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1.
Pharmacol Biochem Behav ; 242: 173817, 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-39002806

ABSTRACT

Most cases of anxiety are currently treated with either benzodiazepines or serotonin reuptake inhibitors. These drugs carry with them risks for a multitude of side effects, and patient compliance suffers for this reason. There is thus a need for novel anxiolytics, and among the most compelling prospects in this vein is the study of the TAARs. The anxiolytic potential of ulotaront, a full agonist at the human TAAR1, is currently being investigated in patients with generalized anxiety disorder. Irrespective of whether this compound succeeds in clinical trials, a growing body of preclinical literature underscores the relevance of modulating the TAARs in anxiety. Multiple behavioral paradigms show anxiolytic-like effects in rodents, possibly due to increased neurogenesis and plasticity, in addition to a panoply of interactions between the TAARs and other systems. Crucially, multiple lines of evidence suggest that the TAARs, particularly TAAR1, TAAR2, and TAAR5, are expressed in the extended amygdala and hippocampus. These regions are central in the actuation of anxiety, and are particularly susceptible to neurogenic and neuroplastic effects which the TAARs are now known to regulate. The TAARs also regulate the dopamine and serotonin systems, both of which are implicated in anxiety. Ligands of the TAARs may thus constitute a new class of anxiolytics.

2.
Neurosci Lett ; 837: 137898, 2024 Jul 14.
Article in English | MEDLINE | ID: mdl-39013536

ABSTRACT

PURPOSE: Sex differences play a crucial role in understanding vulnerability to opioid addiction, yet there have been limited preclinical investigations of this effect during the transition from adolescence to adulthood. The present study compared the behaviors of male and female rodents in response to fentanyl treatment and targeted molecular correlates in the striatum and medial prefrontal cortex. MATERIALS AND METHODS: Thirty adolescent C57BL/6J mice underwent a 1-week fentanyl treatment with an escalating dose. In addition to evaluating locomotor activity and anxiety-related parameters, we also assessed naloxone-induced fentanyl acute withdrawal jumps. We employed real-time quantitative PCR (qPCR) to assess overall gene expression of dopaminergic receptors (Drd1, Drd2, Drd4 and Drd5) and the µ-opioid receptor Oprm1. The levels of epigenetic base modifications including 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) were assessed on CpG islands of relevant genes. RESULTS: Females had higher locomotor activity than males after chronic fentanyl treatment, and they exhibited higher fentanyl withdrawal jumping behavior induced by naloxone. Females also presented lower Drd4 gene expression and DNA methylation (5mC + 5hmC) in the striatum. We found that locomotor activity and fentanyl withdrawal jumps were negatively correlated with Drd4 methylation and gene expression in the striatum, respectively. CONCLUSIONS: The findings suggested that female mice displayed heightened sensitivity to the effects of fentanyl treatment during the transition from adolescence to adulthood. This effect may be associated with molecular alterations related to the Drd4 gene.

3.
Elife ; 122024 Jul 15.
Article in English | MEDLINE | ID: mdl-39008352

ABSTRACT

The basolateral amygdala (BLA), a brain center of emotional expression, contributes to acoustic communication by first interpreting the meaning of social sounds in the context of the listener's internal state, then organizing the appropriate behavioral responses. We propose that modulatory neurochemicals such as acetylcholine (ACh) and dopamine (DA) provide internal-state signals to the BLA while an animal listens to social vocalizations. We tested this in a vocal playback experiment utilizing highly affective vocal sequences associated with either mating or restraint, then sampled and analyzed fluids within the BLA for a broad range of neurochemicals and observed behavioral responses of adult male and female mice. In male mice, playback of restraint vocalizations increased ACh release and usually decreased DA release, while playback of mating sequences evoked the opposite neurochemical release patterns. In non-estrus female mice, patterns of ACh and DA release with mating playback were similar to males. Estrus females, however, showed increased ACh, associated with vigilance, as well as increased DA, associated with reward-seeking. Experimental groups that showed increased ACh release also showed the largest increases in an aversive behavior. These neurochemical release patterns and several behavioral responses depended on a single prior experience with the mating and restraint behaviors. Our results support a model in which ACh and DA provide contextual information to sound analyzing BLA neurons that modulate their output to downstream brain regions controlling behavioral responses to social vocalizations.


Subject(s)
Dopamine , Emotions , Vocalization, Animal , Animals , Male , Female , Vocalization, Animal/physiology , Mice , Dopamine/metabolism , Emotions/physiology , Acetylcholine/metabolism , Amygdala/metabolism , Amygdala/physiology , Behavior, Animal/physiology , Sexual Behavior, Animal/physiology , Mice, Inbred C57BL
4.
Cell Rep ; 43(8): 114483, 2024 Jul 17.
Article in English | MEDLINE | ID: mdl-39024096

ABSTRACT

The striatum integrates dopaminergic and glutamatergic inputs to select preferred versus alternative actions. However, the precise mechanisms underlying this process remain unclear. One way to study action selection is to understand how it breaks down in pathological states. Here, we explored the cellular and synaptic mechanisms of levodopa-induced dyskinesia (LID), a complication of Parkinson's disease therapy characterized by involuntary movements. We used an activity-dependent tool (FosTRAP) in conjunction with a mouse model of LID to investigate functionally distinct subsets of striatal direct pathway medium spiny neurons (dMSNs). In vivo, levodopa differentially activates dyskinesia-associated (TRAPed) dMSNs compared to other dMSNs. We found this differential activation of TRAPed dMSNs is likely to be driven by higher dopamine receptor expression, dopamine-dependent excitability, and excitatory input from the motor cortex and thalamus. Together, these findings suggest how the intrinsic and synaptic properties of heterogeneous dMSN subpopulations integrate to support action selection.

5.
Toxicol Mech Methods ; : 1-10, 2024 Jul 17.
Article in English | MEDLINE | ID: mdl-39021086

ABSTRACT

Chronic exposure to manganese compounds leads to accumulation of the manganese in the basal ganglia and hippocampus. High levels of manganese in these structures lead to oxidative stress, neuroinflammation, imbalance of brain neurotransmitters, and hyperactivation of calpains mediating neurotoxicity and causing motor and cognitive impairment. The purpose of this work was to study the effect of excess manganese chloride intake on rats' spatial memory and on dopamine-ß-hydroxylase (DßH) activity under conditions of calpain activity suppression. Rats were divided into 3 groups of 10 animals each. Group 1 received MnCl2 (30 days, 5 mg/kg/day, intranasally), group 2 received MnCl2 (30 days, 5 mg/kg/day, intranasally) and calpain inhibitor Cast (184-210) (30 days, 5 µg/kg/day, intranasally), and group 3 received sterile saline (30 days in a volume of 20 µl, intranasally). The spatial working memory was assessed using Morris water maze test. DßH activity was determined by HPLC. We have shown that in response to excessive intake of MnCl2, there was a development of cognitive impairments in rats, which was accompanied by a decrease in DßH activity in the hippocampus. The severity of cognitive impairment was reduced by inhibiting the activity of m-calpain. The protective effect of calpain inhibitors was achieved not through an effect on DßH activity. Thus, the development of therapeutic regimens for the treatment of manganism using dopaminomimetics and/or by inhibiting calpains, must be performed taking into account the manganese-induced decrease of DßH activity and the inability to influence this process with calpain inhibitors.

6.
Netw Neurosci ; 8(2): 557-575, 2024.
Article in English | MEDLINE | ID: mdl-38952808

ABSTRACT

In recent years, there has been an increasing interest in studying brain-heart interactions. Methodological advancements have been proposed to investigate how the brain and the heart communicate, leading to new insights into some neural functions. However, most frameworks look at the interaction of only one brain region with heartbeat dynamics, overlooking that the brain has functional networks that change dynamically in response to internal and external demands. We propose a new framework for assessing the functional interplay between cortical networks and cardiac dynamics from noninvasive electrophysiological recordings. We focused on fluctuating network metrics obtained from connectivity matrices of EEG data. Specifically, we quantified the coupling between cardiac sympathetic-vagal activity and brain network metrics of clustering, efficiency, assortativity, and modularity. We validate our proposal using open-source datasets: one that involves emotion elicitation in healthy individuals, and another with resting-state data from patients with Parkinson's disease. Our results suggest that the connection between cortical network segregation and cardiac dynamics may offer valuable insights into the affective state of healthy participants, and alterations in the network physiology of Parkinson's disease. By considering multiple network properties, this framework may offer a more comprehensive understanding of brain-heart interactions. Our findings hold promise in the development of biomarkers for diagnostic and cognitive/motor function evaluation.

7.
Cureus ; 16(5): e61364, 2024 May.
Article in English | MEDLINE | ID: mdl-38947732

ABSTRACT

Dyskinetic movements are characterized as hyperkinetic, repetitive movements of the extremities, facial, and oral musculature, most associated with prolonged dopamine D2 receptor blockade. In rare instances, dyskinetic movements can be brought on by selective serotonin reuptake inhibitor (SSRI) usage via an indirect D2 blockade mechanism, mimicking the D2 blockade observed with dopamine receptor blocking agents (DRBAs), such as in first-generation antipsychotics. This mimicked D2 blockade by SSRIs is said to be due to increased tonic inhibition by serotonin on dopaminergic neurons in the dopaminergic pathways of the brain, specifically the nigrostriatal pathway. In this case report, we look at a patient with a history of cerebral palsy who developed acute dyskinetic movements after short-term citalopram usage. The objective is to bring attention to the possible extrapyramidal side effects (EPS) of SSRI usage.

8.
J Neurol Sci ; 463: 123116, 2024 Jun 27.
Article in English | MEDLINE | ID: mdl-38981418

ABSTRACT

OBJECTIVE: Dysphagia in multiple system atrophy (MSA) is life-threatening and is caused by parkinsonism with cerebellar ataxia as a contributing factor. The present study investigated the relationship between dysphagia severity in MSA and the specific binding ratio (SBR) on dopamine transporter (DaT) SPECT using the Hyodo score, a qualitative scale for use with fiberoptic endoscopic evaluation of swallowing (FEES). METHODS: Hyodo score's ability to predict aspiration during a FEES examination of 88 patients with MSA was first tested. Then the clinical characteristics, Hyodo score, and SBR of patients with either predominant parkinsonism (MSA-P; n = 11) or cerebellar ataxia (MSA-C; n = 25) who underwent FEES and DaT SPECT simultaneously were compared. RESULTS: Logistic regression demonstrated that the Hyodo score was a significant predictive factor of aspiration (p = 0.003). The MSA-P group had a significantly higher Hyodo score (p = 0.026) and lower SBR (p = 0.011) than the MSA-C group while neither group demonstrated any significant difference in disease duration at the FEES examination. Linear regression demonstrated a significant, inverse correlation between the Hyodo score and SBR in the MSA-P (p = 0.044; r = -0.616) and MSA-C (p = 0.044; r = -0.406) groups. When the effect of SBR was removed by analysis of covariance, no significant difference in the Hyodo score remained between the groups. CONCLUSIONS: Our results suggested an association between presynaptic changes in nigrostriatal dopaminergic neurons and dysphagia severity in MSA which largely contributes to the difference in dysphagia severity between MSA-P and MSA-C.

9.
Article in English | MEDLINE | ID: mdl-38984576

ABSTRACT

BACKGROUND AND OBJECTIVE: Globally, Gastric Cancer (GC) ranks as the fifth leading cause of cancer-related deaths. GC is a multifaceted malignancy with diverse etiologies; however, understanding the shared molecular mechanisms can aid in discovering novel targeted therapies for GC. This study has employed a drug repositioning approach to explore new drug candidates for treating GC. METHODS: The human GC cell lines AGS, MKN-45, and KATO-III were treated with different concentrations of dopamine, cabergoline, thioridazine, and entacapone to determine effective doses and IC50 values. In vitro, cytotoxic activity on cancer cell lines was screened based on dose/time using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Quantitative Reverse Transcriptase Polymerase Chain Reaction (qRT-PCR) was used to measure the mRNA expression of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and Proliferating Cell Nuclear Antigen (PCNA) in each group. The percentage of apoptotic cells was evaluated using Annexin V/PI staining. RESULTS: Dopamine, cabergoline, thioridazine, and entacapone elicited cytotoxic effects on AGS and KATO-III cells in a dose-dependent manner and elevated the percentage of Annexin V-positive cells, suggesting the occurrence of apoptosis. The expression of Bcl-2 and PCNA was significantly decreased, whereas the expression of Bax was considerably increased in the AGS and KATO-III cells compared to that in the blank group (p < 0.05); however, no similar effect was observed in MKN-45 cells. CONCLUSION: Through in vitro experiments, this study provides evidence that the antipsychotic drugs cabergoline, dopamine, thioridazine, and entacapone can inhibit gastric cancer growth in AGS and KATO-III cells. These findings suggest that these drugs could be repurposed as novel therapeutic agents for the treatment of gastric cancer.

10.
Article in English | MEDLINE | ID: mdl-38988197

ABSTRACT

Different dopamine subtypes have opposing dynamics at post-synaptic receptors, with the ratio of D1 to D2 receptors determining the relative sensitivity to gains and losses, respectively, during value-based learning. This effective sensitivity to different reward feedback interacts with phasic dopamine levels to determine the effectiveness of learning, particularly in dynamic feedback situations where frequency and magnitude of rewards need to be integrated over time to make optimal decisions. We modeled this effect in simulations of the underlying basal ganglia pathways and then tested the predictions in individuals with a variant of the human dopamine receptor D2 (DRD2; -141C Ins/Del and Del/Del) gene that associates with lower levels of D2 receptor expression (N=119) and compared their performance in the Iowa Gambling Task (IGT) to non-carrier controls (N=319). Ventral striatal (VS) reactivity to rewards was measured in the Cards task with fMRI. DRD2 variant carriers made less effective decisions than non-carriers, but this effect was not moderated by VS reward reactivity as is hypothesized by our model. These results suggest that the interaction between dopamine receptor subtypes and reactivity to rewards during learning may be more complex than originally thought.

11.
Neurotoxicology ; 103: 266-287, 2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38964509

ABSTRACT

Parkinson's disease (PD) is a debilitating neurodegenerative disease affecting millions of individuals worldwide. Hallmark features of PD pathology are the formation of Lewy bodies in neuromelanin-containing dopaminergic (DAergic) neurons of the substantia nigra pars compacta (SNpc), and the subsequent irreversible death of these neurons. Although genetic risk factors have been identified, around 90 % of PD cases are sporadic and likely caused by environmental exposures and gene-environment interaction. Mechanistic studies have identified a variety of chemical PD risk factors. PD neuropathology occurs throughout the brain and peripheral nervous system, but it is the loss of DAergic neurons in the SNpc that produce many of the cardinal motor symptoms. Toxicology studies have found specifically the DAergic neuron population of the SNpc exhibit heightened sensitivity to highly variable chemical insults (both in terms of chemical structure and mechanism of neurotoxic action). Thus, it has become clear that the inherent neurobiology of nigral DAergic neurons likely underlies much of this neurotoxic response to broad insults. This review focuses on inherent neurobiology of nigral DAergic neurons and how such neurobiology impacts the primary mechanism of neurotoxicity. While interactions with a variety of other cell types are important in disease pathogenesis, understanding how inherent DAergic biology contributes to selective sensitivity and primary mechanisms of neurotoxicity is critical to advancing the field. Specifically, key biological features of DAergic neurons that increase neurotoxicant susceptibility.

12.
Talanta ; 278: 126496, 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38996563

ABSTRACT

Dopamine is an important neurotransmitter in the body and closely related to many neurodegenerative diseases. Therefore, the detection of dopamine is of great significance for the diagnosis and treatment of diseases, screening of drugs and unraveling of relevant pathogenic mechanisms. However, the low concentration of dopamine in the body and the complexity of the matrix make the accurate detection of dopamine challenging. Herein, an electrochemical sensor is constructed based on ternary nanocomposites consisting of one-dimensional Pt nanowires, two-dimensional MXene nanosheets, and three-dimensional porous carbon. The Pt nanowires exhibit excellent catalytic activity due to the abundant grain boundaries and highly undercoordinated atoms; MXene nanosheets not only facilitate the growth of Pt nanowires, but also enhance the electrical conductivity and hydrophilicity; and the porous carbon helps induce significant adsorption of dopamine on the electrode surface. In electrochemical tests, the ternary nanocomposite-based sensor achieves an ultra-sensitive detection of dopamine (S/N = 3) with a low limit of detection (LOD) of 28 nM, satisfactory selectivity and excellent stability. Furthermore, the sensor can be used for the detection of dopamine in serum and in situ monitoring of dopamine release from PC12 cells. Such a highly sensitive nanocomposite sensor can be exploited for in situ monitoring of important neurotransmitters at the cellular level, which is of great significance for related drug screening and mechanistic studies.

13.
Inflammopharmacology ; 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38992324

ABSTRACT

"Path to a good mood lies through the gut." This statement seems to imply that it has long been believed that the gut is connected with the brain. Research has shown that eating food activates the reward system and releases dopamine (DA), establishing a link between the peripheral and central nervous system. At the same time, researchers also trust that the gut is involved in the onset of many diseases, including Parkinson's disease (PD), in which gastrointestinal dysfunction is considered a prevalent symptom. Reports suggest that PD starts from the gut and reaches the brain via the vagus nerve. Recent studies have revealed an intriguing interaction between the gut and brain, which links gut dysbiosis to the etiology of PD. This review aims to explore the mechanistic pathway how reactive oxygen species (ROS) generation in the gut affects the makeup and operation of the dopamine circuitry in the brain. Our primary concern is ROS generation in the gut, which disrupts the gut microbiome (GM), causing α-synuclein accumulation and inflammation. This trio contributes to the loss of DA neurons in the brain, resulting in PD development. This review also compiles pre-clinical and clinical studies on antioxidants, demonstrating that antioxidants reduce ROS and increase DA levels. Collectively, the study highlights the necessity of comprehending the gut-brain axis for unraveling the riddles of PD pathogenesis and considering new therapeutic approaches.

14.
Focus (Am Psychiatr Publ) ; 22(3): 328-332, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38988457

ABSTRACT

Eating disorders are severe psychiatric illnesses that are associated with high mortality. Research has identified environmental, psychological, and biological risk factors that could contribute to the psychopathology of eating disorders. Nevertheless, the patterns of self-starvation, binge eating, and purging behaviors are difficult to reconcile with the typical mechanisms that regulate appetite, hunger, and satiety. Here, the authors present a neuroscience and human brain imaging-based model to help explain the detrimental and often persistent behavioral patterns seen in individuals with eating disorders and why it is so difficult to overcome them. This model incorporates individual motivations to change eating, fear conditioning, biological adaptations of the brain and body, and the development of a vicious cycle that drives the individual to perpetuate those behaviors. This knowledge helps to explain these illnesses to patients and their families, and to develop more effective treatments, including biological interventions.

15.
Front Vet Sci ; 11: 1394201, 2024.
Article in English | MEDLINE | ID: mdl-38993275

ABSTRACT

Maternal behavior research in laboratory rats has revealed important behavioral and neurobiological mechanisms governing the onset, maintenance and decline of maternal behavior. However, the extent to which these mechanisms are evolutionarily conserved across species is less clear. This manuscript proposes that examining these mechanisms in dogs may be a viable approach to test their generality and help bridge the gap between rodent and human research, as domestic dogs show greater individual differences and exhibit more human-like maternal characteristics than rodents. These aspects represent advantages over rodent models, which in turn allow systems biological approaches not available in rodents. Additionally, domestic dogs share similar social environments with humans, suffer from the same mental disorders as humans, and can be treated with the same medications. This paper begins with a summary of key findings and theoretical developments from decades of rat maternal behavior research, followed by a literature review of the extant maternal behavior research on dogs and related methodology, highlighting the unique behavioral characteristics of dog maternal behavior and similarities and differences from rat maternal behavior. Finally, several knowledge gaps in dog maternal behavior research, as well as the future research in this area is discussed. It concludes that research on dog maternal behavior will not only advance our understanding of the universality of the neurobiological and behavioral mechanisms in maternal behavior, but also improve our understanding of risk factors associated with postpartum mental disorders.

16.
Schizophr Res ; 271: 19-27, 2024 Jul 12.
Article in English | MEDLINE | ID: mdl-39002526

ABSTRACT

A substantial body of evidence implicates dysfunction in N-methyl-d-aspartate receptors (NMDARs) in the pathophysiology of schizophrenia. This article illustrates how NMDAR dysfunction may give rise to many of the neurobiological phenomena frequently associated with schizophrenia with a particular focus on how NMDAR dysfunction affects the thalamic reticular nucleus (nRT) and pedunculopontine tegmental nucleus (PPTg). Furthermore, this article presents a model for schizophrenia illustrating how dysfunction in the nRT may interrupt prefrontal regulation of midbrain dopaminergic neurons, and how dysfunction in the PPTg may drive increased, irregular burst firing.

17.
Biol Psychiatry ; 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-39002875

ABSTRACT

BACKGROUND: Impulse control disorders (ICD) in Parkinson's disease (PD) are associated with a heavy burden on patients and caretakers. While recovery can occur, ICD persists in many patients despite optimal management. The basis for this inter-individual variability in recovery is unclear and poses a major challenge to personalized health care. METHODS: We adopt a computational psychiatry approach and leverage the longitudinal, prospective Personalized Parkinson Project (N=136 persons with PD, within 5 years of diagnosis) to combine dopaminergic learning theory-informed fMRI with machine learning (at baseline) to predict ICD symptom recovery after two years of follow-up. We focused on a change in QUIP-rs across the entire cohort, regardless of an ICD diagnosis. RESULTS: Greater reinforcement learning signals during gain trials but not loss trials at baseline, including those in the ventral striatum, medial prefrontal cortex and the behavioral accuracy score measured while ON medication were associated with greater recovery from impulse control symptoms two years later. These signals accounted for a unique proportion of the relevant variability over and above that explained by other known factors, such as decreases in dopamine agonist use. CONCLUSIONS: Our results provide a proof of principle for combining generative model-based inference of latent learning processes with machine learning-based predictive modeling of variability in clinical symptom recovery trajectories. Hence, we showed that RL modelling parameters predict recovery from ICD symptoms in PD.

18.
Int J Mol Sci ; 25(13)2024 Jun 28.
Article in English | MEDLINE | ID: mdl-39000265

ABSTRACT

Rotenone, as a common pesticide and insecticide frequently found in environmental samples, may be present in aquatic habitats worldwide. Exposure to low concentrations of this compound may cause alterations in the nervous system, thus contributing to Parkinsonian motor symptoms in both vertebrates and invertebrates. However, the effects of chronic exposure to low doses of rotenone on the activity of neurotransmitters that govern motor functions and on the specific molecular mechanisms leading to movement morbidity remain largely unknown for many aquatic invertebrates. In this study, we analyzed the effects that rotenone poisoning exerts on the activity of dopamine (DA) and acetylcholine (ACh) synthesis enzymes in the central nervous system (CNS) of Asian shore crab, Hemigrapsus sanguineus (de Haan, 1835), and elucidated the association of its locomotor behavior with Parkinson's-like symptoms. An immunocytochemistry analysis showed a reduction in tyrosine hydroxylase (TH) in the median brain and the ventral nerve cord (VNC), which correlated with the subsequent decrease in the locomotor activity of shore crabs. We also observed a variation in cholinergic neurons' activity, mostly in the ventral regions of the VNC. Moreover, the rotenone-treated crabs showed signs of damage to ChAT-lir neurons in the VNC. These data suggest that chronic treatment with low doses of rotenone decreases the DA level in the VNC and the ACh level in the brain and leads to progressive and irreversible reductions in the crab's locomotor activity, life span, and changes in behavior.


Subject(s)
Brachyura , Central Nervous System , Cholinergic Neurons , Dopaminergic Neurons , Rotenone , Animals , Rotenone/toxicity , Dopaminergic Neurons/drug effects , Dopaminergic Neurons/metabolism , Cholinergic Neurons/drug effects , Cholinergic Neurons/metabolism , Central Nervous System/drug effects , Central Nervous System/metabolism , Brachyura/drug effects , Brachyura/metabolism , Dopamine/metabolism , Acetylcholine/metabolism , Insecticides/toxicity , Tyrosine 3-Monooxygenase/metabolism , Locomotion/drug effects
19.
Cell Rep ; 43(7): 114509, 2024 Jul 13.
Article in English | MEDLINE | ID: mdl-39003735

ABSTRACT

Midbrain dopaminergic neurons (DANs) are subject to extensive metabotropic regulation, but the repertoire of G protein-coupled receptors (GPCRs) present in these neurons has not been mapped. Here, we isolate DANs from Dat-eGFP mice to generate a GPCR atlas by unbiased qPCR array expression analysis of 377 GPCRs. Combined with data mining of scRNA-seq databases, we identify multiple receptors in DAN subpopulations with 38 of these receptors representing the majority of transcripts. We identify 41 receptors expressed in midbrain DANs but not in non-DAN midbrain cells, including the free fatty acid receptor 4 (FFAR4). Functional expression of FFAR4 is validated by ex vivo Ca2+ imaging, and in vivo experiments support that FFAR4 negatively regulates food and water intake and bodyweight. In addition to providing a critical framework for understanding metabotropic DAN regulation, our data suggest fatty acid sensing by FFAR4 as a mechanism linking high-energy intake to the dopamine-reward pathway.

20.
Talanta ; 278: 126509, 2024 Jul 13.
Article in English | MEDLINE | ID: mdl-39003839

ABSTRACT

Bipolar electrochemical microscopy (BEM), which visualizes the concentration distribution of molecular species in biological systems by electrochemiluminescence (ECL), is expected to be applied to the high-spatiotemporal-resolution imaging of biomolecules, enabling the analysis of cellular functions. In the past, the molecular species that could be imaged by BEM were generally restricted to oxidized molecules due to the limitation derived from the ECL mechanism of the luminophore. Recently, the imaging of dopamine (DA), a reduced molecule, was achieved using Ru (bpy)32+/glutathione disulfide (GSSG) as a cathodic luminophore. However, a large driving voltage was required for ECL generation, resulting in a low S/N ratio. In this study, we employed N,N'-dimethyl-3,4,9,10-perylenetetracarboxylic diimide (PDI-CH3)/potassium peroxodisulfate (K2S2O8), which is a cathodic luminophore that can be reduced at a nobler potential to produce ECL than [Ru(bpy)3]2+/GSSG. First, the ECL mechanism of PDI-CH3/K2S2O8 was elucidated by using a PDI-CH3 drop-cast glassy carbon electrode (GCE) immersed in K2S2O8 solution as the working electrode in a 3-electrode system. The PDI-CH3 drop-casted GCE, a single closed bipolar electrode (c-BPE), was used as the cathode in the successful quantification of 50-500 µmol L-1 DA in a sample chamber in which a c-BPE anode was immersed, resulting in a high S/N. The selective detection of DA in the presence of ascorbic acid was achieved by modifying the anode with Nafion. Finally, DA imaging was demonstrated using a commercially available anisotropic conducting film with PDI-CH3 coating on the cathode surface as a c-BPE array. The change in the concentration distribution in the inflow of DA was successfully imaged based on the change in the ECL intensity at the c-BPE cathode. This BEM system is expected to be useful for DA imaging of the brain.

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