The Impact of Xanomeline and Trospium Chloride on Cognitive Impairment in Acute Schizophrenia: Replication in Pooled Data From Two Phase 3 Trials.

Objective: Xanomeline and trospium chloride (formerly known as KarXT), a novel M/M muscarinic receptor agonist, demonstrated efficacy across phase 2 and 3 trials as monotherapy for the treatment of inpatients with acute schizophrenia on the Positive and Negative Syndrome Scale total score primary endpoint. In the phase 2 trial, xanomeline/trospium improved performance on a cognitive outcome measure in the subgroup of participants with clinically significant baseline cognitive impairment. The authors sought to confirm this finding using data from two phase 3 trials.

The potential of muscarinic M and M receptor activators for the treatment of cognitive impairment associated with schizophrenia.

Cognitive impairment is a core symptom of schizophrenia and a major determinant of poor long-term functional outcomes. Despite considerable efforts, we do not yet have any approved pharmacological treatments for cognitive impairment associated with schizophrenia (CIAS). A combination of advances in pre-clinical research and recent clinical trial findings have led to a resurgence of interest in the cognition-enhancing potential of novel muscarinic acetylcholine receptor (mAChR) agonists in schizophrenia.

Efficacy of KarXT on negative symptoms in acute schizophrenia: A post hoc analysis of pooled data from 3 trials.

Background: Currently approved antipsychotics do not adequately treat negative symptoms (NS), which are a major determinant of functional disability in schizophrenia. KarXT, an M /M preferring muscarinic receptor agonist, has shown efficacy as a broad-spectrum monotherapy for the treatment of schizophrenia in participants with acute psychosis. Post hoc analyses evaluated the possibility that NS improve independently of positive symptoms with KarXT in a subgroup of participants with moderate-to-severe NS and no predominance of positive symptoms.

Sex differences in effort-related decision-making: role of dopamine D2 receptor antagonism.

Rationale: Depressed individuals demonstrate debilitating symptoms, including depressed mood, anhedonia, and effort-related deficits. Effort-related decision-making can be measured through providing subjects with a choice between high effort/reward and low effort/reward options, which is a dopamine (DA)-dependent behavior. While previous research has shown sex differences in depression rates, this has not been examined within operant-based effort-related decision-making tasks nor has DA been shown to underlie this behavior in female rats.

Chronic corticosterone administration induces negative valence and impairs positive valence behaviors in mice.

Behavioral approaches utilizing rodents to study mood disorders have focused primarily on negative valence behaviors associated with potential threat (anxiety-related behaviors). However, for disorders such as depression, positive valence behaviors that assess reward processing may be more translationally valid and predictive of antidepressant treatment outcome. Chronic corticosterone (CORT) administration is a well-validated pharmacological stressor that increases avoidance in negative valence behaviors associated with anxiety.

Further exploration of an N-aryl phenoxyethoxy pyridinone-based series of mGlu NAMs: Challenging SAR, enantiospecific activity and in vivo efficacy.

This letter describes the further optimization of a series of mGlu NAMs based on an N-aryl phenoxyethoxy pyridinone core. A multidimensional optimization campaign, with focused matrix libraries, quickly established challenging SAR, enantiospecific activity, differences in assay read-outs (Ca flux via a promiscuous G protein (G) versus native coupling to GIRK channels), identified both full and partial mGlu NAMs and a new in vivo tool compound, VU6017587. This mGlu NAM showed efficacy in tail suspension, elevated zero maze and marble burying, suggesting selective inhibition of mGlu affords anxiolytic-like and antidepressant-like phenotypes in mice.

VU6005806/AZN-00016130, an advanced M positive allosteric modulator (PAM) profiled as a potential preclinical development candidate.

This letter describes progress towards an M PAM preclinical candidate that resulted in the discovery of VU6005806/AZN-00016130. While the thieno[2,3-c]pyridazine core has been a consistent feature of key M PAMs, no work had previously been reported with respect to alternate functionality at the C3 position of the pyridazine ring. Here, we detail new chemistry and analogs that explored this region, and quickly led to VU6005806/AZN-00016130, which was profiled as a putative candidate.

Shared Behavioral and Neurocircuitry Disruptions in Drug Addiction, Obesity, and Binge Eating Disorder: Focus on Group I mGluRs in the Mesolimbic Dopamine Pathway.

Accumulated data from clinical and preclinical studies suggest that, in drug addiction and states of overeating, such as obesity and binge eating disorder (BED), there is an imbalance in circuits that are critical for motivation, reward saliency, executive function, and self-control. Central to these pathologies and the extensive topic of this Review are the aberrations in dopamine (DA) and glutamate (Glu) within the mesolimbic pathway. Group I metabotropic glutamate receptors (mGlus) are highly expressed in the mesolimbic pathway and are poised in key positions to modulate disruptions in synaptic plasticity and neurotransmitter release observed in drug addiction, obesity, and BED.

Discovery of an Orally Bioavailable and Central Nervous System (CNS) Penetrant mGlu Negative Allosteric Modulator (NAM) in Vivo Tool Compound: N-(2-(1 H-1,2,4-triazol-1-yl)-5-(trifluoromethoxy)phenyl)-4-(cyclopropylmethoxy)-3-methoxybenzamide (VU6012962).

Herein, we report the discovery of a new, orally bioavailable and CNS-penetrant metabotropic glutamate receptor 7 (mGlu) negative allosteric modulator (NAM) that achieves exposure in cerebral spinal fluid (CSF) 2.5× above the in vitro IC at minimum effective doses (MEDs) of 3 mg/kg in preclinical anxiety models.

Pick Your Model Wisely: Understanding the Negative Symptoms of Schizophrenia in Rodent Models.

While the negative symptoms comprise one of the cardinal symptom domains of schizophrenia, there are numerous deficits that are included in this category of symptoms. Therefore, when modeling negative symptoms preclinically, it is important to consider which symptom is being modeled by a specific assay and to try to gain an understanding of the translational value of the findings. It is hoped that enhancing the translational value of animal models will allow for better treatment outcomes for the negative symptoms of schizophrenia in the future.

Activation of the mGlu metabotropic glutamate receptor has antipsychotic-like effects and is required for efficacy of M muscarinic receptor allosteric modulators.

Recent clinical and preclinical studies suggest that selective activators of the M muscarinic acetylcholine receptor have potential as a novel treatment for schizophrenia. M activation inhibits striatal dopamine release by mobilizing endocannabinoids, providing a mechanism for local effects on dopamine signaling in the striatum but not in extrastriatal areas. G protein-coupled receptors (GPCRs) typically induce endocannabinoid release through activation of Gα-type G proteins whereas M transduction occurs through Gα-type G proteins.

Partial reversal of the effort-related motivational effects of tetrabenazine with the MAO-B inhibitor deprenyl (selegiline): Implications for treating motivational dysfunctions.

People with depression and Parkinsonism frequently show effort-related motivational symptoms, such as anergia, psychomotor retardation, and fatigue. Tasks that assess effort-related choice are being used as animal models of these motivational symptoms. The present studies characterized the ability of monoamine oxidase (MAO) inhibitors with varying selectivity profiles to reverse the low effort bias induced by the monoamine storage inhibitor tetrabenazine.

The monoamine-oxidase B inhibitor deprenyl increases selection of high-effort activity in rats tested on a progressive ratio/chow feeding choice procedure: Implications for treating motivational dysfunctions.

Motivated behaviors often are characterized by a high degree of behavioral activation and work output, and organisms frequently make effort-related decisions based upon cost/benefit analyses. Moreover, people with depression and other disorders frequently show effort-related motivational symptoms, such as anergia, psychomotor retardation, and fatigue. Tasks measuring effort-related choice are being used as animal models of these motivational symptoms.

Cholinergic Projections to the Substantia Nigra Pars Reticulata Inhibit Dopamine Modulation of Basal Ganglia through the M Muscarinic Receptor.

Cholinergic regulation of dopaminergic inputs into the striatum is critical for normal basal ganglia (BG) function. This regulation of BG function is thought to be primarily mediated by acetylcholine released from cholinergic interneurons (ChIs) acting locally in the striatum. We now report a combination of pharmacological, electrophysiological, optogenetic, chemogenetic, and functional magnetic resonance imaging studies suggesting extra-striatal cholinergic projections from the pedunculopontine nucleus to the substantia nigra pars reticulata (SNr) act on muscarinic acetylcholine receptor subtype 4 (M) to oppose cAMP-dependent dopamine receptor subtype 1 (D) signaling in presynaptic terminals of direct pathway striatal spiny projections neurons.

Oral Ingestion and Intraventricular Injection of Curcumin Attenuates the Effort-Related Effects of the VMAT-2 Inhibitor Tetrabenazine: Implications for Motivational Symptoms of Depression.

Effort-related choice tasks are used for studying depressive motivational symptoms such as anergia/fatigue. These studies investigated the ability of the dietary supplement curcumin to reverse the low-effort bias induced by the monoamine storage blocker tetrabenazine. Tetrabenazine shifted effort-related choice in rats, decreasing high-effort lever pressing but increasing chow intake.

Positive allosteric modulation of M and M muscarinic receptors as potential therapeutic treatments for schizophrenia.

Current antipsychotic drugs provide symptomatic relief for positive symptoms of schizophrenia, but do not offer symptom management for negative and cognitive symptoms. In addition, many patients discontinue treatment due to adverse side effects. Therefore, there is a critical need to develop more effective and safe treatment options.

Assessment of a glycine uptake inhibitor in animal models of effort-related choice behavior: implications for motivational dysfunctions.

Rationale: Motivated behavior can be characterized by a substantial exertion of effort, and organisms often make effort-related decisions based upon analyses of work-related response costs and reinforcement preference. Moreover, alterations in effort-based choice can be seen in people with major depression and schizophrenia. Effort-related decision making is studied using tasks offering choices between high effort options leading to highly valued reinforces vs low effort/low reward options.

Effort-related motivational effects of the pro-inflammatory cytokine interleukin-6: pharmacological and neurochemical characterization.

Rationale: Motivational dysfunctions such as anergia, fatigue, and reduced effort expenditure are common in patients with depression and other disorders. Pro-inflammatory cytokines are implicated in depression, and cytokine administration induces motivational deficits in humans.

Objectives: These studies focused on the effects of the cytokine interleukin-6 (IL-6) on effort-related decision-making.

Blockade of uptake for dopamine, but not norepinephrine or 5-HT, increases selection of high effort instrumental activity: Implications for treatment of effort-related motivational symptoms in psychopathology.

Deficits in behavioral activation, exertion of effort, and other psychomotor/motivational symptoms are frequently seen in people with depression and other disorders. Depressed people show a decision bias towards selection of low effort activities, and animal tests of effort-related decision making are being used as models of motivational dysfunctions seen in psychopathology. The present studies investigated the ability of drugs that block dopamine transport (DAT), norepinephrine transport (NET), and serotonin transport (SERT) to modulate work output in rats responding on a test of effort-related decision making (i.