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Cell Research Aug 2023The dopaminergic system, including five dopamine receptors (D1R to D5R), plays essential roles in the central nervous system (CNS); and ligands that activate dopamine...
The dopaminergic system, including five dopamine receptors (D1R to D5R), plays essential roles in the central nervous system (CNS); and ligands that activate dopamine receptors have been used to treat many neuropsychiatric disorders, including Parkinson's Disease (PD) and schizophrenia. Here, we report cryo-EM structures of all five subtypes of human dopamine receptors in complex with G protein and bound to the pan-agonist, rotigotine, which is used to treat PD and restless legs syndrome. The structures reveal the basis of rotigotine recognition in different dopamine receptors. Structural analysis together with functional assays illuminate determinants of ligand polypharmacology and selectivity. The structures also uncover the mechanisms of dopamine receptor activation, unique structural features among the five receptor subtypes, and the basis of G protein coupling specificity. Our work provides a comprehensive set of structural templates for the rational design of specific ligands to treat CNS diseases targeting the dopaminergic system.
Topics: Humans; Receptors, Dopamine; Ligands; Dopamine; Parkinson Disease; Genomics
PubMed: 37221270
DOI: 10.1038/s41422-023-00808-0 -
Expert Opinion on Emerging Drugs Dec 2023In Parkinson's disease, dopamine depletion in the basal ganglia leads to symptoms including bradykinesia, gait abnormalities, and cognitive impairment. Even with... (Review)
Review
INTRODUCTION
In Parkinson's disease, dopamine depletion in the basal ganglia leads to symptoms including bradykinesia, gait abnormalities, and cognitive impairment. Even with treatment, the disease course leads to decreases in the amount of dopamine produced and released into the synapse. As dopamine production falls and the treatment course is insufficient to match the metabolic supply and demand, acute 'off' periods develop that cause reemergence of symptoms. Apomorphine is used to reverse these 'off' periods and restore function in patients with Parkinson's. This review will provide clinicians a concise article to read to learn more about apomorphine and its appropriate utilization.
AREAS COVERED
The research discussed is focused on the history, pharmacokinetics, and mechanism of action of Apomorphine. Its utilization as a treatment for Parkinson's Disease and its comparison to currently utilized drugs is also discussed in this review. We focused on articles published on PubMed and Google Scholar within the last 10 years, but in some instances had to go as far back as 1951 to include early articles published about apomorphine.
EXPERT OPINION
The expert opinion section focuses on the ways in which apomorphine could be administered in the future to better promote utilization and increase tolerability.
Topics: Humans; Apomorphine; Parkinson Disease; Dopamine; Dopamine Agonists; Injections, Subcutaneous; Antiparkinson Agents
PubMed: 37909462
DOI: 10.1080/14728214.2023.2278677 -
International Journal of Molecular... May 2024Dopamine is a key neurotransmitter involved in physiological processes such as motor control, motivation, reward, cognitive function, and maternal and reproductive... (Review)
Review
Dopamine is a key neurotransmitter involved in physiological processes such as motor control, motivation, reward, cognitive function, and maternal and reproductive behaviors. Therefore, dysfunctions of the dopaminergic system are related to a plethora of human diseases. Dopamine, via different circuitries implicated in compulsive behavior, reward, and habit formation, also represents a key player in substance use disorder and the formation and perpetuation of mechanisms leading to addiction. Here, we propose dopamine as a model not only of neurotransmission but also of neuromodulation capable of modifying neuronal architecture. Abuse of substances like methamphetamine, cocaine, and alcohol and their consumption over time can induce changes in neuronal activities. These modifications lead to synaptic plasticity and finally to morphological and functional changes, starting from maladaptive neuro-modulation and ending in neurodegeneration.
Topics: Humans; Dopamine; Animals; Substance-Related Disorders; Neuronal Plasticity; Synaptic Transmission
PubMed: 38791331
DOI: 10.3390/ijms25105293 -
Expert Opinion on Pharmacotherapy 2023Behavioural symptoms are common manifestations of Parkinson's disease and include depression, anxiety, impulse control disorders, hallucinations, psychosis, and... (Review)
Review
INTRODUCTION
Behavioural symptoms are common manifestations of Parkinson's disease and include depression, anxiety, impulse control disorders, hallucinations, psychosis, and cognitive dysfunction. They remain inadequately addressed in many patients despite their relevance for quality of life and disability. This applies also to impulse control disorders where the most common approach in recent literature is to refrain from using dopamine agonists without consideration about their potential benefit on motor complications.
AREAS COVERED
We conducted a narrative review searching for articles on behavioral symptoms in Parkinson disease and selected those which included involved neurotransmitters such as dopamine, noradrenaline, serotonin, acetylcholine. We specifically focused our search on open-label and randomized double-blind studies and biomarkers which could best characterize these clinical manifestations.
EXPERT OPINION
Management of Parkinson disease behavioural manifestations lacks clear guidelines and standardized protocols beside general suggestions of dose adjustments in dopamine replacement therapy and use of antidepressants or antipsychotic drugs with little consideration of patients' age, sex, comorbidities, and motor status. We suggest a pragmatic approach which includes education of affected patients and caring people, dealing with complex cases by experienced multidisciplinary teams, use of cognitive behavioural therapy, and psychological counselling to complement drug treatment.
Topics: Humans; Parkinson Disease; Dopamine; Quality of Life; Psychotic Disorders; Antipsychotic Agents; Randomized Controlled Trials as Topic
PubMed: 37493445
DOI: 10.1080/14656566.2023.2240228 -
Neurochemical Research Sep 2023Dopamine (DA) is a catecholamine neurotransmitter widely distributed in the central nervous system. It participates in various physiological functions, such as feeding,... (Review)
Review
Dopamine (DA) is a catecholamine neurotransmitter widely distributed in the central nervous system. It participates in various physiological functions, such as feeding, anxiety, fear, sleeping and arousal. The regulation of feeding is exceptionally complex, involving energy homeostasis and reward motivation. The reward system comprises the ventral tegmental area (VTA), nucleus accumbens (NAc), hypothalamus, and limbic system. This paper illustrates the detailed mechanisms of eight typical orexigenic and anorexic neuropeptides that regulate food intake through the reward system. According to recent literature, neuropeptides released from the hypothalamus and other brain regions regulate reward feeding predominantly through dopaminergic neurons projecting from the VTA to the NAc. In addition, their effect on the dopaminergic system is mediated by the prefrontal cortex, paraventricular thalamus, laterodorsal tegmental area, amygdala, and complex neural circuits. Research on neuropeptides involved in reward feeding can help identify more targets to treat diseases with metabolic disorders, such as obesity.
Topics: Dopamine; Nucleus Accumbens; Ventral Tegmental Area; Neuropeptides; Dopaminergic Neurons; Reward
PubMed: 37233918
DOI: 10.1007/s11064-023-03954-4 -
Journal of Controlled Release :... Aug 2023Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) resulting in... (Review)
Review
Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) resulting in dopamine (DA) deficiency, which manifests itself in motor symptoms including tremors, rigidity and bradykinesia. Current PD treatments aim at symptom reduction through oral delivery of levodopa (L-DOPA), a precursor of DA. However, L-DOPA delivery to the brain is inefficient and increased dosages are required as the disease progresses, resulting in serious side effects like dyskinesias. To improve PD treatment efficacy and to reduce side effects, recent research focuses on the encapsulation of L-DOPA into polymeric- and lipid-based nanoparticles (NPs). These formulations can protect L-DOPA from systemic decarboxylation into DA and improve L-DOPA delivery to the central nervous system. Additionally, NPs can be modified with proteins, peptides and antibodies specifically targeting the blood-brain barrier (BBB), thereby reducing required dosages and free systemic DA. Alternative delivery approaches for NP-encapsulated L-DOPA include intravenous (IV) administration, transdermal delivery using adhesive patches and direct intranasal administration, facilitating increased therapeutic DA concentrations in the brain. This review provides an overview of the recent advances for NP-mediated L-DOPA delivery to the brain, and debates challenges and future perspectives on the field.
Topics: Humans; Levodopa; Parkinson Disease; Dopamine; Brain; Nanoparticles
PubMed: 37343725
DOI: 10.1016/j.jconrel.2023.06.026 -
Psychiatria Danubina Oct 2023Bipolar disorder and Parkinson's disease are two distinct neurological conditions that share common features related to dopaminergic dysfunction. This article presents a... (Review)
Review
Bipolar disorder and Parkinson's disease are two distinct neurological conditions that share common features related to dopaminergic dysfunction. This article presents a comprehensive review of the existing literature to investigate the association between bipolar disorder and Parkinson's disease, focusing on the dopaminergic hypothesis and potential therapeutic options. The dopaminergic hypothesis suggests that both bipolar disorder and Parkinson's disease involve impairments in the nigrostriatal or mesolimbic dopaminergic pathways. Studies have demonstrated alterations in dopamine regulation during manic and depressive phases of bipolar disorder. Similarly, Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra, resulting in motor symptoms. Recent analyses have highlighted a predisposition to Parkinson's disease in individuals with bipolar disorder. Longitudinal studies and meta-analyses have demonstrated an increased risk of developing Parkinson's disease in patients with bipolar disorder. However, differentiating idiopathic Parkinson's disease from parkinsonism induced by medications used in bipolar disorder can be challenging. Dopamine transporter (DAT) scans can aid in making a differential diagnosis. Treatment options for patients with both bipolar disorder and Parkinson's disease are limited. Neuroleptics, commonly used to manage psychotic symptoms in Parkinson's disease, may worsen motor symptoms and have limitations in bipolar disorder patients. Clozapine has shown efficacy in treating psychosis without worsening motor symptoms. Pimavanserin, an inverse agonist of the 5-HT2A receptor can offer new opportunities. However, its efficacy in bipolar disorder patients with Parkinson's disease remains unexplored. In conclusion, the association between bipolar disorder and Parkinson's disease is supported by the involvement of the dopaminergic system in both conditions. The identification of shared mechanisms opens new avenues for potential therapeutic interventions. Further research is needed to investigate the efficacy of pimavanserin and explore other treatment options for individuals with both bipolar disorder and Parkinson's disease.
Topics: Humans; Parkinson Disease; Bipolar Disorder; Drug Inverse Agonism; Piperidines; Dopamine
PubMed: 37800205
DOI: No ID Found -
Current Biology : CB Sep 2023During central nervous system (CNS) development, a precisely patterned vasculature emerges to support CNS function. How neurons control angiogenesis is not well...
During central nervous system (CNS) development, a precisely patterned vasculature emerges to support CNS function. How neurons control angiogenesis is not well understood. Here, we show that the neuromodulator dopamine restricts vascular development in the retina via temporally limited production by an unexpected neuron subset. Our genetic and pharmacological experiments demonstrate that elevating dopamine levels inhibits tip-cell sprouting and vessel growth, whereas reducing dopamine production by all retina neurons increases growth. Dopamine production by canonical dopaminergic amacrine interneurons is dispensable for these events. Instead, we found that temporally restricted dopamine production by retinal ganglion cells (RGCs) modulates vascular development. RGCs produce dopamine precisely during angiogenic periods. Genetically limiting dopamine production by ganglion cells, but not amacrines, decreases angiogenesis. Conversely, elevating ganglion-cell-derived dopamine production inhibits early vessel growth. These vasculature outcomes occur downstream of vascular endothelial growth factor receptor (VEGFR) activation and Notch-Jagged1 signaling. Jagged1 is increased and subsequently inhibits Notch signaling when ganglion cell dopamine production is reduced. Our findings demonstrate that dopaminergic neural activity from a small neuron subset functions upstream of VEGFR to serve as developmental timing cue that regulates vessel growth.
Topics: Dopamine; Vascular Endothelial Growth Factor A; Retina; Retinal Ganglion Cells; Signal Transduction
PubMed: 37572663
DOI: 10.1016/j.cub.2023.07.040 -
Science Advances Aug 2023Dopamine is broadly implicated in reinforcement learning, but how patterns of dopamine activity are generated is poorly resolved. Here, we demonstrate that two ion...
Dopamine is broadly implicated in reinforcement learning, but how patterns of dopamine activity are generated is poorly resolved. Here, we demonstrate that two ion channels, Kv4.3 and BKCa1.1, regulate the pattern of dopamine neuron firing and dopamine release on different time scales to influence separate phases of reinforced behavior in mice. Inactivation of Kv4.3 in VTA dopamine neurons increases ex vivo pacemaker activity and excitability that is associated with increased in vivo firing rate and ramping dynamics before lever press in a learned instrumental paradigm. Loss of Kv4.3 enhances performance of the learned response and facilitates extinction. In contrast, loss of BKCa1.1 increases burst firing and phasic dopamine release that enhances learning of an instrumental response and enhances extinction burst lever pressing in early extinction that is associated with a greater change in activity between reinforced and unreinforced actions. These data demonstrate that disruption of intrinsic regulators of neuronal activity differentially affects dopamine dynamics during reinforcement and extinction learning.
Topics: Mice; Animals; Dopaminergic Neurons; Dopamine; Reinforcement, Psychology; Learning; Ion Channels
PubMed: 37566654
DOI: 10.1126/sciadv.adg8869 -
Advances in Pharmacology (San Diego,... 2024The availability of monoamine neurotransmitters in the brain is under the control of dopamine, norepinephrine, and serotonin transporters expressed on the plasma... (Review)
Review
The availability of monoamine neurotransmitters in the brain is under the control of dopamine, norepinephrine, and serotonin transporters expressed on the plasma membrane of monoaminergic neurons. By regulating transmitter levels these proteins mediate crucial functions including cognition, attention, and reward, and dysregulation of their activity is linked to mood and psychiatric disorders of these systems. Amphetamine-based transporter substrates stimulate non-exocytotic transmitter efflux that induces psychomotor stimulation, addiction, altered mood, hallucinations, and psychosis, thus constituting a major component of drug neurochemical and behavioral outcomes. Efflux is under the control of transporter post-translational modifications that synergize with other regulatory events, and this review will summarize our knowledge of these processes and their role in drug mechanisms.
Topics: Humans; Amphetamine; Biological Transport; Dopamine; Neurotransmitter Agents; Protein Processing, Post-Translational
PubMed: 38467478
DOI: 10.1016/bs.apha.2023.10.003