Dataset Information

Chronic treatment with D2-antagonist haloperidol leads to inhibitory/excitatory imbalance in striatal D1-neurons.

ABSTRACT: Striatal dysfunction has been implicated in the pathophysiology of schizophrenia, a disorder characterized by positive symptoms such as hallucinations and delusions. Haloperidol is a typical antipsychotic medication used in the treatment of schizophrenia that is known to antagonize dopamine D2 receptors, which are abundantly expressed in the striatum. However, haloperidol's delayed therapeutic effect also suggests a mechanism of action that may go beyond the acute blocking of D2 receptors. Here, we performed proteomic analysis of striatum brain tissue and found more than 400 proteins significantly altered after 30 days of chronic haloperidol treatment in mice, namely proteins involved in glutamatergic and GABAergic synaptic transmission. Cell-type specific electrophysiological recordings further revealed that haloperidol not only reduces the excitability of striatal medium spiny neurons expressing dopamine D2 receptors (D2-MSNs) but also affects D1-MSNs by increasing the ratio of inhibitory/excitatory synaptic transmission (I/E ratio) specifically onto D1-MSNs but not D2-MSNs. Therefore, we propose the slow remodeling of D1-MSNs as a mechanism mediating the delayed therapeutic effect of haloperidol over striatum circuits. Understanding how haloperidol exactly contributes to treating schizophrenia symptoms may help to improve therapeutic outcomes and elucidate the molecular underpinnings of this disorder.

SUBMITTER: Santa C

PROVIDER: S-EPMC10558446 | biostudies-literature | 2023 Oct

REPOSITORIES: biostudies-literature

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Chronic treatment with D2-antagonist haloperidol leads to inhibitory/excitatory imbalance in striatal D1-neurons.

Santa Cátia C Rodrigues Diana D Coelho Joana F JF Anjo Sandra I SI Mendes Vera M VM Bessa-Neto Diogo D Dunn Michael J MJ Cotter David D Baltazar Graça G Monteiro Patrícia P Manadas Bruno B

Translational psychiatry 20231006 1

Striatal dysfunction has been implicated in the pathophysiology of schizophrenia, a disorder characterized by positive symptoms such as hallucinations and delusions. Haloperidol is a typical antipsychotic medication used in the treatment of schizophrenia that is known to antagonize dopamine D2 receptors, which are abundantly expressed in the striatum. However, haloperidol's delayed therapeutic effect also suggests a mechanism of action that may go beyond the acute blocking of D2 receptors. Here, ...[more]

PMID: 37803004

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Project description:Many neurological disorders and diseases including drug addiction are associated with specific neuronal cell types in the brain. The striatum, a region that plays a critically important role in the development of addictive drug-related behavior, provides a good example of the cellular heterogeneity challenges associated with analyses of specific neuronal cell types. Such studies are needed to identify the adaptive changes in neuroproteomic signaling that occur in response to diseases such as addiction. The striatum contains two major cell types, D1 and D2 type dopaminoceptive medium spiny neurons (MSNs), whose cell bodies and processes are intermingled throughout this region. Since little is known about the proteomes of these two neuronal cell populations, we have begun to address this challenge by using fluorescence-activated nuclear sorting (FANS) to isolate nuclei-containing fractions from striatum from D1 and D2 "Translating Ribosome Affinity Purification" (TRAP) mice. This approach enabled us to devise and implement a robust and reproducible workflow for preparing samples from specific MSN cell types for mass spectrometry analyses. These analyses quantified at least 685 proteins in each of four biological replicates of 50 K sorted nuclei from two D1 mice/replicate and from each of four biological replicates of 50 K sorted nuclei from two D2 mice/replicate. Proteome analyses identified 87 proteins that were differentially expressed in D1 versus D2 MSN nuclei and principal component analysis (PCA) of these proteins separated the 8 biological replicates into specific cell types. Central network analysis of the 87 differentially expressed proteins identified Hnrnpd and Hnmpa2b1 in D1 and Cct2 and Cct7 in D2 as potential central interactors. This workflow can now be used to improve our understanding of many neurological diseases including characterizing the short and long-term impact of drugs of abuse on the proteomes of these two dopaminoceptive neuronal populations.

Project description:Schizophrenia is a chronic mental illness that is among the world’s top twenty causes of years lost to disability according to the global burden of disease 2019 (10.1016/S0140-6736(20)30925-9). Positive symptoms, including hallucinations and delusions in schizophrenia, often improved with conventional antipsychotic medication, which exerts its therapeutic effects mainly by antagonizing the dopamine D2 receptors. Haloperidol was one of the first antipsychotics to be approved by the FDA, and it is since then widely used for the treatment of psychotic disorders including schizophrenia. Despite its high affinity for dopamine D2 receptors, it has been shown that haloperidol interacts with other receptors, such as dopamine D3 and D4 receptors, α-adrenergic receptor 1 and to some extent 5HT2A. Dopaminergic dysfunction is known for decades to be involved in the pathophysiology of schizophrenia, but only recently has the striatum been implicated in such devasting disorder. The dorsal striatum is a brain region involved in motor, cognitive and motivational functions, highly impacted by antipsychotic drugs. Particularly, it is well-recognized that chronic haloperidol administration has a tremendous impact on striatal synaptic plasticity, by changing the volume of dorsal striatum, the number of striatal neurons and the synaptic morphology, both in humans and rodents. Despite the overwhelming evidence correlating chronic haloperidol administration with striatum alterations, so far, the exact striatal synaptic mechanism by which haloperidol exerts its beneficial effects remains unclear. Although dopamine D2 receptor blockade can be achieved within hours after haloperidol administration, the onset of action is delayed by weeks. Thus, it is crucial to better understand the neuronal mechanism behind the delayed clinical effects of haloperidol to improve the treatment outcome. Using proteomic analysis and whole-cell patch-clamp recordings (Figure 1), we demonstrate for the first time a possible mechanism by which haloperidol may be contributing to its beneficial long-term therapeutic effect. Specifically, we demonstrate that modulation of D2-MSNs by chronic haloperidol administration leads to a slow remodeling of D1-neurons that may be responsible for its positive therapeutic effects.

Project description:Key pointsImbalances in the activity of the D1-expressing direct pathway and D2-expressing indirect pathway striatal projection neurons (SPNs) are thought to contribute to many basal ganglia disorders, including early-onset neurodevelopmental disorders such as obsessive-compulsive disorder, attention deficit hyperactivity disorder and Tourette's syndrome. This study provides the first detailed quantitative investigation of development of D1 and D2 SPNs, including their cellular properties and connectivity within neural circuits, during the first postnatal weeks. This period is highly dynamic with many properties changing, but it is possible to make three main observations: many aspects of D1 and D2 SPNs progressively mature in parallel; there are notable exceptions when they diverge; and many of the defining properties of mature striatal SPNs and circuits are already established by the first and second postnatal weeks, suggesting guidance through intrinsic developmental programmes. These findings provide an experimental framework for future studies of striatal development in both health and disease.AbstractMany basal ganglia neurodevelopmental disorders are thought to result from imbalances in the activity of the D1-expressing direct pathway and D2-expressing indirect pathway striatal projection neurons (SPNs). Insight into these disorders is reliant on our understanding of normal D1 and D2 SPN development. Here we provide the first detailed study and quantification of the striatal cellular and circuit changes occurring for both D1 and D2 SPNs in the first postnatal weeks using in vitro whole-cell patch-clamp electrophysiology. Characterization of their intrinsic electrophysiological and morphological properties, the excitatory long-range inputs coming from cortex and thalamus, as well their local gap junction and inhibitory synaptic connections reveals this period to be highly dynamic with numerous properties changing. However it is possible to make three main observations. Firstly, many aspects of SPNs mature in parallel, including intrinsic membrane properties, increases in dendritic arbours and spine densities, general synaptic inputs and expression of specific glutamate receptors. Secondly, there are notable exceptions, including a transient stronger thalamic innervation of D2 SPNs and stronger cortical NMDA receptor-mediated inputs to D1 SPNs, both in the second postnatal week. Thirdly, many of the defining properties of mature D1 and D2 SPNs and striatal circuits are already established by the first and second postnatal weeks, including different electrophysiological properties as well as biased local inhibitory connections between SPNs, suggesting this is guided through intrinsic developmental programmes. Together these findings provide an experimental framework for future studies of D1 and D2 SPN development in health and disease.

Dataset Information

Chronic treatment with D2-antagonist haloperidol leads to inhibitory/excitatory imbalance in striatal D1-neurons.

Publications

Chronic treatment with D2-antagonist haloperidol leads to inhibitory/excitatory imbalance in striatal D1-neurons.

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