Increased Dopamine Levels Research Articles

The Gut Microbiome Regulates the Psychomotor Effects and Context-Dependent Rewarding Responses to Cocaine in Germ-Free and Antibiotic-Treated Animal Models.

Cocaine use disorder remains a major global health concern, with growing evidence that the gut microbiome modulates drug-related behaviors. This study examines the microbiome's role in cocaine-induced psychomotor activation and context-dependent reward responses using germ-free (GF) and antibiotic-treated (ABX) models. In GF mice, the absence of a microbiome blunted cocaine-induced psychomotor activation (p = 0.013), which was restored after conventionalization. GF mice also showed reduced cocaine-conditioned place preference (CPP) (p = 0.002), which normalized after conventionalization. Dopaminergic function, critical for psychomotor responses and reward, was microbiome-dependent, with increased dopamine levels (p = 0.009) and normalized turnover ratios after conventionalization. In the ABX model, microbiome depletion reduced both cocaine-induced locomotion and CPP responses (p ≤ 0.009), further supporting the role of gut microbes in modulating psychomotor and reward behaviors. ABX-treated mice also showed significant declines in microbial diversity, shifts in bacterial structure, and dysregulation in metabolic, immune, and neurotransmitter pathways (p ≤ 0.0001), including alterations in short-chain fatty acids and gamma-aminobutyric acid metabolism. These findings highlight the gut microbiome's critical role in regulating cocaine's psychomotor and rewarding effects, offering insights into potential therapeutic strategies for cocaine use disorder.

Tribuli Fructus alleviates 1-methyl-4-phenyl 1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease by suppressing neuroinflammation via JNK signaling.

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons. In particular, neuroinflammation associated with phosphorylation of c-Jun N-terminal kinase (JNK) is likely to cause the death of dopaminergic neurons. Therefore, protecting dopaminergic neurons through anti-neuroinflammation is a promising therapeutic strategy for PD. This study investigated whether Tribuli Fructus (TF) could alleviate PD by inhibiting neuroinflammation. Mouse primary mixed glial culture cells from the mouse cortex were treated with lipopolysaccharide (LPS) to induce neuroinflammation, and 1h later, cells were treated with TF. 1-methyl-4-phenyl 1,2,3,6-tetrahydropyridine (MPTP) was injected into C57BL/6J mice for 5 days, and TF was co and post-administered for 12 days. Our study showed that TF attenuated pro-inflammatory mediators and cytokines in LPS-stimulated primary mixed glial cultures. In the brains of MPTP-induced PD mouse model, TF inhibited the activation of microglia and astrocytes, protected dopaminergic neurons, and increased dopamine levels. TF alleviated MPTP-induced bradykinesia, a representative behavioral disorder in PD. In addition, the results in vitro and in vivo revealed that TF regulates the phosphorylation of JNK. Collectively, our data suggest that TF may be a new therapeutic candidate for PD by regulating JNK signaling.

The Impact of Dexamphetamine Treatment for Obesity on Executive Function: A Double-Blind Randomised Controlled Pilot Study.

Amphetamines increase dopamine levels in mid-brain regions which, in turn, impact top-down executive function. Repeated exposure is linked to substance use disorders. Nonetheless, amphetamines are used to manage attention-deficit/hyperactivity disorder (ADHD) and eating-related disorders. In ADHD, amphetamines upregulate a system characterised by low dopaminergic tone, assisting to improve executive function. A similar process might be at play with eating disorders; however, the effect of amphetamine treatment on executive function in this case has not been thoroughly considered. Participants (N = 52, Mage = 47.06, SD = 12.29) with a body mass index of 25-60 were randomised to treatment (6-week dexamphetamine titration) or control (placebo) groups. They completed an executive function measure-Barkley Deficits in Executive Functioning Scale (BDEFS-SF)-and response inhibition task-Stop-Signal Task (SST)-at Baseline, throughout titration, at Maintenance, and at Follow-up. Mixed effects models examined whether BDEFS-SF score or the SST variable, stop-signal reaction time (SSRT), changed across sessions as a function of treatment. There was no effect of group (p = 0.440), but an effect of session (p = 0.024) on BDEFS-SF, with scores at Time 2 (p = 0.011, 95% CI [0.47, 3.49]) and Maintenance (p = 0.022, 95% CI [-4.89, -0.39]), respectively, higher and lower than other timepoints. There was no group by session interaction (p = 0.659). R2 (conditional) = 0.74; ICC = 0.73. There was an effect of group (p = 0.039) and session (p < 0.001) on SSRT, but no interaction (p = 0.707). Baseline SSRT was significantly longer than the mean of all subsequent timepoints (p < 0.001, 95% CI [16.29, 33.84]). R2 (conditional) = 0.47; ICC = 0.39. There was no discernible impact of amphetamine treatment for obesity on executive function. Our results suggest some variation related to sample size and/or practice effects. Thus, while treatment appears unlikely to render individuals susceptible to substance use disorders, parallels with ADHD might be overstated.

Potential of soybean-velvet bean combination tempe in improving cognitive function.

Velvet bean is a native Indonesian legume containing L-dopa, yet it remains underutilized. The aim of this study was to analyze the effects of different types of tempe (soybean, velvet bean, and their combination) on cognitive function, brain histology, dopamine levels, and serum β-amyloid in rats, as well as to identify the parameters most influencing cognitive function, including brain mass and volume, hippocampal neuron count, and dopamine and β-amyloid levels. An experimental study was conducted using a completely randomized design with one factor: the protein source of diet. Five rat groups were included based on protein sources: non-protein, casein control, soybean tempe flour, velvet bean tempe flour, and a combination of soybean and velvet bean tempe flour. This study examined cognitive performance by measuring maze completion time, while brain mass and volume, hippocampus histology for neuron cell counts in the dentate gyrus section, cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3), brain dopamine and β- amyloid serum levels were measured after eight weeks of intervention. Our data indicated that rats deprived of protein had significantly slower maze completion times (p < 0.001), underscoring the importance of protein in cognitive processes. Rats treated with non- protein rations had significantly lighter brain masses (p < 0.001) than other treatments. Histological analysis of the hippocampus showed that the three types of tempe rations helped maintain the number and density of neuron cells in the dentate gyrus and CA3 of the hippocampus. Additionally, the protein in the ration could increase dopamine levels and suppress serum β-amyloid levels. There was a strong correlation between brain volume and neuron cell density in the dentate gyrus section of the hippocampus with cognitive function. These results highlight the promising role of combination tempe in increasing cognitive function, brain mass and volume, dopamine levels, and suppressing serum β-amyloid.

N-tert-butoxycarbonyl-methylenedioxymethamphetamine, an methylenedioxymethamphetamine derivative, exhibits rewarding and reinforcing effects by increasing dopamine levels.

An N-protected methylenedioxymethamphetamine (MDMA), N-tert-butoxycarbonyl-3,4-methylenedioxymethamphetamine (t-BOC-3,4-MDMA), contains tert-butoxycarbonyl and can remain undetected in the illicit drug market. It is a new type of precursor substance that is not a chemical intermediate and can be converted into a controlled substance, MDMA, by deprotection of the N-tert-butoxycarbonyl group. Categorization of this chemical into a precursor or psychotropic substance is an issue because it is an unprecedented precursor that could have misuse potential. Although MDMA causes rewarding and reinforcing effect through dopaminergic transmission, the misuse potential of t-BOC-3,4-MDMA has not yet been characterized. Here, we aim to evaluate the misuse potential of t-BOC-3,4-MDMA. The response to the drug at a dose of 5 mg/kg was determined by a climbing test, and its rewarding and reinforcing properties were assessed through conditioned place preference and self-administration tests. In the conditioned place preference test, intraperitoneal administration of t-BOC-3,4-MDMA (5 mg/kg) significantly altered place preference in mice. In the self-administration models, t-BOC-3,4-MDMA induced drug-taking behavior at the dose of 0.5 mg/kg/infusion (intravenous) during 2 hr sessions under fixed-ratio schedules in mice. In addition, microdialysis experiments verified that t-BOC-3,4-MDMA impacted the dopamine levels of the brain (striatum) of rats. These experimental results indicate that t-BOC-3,4-MDMA has a potential for misuse. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Dopamine Regulates Its Own Synthesis via MdORG2 to Improve Low-Nitrogen Tolerance in Apple Plants.

Nitrogen (N) is crucial for plant growth and development. Exogenous dopamine has been shown to improve the N-deficiency tolerance of apple. However, the potential regulatory mechanisms by which dopamine mitigates low-N stress remain unclear. Our data indicated that the dopamine levels in apple (Malus domestica) were elevated by the overexpression (OE) of MdTYDC, which encodes tyrosine decarboxylase, a key enzyme in dopamine biosynthesis. The photosynthetic capacity of the OE lines was enhanced, and the root system was more extensive under low-N stress compared with the wild-type (WT) plants. This enhancement contributed to a greater net nitrate influx at the root surface in the OE lines compared with the WT. Transcriptomic and carbohydrate analyses suggested that the OE of MdTYDC in apple enhanced N-deficiency tolerance by promoting the expression of carbohydrate-related genes, which increased the content of soluble sugars and sorbitol. Both exogenous dopamine and MdTYDC OE activated the expression of MdORG2 (a bHLH transcription factor), which, in turn, directly binds to the promoter of MdTYDC, activating its expression, increasing dopamine levels, and consequently conferring strong low-N tolerance in apple. Thus, this reveals the molecular pathways by which dopamine regulates low-N tolerance in apple through pathways involving MdTYDC and MdORG2.

Microdialysis-integrated HPLC system with dual-electrode detection using track-etched membrane electrodes for in vivo monitoring of dopamine dynamics

A capillary high-performance liquid chromatography (HPLC) system equipped with a dual-electrode detector utilizing track-etched membrane electrodes (TEMEs) was combined with a microdialysis sampling setup. The electrochemical detector benefits from the high electrolysis efficiency of TEMEs, allowing for calibration-free coulometric detection and simplifying data analysis to determine the dopamine recovery through a dialysis probe. Additionally, this system was used for in vivo monitoring of dopamine in the right striatum of a mouse brain. Temporal changes in dopamine levels, including an exponential decay immediately after the dialysis probe insertion and an excess release of dopamine induced by a high concentration of potassium ions, confirmed the system’s proper operation. Furthermore, subsequent measurements following the intraperitoneal injection of mirtazapine showed no increase in dopamine levels in the right dorsal striatum. The dual-electrode system displayed characteristic dopamine detection behavior, with anodic and cathodic peak pairs indicative of reversible electrochemical reactions. This capability facilitated the identification of the dopamine peak within the complex chromatogram of the mouse brain dialysate. The consistency between dopamine collection efficiency from standard solutions and dialysate indicated the absence of interfering electroactive substances overlapping with the dopamine peak in the chromatogram. This integrated analysis system successfully tracked temporal fluctuations in dopamine concentration within the mouse brain.

How to optimise medicines management for people with Parkinson's disease in hospital.

Hospital admissions can be challenging for people with Parkinson's disease, in part because of the lack of understanding, among some healthcare professionals, of the importance of administering antiparkinsonian medicines on time. This article outlines the steps that nurses can take to optimise medicines management for people with Parkinson's disease who are admitted to hospital. • Pharmacotherapy is the primary treatment for Parkinson's disease and aims to increase dopamine levels in the brain to relieve symptoms. • People with Parkinson's disease require careful administration, titration, adjustment and monitoring of their antiparkinsonian medicines regimen, which is highly individualised. • It is crucial that people with Parkinson's disease take their antiparkinsonian medicines at exactly the right time, since the inaccurate timing of these medicines can have significant adverse health implications. REFLECTIVE ACTIVITY: 'How to' articles can help to update your practice and ensure it remains evidence-based. Apply this article to your practice. Reflect on and write a short account of: • How this article might improve your practice when undertaking medicines management for people with Parkinson's disease in hospital. • How you could use this information to educate nursing students or your colleagues on optimising medicines management for people with Parkinson's disease in hospital.

Evaluation of (S)-T1 and (S)-T2 ligands targeting α3β4 nAChR as potential nicotine addiction pharmacotherapy.

Substance use disorders (SUDs) represent a significant global health concern, demanding the development of effective pharmacological treatments. To address this, an investigation was conducted to examine the anti-addictive properties of two compounds, (S)-T1 and (S)-T2, which specifically target the α3β4 nicotinic acetylcholine receptor (nAChR). The effects of (S)-T1 and (S)-T2 on nicotine-induced conditioned place preference (CPP), locomotor activity and dopamine levels in particular brain regions associated to addiction were investigated and compared in male C57BL/6N mice. The results demonstrate that neither (S)-T1 nor (S)-T2 induced place conditioning or conditioned place aversion (CPA), suggesting the absence of rewarding or aversive effects. Both compounds significantly attenuated nicotine-induced CPP, with (S)-T1 exhibiting a dose-dependent effect. Furthermore, the co-administration of (S)-T2 (10mg/kg) with nicotine markedly reduced locomotor activity compared to nicotine treatment alone. Additionally, dopamine analysis revealed that nicotine increased dopamine levels in the nucleus accumbens (NAc) and dorsal striatum, whereas the co-administration of (S)-T1 (1, 3, and 10mg/kg) and (S)-T2 (10mg/kg) significantly decreased dopamine levels in these brain regions. No significant effects were observed in the prefrontal cortex (PFC). These findings suggest that (S)-T1 and (S)-T2 hold promise for treating nicotine addiction by attenuating nicotine-induced CPP and modulating dopamine release in key reward-related brain regions. Further research is needed to gain insights into the underlying mechanisms behind their anti-addictive effects and substantiate their potential for treating nicotine addiction.

Efficient application of Pyrosin B for nano-gram level assay of antiparkinsonian medication, rasagiline: Evaluation of tablets and content uniformity.

Rasagiline (RAS) is a medication for Parkinson's disease that increases dopamine levels in the brain by inhibiting monoamine oxidase, helping to alleviate symptoms. The proposed study aims to develop an efficient, feasible, and sensitive method for RAS assay, utilizing Pyrosin B dye, a convenient fluorescent ligand. Combining the RAS analyte with Pyrosin B ligand in a mildly acidic buffered solution rapidly quenches the native fluorescence of the ligand. This quenching results from the formation of a specific ion-dipole association complex between the lone pair-bearing atoms of the ligand and the protonated amine moiety of RAS, highlighting their interactive chemistry under these conditions. The degree of this interaction demonstrated superior sensitivity compared with reported alternatives, exhibiting a linear range of 50.0 to 1000.0ng/mL. The method is characterized by a limit of detection (LOD) of 16.0ng/mL and a limit of quantification (LOQ) of 48.0ng/mL. By optimizing the RAS-Pyrosin B system, the variable parameters were finely tuned, ensuring the assay method's reliability. The method's accuracy, precision, selectivity, and robustness were validated according to International Council for Harmonization (ICH) guidelines, enabling precise and efficient analysis of RAS in the nanogram range. This method streamlines the analysis procedure and reduces environmental impact, making it a promising approach for the quality control of ParkintreatR tablets (1mg) and other analytical applications.

Subthalamic nucleus deep brain stimulation induces functional deficits in norepinephrinergic neurotransmission in a Parkinson’s disease model

BackgroundDeep brain stimulation of the subthalamic nucleus (STN-DBS) is a successful treatment option in Parkinson’s disease (PD) for different motor and non-motor symptoms, but has been linked to postoperative cognitive impairment. AimSince both dopaminergic and norepinephrinergic neurotransmissions play important roles in symptom development, we analysed STN-DBS effects on dopamine and norepinephrine availability in different brain regions and morphological alterations of catecholaminergic neurons in the 6-hydroxydopamine PD rat model. MethodsWe applied one week of continuous unilateral STN-DBS or sham stimulation, respectively, in groups of healthy and 6-hydroxydopamine-lesioned rats to quantify dopamine and norepinephrine contents in the striatum, olfactory bulb and dentate gyrus. In addition, we analysed dopaminergic cell counts in the substantia nigra pars compacta and area tegmentalis ventralis and norepinephrinergic neurons in the locus coeruleus after one and six weeks of STN-DBS. ResultsIn 6-hydroxydopamine-lesioned animals, one week of STN-DBS did not alter dopamine levels, while striatal norepinephrine levels were decreased. However, neither one nor six weeks of STN-DBS altered dopaminergic neuron numbers in the midbrain or norepinephrinergic neuron counts in the locus coeruleus. Dopaminergic fibre density in the dorsal and ventral striatum also remained unchanged after six weeks of STN-DBS. In healthy animals, one week of STN-DBS resulted in increased dopamine levels in the olfactory bulb and decreased contents in the dentate gyrus, but had no effects on norepinephrine availability. ConclusionsSTN-DBS modulates striatal norepinephrinergic neurotransmission in a PD rat model. Additional behavioural studies are required to investigate the functional impact of this finding.

An overview of the role of monoamine oxidase-B in Parkinson’s disease: implications for neurodegeneration and therapy

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by both non-motor and motor symptoms, due to the loss of dopamine-producing neurons in the brain. Monoamine oxidase-B (MAO-B) inhibitors are essential in the treatment of PD, as they increase dopamine levels and could potentially slow down the progression of the disease. MAO-B inhibitors block the ability of the enzyme to degrade dopamine in the brain. MAO-B inhibitors work by inhibiting this enzyme, which raises dopamine levels and helps reduce motor symptoms, such as akinesia and stiffness in the muscles. In addition to their impact on dopamine levels, MAO-B inhibitors may possess neuroprotective properties. Research indicates that these inhibitors can shield neurons from the harmful byproducts of dopamine breakdown, such as dihydroxy acetaldehyde and hydrogen peroxide. This neuroprotective effect could potentially slow the progression of PD and protect against neuronal damage. MAO-B inhibitors are effective in treating both advanced and early stages of PD. They are recommended as initial treatments for individuals with early PD and can also be used as supplementary therapy in advanced PD to assist in managing motor complications. Additionally, MAO-B inhibitors have shown promise for the treatment of non-motor symptoms of PD, such as fatigue and sleep disturbances. MAO-B inhibitors are an important class of drugs for the treatment of PD, offering both symptomatic relief and potential disease-modifying effects. The goal of ongoing research and development of MAO-B inhibitors is to enhance their safety and selectivity profiles, which could lead to improved treatment approaches for PD and other neurodegenerative disorders.

Crosstalk between gut-brain axis: unveiling the mysteries of gut ROS in progression of Parkinson's disease.

"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.

Drug Evaluation of Parkinson's Disease Patient-Derived Midbrain Organoids Using Mesoporous Au Nanodot-Patterned 3D Concave Electrode.

Brain organoids are being recognized as valuable tools for drug evaluation in neurodegenerative diseases due to their similarity to the human brain's structure and function. However, a critical challenge is the lack of selective and sensitive electrochemical sensing platforms to detect the response of brain organoids, particularly changes in the neurotransmitter concentration upon drug treatment. This study introduces a 3D concave electrode patterned with a mesoporous Au nanodot for the detection of electrochemical signals of dopamine in response to drugs in brain organoids for the first time. The mesoporous Au nanodot-patterned film was fabricated using laser interference lithography and electrochemical deposition. Then, the film was attached to a polymer-based 3D concave mold to obtain a 3D concave electrode. Midbrain organoids generated from Parkinson's disease (PD) patient-derived iPSCs with gene mutations (named as PD midbrain organoid) or normal midbrain organoids were positioned on the developed 3D concave electrode. The 3D concave electrode showed a 1.4 times higher electrochemical signal of dopamine compared to the bare gold electrode. And the dopamine secreted from normal midbrain organoids or PD midbrain organoids on the 3D concave electrode could be detected electrochemically. After the treatment of PD midbrain organoids with levodopa, the drug for PD, the increase in dopamine level was detected due to the activation of dopaminergic neurons by the drug. The results suggest the potential of the proposed 3D concave electrode combined with brain organoids as a useful tool for assessing drug efficacy. This sensing system can be applied to a variety of organoids for a comprehensive drug evaluation.

Navacaprant, a novel and selective kappa opioid receptor antagonist, has no agonist properties implicated in opioid-related abuse

Kappa opioid receptors (KORs) are implicated in the pathophysiology of various psychiatric and neurological disorders creating interest in targeting the KOR system for therapeutic purposes. Accordingly, navacaprant (NMRA-140) is a potent, selective KOR antagonist being evaluated as a treatment for major depressive disorder. In the present report, we have extended the pharmacological characterization of navacaprant by further demonstrating its selective KOR antagonist properties and confirming its lack of agonist activity at KORs and related targets involved in opioid-related abuse. Using CHO–K1 cells expressing human KOR, mu (MOR), or delta (DOR) opioid receptors, navacaprant demonstrated selective antagonist properties at KOR (IC50 = 0.029 μM) versus MOR (IC50 = 3.3 μM) and DOR (IC50 > 10 μM) in vitro. In vivo, navacaprant (10–30 mg/kg, i.p.) dose-dependently abolished KOR-agonist induced analgesia in the mouse tail-flick assay. Additionally, navacaprant (10, 30 mg/kg, p.o.) significantly reduced KOR agonist–stimulated prolactin release in mice and rats, confirming KOR antagonism in vivo. Navacaprant showed no agonist activity at any opioid receptor subtype (EC50 > 10 μM) in vitro and exhibited no analgesic effect in the tail-flick assays at doses ≤100 mg/kg, p.o. thereby confirming a lack of opioid receptor agonist activity in vivo. Importantly, navacaprant did not alter extracellular dopamine concentrations in the nucleus accumbens shell of freely-moving rats following doses ≤100 mg/kg, p.o., whereas morphine (10, 20 mg/kg, i.p.) significantly increased dopamine levels. These results demonstrate that navacaprant is a KOR-selective antagonist with no pharmacological properties implicated in opioid-related abuse.

Inhibition of GSDMD-dependent pyroptosis decreased methamphetamine self-administration in rats

It is widely believed that the activation of the central dopamine (DA) system is crucial to the rewarding effects of methamphetamine (METH) and to the behavioral outcomes of METH use disorder. It was reported that METH exposure induced gasdermin D (GSDMD)-dependent pyroptosis in rats. The membrane pore formation caused by METH-induced pyroptosis may also contribute to the overflow of DA into the extracellular space and subsequently increase the DA levels in the brain. The present study firstly investigated whether the membrane pore information induced by GSDMD-dependent pyroptosis was associated with the increased DA levels in the ventral tegmental area (VAT) and nucleus accumbens (NAc) of rats self-administering METH and SY-SH5Y cells treated by METH. Subsequently, the effect of pore formation blockade or genetic inhibition of GSDMD on the reinforcing and motivational effect of METH was determined in rats, using the animal model of METH self-administration (SA). METH exposure significantly increased the activity of NLRP1/Cas-1/GSDMD pathway and the presence of pyroptosis, accompanied by the significantly increased DA levels in VTA and NAc. Moreover, intraperitoneal injections of disulfiram (DSF) or microinjection of rAAV-shGSDMD into VTA/NAc significantly reduced the reinforcing and motivational effect of METH, accompanied by the decreased level of DA in VTA and NAc. The results provided novel evidence that METH-induced pyroptosis could increase DA release in VTA and NAc via the NLRP1/Cas-1/GSDMD pathway. Additionally, membrane pores or GSDMD blockade could significantly reduce the reinforcing and motivational effect of METH. In conclusion, blocking GSDMD and membrane pore formation could be a promising potential target for the development of agents to treat METH use disorder.

Chronic ultraviolet irradiation induces memory deficits via dysregulation of the dopamine pathway

The effects of ultraviolet (UV) radiation on brain function have previously been investigated; however, the specific neurotransmitter-mediated mechanisms responsible for UV radiation-induced neurobehavioral changes remain elusive. In this study, we aimed to explore the mechanisms underlying UV radiation-induced neurobehavioral changes. In a mouse model, we observed that UV irradiation of the skin induces deficits in hippocampal memory, synaptic plasticity, and adult neurogenesis, as well as increased dopamine levels in the skin, adrenal glands, and brain. Chronic UV exposure altered the expression of genes involved in dopaminergic neuron differentiation. Furthermore, chronic peripheral dopamine treatments resulted in memory deficits. Systemic administration of a dopamine D1/D5 receptor antagonist reversed changes in memory, synaptic plasticity, adult neurogenesis, and gene expression in UV-irradiated mice. Our findings provide converging evidence that chronic UV exposure alters dopamine levels in the central nervous system and peripheral organs, including the skin, which may underlie the observed neurobehavioral shifts, such as hippocampal memory deficits and impaired neurogenesis. This study underscores the importance of protection from UV exposure and introduces the potential of pharmacological approaches targeting dopamine receptors to counteract the adverse neurological impacts of UV exposure.

Dopamine β-hydroxylase shapes intestinal inflammation through modulating T cell activation

BackgroundInflammatory bowel disease (IBD) is a chronic and relapsing disease characterized by immune-mediated dysfunction of intestinal homeostasis. Alteration of the enteric nervous system and the subsequent neuro-immune interaction are thought to contribute to the initiation and progression of IBD. However, the role of dopamine beta-hydroxylase (DBH), an enzyme converting dopamine into norepinephrine, in modulating intestinal inflammation is not well defined. MethodsCD4+CD45RBhighT cell adoptive transfer, and 2,4-dinitrobenzene sulfonic acid (DNBS) or dextran sodium sulfate (DSS)-induced colitis were collectively conducted to uncover the effects of DBH inhibition by nepicastat, a DBH inhibitor, in mucosal ulceration, disease severity, and T cell function. ResultsInhibition of DBH by nepicastat triggered therapeutic effects on T cell adoptive transfer induced chronic mouse colitis model, which was consistent with the gene expression of DBH in multiple cell populations including T cells. Furthermore, DBH inhibition dramatically ameliorated the disease activity and colon shortening in chemically induced acute and chronic IBD models, as evidenced by morphological and histological examinations. The reshaped systemic inflammatory status was largely associated with decreased pro-inflammatory mediators, such as TNF-α, IL-6 and IFN-γ in plasma and re-balanced Th1, Th17 and Tregs in mesenteric lymph nodes (MLNs) upon colitis progression. Additionally, the conversion from dopamine (DA) to norepinephrine (NE) was inhibited resulting in increase in DA level and decrease in NE level and DA/NE showed immune-modulatory effects on the activation of immune cells. ConclusionModulation of neurotransmitter levels via inhibition of DBH exerted protective effects on progression of murine colitis by modulating the neuro-immune axis. These findings suggested a promising new therapeutic strategy for attenuating intestinal inflammation.

Mitigating gut microbial degradation of levodopa and enhancing brain dopamine: Implications in Parkinson’s disease

Parkinson’s disease is managed using levodopa; however, as Parkinson’s disease progresses, patients require increased doses of levodopa, which can cause undesirable side effects. Additionally, the oral bioavailability of levodopa decreases in Parkinson’s disease patients due to the increased metabolism of levodopa to dopamine by gut bacteria, Enterococcus faecalis, resulting in decreased neuronal uptake and dopamine formation. Parkinson’s disease patients have varying levels of these bacteria. Thus, decreasing bacterial metabolism is a promising therapeutic approach to enhance the bioavailability of levodopa in the brain. In this work, we show that Mito-ortho-HNK, formed by modification of a naturally occurring molecule, honokiol, conjugated to a triphenylphosphonium moiety, mitigates the metabolism of levodopa—alone or combined with carbidopa—to dopamine. Mito-ortho-HNK suppresses the growth of E. faecalis, decreases dopamine levels in the gut, and increases dopamine levels in the brain. Mitigating the gut bacterial metabolism of levodopa as shown here could enhance its efficacy.

Evaluation of the Parkinson's Remote Interactive Monitoring System in a Clinical Setting: Usability Study.

The fastest-growing neurological disorder is Parkinson disease (PD), a progressive neurodegenerative disease that affects 10 million people worldwide. PD is typically treated with levodopa, an oral pill taken to increase dopamine levels, and other dopaminergic agonists. As the disease advances, the efficacy of the drug diminishes, necessitating adjustments in treatment dosage according to the patient's symptoms and disease progression. Therefore, remote monitoring systems that can provide more detailed and accurate information on a patient's condition regularly are a valuable tool for clinicians and patients to manage their medication. The Parkinson's Remote Interactive Monitoring System (PRIMS), developed by PragmaClin Research Inc, was designed on the premise that it will be an easy-to-use digital system that can accurately capture motor and nonmotor symptoms of PD remotely. We performed a usability evaluation in a simulated clinical environment to assess the ease of use of the PRIMS and determine whether the product offers suitable functionality for users in a clinical setting. Participants were recruited from a user sign-up web-based database owned by PragmaClin Research Inc. A total of 11 participants were included in the study based on the following criteria: (1) being diagnosed with PD and (2) not being diagnosed with dementia or any other comorbidities that would make it difficult to complete the PRIMS assessment safely and independently. Patient users completed a questionnaire that is based on the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale. Interviews and field notes were analyzed for underlying themes and topics. In total, 11 people with PD participated in the study (female individuals: n=5, 45%; male individuals: n=6, 55%; age: mean 66.7, SD 7.77 years). Thematic analysis of the observer's notes revealed 6 central usability issues associated with the PRIMS. These were the following: (1) the automated voice prompts are confusing, (2) the small camera is problematic, (3) the motor test exhibits excessive sensitivity to the participant's orientation and position in relation to the cameras, (4) the system poses mobility challenges, (5) navigating the system is difficult, and (6) the motor test exhibits inconsistencies and technical issues. Thematic analysis of qualitative interview responses revealed four central themes associated with participants' perspectives and opinions on the PRIMS, which were (1) admiration of purpose, (2) excessive system sensitivity, (3) video instructions preferred, and (4) written instructions disliked. The average system usability score was calculated to be 69.2 (SD 4.92), which failed to meet the acceptable system usability score of 70. Although multiple areas of improvement were identified, most of the participants showed an affinity for the overarching objective of the PRIMS. This feedback is being used to upgrade the current PRIMS so that it aligns more with patients' needs.