WS-50030 [7-{4-[3-(1H-inden-3-yl)propyl]piperazin-1-yl}-1,3-benzoxazol-2(3H)-one]: a novel dopamine D2 receptor partial agonist/serotonin reuptake inhibitor with preclinical antipsychotic-like and antidepressant-like activity

Cognitive Effects of Lurasidone and Cariprazine: A Mini Systematic Review

Cognitive deficits are associated with schizophrenia and show a progressive worsening, often being unresponsive to treatment. New antipsychotic molecules acting as antagonist at the serotoninergic 5-hydroxytryptamine receptor 7 (e.g. lurasidone) or partial agonists at dopamine D3 receptor (e.g. cariprazine) could have an impact on cognition in this patient group. The aim of the systematic review is to explore the efficacy of lurasidone and cariprazine in improving cognition in both animal models and human studies. The following terms: (lurasidone AND cognit*) OR (cariprazine AND cognit*) were searched in Web of Science from inception to December 2021. We included all studies that assessed changes in cognitive function after treatment with cariprazine or lurasidone. Of 201 selected articles, 36 were included. Twenty-four articles used animal models (rats, mice and marmosets), five evaluating the effects of cariprazine and 19 the effects of lurasidone. Twelve articles were clinical studies (cariprazine n = 2; lurasidone n = 10). In both animal and human studies lurasidone showed a greater efficacy on cognitive performance compared to placebo, quetiapine, ziprasidone or treatmentas- usual. Cariprazine was superior to other antipsychotics in improving cognitive functions in both animal and human studies. The cognitive effect of lurasidone could be explained by its potent antagonism at the 5-HT7 receptors combined with partial agonism at 5-HT1A receptors. The pro-cognitive effect of cariprazine is probably explained by its very high affinity for D3 receptors. Head-to-head studies comparing lurasidone and cariprazine are needed to establish the "first-choice" treatment for cognitive dysfunction associated with schizophrenia.

Alterations in behavioral responses to dopamine agonists in olfactory bulbectomized mice: relationship to changes in the striatal dopaminergic system

BACKGROUND

Olfactory bulbectomy (OBX) in rodents is considered a putative animal model of depression. It has been reported that some abnormal behaviors observed in this animal model of depression involve dopaminergic neurons of the mesolimbic pathway. Therefore, we examined changes in the dopaminergic system in the caudate putamen (CPu), nucleus accumbens core (NAcC), and shell (NAcSh) of OBX mice and whether or not these alterations were reversed by chronic administration of imipramine.

METHODS

We observed climbing behavior, which is a dopamine (DA) receptor-associated behavior, to demonstrate changes in the dopaminergic system of the mesolimbic pathway, when mice were administrated either the nonselective DA agonist apomorphine only or were pre-treated with the selective D1 antagonist SCH23390, with the selective D2 antagonist sulpiride, or with the D2/D3 partial agonist aripiprazole (ARI). Moreover, we examined tyrosine hydroxylase (TH) and D1- and D2-like receptor levels in the CPu, NAcC, and NAcSh using immunohistochemistry and autoradiography.

RESULTS

The OBX group exhibited significantly enhanced apomorphine-induced climbing behavior, and this enhanced behavior was reversed by administration of sulpiride, ARI, and imipramine but not SCH23390. Moreover, we found a reduction in TH levels in the CPu, NAcC, and NAcSh of OBX mice and an increase in D2 receptor densities in the NAcC of OBX mice. The increased D2 receptor density observed in OBX mice was reversed by imipramine administration.

CONCLUSIONS

These findings reveal that OBX mice display enhanced DA receptor responsiveness, which may relate to some of the behavioral abnormalities reported in this animal model.

Functional profile of a novel modulator of serotonin, dopamine, and glutamate neurotransmission

RATIONALE

Schizophrenia remains among the most prevalent neuropsychiatric disorders, and current treatment options are accompanied by unwanted side effects. New treatments that better address core features of the disease with minimal side effects are needed.

OBJECTIVES

As a new therapeutic approach, 1-(4-fluoro-phenyl)-4-((6bR, 10aS)-3-methyl-2,3,6b,9,10,10a-hexahydro-1H,7H-pyrido[3',4':4,5]pyrrolo[1,2,3-de]quinoxalin-8-yl)-butan-1-one (ITI-007) is currently in human clinical trials for the treatment of schizophrenia. Here, we characterize the preclinical functional activity of ITI-007.

RESULTS

ITI-007 is a potent 5-HT2A receptor ligand (K i  = 0.5 nM) with strong affinity for dopamine (DA) D2 receptors (K i  = 32 nM) and the serotonin transporter (SERT) (K i  = 62 nM) but negligible binding to receptors (e.g., H1 histaminergic, 5-HT2C, and muscarinic) associated with cognitive and metabolic side effects of antipsychotic drugs. In vivo it is a 5-HT2A antagonist, blocking (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI)-induced headtwitch in mice with an inhibitory dose 50 (ID50) = 0.09 mg/kg, per oral (p.o.), and has dual properties at D2 receptors, acting as a postsynaptic D2 receptor antagonist to block D-amphetamine hydrochloride (D-AMPH) hyperlocomotion (ID50 = 0.95 mg/kg, p.o.), yet acting as a partial agonist at presynaptic striatal D2 receptors in assays measuring striatal DA neurotransmission. Further, in microdialysis studies, this compound significantly and preferentially enhances mesocortical DA release. At doses relevant for antipsychotic activity in rodents, ITI-007 has no demonstrable cataleptogenic activity. ITI-007 indirectly modulates glutamatergic neurotransmission by increasing phosphorylation of GluN2B-type N-methyl-D-aspartate (NMDA) receptors and preferentially increases phosphorylation of glycogen synthase kinase 3β (GSK-3β) in mesolimbic/mesocortical dopamine systems.

CONCLUSION

The combination of in vitro and in vivo activities of this compound support its development for the treatment of schizophrenia and other psychiatric and neurologic disorders.

On 'polypharmacy' and multi-target agents, complementary strategies for improving the treatment of depression: a comparative appraisal

Major depression is a heterogeneous disorder, both in terms of symptoms, ranging from anhedonia to cognitive impairment, and in terms of pathogenesis, with many interacting genetic, epigenetic, developmental and environmental causes. Accordingly, it seems unlikely that depressive states could be fully controlled by a drug possessing one discrete mechanism of action and, in the wake of disappointing results with several classes of highly selective agent, multi-modal treatment concepts are attracting attention. As concerns pharmacotherapy, there are essentially two core strategies. First, multi-target antidepressants that act via two or more complementary mechanisms and, second, polypharmacy, which refers to co-administration of two distinct drugs, usually in separate pills. Both multi-target agents and polypharmacy ideally couple a therapeutically unexploited action to a clinically established mechanism in order to enhance efficacy, moderate side-effects, accelerate onset of action and treat a broader range of symptoms. The melatonin MT1/MT2 agonist and 5-HT(2C) antagonist, agomelatine, which is effective in the short- and long-term treatment of depression, exemplifies the former approach, while evidence-based polypharmacy is illustrated by the adjunctive use of second-generation antipsychotics with serotonin reuptake inhibitors for treatment of resistant depression. Histone acetylation and methylation, ghrelin signalling, inflammatory modulators, metabotropic glutamate-7 receptors and trace amine-associated-1 receptors comprise attractive substrates for new multi-target and polypharmaceutical strategies. The present article outlines the rationale underpinning multi-modal approaches for treating depression, and critically compares and contrasts the pros and cons of established and potentially novel multi-target vs. polypharmaceutical treatments. On balance, the former appear the most promising for the elaboration, development and clinical implementation of innovative concepts for the more effective management of depression.

Aripiprazole in the treatment of Alzheimer's disease

INTRODUCTION

Psychosis is a common and difficult to treat symptom in Alzheimer's disease (AD). It is a cause of diminished quality of life and caregiver distress. Atypical antipsychotics are frequently used for the treatment of dementia-related psychosis, despite FDA warnings because of increased mortality associated with the use of these medications in dementia patients. Aripiprazole is a newer atypical antipsychotic drug with partial agonist activity at dopamine receptors and antagonist activity at 5-HT(2A) receptors, with a low side-effect profile.

AREAS COVERED

This descriptive review gives a short overview of the pathology and epidemiology of AD, including psychotic symptoms, and describes the mode of action of aripiprazole and results of preclinical studies. Finally, randomized controlled trials evaluating the use of aripiprazole in AD-related psychosis and agitation are discussed. Whenever relevant, meta-analytical data from literature are referred to.

EXPERT OPINION

In randomized placebo-controlled clinical trials, aripiprazole shows modest efficacy in the treatment of AD-related psychosis. Neuropsychiatric symptoms alleviated were predominantly psychotic features and agitation. In individual trials, aripiprazole was generally well tolerated, serious side effects were seldom reported and included accidental injury and somnolence. Meta-analyses however demonstrated increased mortality as a class effect for atypical, but also for typical antipsychotics. No increased cardiovascular outcomes, cerebrovascular accidents, increased appetite or weight gain were demonstrated in meta-analyses for aripiprazole-treated patients with psychosis of dementia. Aripiprazole was found to induce sedation. Aripiprazole should only be used in selected patient populations resistant to non-pharmacological treatment with persisting or severe psychotic symptoms and/or agitation, and in which symptoms lead to significant morbidity, patient suffering and potential self-harm. The indication for continuing treatment should be revised regularly.

Partial agonists in schizophrenia--why some work and others do not: insights from preclinical animal models

While dopamine D2 receptor partial agonists (PAs) have been long considered for treating schizophrenia, only one, aripiprazole, is clinically available for therapeutic use. This raises critically important questions as to what is unique about aripiprazole and to what extent animal models can predict therapeutic success. A number of PAs whose clinical fate is known: aripiprazole, preclamol, terguride, OPC-4392 and bifeprunox were compared to haloperidol (a reference antipsychotic) in several convergent preclinical animal models; i.e. amphetamine-induced locomotion (AIL) and conditioned avoidance response (CAR), predictive of antipsychotic effects; unilateral nigrostriatal lesioned rats, a model of hypo-dopaminergia; striatal Fos induction, a molecular marker for antipsychotic activity; and side-effects common to this class of drugs: catalepsy (motor side-effects) and prolactaemia. The results were compared across drugs with reference to their measured striatal D2 receptor occupancy. All the PAs occupied striatal D2 receptors in a dose dependent manner, inhibited AIL and CAR, and lacked motor side-effects or prolactinaemia despite D2 receptor occupancy exceeding 80%. At comparative doses, aripiprazole distinguished itself from the other PAs by causing the least rotation in the hypo-dopaminergic model (indicating the least intrinsic activity) and showed the highest Fos expression in the nucleus accumbens (indicating functional D2 antagonism). Although a number of PAs are active in antipsychotic animal models, not all of them succeed. Given that only aripiprazole is clinically available, it can be inferred that low functional intrinsic activity coupled with sufficient functional antagonism as reflected in the animal models may be a marker of success.

Dopamine receptor homooligomers and heterooligomers in schizophrenia

Over the past two decades the dopamine D2 receptor has been undoubtedly the most widely studied dopamine receptor for the therapeutic treatment of schizophrenia, as the majority of antipsychotics exhibit antagonism at this receptor. However, the cognitive symptoms of the disorder are mostly resistant to the majority of available antipsychotic treatments and, as a result, there is a critical need to develop novel therapies that ameliorate all symptoms. The recognition that dopamine receptors, such as all G protein-coupled receptors (GPCRs), exist as oligomeric complexes has provided new avenues for drug design in the search for novel therapies. Furthermore, that it is now known that dopamine receptors can form heteromers, such as the dopamine D1-D2 receptor heteromer, with pharmacology and function distinct from its constituent receptors, has significantly expanded the range of potential drug targets. The aim of this review is to discuss the therapeutic relevance of these dopamine receptor oligomers to schizophrenia and to address the potential value of dopamine receptor heteromers in the search for new therapeutic strategies.

Schizophrenia, "just the facts" 5. Treatment and prevention. Past, present, and future

The introduction of second-generation antipsychotics and cognitive therapies for schizophrenia over the past two decades generated considerable optimism about possibilities for recovery. To what extent have these developments resulted in better outcomes for affected individuals? What is the current state of our science and how might we address the many unmet needs in the prevention and treatment of schizophrenia? We trace the evolution of various treatments for schizophrenia and summarize current knowledge about available pharmacological and psychosocial treatments. We consider the widely prevalent efficacy-effectiveness gap in the application of available treatments and note the significant variability in individual treatment response and outcome. We outline an individualized treatment approach which emphasizes careful monitoring and collaborative decision-making in the context of ongoing benefit-risk assessment. We note that the evolution of both pharmacological and psychosocial treatments thus far has been based principally on serendipity and intuition. In view of our improved understanding of the etiology and pathophysiology of schizophrenia, there is an opportunity to develop prevention strategies and treatments based on this enhanced knowledge. In this context, we discuss potential psychopathological treatment targets and enumerate current pharmacological and psychosocial development efforts directed at them. Considering the stages of schizophrenic illness, we review approaches to prevent progression from the pre-symptomatic high-risk to the prodrome to the initial psychotic phase to chronicity. In view of the heterogeneity of risk factors, we summarize approaches towards targeted prevention. We evaluate the potential contribution of pharmacogenomics and other biological markers in optimizing individual treatment and outcome in the future.

Development and application of an LC-MS/MS method for measuring the effect of (partial) agonists on cAMP accumulation in vitro

Cyclic-adenosine monophosphate (cAMP) plays an important role in cell signalling and is widely used as a marker for receptor activation and as a target for treating various diseases. In this paper we present the development and validation of a new method for the determination of cAMP and ATP (adenosine triphosphate) and other nucleotides in a biological system by combining zwitterionic hydrophilic interaction liquid chromatography (HILIC) and tandem mass spectrometry (MS/MS). The HILIC-MS/MS method was developed for the simultaneous quantitative analysis of cAMP and ATP, and was validated by assessment of linearity (over a range from 0.5 to 100nM for cAMP and 50 nM to 50 microM for ATP (r(2)>0.999)), resolution, limit of detection (0.5 and 50 nM for cAMP and ATP, respectively) and reproducibility. Furthermore, the method was validated and applied in vitro to determine cAMP accumulation in biological samples. The effect of several dopamine D(2) (partial) agonists and antagonists on cAMP accumulation was assessed by determination of the cAMP/ATP ratio in cells transfected with the human dopamine D(2L) receptor. Quinpirole, dopamine and ropinirole produced agonist effects on cAMP accumulation, with a potency of quinpirole>ropinirole>dopamine. Lisuride, terguride and bifeprunox were found to be partial agonists with efficacies of lisuride>terguride>bifeprunox. As expected, haloperidol, (-)-sulpiride and LY-741626 were antagonists. These results demonstrate that the present analytical method was robust, fast, sensitive, and selective. Moreover, it showed utility in determining cAMP/ATP in biological systems and the ability to study the effect of (partial) agonists and antagonists which makes it a useful tool for drug discovery.