at higher concentrations. Hydrogen peroxide production was significantly increased at 10 µM brexpiprazole and lurasidone and at 100 µM cariprazine and loxapine. All antipsychotics acted as partial inhibitors of MAO-A, brexpiprazole and loxapine partially inhibited MAO-B. Based on our results, novel antipsychotics probably lacked oxygen uncoupling properties. The mitochondrial effects of novel antipsychotics might contribute on their adverse effects, which are mostly related to decreased ATP production and increased ROS production, while MAO-A inhibition might contribute to their antidepressant effect, and brexpiprazole- and loxapine-induced MAO-B inhibition might likely promote neuroplasticity and neuroprotection. The assessment of drug-induced mitochondrial dysfunctions is important in development of new drugs as well as in the understanding of molecular mechanism of adverse or side drug effects.

Novel approaches in schizophrenia-from risk factors and hypotheses to novel drug targets.

Schizophrenia is a severe psychiatric disorder characterized by emotional, behavioral and cognitive disturbances, and the treatment of schizophrenia is often complicated by noncompliance and pharmacoresistance. The search for the pathophysiological mechanisms underlying schizophrenia has resulted in the proposal of several hypotheses to explain the impacts of environmental, genetic, neurodevelopmental, immune and inflammatory factors on disease onset and progression. This review discusses the newest insights into the pathophysiology of and risk factors for schizophrenia and notes novel approaches in antipsychotic treatment and potential diagnostic and theranostic biomarkers. The current hypotheses focusing on neuromediators (dopamine, glutamate, and serotonin), neuroinflammation, the cannabinoid hypothesis, the gut-brain axis model, and oxidative stress are summarized. Key genetic features, including small nucleotide polymorphisms, copy number variations, microdeletions, mutations and epigenetic changes, are highlighted. Current pharmacotherapy of schizophrenia relies mostly on dopaminergic and serotonergic antagonists/partial agonists, but new findings in the pathophysiology of schizophrenia have allowed the expansion of novel approaches in pharmacotherapy and the establishment of more reliable biomarkers. Substances with promising results in preclinical and clinical studies include lumateperone, pimavanserin, xanomeline, roluperidone, agonists of trace amine-associated receptor 1, inhibitors of glycine transporters, AMPA allosteric modulators, mGLUR2-3 agonists, D-amino acid oxidase inhibitors and cannabidiol. The use of anti-inflammatory agents as an add-on therapy is mentioned.

Little in vitro effect of remdesivir on mitochondrial respiration and monoamine oxidase activity in isolated mitochondria.

Remdesivir (RDV) is a novel antiviral drug whose mitochondrial effects are not well known. In vitro effects of RDV on the mitochondrial respiration, individual respiratory complexes, and the activity of monoamine oxidase (MAO-A and MAO-B) were measured in isolated mitochondria. At micromolar RDV concentrations, minimal or no inhibitory effects on the studied mitochondrial enzymes were found. At very high concentrations of RDV, there was partial inhibition of complex I- (IC50 675 µmol/L, residual activity 39.4 %) and complex II-linked (IC50 81.8 µmol/L, residual activity 40.7 %) respiration, without inhibition of complex IV-linked respiration, and partial inhibition both of MAO-A (IC50 26.6 µmol/L, residual activity 35.2 %) and MAO-B (IC50 89.8 µmol/L, residual activity 34.0 %) activity. Individual respiratory complexes (I, II + III, and IV) were partially inhibited at a high drug concentration. The active metabolite of RDV (GS-443902) had very little effect on mitochondrial oxygen consumption rate with residual activity of 87.0 % for complex I-linked respiration, 90.3 % for complex II-linked respiration, and with no inhibition of complex IV-linked respiration. In conclusion, measurement of the effect of RDV and its active metabolite on isolated mitochondria shows that there is very little direct effect on mitochondrial respiration occurs at therapeutic drug concentration.

In vitro effects of antipsychotics on mitochondrial respiration.

Assessment of drug-induced mitochondrial dysfunctions is important in drug development as well as in the understanding of molecular mechanism of therapeutic or adverse effects of drugs. The aim of this study was to investigate the effects of three typical antipsychotics (APs) and seven atypical APs on mitochondrial bioenergetics. The effects of selected APs on citrate synthase, electron transport chain complexes (ETC), and mitochondrial complex I- or complex II-linked respiratory rate were measured using mitochondria isolated from pig brain. Complex I activity was decreased by chlorpromazine, haloperidol, zotepine, aripiprazole, quetiapine, risperidone, and clozapine. Complex II + III was significantly inhibited by zotepine, aripiprazole, quetiapine, and risperidone. Complex IV was inhibited by zotepine, chlorpromazine, and levomepromazine. Mitochondrial respiratory rate was significantly inhibited by all tested APs, except for olanzapine. Typical APs did not exhibit greater efficacy in altering mitochondrial function compared to atypical APs except for complex I inhibition by chlorpromazine and haloperidol. A comparison of the effects of APs on individual respiratory complexes and on the overall mitochondrial respiration has shown that mitochondrial functions may not fully reflect the disruption of complexes of ETC, which indicates AP-induced modulation of other mitochondrial proteins. Due to the complicated processes associated with mitochondrial activity, it is necessary to measure not only the effect of the drug on individual mitochondrial enzymes but also the respiration rate of the mitochondria or a similar complex process. The experimental approach used in the study can be applied to mitochondrial toxicity testing of newly developed drugs.

Both ketamine and NBQX attenuate alcohol drinking in male Wistar rats.

The devastating consequences of alcohol-use disorder (AUD) on the individual and the society are well established. Current treatments of AUD encompass various strategies, all of which have only modest effectiveness. Hence, there is a critical need to develop more efficacious therapies. Recently, specific glutamatergic receptors have been identified as potential novel targets for intervention in AUD. Thus, the current study was designed to evaluate the effects of acute administration of sub-anesthetic doses of ketamine, an NMDA receptor antagonist, as well as NBQX, an AMPA/kainate receptor antagonist on alcohol intake and its possible behavioural consequences. Adult male Wistar rats were trained in drinking in dark paradigm (3 weeks), and following stable alcohol intake, ketamine, NBQX as well as their combination were injected prior to a 90 min drinking session. In addition to alcohol intake, sucrose preference (overnight), and locomotor activity and forced swim test (FST) were also evaluated before and following alcohol intake. Both doses of ketamine (5 and 10 mg/kg) and NBQX (5 and 10 mg/kg) significantly attenuated percent alcohol intake. The combination of the higher dose of ketamine and NBQX, however, did not significantly affect percent alcohol intake. Moreover, animals exposed to alcohol showed decreased sucrose intake (reflective of anhedonia), decreased locomotor activity and swimming in the FST (reflective of helplessness), that were not affected by ketamine and/or NBQX. These results suggest that selective antagonism of the NMDA or AMPA/kainate receptors may be of therapeutic potential in AUD.