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Parkinson's disease (PD) is a neurodegenerative disorder that affects millions of individuals globally. It is characterized by the loss of dopaminergic neurons in Substantia Nigra pars compacta (SNc) and striatum. Neuroimaging techniques such as single-photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI) help diagnosing PD. In this study, the focus was on developing technetium-99 m ([99mTc]Tc) radiolabeled drug delivery systems using plant-derived compounds for the diagnosis of PD. Madecassoside (MA), a plant-derived compound, was conjugated with Levodopa (L-DOPA) to form MA-L-DOPA, which was then encapsulated using Poly Lactic-co-Glycolic Acid (PLGA) to create MA-PLGA and MA-L-DOPA-PLGA nanocapsules. Extensive structural analysis was performed using various methods such as Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), liquid chromatography–mass spectrometry (LC–MS), thin layer chromatography (TLC), high performance liquid chromatography (HPLC), dynamic light scattering (DLS), and scanning electron microscopy (SEM) to characterize the synthesized products. Radiochemical yields of radiolabeled compounds were determined using thin layer radio chromatography (TLRC) and high performance liquid radio chromatography (HPLRC) methods. In vitro cell culture studies were conducted on human neuroblastoma (SH-SY5Y) and rat pheochromocytoma (PC-12) cell lines to assess the incorporation of [99mTc]Tc radiolabeled compounds ([99mTc]Tc-MA, [99mTc]Tc-MA-L-DOPA, [99mTc]Tc-MA-PLGA and [99mTc]Tc-MA-L-DOPA-PLGA) and the cytotoxicity of inactive compounds (MA and MA-L-DOPA compounds and encapsulated compounds (MA-PLGA and MA-L-DOPA-PLGA). Additionally, the biodistribution studies were carried out on healthy male Sprague–Dawley rats and a Parkinson's disease experimental model to evaluate the compounds' bioactivity using the radiolabeled compounds. The radiochemical yields of all radiolabeled compounds except [99mTc]Tc-L-DOPA-PLGA were above 95% and had stability over 6 h. The cytotoxic effects of all substances on SH-SY5Y and PC-12 cells increase with increasing concentration values. The uptake values of PLGA-encapsulated compounds are statistically significant in SH-SY5Y and PC-12 cells. The biodistribution studies showed that [99mTc]Tc-MA is predominantly retained in specific organs and brain regions, with notable uptake in the prostate, muscle, and midbrain. PLGA-encapsulation led to higher uptake in certain organs, suggesting its biodegradable nature may enhance tissue retention, and surface modifications might further optimize brain penetration. Overall, the results indicate that radiolabeled plant-derived encapsulated drug delivery systems with [99mTc]Tc hold potential as diagnostic agents for PD symptoms. This study contributes to the advancement of drug delivery agents in the field of brain research. [ABSTRACT FROM AUTHOR]

Despite the intensive research on gut microbiome-associated diseases over the past 20 years, pharmacological methods for effectively eliminating pathobionts remain unsatisfactory. This study investigated the therapeutic potential of bacteriophages against Enterococcus faecalis, in which bacterial tyrosine decarboxylase (TDC) converts orally administered levodopa (L-DOPA) to dopamine, in an MPTP mouse model of Parkinson's disease (PD). E. faecalis bacteriophages PBEF62, PBEF66, and PBEF67 (4 × 1010 PFU total/200 µl/day), and E. faecalis cells (2 × 109 CFU/200 µl/day) were orally administered at 2-h intervals before every MPTP (i.p.) and/or L-DOPA (p.o.) treatments for 13 days. The relative abundances of E. faecalis cells and bacteriophages in the feces peaked at 4 and 12 h after administration and gradually decreased by 12 and 48 h, respectively. While the administration of E. faecalis cells eliminated the beneficial effect of L-DOPA on MPTP-induced behavioral deficits, as assessed by cylinder and rotarod tests, the co-administration of bacteriophages with bacterial cells restored this effect. The modulating effects of L-DOPA, E. faecalis, and bacteriophages on PD behavior were closely associated with choline acetyltransferase expression levels in the striatum but not with tyrosine hydroxylase in the substantia nigra of each group. Recurrence and extinction of PD behaviors following treatment with E. faecalis and/or bacteriophages were also coincident with the dopamine levels in the blood and brain tissues of PD mice. The effectiveness of L-DOPA was restored after the three types of E. faecalis bacteriophages selectively eliminated E. faecalis cells, along with the TDC gene copies and transcripts responsible for converting L-DOPA to dopamine in the gastrointestinal tract. In conclusion, a combination of bacteriophages PBEF62, PBEF66, and PBEF67 targeting E. faecalis demonstrates potential as a valuable supplement to L-DOPA therapy for PD. [ABSTRACT FROM AUTHOR]

Diabetic striatopathy, a rare hyperglycemia complication, is characterized by chorea/ballism and striatal anomalies on neuroimaging, usually managed with glycemic control and haloperidol. However, practical strategies for haloperidol‐resistant cases are scarce. We describe a 76‐year‐old Japanese woman with diabetic striatopathy who initially presented with polydipsia, polyuria, and lower‐extremity weakness. Despite pronounced hyperglycemia (725 mg/dL), her blood glucose levels were reduced through saline infusion and intravenous insulin. Subsequently, she developed whole‐body ballism concomitant with striatal hyperintensity on T1‐weighted magnetic resonance imaging, which initially responded to haloperidol. Upon discontinuation of haloperidol, her symptoms relapsed and did not improve with the reintroduction of haloperidol. Dopamine transporter single photon emission computed tomography revealed diminished bilateral striatal uptake, suggesting presynaptic dopaminergic dysfunction. This finding prompted the initiation of L‐dopa, which significantly improved her symptoms. This case underlines the need to consider presynaptic dopaminergic dysfunction in diabetic striatopathy patients unresponsive to standard treatments, highlighting the effectiveness of L‐dopa in such scenarios. [ABSTRACT FROM AUTHOR]

Global cultivation of the faba bean (Vicia faba L.), a nutritious member of the fabaceae family, is a popular coldtolerant crop. Leading faba bean-producing countries encompass China, Ethiopia, the United Kingdom, Australia, and France. Recently, the exploration of different foods enriched with bioactive components that offer enhanced functionality, nutritional value, and health benefits has sparked a growing interest in the health advantages of faba beans. Vicia faba is rich in derivatives of minerals, vitamins, carbohydrates, proteins abundant in lysine and numerous bioactive compounds. Furthermore, it serves as an excellent source of L-DOPA, a dopamine precursor with potential implications in Parkinson's disease treatment. The edible forms of faba bean seeds include dried, roasted, boiled, soaked, frozen and canned edibles. Yet, a number of antinutritional factors, such as phytic acid, trypsin inhibitors, saponins, vicine and convicine (substances associated with favism), lectins and condensed tannins, impede the best possible utilization of faba beans, thereby undermining their biological value. This comprehensive review encompasses global production, dietary characteristics and an array of antinutritional conditions. [ABSTRACT FROM AUTHOR]

The use of phosphodiesterase inhibitors in the treatment of Parkinson's disease is currently widely discussed. The study aimed to investigate the impact of acute and chronic treatment with the phosphodiesterase 5 inhibitor, sildenafil, at low and moderate doses of 2 mg/kg and 6 mg/kg, and L-DOPA (12.5 mg/kg), alone or in combination, on asymmetric behavior and dopamine (DA) and serotonin metabolism in the striatum and substantia nigra of unilaterally 6-OHDA-lesioned rats. Acute administration of sildenafil at both tested doses jointly with L-DOPA significantly increased the number of contralateral rotations during a 2 h measurement compared to L-DOPA alone. The effect of a lower dose of sildenafil combined with L-DOPA was much greater in the second hour of measurement. However, the acute combined administration of a higher dose of sildenafil with L-DOPA resulted in an immediate and much stronger increase in the number of contralateral rotations compared to L-DOPA alone, already visible in the first hour of measurement. Interestingly, the chronic combined administration of 2 mg/kg of sildenafil and L-DOPA significantly reduced the number of contralateral rotations, especially during the first hour of measurement, compared to the long-term treatment with L-DOPA alone. Such an effect was not observed after the long-term combined treatment of a higher dose of sildenafil and L-DOPA compared to L-DOPA alone. The concentration of DA in the ipsilateral striatum and substantia nigra after the last combined chronic dose of sildenafil (2 or 6 mg/kg) and L-DOPA (12.5 mg/kg) was significantly higher than after L-DOPA alone. In spite of much stronger increases in the DA concentration in the ipsilateral striatum and substantia nigra, the number of contralateral rotations was reduced in the group of rats treated with the combination of 2 mg/kg sildenafil and L-DOPA compared to the group receiving L-DOPA alone. Moreover, the combined treatment with a low dose of sildenafil and L-DOPA had an opposite effect on DA catabolism, as assessed by DOPAC/DA and HVA/DA indexes, and these indexes were reduced in the ipsilateral striatum but increased in the contralateral striatum and substantia nigra compared to the treatment with L-DOPA alone. The results of the present study show that the addition of a low dose of a PDE5 inhibitor to the standard L-DOPA therapy differently modulates rotational behavior, the tissue DA concentration and its catabolism in the striatum and substantia nigra. [ABSTRACT FROM AUTHOR]

Background: Both dopamine and adenosine are physiologically involved in cellular energy metabolism. Aim: Novel approaches targeting delaying progression strategies for Parkinson's disease (PD) examined the effects of long‐term use of A2AR antagonist/istradefylline (IST) adjunct to L‐DOPA (LD), nutshell IST‐LD, with an expected energy coupling (EC) to attenuate neuronal excitotoxicity. Methods: A single‐center prospective open cohort study was conducted at the Department of Neurology, Okinawa Islands, Japan. The cohort included incident and prevalent PD cases that were non‐randomly assigned to the IST‐LD (n = 90) and LD (n = 157) groups, followed by an open‐label treatment in clinical practice from October 2013 to September 2020. Patients were evaluated using physician‐rated MDS‐UPDRS I/III, and patient‐rated MDS‐NMS using the total score, body weight, and blood biomarkers of EC. Results: As the primary clinical outcome, MDS‐UPDRS part III scores showed less worsening in the IST‐LD than in the LD group (1.29 ± 6.0 vs. 5.0 ± 6.5, p < 0.01) and off‐time Hoehn and Yahr stage (0.05 ± 0.49 vs. 0.26 ± 0.54, p < 0.01). As the secondary clinical outcome, the detected mean body weight losses were similar between the two groups; however, the evident linkage of the daily dose of LD and variations in the blood markers of IGF‐I and HKII, which were inferred as LD‐mediated energy demand effects, were partially attenuated by IST. Conclusion: IST‐LD plays an essential role in behavioral outputs for patients with PD and might contribute to the interplay of energy‐consuming demands of LD with the attenuation of weight loss and emerging type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

Tyrosinase, an enzyme involved in browning reactions in plants/crops exposed to mechanical injury, was isolated from the pulp of some different locally available bananas (M. cavendish, M. acuminata, and M. paradisiaca). Tyrosinase from the pulps was extracted, purified, immobilized, and characterized. Thereafter, the potentials of the immobilized tyrosinase in the possible production of l-3,4-dihydroxyphenylalanine (L-DOPA) in an improvised batch reactor was exploited using tyrosine and ascorbate as the substrates. L-DOPA production was monitored via thin-layer chromatography and spectrophotometry (Arnow's method). L-DOPA is a drug that is used in the treatment of Parkinson's disease. Hence, this study exploited a non-chemical route for its synthesis using the tyrosinase obtained from the banana pulps. The purified tyrosinase had an optimum pH and temperature of 6.5 and 7.0, respectively. The molecular weight of the purified tyrosinase was 45 kDa. Quercetin and resorcinol both competitively inhibited the purified tyrosinase from the three cultivars. Immobilized M. cavendish tyrosinase produced the highest concentration (0.60 mM) of L-DOPA after 8 h in an improvised batch reactor. The tyrosinase in the banana pulps serves as a cheap and readily available green route for the possible production of L-DOPA. [ABSTRACT FROM AUTHOR]

Introduction: In childhood, growth hormone (GH) deficiency (GHD) diagnosis is based on auxological assessment and biochemical provocative tests, whose reliability remains disputed. Recently, several papers have been published on standardising the duration of some tests. The aim of our study was to analyse the possible length reduction of the L‐DOPA provocative test. Methods: We retrospectively investigated the response of GH to L‐DOPA in 256 children, analysing 267 tests (some patients were retested over time for the persistence of severe auxopathy). We studied the same data considering GH peak threshold both at 8 ng/mL (Italian GHD cut‐off) and at 10 ng/mL (international cut‐off). Based on stimulation tests, patients were divided into two groups: GHD and no‐GHD short children. We described the results in the whole population and then clustering for gender and pubertal stage. We termed as index the test stopped at 90 min. Results: The GH peak after L‐DOPA mostly occurred at 60 min. The sensitivity of the index test was the highest, while the specificity was slightly higher using the 8 ng/mL threshold (specificity = 0.68; 95% CI 0.60–0.76) then using the 10 ng/mL threshold (specificity = 0.56; 95% CI 0.47–0.65) at 90 min. The two ROC curves showed moderate performance of the test at 90 min. While the negative predictive value was 100% in both tests, the positive predictive value was slightly better with 10 ng/mL cut‐off. Considering the two groups established by GHD definition and placing a GH threshold at 10 ng/mL, stopping L‐DOPA test time at 90 min would have changed the test result and subsequentially patient's classification in 3/267 of the analysed tests (1.1%), while with the Italian GH threshold value at 8 ng/mL in 7/267 of the tests (2.6%). Conclusions: Our research shows that omitting 120‐min time reduces L‐DOPA test specificity, especially with GHD cut‐off at 10 ng/mL. [ABSTRACT FROM AUTHOR]

Abstract Background Geographic atrophy (GA) is a significant cause of vision loss in patients with age-related macular degeneration (AMD). Current treatments are limited to anti-complement drugs, which have limited efficacy to delay progression with significant risk of complications. Levodopa (L-DOPA) is a byproduct of melanin synthesis that is associated with reduced development of neovascular AMD. In this study, we determined if L-DOPA was associated with a reduced likelihood of new-onset GA. Methods We performed a retrospective analysis in the Vestrum Health Retina Database. We included eyes with non-neovascular AMD without GA and 1–5 years of follow-up. Eyes were divided into two groups. Exposed to L-DOPA before or on the date of non-neovascular AMD without GA diagnosis, and eyes not exposed to L-DOPA. We extracted age, sex, AREDS2 status, dry AMD stage, smoking history, and conversion rate to GA at years 1 through 5. Propensity score matching was used to match L-DOPA and control groups. Cox proportional hazard regression, adjusting for age, sex, AMD severity, AREDS2 use, smoking status, and L-DOPA use was employed to calculate hazard ratios for new-onset GA detection. Results We identified 112,089 control and 844 L-DOPA exposed eyes with non-neovascular AMD without GA. After propensity score matching, 2532 control and 844 L-DOPA exposed eyes remained that were well-matched for age, sex, AMD severity, AREDS2 use, and smoking status. We found that L-DOPA exposure was associated with a significantly reduced likelihood (HR = 0.68, 95% CI: 0.48–0.95, P = 0.025) of new-onset GA detection. Conclusion L-DOPA use was associated with reduced detection of new-onset GA.

Abstract Despite the intensive research on gut microbiome-associated diseases over the past 20 years, pharmacological methods for effectively eliminating pathobionts remain unsatisfactory. This study investigated the therapeutic potential of bacteriophages against Enterococcus faecalis, in which bacterial tyrosine decarboxylase (TDC) converts orally administered levodopa (L-DOPA) to dopamine, in an MPTP mouse model of Parkinson’s disease (PD). E. faecalis bacteriophages PBEF62, PBEF66, and PBEF67 (4 × 1010 PFU total/200 µl/day), and E. faecalis cells (2 × 109 CFU/200 µl/day) were orally administered at 2-h intervals before every MPTP (i.p.) and/or L-DOPA (p.o.) treatments for 13 days. The relative abundances of E. faecalis cells and bacteriophages in the feces peaked at 4 and 12 h after administration and gradually decreased by 12 and 48 h, respectively. While the administration of E. faecalis cells eliminated the beneficial effect of L-DOPA on MPTP-induced behavioral deficits, as assessed by cylinder and rotarod tests, the co-administration of bacteriophages with bacterial cells restored this effect. The modulating effects of L-DOPA, E. faecalis, and bacteriophages on PD behavior were closely associated with choline acetyltransferase expression levels in the striatum but not with tyrosine hydroxylase in the substantia nigra of each group. Recurrence and extinction of PD behaviors following treatment with E. faecalis and/or bacteriophages were also coincident with the dopamine levels in the blood and brain tissues of PD mice. The effectiveness of L-DOPA was restored after the three types of E. faecalis bacteriophages selectively eliminated E. faecalis cells, along with the TDC gene copies and transcripts responsible for converting L-DOPA to dopamine in the gastrointestinal tract. In conclusion, a combination of bacteriophages PBEF62, PBEF66, and PBEF67 targeting E. faecalis demonstrates potential as a valuable supplement to L-DOPA therapy for PD.

ABSTRACT Diabetic striatopathy, a rare hyperglycemia complication, is characterized by chorea/ballism and striatal anomalies on neuroimaging, usually managed with glycemic control and haloperidol. However, practical strategies for haloperidol‐resistant cases are scarce. We describe a 76‐year‐old Japanese woman with diabetic striatopathy who initially presented with polydipsia, polyuria, and lower‐extremity weakness. Despite pronounced hyperglycemia (725 mg/dL), her blood glucose levels were reduced through saline infusion and intravenous insulin. Subsequently, she developed whole‐body ballism concomitant with striatal hyperintensity on T1‐weighted magnetic resonance imaging, which initially responded to haloperidol. Upon discontinuation of haloperidol, her symptoms relapsed and did not improve with the reintroduction of haloperidol. Dopamine transporter single photon emission computed tomography revealed diminished bilateral striatal uptake, suggesting presynaptic dopaminergic dysfunction. This finding prompted the initiation of L‐dopa, which significantly improved her symptoms. This case underlines the need to consider presynaptic dopaminergic dysfunction in diabetic striatopathy patients unresponsive to standard treatments, highlighting the effectiveness of L‐dopa in such scenarios.

Abstract Parkinson’s disease (PD) is a chronic neurodegenerative case. As the disease progresses, the response time to doses of levodopa (L-Dopa) becomes shorter and the effects of the drug are severely limited by some undesirable side effects such as the ‘on–off’ phenomenon. In several diseases, including Parkinson’s, nanoparticles can deliver antioxidant compounds that reduce oxidative stress. This study evaluates and compares the neuroprotective effects of L-Dopa-modified zinc nanoparticles (ZnNPs) in the 6-hydroxydopamine (6-OHDA)-induced PD rat model. For this purpose, the synthesis of NPs was carried out. Scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectrophotometer were used for characterization. The rats were randomized into 9 experimental groups: control, lesion group (6-OHDA), 6-OHDA + 5 mg/kg L-Dopa, 6-OHDA + 10 mg/kg L-Dopa, 6-OHDA + 20 mg/kg L-Dopa, 6-OHDA + 20 mg/kg ZnNPs, 6-OHDA + 40 mg/kg ZnNPs, 6-OHDA + 30 mg/kg ZnNPs + L-Dopa, and 6-OHDA + 60 mg/kg ZnNPs + L-Dopa. Behavioral tests were performed on all groups 14 days after treatment. Phosphatase and tensin homolog, Excitatory amino acid transporter 1/2, and Glutamine synthetase gene analyses were performed on brain samples taken immediately after the tests. In addition, histological and immunohistochemical methods were used to determine the general structure and properties of the tissues. We obtained important findings that L-Dopa-modified ZnNPs increased the activity of glutamate transporters. Our experiment showed that glutamate increases neuronal cell vitality and improves behavioral performance. Therefore, L-Dopa-modified ZnNPs can be used to prevent neurotoxicity. According to what we found, results show that L-Dopa-modified ZnNPs will lend to the effective avoidance and therapy of PD.

Abstract Background Chronic kidney disease (CKD) and hypertension are chronic diseases affecting a large portion of the population frequently coexistent and interdependent. The inability to produce/use adequate renal dopamine may contribute to the development of hypertension and renal dysfunction. The heterodimeric amino acid transporter LAT2/4F2hc (SLC7A8/SLC3A2 genes) promotes the uptake of L-DOPA, the natural precursor of dopamine. We examined the plausibility that SLC7A8/SLC3A2 gene polymorphisms may contribute to hypertensive CKD by affecting the L-DOPA uptake. Methods 421 subjects (203 men and 218 women, mean age of 78.9 ± 9.6 years) were recruited and divided in four groups according to presence/absence of CKD, defined as reduced estimated glomerular filtration rate (eGFR

Mutations in proline‐rich transmembrane protein 2 (PRRT2) cause paroxysmal kinesigenic dyskinesia (PKD). Recently, we reported that a Prrt2 mutation exacerbated L‐dopa‐induced motor deficits in mice, suggesting that the basal ganglia might contribute to PKD pathology. Here, we demonstrated that the Prrt2 mutation enhanced depolarization stimuli‐induced extracellular dopamine levels in the mouse striatum, which were attenuated by repeated stimulation. L‐dopa administration maintained high dopamine levels in Prrt2‐KI mice even during repetitive stimuli but did not affect dopamine levels in wild‐type mice. Thus, the enhanced and prolonged responsiveness of dopamine release in nigrostriatal dopaminergic neurons to sequential excitation may be partially implicated in Prrt2‐related dyskinesia. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a chronic neurodegenerative case. As the disease progresses, the response time to doses of levodopa (L-Dopa) becomes shorter and the effects of the drug are severely limited by some undesirable side effects such as the 'on–off' phenomenon. In several diseases, including Parkinson's, nanoparticles can deliver antioxidant compounds that reduce oxidative stress. This study evaluates and compares the neuroprotective effects of L-Dopa-modified zinc nanoparticles (ZnNPs) in the 6-hydroxydopamine (6-OHDA)-induced PD rat model. For this purpose, the synthesis of NPs was carried out. Scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectrophotometer were used for characterization. The rats were randomized into 9 experimental groups: control, lesion group (6-OHDA), 6-OHDA + 5 mg/kg L-Dopa, 6-OHDA + 10 mg/kg L-Dopa, 6-OHDA + 20 mg/kg L-Dopa, 6-OHDA + 20 mg/kg ZnNPs, 6-OHDA + 40 mg/kg ZnNPs, 6-OHDA + 30 mg/kg ZnNPs + L-Dopa, and 6-OHDA + 60 mg/kg ZnNPs + L-Dopa. Behavioral tests were performed on all groups 14 days after treatment. Phosphatase and tensin homolog, Excitatory amino acid transporter 1/2, and Glutamine synthetase gene analyses were performed on brain samples taken immediately after the tests. In addition, histological and immunohistochemical methods were used to determine the general structure and properties of the tissues. We obtained important findings that L-Dopa-modified ZnNPs increased the activity of glutamate transporters. Our experiment showed that glutamate increases neuronal cell vitality and improves behavioral performance. Therefore, L-Dopa-modified ZnNPs can be used to prevent neurotoxicity. According to what we found, results show that L-Dopa-modified ZnNPs will lend to the effective avoidance and therapy of PD. [ABSTRACT FROM AUTHOR]

Vicia faba L. is a leguminous plant with seeds rich in nutritional compounds, such as polyphenols and L-dopa, a dopamine precursor and first-line treatment for Parkinson's symptoms. Recently, its by-products have been revalued as a sustainable source of bioactive compounds. In this study, aqueous extracts of Lucan broad bean pod valves (BPs) were characterized to evaluate their potential use as adjuvants in severe Parkinson's disease. L-dopa content, quantified by LC-UV, was much higher in BPs than in seeds (28.65 mg/g dw compared to 0.76 mg/g dw). In addition, vicine and convicine, the metabolites responsible for favism, were not detected in pods. LC-ESI/LTQ-Orbitrap/MS2 allowed the identification of the major polyphenolic compounds, including quercetin and catechin equivalents, that could ensure neuroprotection in Parkinson's disease. ESI(±)-FT-ICR MS was used to build 2D van Krevelen diagrams; polyphenolic compounds and carbohydrates were the most representative classes. The neuroprotective activity of the extracts after MPP+-induced neurotoxicity in SH-SY5Y cells was also investigated. BP extracts were more effective than synthetic L-dopa, even at concentrations up to 100 µg/mL, due to the occurrence of antioxidants able to prevent oxidative stress. The stability and antioxidant component of the extracts were then emphasized by using naturally acidic solutions of Punica granatum L., Ribes rubrum L., and gooseberry (Phyllanthus emblica L.) as extraction solvents. [ABSTRACT FROM AUTHOR]

The genus Mucuna is a potential protein source, but it has been underutilized due to the presence of antinutritional factors, especially L-DOPA. Solid-state fermentation with lactic acid bacteria could be an effective and simple method for reducing these antinutritional factors while simultaneously enriching the protein content. In this work, an experimental analysis identified the variables with the greatest influence on the solid-state fermentation of Mucuna deeringiana. In general, we observed a decrease in pH due to the production of and increase in lactic acid, resulting in a 91% (6.40 to 0.55 g/100 g sample) reduction in L-DOPA, 51% decrease in phenolic compounds (11.65 to 5.70 g/100 g sample), 97% decrease in tannins (1.26 to 0.04 g/100 g sample), and the antioxidant capacity of the fermented flour was 97%, with an increase in protein content of 12%. Furthermore, it demonstrated greater stability over 24 days compared to the control samples, which remained stable for only 3 days. These results suggest that the bacterium has a positive effect on the production of lactic acid, and the nutritional composition can be enhanced by reducing antinutritional factors, especially L-DOPA, that limit the use of this legume. This process proves to be a cost-effective and sustainable method for developing nutritious feed products derived from Mucuna flours. [ABSTRACT FROM AUTHOR]

Graphene is a promising biomaterial. However, its dispersion in aqueous medium is challenging. This study aimed to modify graphene nanoparticles with L-dopa to improve the properties of experimental dental adhesives. Adhesives were formulated with 0% (control), 0.25%, 0.5%, and 0.75% of graphene, modified or not. Particle modification and dispersion were microscopically assessed. Degree of conversion was tested by Fourier-transform infrared spectroscopy. Flexural strength and modulus of elasticity were evaluated by a 3-point flexural test. Bond strength was tested by shear. To test water sorption/solubility, samples were weighed during hydration and dehydration. Antibacterial activity was tested by Streptococcus mutans colony-forming units quantification. Cytotoxicity on fibroblasts was evaluated through a dentin barrier test. The modification of graphene improved the particle dispersion. Control presented the highest degree of conversion, flexural strength, and bond strength. In degree of conversion, 0.25% of groups were similar to control. In bond strength, groups of graphene modified by L-dopa were similar to Control. The modulus of elasticity was similar between groups. Cytotoxicity and water sorption/solubility decreased as particles increased. Compared to graphene, less graphene modified by L-dopa was needed to promote antibacterial activity. By modifying graphene with L-dopa, the properties of graphene and, therefore, the adhesives incorporated by it were enhanced. [ABSTRACT FROM AUTHOR]

Objectives: Dopamine and related receptors are evidenced in pancreatic endocrine tissue, but the impact on islet β-cell stimulus-secretion as well as (patho)physiological role are unclear. Methods: The present study has evaluated islet cell signalling pathways and biological effects of dopamine, as well as alterations of islet dopamine in rodent models of diabetes of different aetiology. Key findings: The dopamine precursor l-DOPA partially impaired glucose tolerance in mice and attenuated glucose-, exendin-4, and alanine-induced insulin secretion. The latter effect was echoed by the attenuation of glucose-induced [Ca2+]i dynamics and elevation of ATP levels in individual mouse islet cells. l-DOPA significantly decreased β-cell proliferation rates, acting predominantly via the D2 receptor, which was most abundant at the mRNA level. The administration of streptozotocin (STZ) or high-fat diet (HFD) in mice significantly elevated numbers of dopamine-positive islet cells, with HFD also increasing colocalization of dopamine with insulin. At the same time, colocalization of dopamine with glucagon was increased in STZ-treated and pregnant mice, but unaffected by HFD. Conclusion: These findings highlight a role for dopamine receptor signalling in islet cell biology adaptations to various forms of metabolic stress. [ABSTRACT FROM AUTHOR]

L-DOPA-induced dyskinesia (LID) is a debilitating motor side effect arising from chronic dopamine (DA) replacement therapy with L-DOPA for the treatment of Parkinson’s disease. LID is associated with supersensitivity of striatal dopaminergic signaling and fluctuations in synaptic DA following each L-DOPA dose, shrinking the therapeutic window. The heterogeneous composition of the striatum, including subpopulations of medium spiny output neurons (MSNs), interneurons, and supporting cells, complicates the identification of cell(s) underlying LID. We used single-nucleus RNA sequencing (snRNA-seq) to establish a comprehensive striatal transcriptional profile during LID development. Male hemiparkinsonian mice were treated with vehicle or L-DOPA for 1, 5, or 10 d, and striatal nuclei were processed for snRNA-seq. Analyses indicated a limited population of DA D1 receptor–expressing MSNs (D1-MSNs) formed three subclusters in response to L-DOPA treatment and expressed cellular markers of activation. These activated D1-MSNs display similar transcriptional changes previously associated with LID; however, their prevalence and transcriptional behavior were differentially influenced by L-DOPA experience. Differentially expressed genes indicated acute upregulation of plasticity-related transcription factors and mitogen-activated protein kinase signaling, while repeated L-DOPA-induced synaptic remodeling, learning and memory, and transforming growth factor-β (TGF-β) signaling genes. Notably, repeated L-DOPA sensitized Inhba, an activin subunit of the TGF-β superfamily, in activated D1-MSNs, and its pharmacological inhibition impaired LID development, suggesting that activin signaling may play an essential role in LID. These data suggest distinct subsets of D1-MSNs become differentially L-DOPA-responsive due to aberrant induction of molecular mechanisms necessary for neuronal entrainment, similar to processes underlying hippocampal learning and memory [ABSTRACT FROM AUTHOR]

Background: Chronic kidney disease (CKD) and hypertension are chronic diseases affecting a large portion of the population frequently coexistent and interdependent. The inability to produce/use adequate renal dopamine may contribute to the development of hypertension and renal dysfunction. The heterodimeric amino acid transporter LAT2/4F2hc (SLC7A8/SLC3A2 genes) promotes the uptake of L-DOPA, the natural precursor of dopamine. We examined the plausibility that SLC7A8/SLC3A2 gene polymorphisms may contribute to hypertensive CKD by affecting the L-DOPA uptake. Methods: 421 subjects (203 men and 218 women, mean age of 78.9 ± 9.6 years) were recruited and divided in four groups according to presence/absence of CKD, defined as reduced estimated glomerular filtration rate (eGFR < 60 ml/min/m2) calculated using the creatinine-based Berlin Initiative Study–1 (BIS1) equation, and to presence/absence of hypertension (systolic blood pressure ≥ 140 and/or diastolic blood pressure ≥ 90 mmHg). Subjects were analysed for selected SNPs spanning the SLC7A8 and SLC3A2 loci by Sequenom MassARRAY iPLEX platform. Results: The most significant SNP at the SLC3A2 (4F2hc) locus was rs2282477-T/C, with carriers of the C-allele having a lower chance to develop hypertension among CKD affected individuals [OR = 0.33 (CI 0.14–0.82); p = 0.016]. A similar association with hypertensive CKD was found for the SLC7A8 (LAT2) rs3783436-T/C, whose C-allele resulted associated with decreased risk of hypertension among subjects affected by CKD [OR = 0.56 (95% CI 0.35–0.90; p = 0.017]. The two variants were predicted to be potentially functional. Conclusions: The association between SLC3A2 and SLC7A8 variants to hypertension development in patients with renal failure could be linked to changes in L-DOPA uptake and consequently dopamine synthesis. Although the associations do not survive correction for Bonferroni multiple testing, and additional research is needed, our study opens new avenues for future basic and translational research in the field of hypertensive CKD. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD), the most common neurodegenerative ailment, is caused by progressive damage in dopamine-secreting cells in the substantianigra. Oxidative stress plays a major role in the degeneration of dopaminergic neurons in PD. All organisms have developed adaptive responses to oxidative stress that result in increased production of defensive enzymes and antioxidant molecules. The mutations in a-synuclein protein have a role in modulating the dopamine activity. In this study, we have illustrated the protective effects of bioactive compounds of Mucuna monosperma (MM) against paraquat (PQ)-induced oxidative stress in a transgenic Parkinson's disease model (Elav/SNCAA30P) of Drosophila melanogaster. The isolated L-Dopa and Ursolic compounds exhibit antioxidant properties. The activity of antioxidant enzymes and LPO has been measured in L-dopa and Ursolic acid-supplemented PD lines under oxidative stress conditions. The oxidative stress caused by PQ was averted and antioxidant enzyme activity was significantly increased in flies that were fed with a mixture of L-Dopa and Ursolic acid. SOD activities were elevated by 4.2 fold, CAT activates increased by 3.8 fold and G6Pd activates were increased by 4.6 fold under stress conditions. The synergetic effect of these bioactive compounds decreases the LPO activity by 2 fold with the increase of glutathione by 3.36 fold in transgenic PD flies. Based on the findings, we speculate that L-Dopa with Ursolic acid of M. monosperma prevents oxidative stress-related disorders and can be used as a possible therapeutic agent against PD disorder. [ABSTRACT FROM AUTHOR]

In this work, nano-levodopa-liposomes (L-dopa-Lip) suspension was prepared by rotary-evaporated film-ultrasonic method, and freeze-drying powders of L-dopa-Lip were also obtained to improve the stability. The products were characterized by TEM, DLS, and TG-DSC, and the phase-transition temperature (Tm) and encapsulation efficiency were calculated. The brain-targeting and in vitro release of the drug was also studied. The results showed that L-dopa-Lip were well-formed spherical vesicles, and the sizes were about 100 nm, and the encapsulation efficiency was higher than 90%. The drug release temperature of L-dopa-Lip was 68 °C, and the in vitro release property and mathematical model were also studied. The brain targeting of L-dopa-Lip in vivo was explored by injecting the gold nanoparticles (AuNPs) labeled L-dopa-Lip (AuNPs-L-dopa-Lip) through the tail vein. ICP-MS and TEM showed that L-dopa-Lip had brain targeting, suggesting the potential treatment of L-dopa-Lip on brain dysfunction. The results of this work might be helpful for designing drug-loaded liposomes for the treatment of central nervous system (CNS) diseases and monitoring their distributions in vivo. [ABSTRACT FROM AUTHOR]

The use of transcriptomic data to make inferences about plant metabolomes is a useful tool to help the discovery of important compounds in the available biodiversity. To unveil previously undiscovered metabolites of Coffea, of phytotherapeutic and economic value, we employed 24 RNAseq libraries. These libraries were sequenced from leaves exposed to a diverse range of environmental conditions. Subsequently, the data were meticulously processed to create models of putative metabolic networks, which shed light on the production of potential natural compounds of significant interest. Then, we selected one of the predicted compounds, the L-3,4-dihydroxyphenylalanine (L-DOPA), to be analyzed by LC-MS/MS using three biological replicates of flowers, leaves, and fruits from Coffea arabica and Coffea canephora. We were able to identify metabolic pathways responsible for producing several compounds of economic importance. One of the identified pathways involved in isoquinoline alkaloid biosynthesis was found to be active and producing L-DOPA, which is a common product of POLYPHENOL OXIDASES (PPOs, EC 1.14.18.1 and EC 1.10.3.1). We show that coffee plants are a natural source of L-DOPA, a widely used medicine for treatment of the human neurodegenerative condition called Parkinsons disease. In addition, dozens of other compounds with medicinal significance were predicted as potential natural coffee products. By further refining analytical chemistry techniques, it will be possible to enhance the characterization of coffee metabolites, enabling a deeper understanding of their properties and potential applications in medicine.

ABSTRACT Introduction In childhood, growth hormone (GH) deficiency (GHD) diagnosis is based on auxological assessment and biochemical provocative tests, whose reliability remains disputed. Recently, several papers have been published on standardising the duration of some tests. The aim of our study was to analyse the possible length reduction of the L‐DOPA provocative test. Methods We retrospectively investigated the response of GH to L‐DOPA in 256 children, analysing 267 tests (some patients were retested over time for the persistence of severe auxopathy). We studied the same data considering GH peak threshold both at 8 ng/mL (Italian GHD cut‐off) and at 10 ng/mL (international cut‐off). Based on stimulation tests, patients were divided into two groups: GHD and no‐GHD short children. We described the results in the whole population and then clustering for gender and pubertal stage. We termed as index the test stopped at 90 min. Results The GH peak after L‐DOPA mostly occurred at 60 min. The sensitivity of the index test was the highest, while the specificity was slightly higher using the 8 ng/mL threshold (specificity = 0.68; 95% CI 0.60–0.76) then using the 10 ng/mL threshold (specificity = 0.56; 95% CI 0.47–0.65) at 90 min. The two ROC curves showed moderate performance of the test at 90 min. While the negative predictive value was 100% in both tests, the positive predictive value was slightly better with 10 ng/mL cut‐off. Considering the two groups established by GHD definition and placing a GH threshold at 10 ng/mL, stopping L‐DOPA test time at 90 min would have changed the test result and subsequentially patient's classification in 3/267 of the analysed tests (1.1%), while with the Italian GH threshold value at 8 ng/mL in 7/267 of the tests (2.6%). Conclusions Our research shows that omitting 120‐min time reduces L‐DOPA test specificity, especially with GHD cut‐off at 10 ng/mL.

Abstract Dopamine plays important roles in cognitive function and inflammation and therefore is involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). Drugs that increase or maintain dopamine levels in the brain could be a therapeutic strategy for AD. However, the effects of dopamine and its precursor levodopa (L-DOPA) on Aβ/tau pathology in vivo and the underlying molecular mechanisms have not been studied in detail. Here, we investigated whether L-DOPA treatment alters neuroinflammation, Aβ pathology, and tau phosphorylation in 5xFAD mice, a model of AD. We found that L-DOPA administration significantly reduced microgliosis and astrogliosis in 5xFAD mice. In addition, L-DOPA treatment significantly decreased Aβ plaque number by upregulating NEP and ADAM17 levels in 5xFAD mice. However, L-DOPA-treated 5xFAD mice did not exhibit changes in tau hyperphosphorylation or tau kinase levels. These data suggest that L-DOPA alleviates neuroinflammatory responses and Aβ pathology but not tau pathology in this mouse model of AD.

Background: Opicapone (OPC) is a third-generation, selective peripheral COMT inhibitor that improves peripheral L-DOPA bioavailability and reduces OFF time and end-of-dose motor fluctuations in Parkinson's disease (PD) patients. Objectives: In this study, we objectively assessed the effects of adding OPC to L-DOPA on bradykinesia in PD through kinematic analysis of finger movements. Methods: We enrolled 20 treated patients with PD and motor fluctuations. Patients underwent two experimental sessions (L-DOPA, L-DOPA + OPC), separated by at least 1 week. In each session, patients were clinically evaluated and underwent kinematic movement analysis of repetitive finger movements at four time points: (i) before their usual morning dose of L-DOPA (T0), (ii) 30 min (T1), (iii) 1 h and 30 min (T2), and (iv) 3 h and 30 min after the L-DOPA intake (T3). Results: Movement velocity and amplitude of finger movements were higher in PD patients during the session with OPC compared to the session without OPC at all the time points tested. Importantly, the variability of finger movement velocity and amplitude across T0–T3 was significantly lower in the L-DOPA + OPC than L-DOPA session. Conclusions: This study is the first objective assessment of the effects of adding OPC to L-DOPA on bradykinesia in patients with PD and motor fluctuations. OPC, in addition to the standard dopaminergic therapy, leads to significant improvements in bradykinesia during clinically relevant periods associated with peripheral L-DOPA dynamics, i.e., the OFF state in the morning, delayed-ON, and wearing-OFF periods. [ABSTRACT FROM AUTHOR]

Arginine-stimulated serum copeptin has been proposed as a new method to diagnose arginine vasopressin (AVP) deficiency in children and adolescents. Herein we investigated the secretagogic potential of clonidine or L-Dopa on the copeptin serum levels in children. Eight stimulation tests (4 with clonidine and 4 with L-Dopa) were performed in eight children (5 boys and 3 girls) with a median age of 6.5 years-old, evaluated for short stature due to possible growth hormone deficiency. Serum copeptin levels were measured at 30, 60, 90, and 120 min after administration of clonidine or L-Dopa. Copeptin levels in serum did not show any significant change in either test (clonidine or L-Dopa). The values of copeptin levels compared to the baseline value did not deviate more than 5 % in the clonidine arm (p=0.60) or 8 % in the L-Dopa arm (p=0.75) respectively. Data do not support the use of L-Dopa or clonidine as stimulants for evaluating AVP relating disorders in clinical pediatric practice. [ABSTRACT FROM AUTHOR]

Faba bean (Vicia faba L.) is a winter season grain legume and a rich source of the anti-parkinson drug, L-3,4-dihydroxyphenylalanine (L-DOPA). The biosynthesis of L-DOPA in plants is not uniform and remains largely unexplored. While the hydroxylase activities of Tyrosine Hydroxylase (TH), the Cytochrome P450 (CYP450) class of enzymes, and Polyphenol Oxidases (PPOs) on tyrosine substrate have been reported in plants, only the roles of PPOs in L-DOPA biosynthesis have been recently established in velvet bean (Mucuna pruriens). To understand the differential accumulation of L-DOPA in different tissues of faba bean, profiling of L-Tyrosine, L-DOPA, Tyramine, and Dopamine in different tissues was performed. Differential accumulation of L-DOPA depended on tissue type and maturity. Furthermore, dopamine biosynthesis through L-DOPA from L-Tyr was confirmed in faba bean. The expression analysis of PPOs in leaf and flower tissues revealed the selective induction of only four (HePPO-2, HePPO-7, HePPO-8b, and HePPO-10) out of ten genes encoding different PPOs mined from the faba bean genome. Higher accumulation of L-DOPA in young leaves and flower buds than in mature leaves and flowers was accompanied by significantly higher expression of HePPO-10 and HePPO-7, respectively. The role of various transcription factors contributing to such metabolite dynamics was also predicted. Further exploration of this mechanism using a multi-omics approach can provide meaningful insight and pave the way for enhancing L-DOPA content in crops. [ABSTRACT FROM AUTHOR]

Dopamine plays important roles in cognitive function and inflammation and therefore is involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). Drugs that increase or maintain dopamine levels in the brain could be a therapeutic strategy for AD. However, the effects of dopamine and its precursor levodopa (L-DOPA) on Aβ/tau pathology in vivo and the underlying molecular mechanisms have not been studied in detail. Here, we investigated whether L-DOPA treatment alters neuroinflammation, Aβ pathology, and tau phosphorylation in 5xFAD mice, a model of AD. We found that L-DOPA administration significantly reduced microgliosis and astrogliosis in 5xFAD mice. In addition, L-DOPA treatment significantly decreased Aβ plaque number by upregulating NEP and ADAM17 levels in 5xFAD mice. However, L-DOPA-treated 5xFAD mice did not exhibit changes in tau hyperphosphorylation or tau kinase levels. These data suggest that L-DOPA alleviates neuroinflammatory responses and Aβ pathology but not tau pathology in this mouse model of AD. [ABSTRACT FROM AUTHOR]

L‐3,4‐dihydroxyphenylalanine (levodopa or L–DOPA) a precursor of neurotransmitter dopamine, has been universally prescribed as a gold standard for treatment of Parkinson's Disease (PD). However, direct administration of L–DOPA has risky adverse effects which makes it challenging in the treatment of PD. Hence developing simple detection platform for sensing of L–DOPA is significant. In this work, we have developed cysteine stabilized copper nanocluster quenched with Fe2+ (Fe2+@cys@CuNC) and used as both fluorescent and colorimetric probe for detection of L–DOPA. L–DOPA attributed a fluorescence quenching effect on developed probe. Fe2+@cys@CuNC detected L–DOPA within a linear range from 0.06 mM to 1.31 mM with a low limit of detection (LoD) of 6.57 nM. The probe also exhibited high selectivity for L–DOPA over other biomolecules and neurotransmitters. Furthermore, the capability of this probe was validated by sensing L–DOPA from human serum with excellent recovery rates of 85.75 % to 115.07 %. A low‐cost paper strip‐based portable detection platform was also developed for visual detection of L–DOPA. [ABSTRACT FROM AUTHOR]

Genus Mucuna encompasses several plant species renowned for their utilization in traditional Ayurvedic medicine for the treatment of Parkinson's disease, chiefly due to their exceptionally high L-dopa content relative to other plants. However, limited information exists regarding Mucuna laticifera, a newly identified species within the Mucuna genus. This study unveils a remarkable L-dopa content of 174.3 mg/g in M. laticifera seeds, surpassing all previously documented Mucuna species. Moreover, this research marks the first documentation of L-dopa, flavonoids, and phenolics within M. laticifera seeds. Furthermore, the aqueous extract derived from these seeds exhibits robust antioxidant properties. Investigation into its anti-inflammatory potential reveals a significant reduction in paw swelling and neutrophil infiltration at inflammatory sites in a carrageenan-induced rat model. Gene expression analysis utilizing a rat paw model demonstrates that the seed extract significantly downregulates the expression of various inflammation-related genes compared to carrageenan-treated rats. Collectively, these findings clearly substantiate the anti-inflammatory activity of M. laticifera seed extract. The exceptional L-dopa content combined with its anti-inflammatory properties position M. laticifera seeds as a promising therapeutic option for neurodegenerative diseases like Parkinson's, as well as various inflammatory conditions. [ABSTRACT FROM AUTHOR]

A fully reusable electrochemical device is proposed for the first time made from laser cutting and a homemade conductive ink composed of carbon and nail polish. As a sensor substrate, we applied polymethyl methacrylate, which allows the surface to be renewed by simply removing and reapplying a new layer of ink. In addition to the ease of renewing the sensor’s conductive surface, the design of the device has allowed for the integration of different forms of analysis. The determination of L-Dopa was performed using DPV, which presented a linear response range between 5.0 and 1000.0 μmol L−1, and a LOD of 0.11 μmol L−1. For dopamine, a flow injection analysis system was employed, and using the amperometric technique measurements were performed with a linear ranging from 2.0 to 100.0 μmol L−1 and a LOD of 0.26 μmol L−1. To demonstrate its applicability, the device was used in the quantification of analytes in pharmaceutical drug and synthetic urine samples. [ABSTRACT FROM AUTHOR]

Harvesting energy from the salinity gradient of seawater and river water using pressure retarded osmosis (PRO) has been a major research topic of recent years. However, there is a need for efficient PRO membranes that can generate high power density and are pressure resistant, as the performance of current membranes on the market is poor. In this study, specific energy potential of PRO process using LDOPA+ TiO2 modified BW30-LE membrane was evaluated on synthetic and real water samples. Polyamide BW30-LE RO membrane was modified by L-DOPA, L-DOPA+0.5 wt% TiO2 and L-DOPA+1 wt% TiO2. The effect of hydraulic pressure and temperature on generation of power density were evaluated for 5, 10, and 15 bar pressures, as well as 10 °C, 20 °C, and 30 °C degrees. The incorporation of TiO2 nanoparticles with L-DOPA increased the water flux by increasing the surface hydrophilicity and roughness of the membrane surface. The maximum specific power was observed as 1.6 W/m² for L-DOPA+1 wt% TiO2 modified BW30-LE membrane at 15 bar pressure. Besides, Mediterranean and Aegean, Black Sea water samples were used as draw solution and Seyhan, Ceyhan, Buyuk Menderes, Gediz, Yesilirmak, and Kizilirmak Rivers were used as feed solution. The highest osmotic power density was obtained by using L-DOPA+1 wt% TiO2 modified BW30-LE membrane with Ceyhan River as feed and Mediterranean Sea water as draw solution, which have the highest differences in salinity. In the mixture of Mediterranean and Ceyhan River, the highest power density was obtained at 10 bar pressure at 30 ± 5°C with 0.70 W/m². [ABSTRACT FROM AUTHOR]

Nelotanserin is a serotonin 2A and 2C (5‐HT2A/2C) inverse agonist that was previously tested in the clinic for rapid‐eye movement sleep behaviour disorder and psychosis in patients with Parkinson's disease (PD) dementia. Its effect on L‐3,4‐dihydroxyphenylalanine (L‐DOPA)‐induced dyskinesia has however not been investigated. As 5‐HT2A antagonism/inverse agonism is a validated approach to alleviate dyskinesia, we undertook the current study to evaluate the anti‐dyskinetic potential of nelotanserin in the 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐lesioned marmoset. Parkinsonism was induced in six common marmosets (Callithrix jacchus, three females and three males) that were then chronically treated with L‐DOPA to induce dyskinesia. On experimental days, they were administered L‐DOPA in combination with vehicle or nelotanserin (0.1, 0.3 and 1 mg/kg) subcutaneously, in a randomised fashion. Dyskinesia and parkinsonism were rated post hoc by a blinded observer. In comparison to vehicle, the addition of nelotanserin 0.3 and 1 mg/kg to L‐DOPA diminished peak dose dyskinesia by 47% (P < 0.05) and 69% (P < 0.001). Nelotanserin 0.3 and 1 mg/kg also reduced the severity of global dyskinesia, by 40% (P < 0.01) and 55% (P < 0.001), when compared to vehicle. Nelotanserin 0.1 mg/kg did not alleviate peak dose or global dyskinesia severity. Nelotanserin had no impact on the anti‐parkinsonian action of L‐DOPA. Our results highlight that nelotanserin may represent an efficacious anti‐dyskinetic drug and provide incremental evidence of the potential benefit of 5‐HT2A/2C antagonism/inverse agonism for drug‐induced dyskinesia in PD. [ABSTRACT FROM AUTHOR]

Dopamine neurons play crucial roles in pleasure, reward, memory, learning, and fine motor skills and their dysfunction is associated with various neuropsychiatric diseases. Dopamine receptors are the main target of treatment for neurologic and psychiatric disorders. Antipsychotics that antagonize the dopamine D2 receptor (DRD2) are used to alleviate the symptoms of these disorders but may also sometimes cause disabling side effects such as parkinsonism (catalepsy in rodents). Here we show that GPR143, a G-protein-coupled receptor for L-3,4-dihydroxyphenylalanine (L-DOPA), expressed in striatal cholinergic interneurons enhances the DRD2-mediated side effects of haloperidol, an antipsychotic agent. Haloperidol-induced catalepsy was attenuated in male Gpr143 gene-deficient (Gpr143-/y) mice compared with wild-type (Wt) mice. Reducing the endogenous release of L-DOPA and preventing interactions between GPR143 and DRD2 suppressed the haloperidol-induced catalepsy in Wt mice but not Gpr143-/y mice. The phenotypic defect in Gpr143-/y mice was mimicked in cholinergic interneuron-specific Gpr143-/y (Chat-cre;Gpr143flox/y) mice. Administration of haloperidol increased the phosphorylation of ribosomal protein S6 at Ser240/244 in the dorsolateral striatum of Wt mice but not Chat-cre;Gpr143flox/y mice. In Chinese hamster ovary cells stably expressing DRD2, co-expression of GPR143 increased cell surface expression level of DRD2, and L-DOPA application further enhanced the DRD2 surface expression. Shorter pauses in cholinergic interneuron firing activity were observed after intrastriatal stimulation in striatal slice preparations from Chat-cre; Gpr143flox/y mice compared with those from Wt mice. Together, these findings provide evidence that GPR143 regulates DRD2 function in cholinergic interneurons and may be involved in parkinsonism induced by antipsychotic drugs. [ABSTRACT FROM AUTHOR]

D-ribose L-cysteine is a glutathione precursor that acts as an antioxidant. In the present study, we investigated the effect of D-ribose L-cysteine and L-dopa combination against paraquat toxicity in Drosophila melanogaster. Adult wild-type flies were exposed to Paraquat (500 μM), RLC (250 μM), and/or L-dopa (0.1 mM) in their diet for 7 days. The survival rate, locomotion activities, and markers of antioxidants (Catalase, glutathione-S-transferase, superoxide dismutase, thioredoxin reductase, total and non-protein thiol), oxidative stress (hydrogen peroxide, protein carbonyl, malondialdehyde, nitrite/nitrates), and dehydrogenase activity were measured in the flies. The results showed a non-toxic effect of the combination of RLC and L-dopa. In addition, elevated oxidative stress markers due to paraquat treatments were significantly reduced after treatments with RLC and L-dopa. Combination treatment also significantly restored altered antioxidant status, improved survival rate, and impaired locomotion induced by paraquat. This study suggests that RLC could serve as adjunct therapy with L-dopa in managing Parkinson's disease and toxicity associated with paraquat and related compounds [ABSTRACT FROM AUTHOR]

Parkinson's disease is caused by a selective vulnerability and cell loss of dopaminergic neurons of the Substantia Nigra pars compacta and, consequently, striatal dopamine depletion. In Parkinson's disease therapy, dopamine loss is counteracted by the administration of L-DOPA, which is initially effective in ameliorating motor symptoms, but over time leads to a burdening side effect of uncontrollable jerky movements, termed L-DOPA-induced dyskinesia. To date, no efficient treatment for dyskinesia exists. The dopaminergic and serotonergic systems are intrinsically linked, and in recent years, a role has been established for pre-synaptic 5-HT1a/b receptors in L-DOPA-induced dyskinesia. We hypothesized that post-synaptic serotonin receptors may have a role and investigated the effect of modulation of 5-HT4 receptor on motor symptoms and L-DOPA-induced dyskinesia in the unilateral 6-OHDA mouse model of Parkinson's disease. Administration of RS 67333, a 5-HT4 receptor partial agonist, reduces L-DOPA-induced dyskinesia without altering L-DOPA's pro-kinetic effect. In the dorsolateral striatum, we find 5-HT4 receptor to be predominantly expressed in D2R-containing medium spiny neurons, and its expression is altered by dopamine depletion and L-DOPA treatment. We further show that 5-HT4 receptor agonism not only reduces L-DOPA-induced dyskinesia, but also enhances the activation of the cAMP-PKA pathway in striatopallidal medium spiny neurons. Taken together, our findings suggest that agonism of the post-synaptic serotonin receptor 5-HT4 may be a novel therapeutic approach to reduce L-DOPA-induced dyskinesia.

Developing efficient bioprocesses requires selecting the best biosynthetic pathways, which can be challenging and time-consuming due to the vast amount of data available in databases and literature. The extension of the shikimate pathway for the biosynthesis of commercially attractive molecules often involves promiscuous enzymes or lacks well-established routes. To address these challenges, we developed a computational workflow integrating enumeration/retrosynthesis algorithms, a toolbox for pathway analysis, enzyme selection tools, and a gene discovery pipeline, supported by manual curation and literature review. Our focus has been on implementing biosynthetic pathways for tyrosine-derived compounds, specifically L-3,4-dihydroxyphenylalanine (L-DOPA) and dopamine, with significant applications in health and nutrition. We selected one pathway to produce L-DOPA and two different pathways for dopamine–one already described in the literature and a novel pathway. Our goal was either to identify the most suitable gene candidates for expression in Escherichia coli for the known pathways or to discover innovative pathways. Although not all implemented pathways resulted in the accumulation of target compounds, in our shake-flask experiments we achieved a maximum L-DOPA titer of 0.71 g/L and dopamine titers of 0.29 and 0.21 g/L for known and novel pathways, respectively. In the case of L-DOPA, we utilized, for the first time, a mutant version of tyrosinase from Ralstonia solanacearum. Production of dopamine via the known biosynthesis route was accomplished by coupling the L-DOPA pathway with the expression of DOPA decarboxylase from Pseudomonas putida, resulting in a unique biosynthetic pathway never reported in literature before. In the context of the novel pathway, dopamine was produced using tyramine as the intermediate compound. To achieve this, tyrosine was initially converted into tyramine by expressing TDC from Levilactobacillus brevis, which, in turn, was converted into dopamine through the action of the enzyme encoded by ppoMP from Mucuna pruriens. This marks the first time that an alternative biosynthetic pathway for dopamine has been validated in microbes. These findings underscore the effectiveness of our computational workflow in facilitating pathway enumeration and selection, offering the potential to uncover novel biosynthetic routes, thus paving the way for other target compounds of biotechnological interest.

Mitochondrial dysmorphology/dysfunction follow global cerebral ischemia-reperfusion (GCI/R) injury, leading to neuronal death. Our previous researches demonstrated that Levodopa (L-DOPA) improves learning and memory impairment in GCI/R rats by increasing synaptic plasticity of hippocampal neurons. This study investigates if L-DOPA, used in Parkinson's disease treatment, alleviates GCI/R-induced cell death by enhancing mitochondrial quality. Metabolomics and transcriptomic results showed that GCI/R damage affected the Tricarboxylic acid (TCA) cycle in the hippocampus. The results of this study show that L-DOPA stabilized mitochondrial membrane potential and ultrastructure in hippocampus of GCI/R rats, increased dopamine level in hippocampus, decreased succinic acid level, and stabilized Ca2+ level in CA1 subregion of hippocampus. As a precursor of dopamine, L-DOPA is presumed to improves mitochondrial function in hippocampus of GCI/R rats. However, dopamine cannot cross the blood-brain barrier, so L-DOPA is used in clinical therapy to supplement dopamine. In this investigation, OGD/R models were established in isolated mouse hippocampal neurons (HT22) and primary rat hippocampal neurons. Notably, dopamine exhibited a multifaceted impact, demonstrating inhibition of mitochondrial reactive oxygen species (mitoROS) production, stabilization of mitochondrial membrane potential and Ca2+ level, facilitation of TCA circulation, promotion of aerobic respiratory metabolism, and downregulation of succinic acid-related gene expression. Consistency between in vitro and in vivo results underscores dopamine's significant neuroprotective role in mitigating mitochondrial dysfunction following global cerebral hypoxia and ischemia injury. Supplement dopamine may represent a promising therapy to the cognitive impairment caused by GCI/R injury.

Background and Aim: In healthy people, dopamine stimulates ghrelin secretion. The level of dopamine release and ghrelin is lower in the patients with polycystic ovary syndrome (PCOS). In the present study,we investigated the effects of doplamin and L-dopa on relative gene expression of ghrelin in PCOS model rats. Materials and Methods: In the first step of the study, PCOS was induced in 25 female Wistar rat (Rattus norvegicus) by injection of estradiol. Then, the rats received saline, dopamine (5µg), L-dopa (5µg) or simultaneous injections of sulpride (10µg/kg), SCH23390 hydrochloride (10µg/kg) and dopamine or L-dopa respectively via third cerebral ventricular. In the second part of the study, 15 PCOS rats received saline L-dopa (100mg/kg) or dopamine (50mg/kg) intraperitoneally. Hypothalamic and ovarian samples were dissected. Mean relative ghrelin gene expression was determined by real- time-PCR method. Results: Mean relative gene expression of ghrelin significantly decreased in the hypothalamus and ovary of the rats with PCOS compared to those in the intact rats. Intraventricular injection of dopamine or L-dopa significantly increased the hypothalamic ghrelin gene expression in comparison to that in the rats in the PCOS group. Dopamine or L-dopa did not significantly increase the gene expression of ovarian ghrelin in comparison to that in PCOS group. Injections of sulpride and SCH23390 significantly blocked the stimulatory effects of dopamine or L-dopa on the ghrelin gene expression in hypothalamus compared to those in the dopamine or L-dopa group. Conclusion: The dopaminergic pathway may be involved in increasing ghrelin gene expresion extremely via hypothamic level in PCOS condition.

The use of phosphodiesterase inhibitors in the treatment of Parkinson’s disease is currently widely discussed. The study aimed to investigate the impact of acute and chronic treatment with the phosphodiesterase 5 inhibitor, sildenafil, at low and moderate doses of 2 mg/kg and 6 mg/kg, and L-DOPA (12.5 mg/kg), alone or in combination, on asymmetric behavior and dopamine (DA) and serotonin metabolism in the striatum and substantia nigra of unilaterally 6-OHDA-lesioned rats. Acute administration of sildenafil at both tested doses jointly with L-DOPA significantly increased the number of contralateral rotations during a 2 h measurement compared to L-DOPA alone. The effect of a lower dose of sildenafil combined with L-DOPA was much greater in the second hour of measurement. However, the acute combined administration of a higher dose of sildenafil with L-DOPA resulted in an immediate and much stronger increase in the number of contralateral rotations compared to L-DOPA alone, already visible in the first hour of measurement. Interestingly, the chronic combined administration of 2 mg/kg of sildenafil and L-DOPA significantly reduced the number of contralateral rotations, especially during the first hour of measurement, compared to the long-term treatment with L-DOPA alone. Such an effect was not observed after the long-term combined treatment of a higher dose of sildenafil and L-DOPA compared to L-DOPA alone. The concentration of DA in the ipsilateral striatum and substantia nigra after the last combined chronic dose of sildenafil (2 or 6 mg/kg) and L-DOPA (12.5 mg/kg) was significantly higher than after L-DOPA alone. In spite of much stronger increases in the DA concentration in the ipsilateral striatum and substantia nigra, the number of contralateral rotations was reduced in the group of rats treated with the combination of 2 mg/kg sildenafil and L-DOPA compared to the group receiving L-DOPA alone. Moreover, the combined treatment with a low dose of sildenafil and L-DOPA had an opposite effect on DA catabolism, as assessed by DOPAC/DA and HVA/DA indexes, and these indexes were reduced in the ipsilateral striatum but increased in the contralateral striatum and substantia nigra compared to the treatment with L-DOPA alone. The results of the present study show that the addition of a low dose of a PDE5 inhibitor to the standard L-DOPA therapy differently modulates rotational behavior, the tissue DA concentration and its catabolism in the striatum and substantia nigra.

Alterations of serotonin type 4 receptor levels are linked to mood disorders and cognitive deficits in several conditions. However, few studies have investigated 5-HT4R alterations in movement disorders. We wondered whether striatal 5-HT4R expression is altered in experimental parkinsonism. We used a brain bank tissue from a rat and a macaque model of Parkinson's disease (PD). We then investigated its in vivo PET imaging regulation in a cohort of macaques. Dopaminergic depletion increases striatal 5-HT4R in the two models, further augmented after dyskinesia-inducing L-Dopa. Pending confirmation in PD patients, the 5-HT4R might offer a therapeutic target for dampening PD's symptoms. [ABSTRACT FROM AUTHOR]

Betalains are health-promoting plant pigments accumulated in non-anthocyanic plants. Owing to its limited distribution in nature, metabolic trade-offs of inhibiting them are poorly understood. The aim of this study was to investigate the effects of inhibition of betalains in Amaranthus tricolor seedlings to gain insights into the relationship of betalain biosynthesis with other biosynthetic pathways in betalain-accumulating plants. Phenylalanine (Phe; 12.5, 25, and 50 mmol L−1) and 3-methyl-2-benzothiazolinone hydrazone (MBTH) (25 mmol L−1) were treated to inhibit betalain biosynthesis in ten-day-old A. tricolor (red) seedlings. After two and six days of treatment, target (betalain-related metabolites) and non-target metabolites were analyzed. In two days, Phe content increased by 2.6, 8.5, and 17.4-fold in Phe (12.5, 25, and 50 mmol L−1)-treated seedlings, respectively, compared to control, indicating the uptake of Phe by the seedlings. Phe treatment led to a 10.1–18% decrease in betacyanins, while MBTH caused an 18.3% decrease in two days. In both treatments, cyclo-DOPA formation, which is essential for betacyanin biosynthesis, seems to be inhibited, albeit through different mechanisms. Betalain biosynthetic precursors and intermediates, viz., tyrosine, L-DOPA, and dopamine decreased differentially. Ascorbic acid, α-tocopherol, and retinol contents increased in both treatments concomitant with the reduction in betalains, total phenols, and antioxidant enzymes. Therefore, Phe treatment is beneficial in enhancing antioxidant metabolites in betalain-accumulating plants. However, the mechanism of increasing ascorbic acid on inhibiting betalains needs further investigation in other betalain-producing plants also to understand if ascorbic acid is involved in regulating betalain biosynthesis. [ABSTRACT FROM AUTHOR]