Tricompartmental Microcarriers with Controlled Release for Efficient Management of Parkinson's Disease.

Parkinson's is a progressive neurodegenerative disease of the nervous system. It has no cure, but its symptoms can be managed by supplying dopamine artificially to the brain.This work aims to engineer tricompartmental polymeric microcarriers by electrohydrodynamic cojetting technique to encapsulate three PD (Parkinson's disease) drugs incorporated with high encapsulation efficiency (∼100%) in a single carrier at a fixed drug ratio of 4:1:8 (Levodopa (LD): Carbidopa(CD): Entacapone (ENT)). Upon oral administration, the drug ratio needs to be maintained during subsequent release from microparticles to enhance the bioavailability of primary drug LD. This presents a notable challenge, as the three drugs vary in their aqueous solubility (LD > CD > ENT). The equilibrium of therapeutic release was achieved using a combination of FDA-approved polymers (PLA, PLGA, PCL, and PEG) and the disc shape of particles. In vitro studies demonstrated the simultaneous release of all the three therapeutics in a sustained and controlled manner. Additionally, pharmacodynamics and pharmacokinetics studies in Parkinson's disease rats induced by rotenone showed a remarkable improvement in PD conditions for the microparticles-fed rats, thereby showing a great promise toward efficient management of PD.

Serotonergic Regulation of Synaptic Dopamine Levels Mitigates L-DOPA-Induced Dyskinesia in a Mouse Model of Parkinson's Disease.

Background: The serotonin (5-HT) system can manipulate the processing of exogenous L-DOPA in the DA-denervated striatum, resulting in the modulation of L-DOPA-induced dyskinesia (LID). Objective: To characterize the effects of the serotonin precursor 5-hydroxy-tryptophan (5-HTP) or the serotonin transporter (SERT) inhibitor, Citalopram on L-DOPA-induced behavior, neurochemical signals, and underlying protein expressions in an animal model of Parkinson's disease. Methods: MitoPark (MP) mice at 20 weeks of age, subjected to a 14-day administration of L-DOPA/Carbidopa, displayed dyskinesia, referred to as LID. Subsequent investigations explored the effects of 5-HT-modifying agents, such as 5-HTP and Citalopram, on abnormal involuntary movements (AIMs), locomotor activity, neurochemical signals, serotonin transporter activity, and protein expression in the DA-denervated striatum of LID MP mice. Results: 5-HTP exhibited duration-dependent suppressive effects on developing and established LID, especially related to abnormal limb movements observed in L-DOPA-primed MP mice. However, Citalopram, predominantly suppressed abnormal axial movement induced by L-DOPA in LID MP mice. We demonstrated that 5-HTP could decrease L-DOPA-upregulation of DA turnover rates while concurrently upregulating 5-HT metabolism. Additionally, 5-HTP was shown to reduce the expressions of p-ERK and p-DARPP-32 in the striatum of LID MP mice. The effect of Citalopram in alleviating LID development may be attributed to downregulation of SERT activity in the dorsal striatum of LID MP mice. Conclusions: While both single injection of 5-HTP and Citalopram effectively mitigated the development of LID, the difference in mitigation of AIM subtypes may be linked to the unique effects of these two serotonergic agents on L-DOPA-derived DA and 5-HT metabolism.

Effects of Continuous Dopaminergic Stimulation on Parkinson's Disease Gait: A Longitudinal Prospective Study with Levodopa Intestinal Gel Infusion.

Background: Gait issues, including reduced speed, stride length and freezing of gait (FoG), are disabling in advanced phases of Parkinson's disease (PD), and their treatment is challenging. Levodopa/carbidopa intestinal gel (LCIG) can improve these symptoms in PD patients with suboptimal control of motor fluctuations, but it is unclear if continuous dopaminergic stimulation can further improve gait issues, independently from reducing Off-time. Objective: To analyze before (T0) and after 3 (T1) and 6 (T2) months of LCIG initiation: a) the objective improvement of gait and balance; b) the improvement of FoG severity; c) the improvement of motor complications and their correlation with changes in gait parameters and FoG severity. Methods: This prospective, longitudinal 6-months study analyzed quantitative gait parameters using wearable inertial sensors, FoG with the New Freezing of Gait Questionnaire (NFoG-Q), and motor complications, as per the MDS-UPDRS part IV scores. Results: Gait speed and stride length increased and duration of Timed up and Go and of sit-to-stand transition was significantly reduced comparing T0 with T2, but not between T0-T1. NFoG-Q score decreased significantly from 19.3±4.6 (T0) to 11.8±7.9 (T1) and 8.4±7.6 (T2) (T1-T0 p = 0.018; T2-T0 p < 0.001). Improvement of MDS-UPDRS-IV (T0-T2, p = 0.002, T0-T1 p = 0.024) was not correlated with improvement of gait parameters and NFoG-Q from T0 to T2. LEDD did not change significantly after LCIG initiation. Conclusion: Continuous dopaminergic stimulation provided by LCIG infusion progressively ameliorates gait and alleviates FoG in PD patients over time, independently from improvement of motor fluctuations and without increase of daily dosage of dopaminergic therapy.

The effect of anticholinergic drugs on cognition of patients with Parkinson's disease: a cohort study from the Egyptian population.

BACKGROUND: Cognitive dysfunction is a non-motor manifestation of Parkinson's disease (PD). We aimed to determine the frequency and patterns of cognitive dysfunction in treated patients with PD and their predictors. RESEARCH DESIGN AND METHODS: This study included 80 patients (male = 48; female = 32) and 30 healthy individuals. They underwent neuropsychiatric evaluations. Measurements included Beck's depression inventory - II (BDI-II), mini-mental state examination (MMSE) and Montreal cognitive assessment (MoCA). RESULTS: Patients had mean age of 55.56 ± 9.06 yrs, duration of PD of 4.86 ± 2.71 yrs and Hoehn and Yahr Scoring of 2.19 ± 0.89. They were on levodopa/carbidopa therapy and adjuvant therapy with benztropine mesylate, an anticholinergic drug, (n = 51) or amantadine sulfate, a dopaminergic drug, (n = 29). Sixteen (20%) had moderate depressive symptoms. Mild and moderate cognitive impairments were reported in 38.8% and 28.8% (by MMSE) and 46.3% and 31.3% (by MoCA). Patients had lower global cognitive scoring (p = 0.0001) and scorings of different cognitive functions (naming, attention, language, abstraction, memory and orientation) than controls. Patients treated with benztropine had lower cognition than with amantadine. Correlation analyses showed that lower cognition was only associated with chronic PD and its treatment (p = 0.0001). CONCLUSIONS: Cognitive dysfunction is common with PD (77.5%) particularly with anticholinergic drugs. De-prescription of anticholinergics is recommended for patients with PD.

Very Early Levodopa May Prevent Self-Injury in Lesch-Nyhan Disease.

BACKGROUND: In Lesch-Nyhan disease (LND), early dopamine deficiency is thought to contribute to dystonia and self-injury, gradually developing over the first years of life. Previous attempts to restore dopamine levels in older patients have been unsuccessful. Based on the hypothesis that very early dopamine replacement can prevent full phenotypic development, we treated three patients with LND from infancy with levodopa. METHODS: Levodopa/carbidopa (4:1) was started at age 11 to 13 months, aiming at escalating to 5 to 6 mg/kg levodopa per day. Follow-up focused on dystonia severity and whether self-injury occurred. In addition, the literature was reviewed to delineate the age at onset of self-injury for all reported cases to date. RESULTS: During long-term follow-up, self-injury appears to have been prevented in two patients (now aged 14 and 15.5 years), as their HPRT1 gene mutations had been invariably associated with self-injury before. Future self-injury is unlikely, as only 1.1% of 264 published cases had self-injury onset later in life than these patients' current ages. The third patient started self-injury at age 1.5 years, while on a substantially lower levodopa dose. A clear effect of levodopa on dystonia could not be determined. CONCLUSIONS: Our observations suggest that levodopa, given early enough and sufficiently dosed, might be able to prevent self-injury in LND. Therefore, levodopa could be considered in patients with LND as early as possible, at least before the self-injury appears. Further research is needed to establish very early levodopa as an effective treatment strategy in LND, and to optimize timing and dosing.

Investigating the effects of dopamine on short- and long-latency afferent inhibition.

Short- and long-latency afferent inhibition (SAI and LAI respectively) are phenomenon whereby the motor evoked potential induced by transcranial magnetic stimulation (TMS) is inhibited by a sensory afferent volley consequent to nerve stimulation. It remains unclear whether dopamine participates in the genesis or modulation of SAI and LAI. The present study aimed to determine if SAI and LAI are modulated by levodopa (l-DOPA). In this placebo-controlled, double-anonymized study Apo-Levocarb (100 mg l-DOPA in combination with 25 mg carbidopa) and a placebo were administered to 32 adult males (mean age 24 ± 3 years) in two separate sessions. SAI and LAI were evoked by stimulating the median nerve and delivering single-pulse TMS over the motor hotspot corresponding to the first dorsal interosseous muscle of the right hand. SAI and LAI were quantified before and 1 h following ingestion of drug or placebo corresponding to the peak plasma concentration of Apo-Levocarb. The results indicate that Apo-Levocarb increases SAI and does not significantly alter LAI. These findings support literature demonstrating increased SAI following exogenous dopamine administration in neurodegenerative disorders. KEY POINTS: Short- and long-latency afferent inhibition (SAI and LAI respectively) are measures of corticospinal excitability evoked using transcranial magnetic stimulation. SAI and LAI are reduced in conditions such as Parkinson's disease which suggests dopamine may be involved in the mechanism of afferent inhibition. 125 mg of Apo-Levocarb (100 mg dopamine) increases SAI but not LAI. This study increases our understanding of the pharmacological mechanism of SAI and LAI.

OFF-times before, during, and after nighttime sleep periods in Parkinson's disease patients with motor fluctuations and the effects of opicapone: A post hoc analysis of diary data from BIPARK-1 and -2.

INTRODUCTION: In BIPARK-1 and BIPARK-2, addition of once-daily opicapone to levodopa/carbidopa significantly reduced daily "OFF"-time relative to placebo in adults with Parkinson's disease (PD) and motor fluctuations. Diary data from these studies were pooled and analyzed post hoc to characterize "OFF"-times around nighttime sleep and to explore the effects of opicapone 50 mg. METHODS: "OFF" before sleep (OBS), "OFF during the nighttime sleep period" (ODNSP), early morning "OFF" (EMO), and duration of nighttime sleep and awake periods were analyzed descriptively at baseline. Mean changes from baseline to Week 14/15 (end of double-blind treatment) were analyzed using two-sided t-tests in participants with data for both visits. RESULTS: At baseline, 88.3 % (454/514) of participants reported having OBS (34.0 %), ODNSP (17.1 %), or EMO (79.6 %). Those with ODNSP had substantially shorter mean duration of uninterrupted sleep (4.4 h) than the overall pooled population (7.1 h). At Week 14/15, mean decrease from baseline in ODNSP duration was significantly greater with opicapone than with placebo (-0.9 vs. -0.4 h, P < 0.05). In participants with ODNSP at baseline, the decrease in total time spent awake during the night-time sleep period was significantly greater with opicapone than with placebo (-1.0 vs. -0.4 h, P < 0.05), as was the reduction in percent time spent awake during the night-time sleep period (-12.8 % vs. -4.5 %, P < 0.05). CONCLUSION: "OFF"-times around nighttime sleep were common in BIPARK-1 and BIPARK-2. Opicapone may improve sleep by decreasing the amount of time spent awake during the night in patients with PD who have night-time sleep period "OFF" episodes.

Antinociceptive effects of carbidopa levodopa on normal rats and Parkinson's disease mice.

Carbidopa levodopa is widely used to ameliorate motor symptoms of Parkinson's disease (PD) patients. Pain is one of common symptoms of PD. The aim of this experiment is to study antinociceptive effects of carbidopa levodopa on normal rats and PD mice. Rats were intragastrically treated with carbidopa levodopa and the hind paw withdrawal latency (HWL) was investigated. PD mouse model was prepared with MPTP and then the antinociceptive effects of carbidopa levodopa on PD mice were evaluated. In normal rats, the HWL to thermal stimulus was augmented after carbidopa levodopa administration (p<0.05 or p<0.01) and carbidopa levodopa increased the HWL (p<0.05 or p<0.01) to mechanical stimulus. In PD mice, carbidopa levodopa elevated the HWL of the thermal stimulus in PD mice (p<0.05). Furthermore, the HWL in the inflammatory pain of PD mice was also increased by carbidopa levodopa treatmet (p<0.01). The current findings indicate that carbidopa levodopa has an antinociceptive effects in normal rats and PD mice. The analgesic effect of carbidopa levodopa on patients with or without PD is worth studying in further research.

Human equivalent doses of L-DOPA rescues retinal morphology and visual function in a murine model of albinism.

L-DOPA is deficient in the developing albino eye, resulting in abnormalities of retinal development and visual impairment. Ongoing retinal development after birth has also been demonstrated in the developing albino eye offering a potential therapeutic window in humans. To study whether human equivalent doses of L-DOPA/Carbidopa administered during the crucial postnatal period of neuroplasticity can rescue visual function, OCA C57BL/6 J-c2J OCA1 mice were treated with a 28-day course of oral L-DOPA/Carbidopa at 3 different doses from 15 to 43 days postnatal age (PNA) and for 3 different lengths of treatment, to identify optimum dosage and treatment length. Visual electrophysiology, acuity, and retinal morphology were measured at 4, 5, 6, 12 and 16 weeks PNA and compared to untreated C57BL/6 J (WT) and OCA1 mice. Quantification of PEDF, ßIII-tubulin and syntaxin-3 expression was also performed. Our data showed impaired retinal morphology, decreased retinal function and lower visual acuity in untreated OCA1 mice compared to WT mice. These changes were diminished or eliminated when treated with higher doses of L-DOPA/Carbidopa. Our results demonstrate that oral L-DOPA/Carbidopa supplementation at human equivalent doses during the postnatal critical period of retinal neuroplasticity can rescue visual retinal morphology and retinal function, via PEDF upregulation and modulation of retinal synaptogenesis, providing a further step towards developing an effective treatment for albinism patients.

Development and Validation of a New LC-MS/MS Bioanalytical Method for the Simultaneous Determination of Levodopa, Levodopa Methyl Ester, and Carbidopa in Human Plasma Samples.

Levodopa (L-DOPA) treatment, combined with the administration of dopa-decarboxylase inhibitors (DDCIs), is still the most effective symptomatic treatment of Parkinson's disease (PD). Although its efficacy in the early stage of the disease has been confirmed, its complex pharmacokinetics (PK) increases the variability of the intra-individual motor response, thus amplifying the risk of motor/non-motor fluctuations and dyskinesia. Moreover, it has been demonstrated that L-DOPA PK is strongly influenced by several clinical, therapeutic, and lifestyle variables (e.g., dietary proteins). L-DOPA therapeutic monitoring is therefore crucial to provide personalized therapy, hence improving drug efficacy and safety. To this aim, we have developed and validated an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to quantify L-DOPA, levodopa methyl ester (LDME), and the DDCI carbidopa in human plasma. The compounds were extracted by protein precipitation and samples were analyzed with a triple quadrupole mass spectrometer. The method showed good selectivity and specificity for all compounds. No carryover was observed, and dilution integrity was demonstrated. No matrix effect could be retrieved; intra-day and inter-day precision and accuracy values met the acceptance criteria. Reinjection reproducibility was assessed. The described method was successfully applied to a 45-year-old male patient to compare the pharmacokinetic behavior of an L-DOPA-based medical treatment involving commercially available Mucuna pruriens extracts and an LDME/carbidopa (100/25 mg) formulation.

Carbidopa suppresses estrogen receptor-positive breast cancer via AhR-mediated proteasomal degradation of ERα.

Estrogen receptor-α (ERα) promotes breast cancer, and ER-positive cancer accounts for ~ 80% of breast cancers. This subtype responds positively to hormone/endocrine therapies involving either inhibition of estrogen synthesis or blockade of estrogen action. Carbidopa, a drug used to potentiate the therapeutic efficacy of L-DOPA in Parkinson's disease, is an agonist for aryl hydrocarbon receptor (AhR). Pharmacotherapy in Parkinson's disease decreases the risk for cancers, including breast cancer. The effects of carbidopa on ER-positive breast cancer were evaluated in cell culture and in mouse xenografts. The assays included cell proliferation, apoptosis, cell migration/invasion, subcellular localization of AhR, proteasomal degradation, and tumor growth in xenografts. Carbidopa decreased proliferation and migration of ER-positive human breast cancer cells in vitro with no significant effect on ER-negative breast cancer cells. Treatment of ER-positive cells with carbidopa promoted nuclear localization of AhR and expression of AhR target genes; it also decreased cellular levels of ERα via proteasomal degradation in an AhR-dependent manner. In vivo, carbidopa suppressed the growth of ER-positive breast cancer cells in mouse xenografts; this was associated with increased apoptosis and decreased cell proliferation. Carbidopa has therapeutic potential for ER-positive breast cancer either as a single agent or in combination with other standard chemotherapies.

Effects of Levodopa-Carbidopa Intestinal Gel on Dyskinesia and Non-Motor Symptoms Including Sleep: Results from a Meta-Analysis with 24-Month Follow-Up.

BACKGROUND: In advanced Parkinson's disease (PD), dyskinesias and non-motor symptoms such as sleep dysfunction can significantly impair quality of life, and high-quality management is an unmet need. OBJECTIVE: To analyze changes in dyskinesia and non-motor symptoms (including sleep) among studies with levodopa-carbidopa intestinal gel (LCIG) in patients with advanced PD. METHODS: A comprehensive literature review identified relevant studies examining LCIG efficacy. Outcomes of interest were dyskinesia (UDysRS, UPDRS IV item 32), overall non-motor symptoms (NMSS), mentation/behavior/mood (UPDRS I), and sleep/daytime sleepiness (PDSS-2, ESS). The pooled mean (95% confidence interval) change from baseline per outcome was estimated for each 3-month interval with sufficient data (i.e., reported by≥3 studies) up to 24 months using a random-effects model. RESULTS: Seventeen open-label studies evaluating 1243 patients with advanced PD were included. All outcomes of interest with sufficient data for meta-analysis showed statistically significant improvement within 6 months of starting LCIG. There were statistically significant improvements in dyskinesia duration as measured by UPDRS IV item 32 at 6 months (-1.10 [-1.69, -0.51] h/day) and 12 months (-1.35 [-2.07, -0.62] h/day). There were statistically and clinically significant improvements in non-motor symptoms as measured by NMSS scores at 3 months (-28.71 [-40.26, -17.15] points). Significant reduction of NMSS burden was maintained through 24 months (-17.61 [-21.52, -13.70] points). UPDRS I scores significantly improved at 3 months (-0.39 [-0.55, -0.22] points). Clinically significant improvements in PDSS-2 and ESS scores were observed at 6 and 12 months in individual studies. CONCLUSION: Patients with advanced PD receiving LCIG showed significant sustained improvements in the burden of dyskinesia and non-motor symptoms up to 24 months after initiation.

Carbidopa, an activator of aryl hydrocarbon receptor, suppresses IDO1 expression in pancreatic cancer and decreases tumor growth.

IDO1 is an immunomodulatory enzyme responsible for tryptophan catabolism. Its expression in immune cells, especially the DCs, has attracted attention because it leads to tryptophan depletion at the immunological synapse, thereby causing T-cell anergy and immune evasion by the tumor cells. Cancer cells also overexpress IDO1. Immunotherapy targeting IDO1 has been one of the focus areas in cancer biology, but lately studies have identified non-immune related functions of IDO1 leading to a paradigm shift with regard to IDO1 function in the context of tumor cells. In this study, we show that PDAC tissues and PDAC cells overexpress IDO1. The expression level is reciprocally related to overall patient survival. We further show that carbidopa, an FDA-approved drug for Parkinson's disease as well as an AhR agonist, inhibits IDO1 expression in PDAC cells. Using athymic nude mice, we demonstrate that carbidopa-mediated suppression of IDO1 expression attenuates tumor growth. Mechanistically, we show that AhR is responsible for carbidopa-mediated suppression of IDO1, directly as a transcription factor and indirectly by interfering with the JAK/STAT pathway. Overall, targeting IDO1 not only in immune cells but also in cancer cells could be a beneficial therapeutic strategy for PDAC and potentially for other cancers as well and that carbidopa could be repurposed to treat cancers that overexpress IDO1.

Continuous Dopaminergic Stimulation Improves Cortical Maladaptive Changes in Advanced Parkinson's Disease.

BACKGROUND: With the progression of Parkinson's disease (PD), pulsatile treatment with oral levodopa causes maladaptive changes within basal ganglia-thalamo-cortical circuits, which are clinically expressed as motor fluctuations and dyskinesias. At the level of the motor cortex, these changes may be detected using transcranial magnetic stimulation (TMS), as abnormal corticospinal and intracortical excitability and absent response to plasticity protocols. OBJECTIVE: We investigated the effect of continuous dopaminergic stimulation on cortical maladaptive changes related to oral levodopa treatment. METHODS: Twenty patients with advanced PD were tested using TMS within 1 week before and again 6 months after the introduction of levodopa-carbidopa intestinal gel. We measured resting and active motor thresholds, input/output curve, short interval intracortical inhibition curve, cortical silent period, and response to intermittent theta burst stimulation. Patients were clinically assessed with Part III and Part IV of the Movement Disorders Society Unified Parkinson's Disease Rating Scale. RESULTS: Six months after the introduction of levodopa-carbidopa intestinal gel, motor fluctuations scores (P = 0.001) and dyskinesias scores (P < 0.001) were reduced. Resting and active motor threshold (P = 0.012 and P = 0.015) and x-intercept of input/output curve (P = 0.005) were also decreased, while short-interval intracortical inhibition and response to intermittent theta bust stimulation were improved (P = 0.026 and P = 0.031, respectively). Changes in these parameters correlated with clinical improvement. CONCLUSIONS: In patients with advanced PD, switching from intermittent to continuous levodopa delivery increased corticospinal excitability and improved deficient intracortical inhibition and abnormal motor cortex plasticity, along with amelioration of motor fluctuations and dyskinesias. Continuous dopaminergic stimulation ameliorates maladaptive changes inflicted by chronic pulsatile dopaminergic stimulation. © 2022 International Parkinson and Movement Disorder Society.

Acute treatment with 5-hydroxytryptophan increases social approach behaviour but does not activate serotonergic neurons in the dorsal raphe nucleus in juvenile male BALB/c mice: A model of human disorders with deficits of sociability.

BACKGROUND: The BALB/c mouse has been proposed as a model of human psychiatric disorders characterised by elevated anxiety and altered sociability. Juvenile BALB/c mice show decreased social exploratory behaviour, increased anxiety, and reduced brain serotonin synthesis compared to other strains including C57BL/6J mice. AIM: To determine whether supplementation of brain serotonin synthesis alters social behaviour and activation of serotonergic neurons across subregions of the dorsal raphe nucleus (DR) in BALB/c mice. METHODS: Juvenile male BALB/c mice were assigned to one of four treatment conditions: vehicle/vehicle, carbidopa (25 mg/kg)/vehicle, vehicle/5-HTP (10 mg/kg), carbidopa (25 mg/kg)/5-HTP (10 mg/kg). Social behaviour was measured using the three-chamber social approach test, followed by immunohistochemical staining for TPH2 and c-Fos to measure activation of serotonergic neurons across subregions of the DR. RESULTS: Mice treated with carbidopa/5-HTP spent more time in the social cage zone and covered more distance in the social approach test compared to other treatment groups. There was no difference between treatment groups in the activation of serotonergic neurons across subregions of the DR. However, the DRD was associated with increased social approach behaviour in carbidopa/5-HTP treated animals. CONCLUSIONS: Supplementation of serotonin synthesis can increase social approach behaviour in juvenile BALB/c mice. An increase in locomotor behaviour was also observed suggesting that increasing central serotonin synthesis may have led to a reduction in state anxiety, manifesting in increased exploratory behaviour. As no effect on serotonergic activation within the DR was found, alternative mechanisms are likely important for the effects of 5-HTP on social behaviour.

Exogenous glutathione exerts a therapeutic effect in ischemic stroke rats by interacting with intrastriatal dopamine.

We previously showed that oral administration of exogenous glutathione (GSH) exerted a direct and/or indirect therapeutic effect on ischemic stroke rats, but the underlying mechanisms remain elusive. In the current study, we conducted a quantitative proteomic analysis to explore the pathways mediating the therapeutic effect of GSH in cerebral ischemia/reperfusion (I/R) model rats. Rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion. The rats were treated with GSH (250 mg/kg, ig) or levodopa (L-dopa, 100 mg/kg, ig) plus carbidopa (10 mg/kg, ig). Neurologic deficits were assessed, and the rats were sacrificed at 24 h after cerebral I/R surgery to measure brain infarct sizes. We conducted a proteomic analysis of the lesion side striatum samples and found that tyrosine metabolism and dopaminergic synapse were involved in the occurrence of cerebral stroke and the therapeutic effect of GSH. Western blot assay revealed that tyrosine hydroxylase (TH) mediated the occurrence of I/R-induced ischemic stroke and the therapeutic effect of GSH. We analyzed the regulation of GSH on endogenous small molecule metabolites and showed that exogenous GSH had the most significant effect on intrastriatal dopamine (DA) in I/R model rats by promoting its synthesis and inhibiting its degradation. To further explore whether DA-related alterations were potential targets of GSH, we investigated the therapeutic effect of DA accumulation on ischemic brain injury. The combined administration of the precursor drugs of DA (L-dopa and carbidopa) significantly ameliorated neurological deficits, reduced infarct size, and oxidative stress, and decreased pro-inflammatory cytokines levels in the striatum of I/R injury rats. More interestingly, exogenous L-dopa/carbidopa could also greatly enhance the exposure of intracerebral GSH by upregulating GSH synthetases and enhancing homocysteine (HCY) levels in the striatum. Thus, administration of exogenous GSH exerts a therapeutic effect on ischemic stroke by increasing intrastriatal DA, and the accumulated DA can, in turn, enhance the exposure of GSH and its related substances, thus promoting the therapeutic effect of GSH.

Modulation of dopamine tone induces frequency shifts in cortico-basal ganglia beta oscillations.

Βeta oscillatory activity (human: 13-35 Hz; primate: 8-24 Hz) is pervasive within the cortex and basal ganglia. Studies in Parkinson's disease patients and animal models suggest that beta-power increases with dopamine depletion. However, the exact relationship between oscillatory power, frequency and dopamine tone remains unclear. We recorded neural activity in the cortex and basal ganglia of healthy non-human primates while acutely and chronically up- and down-modulating dopamine levels. We assessed changes in beta oscillations in patients with Parkinson's following acute and chronic changes in dopamine tone. Here we show beta oscillation frequency is strongly coupled with dopamine tone in both monkeys and humans. Power, coherence between single-units and local field potentials (LFP), spike-LFP phase-locking, and phase-amplitude coupling are not systematically regulated by dopamine levels. These results demonstrate that beta frequency is a key property of pathological oscillations in cortical and basal ganglia networks.

Pharmacological evaluation of vanillic acid in rotenone-induced Parkinson's disease rat model.

In the present study, we investigated the anti-Parkinson's effect of vanillic acid (VA) (12 mg/kg, 25 mg/kg, 50 mg/kg p.o.) against rotenone (2 mg/kg s.c.) induced Parkinson's disease (PD) in rats. The continuous administration of rotenone for 35 days resulted in rigidity in muscles, catalepsy, and decrease in locomotor activity, body weight, and rearing behaviour along with the generation of oxidative stress in the brain (rise in the TBARS, and SAG level and reduced CAT, and GSH levels). Co-treatment of VA and levodopa-carbidopa (100 mg/kg + 25 mg/kg p.o.) lead to a significant (P < 0.001) reduction in the muscle rigidity and catalepsy along with a significant (P < 0.001) increase in body weight, rearing behaviour, locomotion and muscle activity as compared to the rotenone-treated group in the dose dependent manner, showing maximum effect at the 50 mg/kg. It also showed reversal of levels of oxidative stress parameters thus, reducing the neuronal oxidative stress. The level of DA was also estimated which showed an increase in the level of DA in the VA plus standard drug treated animals as compared to rotenone treated group. Histopathological evaluation showed a high number of eosinophilic lesions in the rotenone group which were found to be very less in the VA co-treated group. The study thus proved that co-treatment of VA and levodopa-carbidopa, significantly protected the brain from neuronal damage due to oxidative stress and attenuated the motor defects indicating the possible therapeutic potential of VA as a neuroprotective in PD.

Monozygotic twins with DYT-TOR1A showing jerking movements and levodopa responsiveness.

BACKGROUND: DYT-TOR1A is caused by a GAG deletion in the TOR1A gene. While it usually manifests as early-onset dystonia, its phenotype is extremely diverse, even within one family. Recent reports have revealed that some DYT-TOR1A cases have novel mutations in the TOR1A gene while others have mutations in both TOR1A and another DYT gene (THAP1 or SGCE). Our understanding of the correlation between genotype and phenotype is becoming increasingly complicated. CASE PRESENTATIONS: Here, we report on monozygotic twins who developed dystonia in childhood. The two children had different presentations in terms of onset age and dominant disturbances, but both exhibited marked diurnal fluctuation and jerking movements of the limbs as well as levodopa/levodopa-carbidopa responsiveness. These features are commonly associated with DYT/PARK-GCH1 and DYT-SGCE, yet these twins had no mutations in the GCH1 or SGCE genes. Whole exome sequencing eventually revealed a single GAG deletion in the TOR1A gene. CONCLUSION: Monozygotic twins whose only mutation was a GAG deletion in TOR1A exhibited DYT/PARK-GCH1-asssociated features and jerking movements reminiscent of myoclonus. This finding may expand the spectrum of phenotypes associated with DYT-TOR1A, and suggests that levodopa has potential as a treatment for DYT-TOR1A with DYT/PARK-GCH1-associated features.

Effect of levodopa/carbidopa on stress response in zebrafish.

The dopaminergic system of zebrafish is complex and the numerous pathways and receptors in the central nervous system (CNS) are being extensively studied. A critical factor for the synthesis, activation and release of catecholamines (CAs) is the presence of tyrosine hydroxylase, an enzyme which converts L-tyrosine into levodopa. Levodopa thus is the intermediary in the synthesis of dopamine (DA) and norepinephrine (NE) and promotes its release; therefore, CAs play an important role in the CNS with hormonal functions. Here, we use levodopa/carbidopa to clarify the involvement of the dopaminergic pathway in the stress response in zebrafish submitted to an acute stress challenge. Acute stress was induced by chasing fish with a net for 2 min and assessed by measuring whole-body cortisol levels. Two experiments were carried out, the first with exposure to levodopa/carbidopa and the second with exposure to AMPT and levodopa/carbidopa. Levodopa/carbidopa balances the stress response through its action on the zebrafish hypothalamic-pituitary-adrenal (HPA) axis. Changes in cortisol levels suggest that DA was related to the balance of the stress response and that NE decreased this response. These effects were specific to stress since levodopa/carbidopa did not induce changes in cortisol in non-stressed fish.