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EMBO Molecular Medicine Mar 2023Tyrosine hydroxylase deficiency (THD) is a rare genetic disorder leading to dopaminergic depletion and early-onset Parkinsonism. Affected children present with either a...
Tyrosine hydroxylase deficiency (THD) is a rare genetic disorder leading to dopaminergic depletion and early-onset Parkinsonism. Affected children present with either a severe form that does not respond to L-Dopa treatment (THD-B) or a milder L-Dopa responsive form (THD-A). We generated induced pluripotent stem cells (iPSCs) from THD patients that were differentiated into dopaminergic neurons (DAn) and compared with control-DAn from healthy individuals and gene-corrected isogenic controls. Consistent with patients, THD iPSC-DAn displayed lower levels of DA metabolites and reduced TH expression, when compared to controls. Moreover, THD iPSC-DAn showed abnormal morphology, including reduced total neurite length and neurite arborization defects, which were not evident in DAn differentiated from control-iPSC. Treatment of THD-iPSC-DAn with L-Dopa rescued the neuronal defects and disease phenotype only in THDA-DAn. Interestingly, L-Dopa treatment at the stage of neuronal precursors could prevent the alterations in THDB-iPSC-DAn, thus suggesting the existence of a critical developmental window in THD. Our iPSC-based model recapitulates THD disease phenotypes and response to treatment, representing a promising tool for investigating pathogenic mechanisms, drug screening, and personalized management.
Topics: Dopaminergic Neurons; Induced Pluripotent Stem Cells; Levodopa; Phenotype; Humans
PubMed: 36740977
DOI: 10.15252/emmm.202215847 -
Cellular and Molecular Neurobiology Aug 2023Parkinson's disease (PD) is one of the most common degenerative brain disorders caused by the loss of dopaminergic neurons in the substantia nigra (SN). Lewy bodies and... (Review)
Review
Parkinson's disease (PD) is one of the most common degenerative brain disorders caused by the loss of dopaminergic neurons in the substantia nigra (SN). Lewy bodies and -synuclein accumulation in the SN are hallmarks of the neuropathology of PD. Due to lifestyle changes and prolonged L-dopa administration, patients with PD frequently have vitamin deficiencies, especially folate, vitamin B6, and vitamin B12. These disorders augment circulating levels of Homocysteine with the development of hyperhomocysteinemia, which may contribute to the pathogenesis of PD. Therefore, this review aimed to ascertain if hyperhomocysteinemia may play a part in oxidative and inflammatory signaling pathways that contribute to PD development. Hyperhomocysteinemia is implicated in the pathogenesis of neurodegenerative disorders, including PD. Hyperhomocysteinemia triggers the development and progression of PD by different mechanisms, including oxidative stress, mitochondrial dysfunction, apoptosis, and endothelial dysfunction. Particularly, the progression of PD is linked with high inflammatory changes and systemic inflammatory disorders. Hyperhomocysteinemia induces immune activation and oxidative stress. In turn, activated immune response promotes the development and progression of hyperhomocysteinemia. Therefore, hyperhomocysteinemia-induced immunoinflammatory disorders and abnormal immune response may aggravate abnormal immunoinflammatory in PD, leading to more progression of PD severity. Also, inflammatory signaling pathways like nuclear factor kappa B (NF-κB) and nod-like receptor pyrin 3 (NLRP3) inflammasome and other signaling pathways are intricate in the pathogenesis of PD. In conclusion, hyperhomocysteinemia is involved in the development and progression of PD neuropathology either directly via induction degeneration of dopaminergic neurons or indirectly via activation of inflammatory signaling pathways.
Topics: Humans; Parkinson Disease; Hyperhomocysteinemia; Levodopa; Substantia Nigra; Neurodegenerative Diseases; Dopaminergic Neurons
PubMed: 37074484
DOI: 10.1007/s10571-023-01350-8 -
The Journal of Physiology Oct 2021In newborn rats, L-DOPA increases the occurrence of air-stepping activity without affecting movement characteristics. L-DOPA administration increases the spinal content...
KEY POINTS
In newborn rats, L-DOPA increases the occurrence of air-stepping activity without affecting movement characteristics. L-DOPA administration increases the spinal content of dopamine in a dose-dependent manner. Injection of 5-HTP increases the spinal serotonin content but does not trigger air-stepping. 5-HTP counteracts the pro-locomotor action of L-DOPA. Less dopamine and serotonin are synthesized when L-DOPA and 5-HTP are administered as a cocktail.
ABSTRACT
The catecholamine precursor, L-3,4-dihydroxyphenylalanine (L-DOPA), is a well-established pharmacological agent for promoting locomotor action in vertebrates, including triggering air-stepping activities in the neonatal rat. Serotonin is also a well-known neuromodulator of the rodent spinal locomotor networks. Here, using kinematic analysis, we compared locomotor-related activities expressed by newborn rats in response to varying doses of L-DOPA and the serotonin precursor 5-hydroxytryptophan (5-HTP) administered separately or in combination. L-DOPA alone triggered episodes of air-stepping in a dose-dependent manner (25-100 mg/kg), notably determining the duration of locomotor episodes, but without affecting step cycle frequency or amplitude. In contrast, 5-HTP (25-150 mg/kg) was ineffective in instigating air-stepping, but altered episode durations of L-DOPA-induced air-stepping, and decreased locomotor cycle frequency. High performance liquid chromatography revealed that L-DOPA, which was undetectable in control conditions, accumulated in a dose-dependent manner in the lumbar spinal cord 30 min after its administration. This was paralleled by an increase in dopamine levels, whereas the spinal content of noradrenaline and serotonin remained unaffected. In the same way, the spinal levels of serotonin increased in parallel with the dose of 5-HTP without affecting the levels of dopamine and noradrenaline. When both precursors are administrated, they counteract each other for the production of serotonin and dopamine. Our data thus indicate for the first time that both L-DOPA and 5-HTP exert opposing neuromodulatory actions on air-stepping behaviour in the developing rat, and we speculate that competition for the production of dopamine and serotonin occurs when they are administered as a cocktail.
Topics: 5-Hydroxytryptophan; Animals; Animals, Newborn; Dopamine; Levodopa; Rats; Serotonin
PubMed: 34411301
DOI: 10.1113/JP281983 -
Cerebellum (London, England) Oct 2023Multiple system atrophy (MSA) is a rare, adult-onset, progressive neurodegenerative disorder with major diagnostic challenges. Aiming for a better diagnostic accuracy... (Review)
Review
Multiple system atrophy (MSA) is a rare, adult-onset, progressive neurodegenerative disorder with major diagnostic challenges. Aiming for a better diagnostic accuracy particularly at early disease stages, novel Movement Disorder Society criteria for the diagnosis of MSA (MDS MSA criteria) have been recently developed. They introduce a neuropathologically established MSA category and three levels of clinical diagnostic certainty including clinically established MSA, clinically probable MSA, and the research category of possible prodromal MSA. The diagnosis of clinically established and clinically probable MSA is based on the presence of cardiovascular or urological autonomic failure, parkinsonism (poorly L-Dopa-responsive for the diagnosis of clinically established MSA), and cerebellar syndrome. These core clinical features need to be associated with supportive motor and non-motor features (MSA red flags) and absence of any exclusion criteria. Characteristic brain MRI markers are required for a diagnosis of clinically established MSA. A research category of possible prodromal MSA is devised to capture patients manifesting with autonomic failure or REM sleep behavior disorder and only mild motor signs at the earliest disease stage. There is a number of promising laboratory markers for MSA that may help increase the overall clinical diagnostic accuracy. In this review, we will discuss the core and supportive clinical features for a diagnosis of MSA in light of the new MDS MSA criteria, which laboratory tools may assist in the clinical diagnosis and which major differential diagnostic challenges should be borne in mind.
Topics: Adult; Humans; Multiple System Atrophy; Diagnosis, Differential; Parkinsonian Disorders; Magnetic Resonance Imaging; Levodopa
PubMed: 35986227
DOI: 10.1007/s12311-022-01453-w -
Archives of Razi Institute Apr 2023Phenylalanine (PHE) is an essential amino acid. Dietary PHE converts to tyrosine by phenylalanine hydroxylase (PAH) activity. Phenylketonuria (PKU) is an...
Phenylalanine (PHE) is an essential amino acid. Dietary PHE converts to tyrosine by phenylalanine hydroxylase (PAH) activity. Phenylketonuria (PKU) is an autosomal-recessive disorder resulting from PAH enzyme deficiency. Elevations of PHE in plasma are classified based on the degree of enzyme deficiency into classic PKU (PHE≥1200 μmol/l), mild PKU (PHE>600 μmol/l and <1200 μmol/l), and non-PKU-hyperphenylalaninemia (HPA) or mild hyperphenylalaninemia (MHP) (PHE≤600 μmol/l). This is a single-center study of consecutive patients managed at the Pediatric Neurology Department and the outpatient clinic at Children's Welfare Teaching Hospital, Medical City, Baghdad, Iraq, from the 1st of October 2019 to the 1st of October 2020. Five patients were selected who were proven to have non-PKU-HPA (PHE<600 µmol/L) confirmed by the high-performance liquid chromatography analysis and assured to have sapropterin response by the sapropterin loading test which showed >30% decrease in PHE level. All patients presented with a neurological complaint, they were between three months and 15 years, and they were treated with sapropterin, Levodopa (L-Dopa), and 5-hydroxytryptamine (5-HT). The study included the demographic and clinical profile, biochemical response to sapropterin, and clinical response to treatment according to the development quotient. The five patients enrolled in this study had a gross motor developmental delay as their main symptom. One case also had a seizure and dystonia, another had a fluctuation of symptoms, four had a consanguineous marriage, and two had a family history of the same condition. Moreover, all cases had a higher than 30% decrease in PHE level by the tetrahydrobiopterin (BH4) loading test, and all of them showed significant clinical improvements after treatment except for one that showed only a moderate improvement. The BH4 therapy significantly enhanced dietary PHE tolerance and permitted a PHE-free medical formula to be discontinued in all patients with PHE within an achieved therapeutic target (120-300 μM]. MHP is not a mild disease as it may be related to neurotransmitter disorders. Sapropterin, L-DOPA, and 5-HT are always used for patients suspected of having neurotransmitter diseases, particularly those with MHP.
Topics: Child; Humans; Levodopa; Serotonin; Phenylketonurias; Diet; Phenylalanine
PubMed: 37396747
DOI: 10.22092/ARI.2022.359480.2431 -
Inorganic Chemistry Jul 2022Gold nanoparticles (AuNPs) have found applications in biomedicine as diagnostic tools, but extensive research efforts have been also directed toward their development as...
Gold nanoparticles (AuNPs) have found applications in biomedicine as diagnostic tools, but extensive research efforts have been also directed toward their development as more efficient drug delivery agents. The high specific surface area of AuNPs may provide dense loading of molecules like catechols (L-DOPA and dopamine) on nanosurfaces, enabling functionalization strategies for advancing conventional therapy and diagnostic approaches of neurodegenerative diseases. Despite numerous well-described procedures in the literature for preparation of different AuNPs, possible transformation and structural changes of surface functionalization agents have not been considered thoroughly. As a case in point, the catechols L-DOPA and dopamine were selected because of their susceptibility to oxidation, cyclization, and polymerization. To assess the fate of coating and functionalization agents during the preparation of AuNPs or interaction at the nano-bio interface, a combination of spectroscopy, light scattering, and microscopy techniques was used while structural information and reaction mechanism were obtained by NMR in combination with computational tools. The results revealed that the final form of catechol on the AuNP nanosurface depends on the molar ratio of Au used for AuNP preparation. A large molar excess of L-DOPA or dopamine is needed to prepare AuNPs funtionalized with fully reduced catechols. In the case of molar excess of Au, the oxidation of catechols to dopamine quinone and dopaquinone was promoted, and dopaquinone underwent intramolecular cyclization in which additional oxidation products, leukodopachrome, dopachrome, or its tautomer, were formed because of the larger intrinsic acidity of the more nucleophilic amino group in dopaquinone. MD simulations showed that, of the oxidation products, dopachrome had the highest affinity for binding to the AuNPs surface. The results highlight how a more versatile methodological approach, combining experimental and techniques, allows more reliable characterization of binding events at the surface of AuNPs for possible applications in biomedicine.
Topics: Catechols; Dopamine; Gold; Levodopa; Metal Nanoparticles
PubMed: 35785790
DOI: 10.1021/acs.inorgchem.2c00996 -
Journal of Pharmacological Sciences Jul 2023Methylphenidate (MPH) and methamphetamine (METH) are the current treatments of choice for attention deficit/hyperactivity disorder. We previously reported that METH...
Methylphenidate (MPH) and methamphetamine (METH) are the current treatments of choice for attention deficit/hyperactivity disorder. We previously reported that METH induces the release of dopamine (DA) and of the neurotransmitter candidate L-3,4-dihydroxyphenylalanine (L-DOPA). In contrast, we here found that MPH increased the DA release while it did not affect the L-DOPA release from the dorsolateral striatum. Nevertheless, MPH-induced hyperlocomotion was reduced in Gpr143 (L-DOPA receptor) gene-deficient (Gpr143) mice. The rewarding effect and increased c-fos expression induced by MPH were also attenuated in Gpr143 mice. Together, these findings suggest that GPR143 is involved in the acute and chronic actions of MPH.
Topics: Mice; Animals; Methylphenidate; Levodopa; Receptors, Neurotransmitter; Dopamine; Methamphetamine; Central Nervous System Stimulants
PubMed: 37257945
DOI: 10.1016/j.jphs.2023.04.006 -
Experimental Neurology May 2022Gamma oscillations comprise a loosely defined, heterogeneous group of functionally different activities between 30 and 100 Hz in the cortical and subcortical local... (Review)
Review
Gamma oscillations comprise a loosely defined, heterogeneous group of functionally different activities between 30 and 100 Hz in the cortical and subcortical local field potential (LFP) of the motor network. Two distinct patterns seem to emerge which are easily conflated: Finely-tuned gamma (FTG) oscillations - a narrowband activity with peaks between 60 and 90 Hz - have been observed in multiple movement disorders and are induced by dopaminergic medication or deep brain stimulation (DBS). FTG has been linked with levodopa or DBS-induced dyskinesias, which makes it a putative biomarker for adaptive DBS. On the other hand, gamma activity can also present as a broad phenomenon (30-100 Hz) in the context of motor activation and dynamic processing. Here, we contrast FTG, either levodopa-induced or DBS-induced, from movement-related broadband gamma synchronisation and further elaborate on the functional role of FTG and its potential implications for adaptive DBS. Given the unclear distinction of FTG and broad gamma in literature, we appeal for more careful separation of the two. To better characterise cortical and subcortical FTG as biomarkers for dyskinesia, their sensitivity and specificity need to be investigated in a large clinical trial.
Topics: Deep Brain Stimulation; Dyskinesias; Humans; Levodopa
PubMed: 35143832
DOI: 10.1016/j.expneurol.2022.113999 -
Journal of Neural Transmission (Vienna,... Nov 2023Dopamine was initially considered as a mere intermediate in the noradrenaline synthesis but was then found to be a neurotransmitter. Its depletion resulted in... (Review)
Review
Dopamine was initially considered as a mere intermediate in the noradrenaline synthesis but was then found to be a neurotransmitter. Its depletion resulted in characteristic symptoms in experimental studies and could be antagonized by DOPA (3,4-dihydroxyphenylalanin), suggesting a similarity to the human disorder Parkinson´s disease (PD) and a therapeutic potential which was successfully exploited from the 1970s on. This was due to the pioneering work of Arvid Carlsson and clinicians around the world who first worked on the breakthrough of L-DOPA therapy and then on its amendment and modification and on alternative therapies for PD patients. All these developments led to the establishment of PD therapy as we know it today. It is characterized by the availability of many different compounds which are mostly employed in combination and by different methods: orally, intravenously, transdermally, subcutaneously, or duodenally. Here, we present without claim of completeness some personal reflections about causal drug developments for PD patients and reflect on some personal interactions with leading clinicians and basic researchers who cooperated with us. Such interactions are crucial for the creation, sometimes serendipitously, of fresh ideas and to further develop existing concepts to make therapeutical progress.
Topics: Humans; Levodopa; Parkinson Disease; Antiparkinson Agents; Berlin; Dopamine
PubMed: 37796288
DOI: 10.1007/s00702-023-02692-9 -
EBioMedicine Sep 2017
Topics: Brain; Glucagon-Like Peptide-1 Receptor; Humans; Levodopa; Mitochondria; Parkinson Disease; T-Lymphocytes, Cytotoxic; alpha-Synuclein
PubMed: 28919144
DOI: 10.1016/j.ebiom.2017.09.009