Vesicular Monoamine Transporter Research Articles

Developmental exposure to the Parkinson's disease-associated organochlorine pesticide dieldrin alters dopamine neurotransmission in α-synuclein pre-formed fibril (PFF)-injected mice.

Parkinson's disease (PD) is the fastest-growing neurological disease worldwide, with increases outpacing aging and occurring most rapidly in recently industrialized areas, suggesting a role of environmental factors. Epidemiological, post-mortem, and mechanistic studies suggest that persistent organic pollutants, including the organochlorine pesticide dieldrin, increase PD risk. In mice, developmental dieldrin exposure causes male-specific exacerbation of neuronal susceptibility to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and synucleinopathy. Specifically, in the α-synuclein (α-syn) pre-formed fibril (PFF) model, exposure leads to increased deficits in striatal dopamine (DA) turnover and motor deficits on the challenging beam. Here, we hypothesized that alterations in DA handling contribute to the observed changes and assessed vesicular monoamine transporter 2 (VMAT2) function and DA release in this dieldrin/PFF 2-hit model. Female C57BL/6 mice were exposed to 0.3 mg/kg dieldrin or vehicle every 3 days by feeding, starting at 8 weeks of age and continuing throughout breeding, gestation, and lactation. Male offspring from independent litters underwent unilateral, intrastriatal injections of α-syn PFFs at 12 weeks of age, and vesicular 3H-DA uptake assays and fast-scan cyclic voltammetry were performed 4 months post-PFF injection. Dieldrin-induced an increase in DA release in striatal slices in PFF-injected animals, but no change in VMAT2 activity. These results suggest that developmental dieldrin exposure increases a compensatory response to synucleinopathy-triggered striatal DA loss. These findings are consistent with silent neurotoxicity, where developmental exposure to dieldrin primes the nigrostriatal striatal system to have an exacerbated response to synucleinopathy in the absence of observable changes in typical markers of nigrostriatal dysfunction and degeneration.

Neuroprotective effects of osmotin in Parkinson’s disease-associated pathology via the AdipoR1/MAPK/AMPK/mTOR signaling pathways

BackgroundParkinson’s disease (PD) is the second most frequent age-related neurodegenerative disorder and is characterized by the loss of dopaminergic neurons. Both environmental and genetic aspects are involved in the pathogenesis of PD. Osmotin is a structural and functional homolog of adiponectin, which regulates the phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK) via adiponectin receptor 1 (AdipoR1), thus attenuating PD-associated pathology. Therefore, the current study investigated the neuroprotective effects of osmotin using in vitro and in vivo models of PD.MethodsThe study used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced and neuron-specific enolase promoter human alpha-synuclein (NSE-hαSyn) transgenic mouse models and 1-methyl-4-phenylpyridinium (MPP+)- or alpha-synuclein A53T-treated cell models. MPTP was injected at a dose of 30 mg/kg/day for five days, and osmotin was injected twice a week at a dose of 15 mg/kg for five weeks. We performed behavioral tests and analyzed the biochemical and molecular changes in the substantia nigra pars compacta (SNpc) and the striatum.ResultsBased on our study, osmotin mitigated MPTP- and α-synuclein-induced motor dysfunction by upregulating the nuclear receptor-related 1 protein (Nurr1) transcription factor and its downstream markers tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT2). From a pathological perspective, osmotin ameliorated neuronal cell death and neuroinflammation by regulating the mitogen-activated protein kinase (MAPK) signaling pathway. Additionally, osmotin alleviated the accumulation of α-synuclein by promoting the AMPK/mammalian target of rapamycin (mTOR) autophagy signaling pathway. Finally, in nonmotor symptoms of PD, such as cognitive deficits, osmotin restored synaptic deficits, thereby improving cognitive impairment in MPTP- and α-synuclein-induced mice.ConclusionsTherefore, our findings indicated that osmotin significantly rescued MPTP/α-synuclein-mediated PD neuropathology. Altogether, these results suggest that osmotin has potential neuroprotective effects in PD neuropathology and may provide opportunities to develop novel therapeutic interventions for the treatment of PD.

The Plasma Membrane Monoamine Transporter is Highly Expressed in Neuroblastoma and Functions as an mIBG Transporter.

Neuroblastoma (NB) is a pediatric cancer with low survival rates in high-risk patients. 131I-mIBG has emerged as a promising therapy for high-risk NB and kills tumor cells by radiation. Consequently, 131I-mIBG tumor uptake and retention are major determinants for its therapeutic efficacy. mIBG enters NB cells through the norepinephrine transporter (NET), and accumulates in mitochondria through unknown mechanisms. Here we evaluated the expression of monoamine and organic cation transporters in high-risk NB tumors and explored their relationship with MYCN amplification and patient survival. We found that NB mainly expresses NET, the plasma membrane monoamine transporter (PMAT), and the vesicular membrane monoamine transporter 1/2 (VMAT1/2), and that the expression of these transporters is significantly reduced in MYCN-amplified tumor samples. PMAT expression is the highest and correlates with overall survival in high-risk NB patients without MYCN amplification. Immunostaining showed that PMAT resides intracellularly in NB cells and co-localizes with mitochondria. Using cells expressing PMAT, mIBG was identified as a PMAT substrate. In mitochondria isolated from NB cell lines, mIBG uptake was reduced by ∼50% by a PMAT inhibitor. Together, our data suggest that PMAT is a previously unrecognized transporter highly expressed in NB and could impact intracellular transport and therapeutic response to 131I-mIBG. SIGNIFICANCE STATEMENT: This study identified that plasma membrane monoamine transporter (PMAT) is a novel transporter highly expressed in neuroblastoma and its expression level is associated with overall survival rate in high-risk patients without MYCN amplification. PMAT is expressed intracellularly in neuroblastoma cells, transports meta-iodobenzylguanidine (mIBG) and thus could impact tumor retention and response to 131I-mIBG therapy. These findings have important clinical implications as PMAT could represent a novel molecular marker to help inform disease prognosis and predict response to 131I-mIBG therapy.

Amphetamine-induced reverse transport of dopamine does not require cytosolic Ca2+

Amphetamines (AMPHs) are substrates of the dopamine transporter (DAT) and reverse the direction of dopamine (DA) transport. This has been suggested to depend on activation of Ca2+-dependent pathways, but the mechanism underlying reverse transport via endogenously expressed DAT is still unclear. Here, to enable concurrent visualization by live imaging of extracellular DA dynamics and cytosolic Ca2+ levels, we employ the fluorescent Ca2+ sensor jRGECO1a expressed in cultured dopaminergic neurons together with the fluorescent DA sensor GRABDA1H expressed in cocultured "sniffer" cells. In the presence of the Na+-channel blocker tetrodotoxin to prevent exocytotic DA release, AMPH induced in the cultured neurons a profound dose-dependent efflux of DA that was blocked both by inhibition of DAT with cocaine and by inhibition of the vesicular monoamine transporter-2 with Ro-4-1284 or reserpine. However, the AMPH-induced DA efflux was not accompanied by an increase in cytosolic Ca2+ and was unaffected by blockade of voltage-gated calcium channels or chelation of cytosolic Ca2+. The independence of cytosolic Ca2+ was further supported by activation of N-methyl-D-aspartate-type ionotropic glutamate receptors leading to a marked increase in cytosolic Ca2+ without affecting AMPH-induced DA efflux. Curiously, AMPH elicited spontaneous Ca2+ spikes upon blockade of the D2 receptor, suggesting that AMPH can regulate intracellular Ca2+ in an autoreceptor-dependent manner regardless of the apparent independence of Ca2+ for AMPH-induced efflux. We conclude that AMPH-induced DA efflux in dopaminergic neurons does not require cytosolic Ca2+ but is strictly dependent on the concerted action of AMPH on both vesicular monoamine transporter-2 and DAT.

Conditional deletion of neurexins dysregulates neurotransmission from dopamine neurons.

Midbrain dopamine (DA) neurons are key regulators of basal ganglia functions. The axonal domain of these neurons is highly complex, with a large subset of non-synaptic release sites and a smaller subset of synaptic terminals from which in addition to DA, glutamate or GABA are also released. The molecular mechanisms regulating the connectivity of DA neurons and their neurochemical identity are unknown. An emerging literature suggests that neuroligins, trans-synaptic cell adhesion molecules, regulate both DA connectivity and neurotransmission. However, the contribution of their major interaction partners, neurexins (Nrxns) is unexplored. Here we tested the hypothesis that Nrxns regulate DA neuron neurotransmission. Mice with conditional deletion of all Nrxns in DA neurons (DAT::Nrxns KO) exhibited normal basic motor functions. However, they showed an impaired locomotor response to the psychostimulant amphetamine. In line with an alteration in DA neurotransmission, decreased levels of the membrane DA transporter (DAT) and increased levels of the vesicular monoamine transporter (VMAT2) were detected in the striatum of DAT::Nrxns KO mice, along with reduced activity-dependent DA release. Strikingly, electrophysiological recordings revealed an increase of GABA co-release from DA neuron axons in the striatum of these mice. Together, these findings suggest that Nrxns act as regulators of the functional connectivity of DA neurons.

Dopamine and vesicular monoamine transport loss supports incidental Lewy body disease as preclinical idiopathic Parkinson

Incidental Lewy body disease (ILBD) is a neuropathological diagnosis of brains with Lewy bodies without clinical neuropsychiatric symptoms. Dopaminergic deficits suggest a relationship to preclinical Parkinson’s disease (PD). We now report a subregional pattern of striatal dopamine loss in ILBD cases, with dopamine found significantly decreased in the putamen (−52%) and only to a lower extent in the caudate (−38%, not statistically significant); this is similar to the pattern in idiopathic PD in various neurochemical and in vivo imaging studies. We aimed to find out if our recently reported impaired storage of dopamine in striatal synaptic vesicles prepared from striatal tissue of cases with idiopathic PD might be an early or even causative event. We undertook parallel measurements of [3H]dopamine uptake and vesicular monoamine transporter (VMAT)2 binding sites by the specific label [3H]dihydrotetrabenazine on vesicular preparation from caudate and putamen in ILBD. Neither specific uptake of dopamine and binding of [3H]dihydrotetrabenazine, nor mean values of the calculated ratios of dopamine uptake and VMAT2 binding, a measure of uptake rate per transport site, were significantly different between ILBD and controls. ATP-dependence of [3H]dopamine uptake revealed significantly higher rates in putamen than in caudate at saturating concentrations of ATP in controls, a subregional difference lost in ILBD. Our findings support a loss of the normally higher VMAT2 activity in putamen as a contributing factor to the higher susceptibility of the putamen to dopamine depletion in idiopathic PD. Moreover, we suggest ILBD postmortem tissue as a valuable source for testing hypotheses on processes in idiopathic PD.

Real-world experience with VMAT2 inhibitors in Tourette syndrome.

We aimed to review our "real-world" experience with the vesicular monoamine transporter 2 (VMAT2) inhibitors tetrabenazine, deutetrabenazine, and valbenazine for treatment of Tourette syndrome, focusing on therapeutic benefits, side effect profile, and accessibility for the off-label use of these drugs. We performed a retrospective chart review, supplemented with a telephone survey, of all our patients treated for their tics with VMAT2 inhibitors over a period of 4years from January 2017 until January 2021. We identified 164 patients treated with the various VMAT2 inhibitors (tetrabenazine, n = 135; deutetrabenazine, n = 71; valbenazine, n = 20). Data on the mean treatment duration and daily dosages were collected. The response to VMAT2 inhibitors was assessed by a Likert scale by comparing the symptom severity before initiation and while on treatment. Side effects were mild and mostly consisted of depression as the major side effect but there was no suicidality reported. VMAT2 inhibitors are effective and safe in the treatment of tics associated with Tourette syndrome but are not readily accessible by patients in the United States, partly because of lack of approval by the Food and Drug Administration.

Historical developments, hotspots, and trends in tardive dyskinesia research: a scientometric analysis of 54 years of publications.

Since being recognized as an important drug-induced clinical entity during the 1960s, tardive dyskinesia (TD) has generated an extensive body of research seeking to understand its clinical characteristics, epidemiology, pathophysiology and management. Modern scientometric approaches allow interactive visualization of large bodies of literature to identify trends and hotspots within knowledge domains. This study thus aimed to provide a comprehensive scientometric review of the TD literature. Web of Science was searched for articles, reviews, editorials and letters with the term "tardive dyskinesia" in the title, abstract, or keywords through 12/31/2021. A total of 5,228 publications and 182,052 citations were included. Annual research output, prominent research areas, authors, affiliations and countries were summarized. VOSViewer and CiteSpace were used for bibliometric mapping and co-citation analysis. Structural and temporal metrics were used to identify key publications in the network. TD-related publications peaked in the 1990s, gradually declined after 2004, and showed a further small increase after 2015. The most prolific authors were Kane JM, Lieberman JA, and Jeste DV overall (1968-2021), and Zhang XY, Correll CU and Remington G in the last decade (2012-2021). The most prolific journal was the Journal of Clinical Psychiatry overall, and the Journal of Psychopharmacology in the last decade. Knowledge clusters in the 1960-1970s dealt with clinical and pharmacological characterization of TD. In the 1980s, epidemiology, clinical TD assessment, cognitive dysfunction and animal models predominated. During the 1990s, research diverged into pathophysiological studies, especially oxidative stress, and clinical trials on atypical antipsychotics, with a focus on clozapine and bipolar disorder. In the 1990-2000s, pharmacogenetics emerged. More recent clusters include serotonergic receptors, dopamine-supersensitivity psychosis, primary motor abnormalities of schizophrenia, epidemiology/meta-analyses, and advances in TD treatment, particularly vesicular monoamine transporter-2 inhibitors since 2017. This scientometric review visualized the evolution of scientific knowledge on TD over more than five decades. These findings will be useful for researchers to find relevant literature when writing scientific articles, choosing appropriate journals, finding collaborators or mentors for research, and to understand the historical developments and emerging trends in TD research.

Safety and efficacy of valbenazine for the treatment of chorea associated with Huntington's disease (KINECT-HD): a phase 3, randomised, double-blind, placebo-controlled trial

Valbenazine is a highly selective vesicular monoamine transporter 2 (VMAT2) inhibitor approved for treatment of tardive dyskinesia. To address the ongoing need for improved symptomatic treatments for individuals with Huntington's disease, valbenazine was evaluated for the treatment of chorea associated with Huntington's disease. KINECT-HD (NCT04102579) was a phase 3, randomised, double-blind, placebo-controlled trial, performed in 46 Huntington Study Group sites in the USA and Canada. The study included adults with genetically confirmed Huntington's disease and chorea (Unified Huntington's Disease Rating Scale [UHDRS] Total Maximal Chorea [TMC] score of 8 or higher) who were randomly assigned (1:1) via an interactive web response system (with no stratification or minimisation) to oral placebo or valbenazine (≤80 mg, as tolerated) for 12 weeks of double-blinded treatment. The primary endpoint was a least-squares mean change in UHDRS TMC score from the screening and baseline period (based on the average of screening and baseline values for each participant) to the maintenance period (based on the average of week 10 and 12 values for each participant) in the full-analysis set using a mixed-effects model for repeated measures. Safety assessments included treatment-emergent adverse events, vital signs, electrocardiograms, laboratory tests, clinical tests for parkinsonism, and psychiatric assessments. The double-blind placebo-controlled period of KINECT-HD has been completed, and an open-label extension period is ongoing. KINECT-HD was performed from Nov 13, 2019, to Oct 26, 2021. Of 128 randomly assigned participants, 125 were included in the full-analysis set (64 assigned to valbenazine, 61 assigned to placebo) and 127 were included in the safety-analysis set (64 assigned to valbenazine, 63 assigned to placebo). The full-analysis set included 68 women and 57 men. Least-squares mean changes from the screening and baseline period to the maintenance period in the UHDRS TMC score were -4·6 for valbenazine and -1·4 for placebo (least-squares mean difference -3·2, 95% CI -4·4 to -2·0; p<0·0001). The most commonly reported treatment-emergent adverse event was somnolence (ten [16%] with valbenazine, two [3%] with placebo). Serious treatment-emergent adverse events were reported in two participants in the placebo group (colon cancer and psychosis) and one participant in the valbenazine group (angioedema because of allergic reaction to shellfish). No clinically important ch anges in vital signs, electrocardiograms, or laboratory tests were found. No suicidal behaviour or worsening of suicidal ideation was reported in participants treated with valbenazine. In individuals with Huntington's disease, valbenazine resulted in improvement in chorea compared with placebo and was well tolerated. Continued research is needed to confirm the long-term safety and effectiveness of this medication throughout the disease course in individuals with Huntington's disease-related chorea. Neurocrine Biosciences.

Valbenazine as treatment for Huntington's disease chorea

Chorea, the prototypical movement disorder in Huntington's disease, is a syndrome characterised by abrupt involuntary movements resulting from a continuous flow of random muscle contractions. 1 Cardoso F Seppi K Mair KJ Wenning GK Poewe W Seminar on choreas. Lancet Neurol. 2006; 5: 589-602 Summary Full Text Full Text PDF PubMed Scopus (220) Google Scholar Symptomatic treatment of chorea in patients with Huntington's disease should be considered when it causes functional disability, discomfort, or social embarrassment. 1 Cardoso F Seppi K Mair KJ Wenning GK Poewe W Seminar on choreas. Lancet Neurol. 2006; 5: 589-602 Summary Full Text Full Text PDF PubMed Scopus (220) Google Scholar One mainstay of pharmacological treatment is to reduce dopaminergic neurotransmission via inhibition of vesicular monoamine transporter type 2 (VMAT2), leading to presynaptic dopamine depletion. 2 Bashir H Jankovic J Treatment options for chorea. Expert Rev Neurother. 2018; 18: 51-63 Crossref PubMed Scopus (31) Google Scholar , 3 Koch J Shi WX Dashtipour K VMAT2 inhibitors for the treatment of hyperkinetic movement disorders. Pharmacol Ther. 2020; 212107580 Crossref Scopus (5) Google Scholar Safety and efficacy of valbenazine for the treatment of chorea associated with Huntington's disease (KINECT-HD): a phase 3, randomised, double-blind, placebo-controlled trialIn individuals with Huntington's disease, valbenazine resulted in improvement in chorea compared with placebo and was well tolerated. Continued research is needed to confirm the long-term safety and effectiveness of this medication throughout the disease course in individuals with Huntington's disease-related chorea. Full-Text PDF

Baseline Characteristics and Treatment Patterns of a Global Huntington Disease Population Stratified by Chorea Severity (P2-11.011)

<h3>Objective:</h3> To describe baseline characteristics and treatment patterns in Huntington Disease-associated chorea by chorea severity. <h3>Background:</h3> Though multiple treatment options exist for HD-associated chorea, there are little real-world data on treatment patterns, especially across disease trajectory and variation by severity of chorea. <h3>Design/Methods:</h3> Participants were adults from “Enroll-HD”, a global observational registry for patients with HD and their families (data cut 2013 – 31 October, 2020). Data on age, sex, Total Maximal Chorea (TMC) score, vesicular monoamine transporter 2 (VMAT2) inhibitors, and antipsychotic agents (APs; typical, atypical, and other [lithium]) were collected at the baseline visit. Participants were grouped by chorea severity (TMC score categories) recorded at baseline (0–7, 8–14, 15–21, 22–28). <h3>Results:</h3> There were 10,903 participants (TMC 0–7, n=5055; TMC 8–14, n=4374; TMC 15–21, n=1310; TMC 22–28, n=164). 51% were female (51.2%, 51.5%, 51.4%, and 53.1%, respectively) and the mean age at baseline was 53.0 years (50.8, 54.5, 55.9, 54.4, respectively). Overall, VMAT2i use at baseline was 14.9% and increased with chorea severity (10.8%, 16.4%, 23.9%, 29.3%, respectively). The proportion of patients using APs at baseline was 34.5% overall and increased with chorea severity (29.9%, 35.1%, 47.8%, 57.3%, respectively). Overall, 5.8% of patients used VMAT2 inhibitors combined with APs, and combined use increased with chorea severity (3.9%, 5.8%, 11.5%, 15.9%, respectively). <h3>Conclusions:</h3> Use of medications to treat chorea was low across the spectrum of chorea severities but increased incrementally in patients with greater chorea severity. Use of a combination of VMAT2 inhibitors and APs at baseline was low but increased as chorea severity increased. These data suggest that HD-associated chorea may be under treated globally. More data are needed to understand chorea treatment considerations and the utility of VMAT2 inhibitors and APs for treating HD-associated chorea and comorbidities. <b>Disclosure:</b> Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Teva Neuroscience. Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech. Dr. Furr-Stimming has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Teva Pharmaceuticals. Dr. Furr-Stimming has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Michael J. Fox Foundation. Dr. Furr-Stimming has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Teva Pharmaceuticals. The institution of Dr. Furr-Stimming has received research support from Cures within Reach. The institution of Dr. Furr-Stimming has received research support from Huntington’s Disease Society of America. The institution of Dr. Furr-Stimming has received research support from Roche/Genetech. The institution of Dr. Furr-Stimming has received research support from Uniqure. The institution of Dr. Furr-Stimming has received research support from CHDI. The institution of Dr. Furr-Stimming has received research support from Huntington Study Group/Neurocrine. The institution of Dr. Furr-Stimming has received research support from NIH/University of Iowa. The institution of Dr. Furr-Stimming has received research support from Sage Therapeutics. Dr. Furr-Stimming has received publishing royalties from a publication relating to health care. Dr. Reshef has received personal compensation for serving as an employee of Teva. Ms. Willock has received personal compensation for serving as an employee of HCD Economics. Rinat Ribalov has received personal compensation for serving as an employee of TEVA. Miss Brighton has nothing to disclose. Dr. Leo has received personal compensation for serving as an employee of Teva Pharmaceutical Industries.

Real-World Effectiveness and Safety of Deutetrabenazine in Combination with Antipsychotic Drugs in Patients With Chorea Associated With Huntington Disease (P2-11.010)

<h3>Objective:</h3> To describe the effectiveness and safety of vesicular monoamine transporter 2 inhibitor deutetrabenazine (DTBZ) combined with antipsychotic agents (APs) in patients with Huntington disease (HD)-related chorea in a real-world setting. <h3>Background:</h3> DTBZ effectiveness and safety for HD-related chorea have been well documented in clinical trials; however, patients receiving APs were not included. Safety and effectiveness data for DTBZ+AP are needed to inform real-world practice. <h3>Design/Methods:</h3> Data were collected from charts of patients with HD-associated chorea who received DTBZ+AP at Vanderbilt University Medical Center from April 3, 2017, until data collection (May–November 2021). Effectiveness was assessed by Total Maximal Chorea (TMC) scores over time. Safety was assessed via adverse drug reactions (ADRs) based on a predefined list of known DTBZ ADRs. <h3>Results:</h3> Among 57 patients treated with DTBZ+AP, 13 started APs first and had TMC scores available within 1 month before and any time after DTBZ addition, and 8 had TMC scores available within 1 month before AP initiation. After initiating APs and before adding DTBZ, TMC scores improved for 2/8 (25%) patients and worsened for 6 (75%). After adding DTBZ, TMC scores further improved for 8/13 (62%) patients, did not change for 1 (8%), and worsened for 4 (31%). In patients with history of tetrabenazine use, TMC scores improved after adding DTBZ for 4/8 (50%), versus 4/5 (80%) patients without history. Among all 57 patients treated with DTBZ+AP, 25 (44%) patients had ≥1 new/continuing ADR, with agitation, akathisia (both n=7; 12%), and somnolence (n=4; 7%) being most frequent; 2 (4%) patients discontinued DTBZ because of ADRs/tolerability issues while receiving combination treatment. <h3>Conclusions:</h3> In this retrospective chart review, adding DTBZ to APs improved motor signs and had a favorable benefit-risk profile. However, prospective, controlled trials investigating the efficacy and safety of DTBZ+AP in patients with HD-related chorea are needed. <b>Disclosure:</b> Dr. Claassen has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Teva Neuroscience. Dr. Claassen has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Spark . The institution of Dr. Claassen has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Alterity. Dr. Claassen has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Teva Neuroscience. Dr. Claassen has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for HD Insights. The institution of Dr. Claassen has received research support from NIH. The institution of Dr. Claassen has received research support from CHDI. The institution of Dr. Claassen has received research support from HDSA. The institution of Dr. Claassen has received research support from Department of Defense. The institution of Dr. Claassen has received research support from Griffin Family Foundation. The institution of Dr. Claassen has received research support from Neurocrine. The institution of Dr. Claassen has received research support from Vaccinex. The institution of Dr. Claassen has received research support from AbbVie. The institution of Dr. Claassen has received research support from CHDI. The institution of Dr. Claassen has received research support from Genentech/ Roche. The institution of Dr. Claassen has received research support from Prilenia. The institution of Dr. Claassen has received research support from Neurocrine/ HSG. Dr. Romdhani has nothing to disclose. Rajeev Ayyagari, PhD has received personal compensation for serving as an employee of Analysis Group, Inc. . Debbie Goldschmidt has received personal compensation for serving as an employee of Analysis Group. Ms. Moroz has nothing to disclose. Ms. Hernandez has nothing to disclose. Nayla Chaijale has received personal compensation for serving as an employee of Teva Pharmaceuticals. Dr. Leo has received personal compensation for serving as an employee of Teva Pharmaceutical Industries.

Anticholinergics Should Not Be Used to Treat Tardive Dyskinesia: Insights From an Expert Panel of Psychiatry and Neurology Healthcare Professionals

AbstractIntroductionTardive dyskinesia (TD) is a persistent and often disabling hyperkinetic movement disorder associated with prolonged exposure to dopamine receptor blocking agents (e.g., antipsychotics, antiemetics). The use of anticholinergics for the treatment of movement disorders including TD is a common practice, despite a lack of supportive evidence and the potential to worsen TD. Moreover, there are now FDA-approved medications specifically indicated for TD. Two virtual meetings were held with movement disorder experts from neurology and psychiatry to better understand the real-world use of anticholinergics for TD.MethodsIn November 2020, a panel of eight experts was convened to gather insights on the challenges of differentiating TD from other drug-induced movement disorders (DIMDs) and to discuss appropriate treatments for TD and other DIMDs. A follow-up meeting was held in June 2021 to consolidate these insights. Key recommendations based on the panel discussions are presented.ResultsThe panel emphasized that while anticholinergics can help with managing some DIMDs, current evidence indicates that they are not effective in TD and may even worsen symptoms. Therefore, FDA-approved vesicular monoamine transporter 2 (VMAT2) inhibitors like valbenazine were recommended by the panel as first-line TD therapies. The panel noted that TD is often grouped under the term “extrapyramidal symptoms,” which leads to difficulty in differentiating TD from other DIMDs and the inappropriate treatment of TD with anticholinergics. The panel agreed that prophylaxis with anticholinergics is only appropriate in patients at high risk of acute dystonia. However, chronic anticholinergic use should be avoided whenever possible due to potentially serious adverse effects (e.g., cognitive difficulties) and anticholinergic burden, particularly in older patients. The potential for abuse, addiction, and diversion should also be considered when prescribing anticholinergics. Abrupt anticholinergic discontinuation can result in cholinergic rebound, which is characterized by sleep disturbances, gastrointestinal problems, urinary urgency, and manifestations of DIMDs. Thus, when used appropriately (e.g., for acute dystonia), anticholinergics should be prescribed at minimally effective doses and slowly tapered for successful discontinuation.ConclusionsThese findings align with the current TD treatment guidelines, including the lack of evidence for anticholinergic use and recommended first-line treatment with approved VMAT2 inhibitors. Conclusions from this panel highlight educational needs across HCPs on the phenomenology of DIMDs, the inappropriate use of anticholinergics for TD, TD risks and assessment, and treatment strategies for TD.FundingNeurocrine Biosciences, Inc.

Treatment Success and Psychiatric Stability in Adults With Tardive Dyskinesia: Post Hoc Analyses of Two Long-Term Valbenazine Studies

AbstractIntroductionTardive dyskinesia (TD) is a persistent and potentially disabling movement disorder associated with exposure to antipsychotics and other dopamine receptor blocking agents. Effective and comprehensive treatment of TD requires reducing patients’ abnormal involuntary movements without disrupting their psychiatric stability. This can be especially challenging when patients have complex psychiatric conditions (e.g., &gt;1 psychiatric diagnosis) and are taking multiple medications. Valbenazine, a highly potent and selective vesicular monoamine transporter 2 (VMAT2) inhibitor, is approved for the once-daily treatment of TD. This post hoc analysis of two long-term studies (KINECT 3, KINECT 4) was conducted to evaluate changes in psychiatric status and clinician- and patient-reported treatment success in study participants who received valbenazine (40 or 80 mg) for 48 weeks.MethodsData from KINECT 3 and KINECT 4 were pooled and analyzed in participants categorized by their primary psychiatric diagnosis: schizophrenia/schizoaffective disorder (“SCHZ”) or mood disorder (“MD”). Concomitant medications needed for managing these and other psychiatric or medical conditions were allowed. Treatment success was defined as achieving a rating of “much improved” or “very much improved” at Week 48, as assessed using the Clinical Global Impression of Change-Tardive Dyskinesia (CGI-TD) and Patient Global Impression of Change (PGIC). Psychiatric stability was monitored using the following scales: Positive and Negative Syndrome Scale (PANSS) and Calgary Depression Scale for Schizophrenia (CDSS) in the SCHZ subgroup; Young Mania Rating Scale (YMRS) and Montgomery-Åsberg Depression Rating Scale (MADRS) in the MD subgroup. Suicidal ideation/behavior was monitored using the Columbia-Suicide Severity Rating Scale.ResultsMore than 75% of study participants in the SCHZ subgroup achieved treatment success with valbenazine, based on clinician assessment (CGI-TD, 79.7%) and patient self-report (PGIC, 78.0%). Mean changes from baseline to Week 48 for PANSS scores (positive symptoms [-0.7], negative symptoms [‑0.6], general psychopathology [-1.9], total [-3.2]) and CDSS total score (-0.5) indicated maintenance of psychiatric stability in the SCHZ subgroup. Similar treatment success rates were found in the MD subgroup for both CGI-TD (77.6%) and PGIC (84.5%), with mean changes from baseline in YMRS total score (-1.0) and MADRS total score (+0.3) indicating psychiatric stability was maintained. No emergence of suicidal ideation/behavior was observed during the studies.ConclusionsPooled analyses from two 48-week studies indicate that long-term treatment of TD with once-daily valbenazine resulted in substantial clinician- and patient-reported global improvements in TD, while psychiatric stability was maintained regardless of primary psychiatric condition.FundingNeurocrine Biosciences, Inc.

Components of the sympathetic nervous system as targets to modulate inflammation – rheumatoid arthritis synovial fibroblasts as neuron-like cells?

BackgroundCatecholamines are major neurotransmitters of the sympathetic nervous system (SNS) and they are of pivotal importance in regulating numerous physiological and pathological processes. Rheumatoid arthritis (RA) is influenced by the activity of the SNS and its neurotransmitters norepinephrine (NE) and dopamine (DA) and early sympathectomy alleviates experimental arthritis in mice. In contrast, late sympathectomy aggravates RA, since this procedure eliminates anti-inflammatory, tyrosine hydroxylase (TH) positive cells that appear in the course of RA. While it has been shown that B cells can take up, degrade and synthesize catecholamines it is still unclear whether this also applies to synovial fibroblasts, a mesenchymal cell that is actively engaged in propagating inflammation and cartilage destruction in RA. Therefore, this study aims to present a detailed description of the catecholamine pathway and its influence on human RA synovial fibroblasts (RASFs).ResultsRASFs express all catecholamine-related targets including the synthesizing enzymes TH, DOPA decarboxylase, dopamine beta-hydroxylase, and phenylethanolamine N-methyltransferase. Furthermore, vesicular monoamine transporters 1/2 (VMAT1/2), dopamine transporter (DAT) and norepinephrine transporter (NET) were detected. RASFs are also able to degrade catecholamines as they express monoaminoxidase A and B (MAO-A/MAO-B) and catechol-O-methyltransferase (COMT). TNF upregulated VMAT2, MAO-B and NET levels in RASFs. DA, NE and epinephrine (EPI) were produced by RASFs and extracellular levels were augmented by either MAO, COMT, VMAT or DAT/NET inhibition but also by tumor necrosis factor (TNF) stimulation. While exogenous DA decreased interleukin-6 (IL-6) production and cell viability at the highest concentration (100 μM), NE above 1 μM increased IL-6 levels with a concomitant decrease in cell viability. MAO-A and MAO-B inhibition had differential effects on unstimulated and TNF treated RASFs. The MAO-A inhibitor clorgyline fostered IL-6 production in unstimulated but not TNF stimulated RASFs (10 nM-1 μM) while reducing IL-6 at 100 μM with a dose-dependent decrease in cell viability in both groups. The MAO-B inhibitor lazabemide hydrochloride did only modestly decrease cell viability at 100 μM while enhancing IL-6 production in unstimulated RASFs and decreasing IL-6 in TNF stimulated cells.ConclusionsRASFs possess a complete and functional catecholamine machinery whose function is altered under inflammatory conditions. Results from this study shed further light on the involvement of sympathetic neurotransmitters in RA pathology and might open therapeutic avenues to counteract inflammation with the MAO enzymes being key candidates.

Behavioral and Transcriptomic Changes Following Brain-Specific Loss of Noradrenergic Transmission.

Noradrenaline (NE) plays an integral role in shaping behavioral outcomes including anxiety/depression, fear, learning and memory, attention and shifting behavior, sleep-wake state, pain, and addiction. However, it is unclear whether dysregulation of NE release is a cause or a consequence of maladaptive orientations of these behaviors, many of which associated with psychiatric disorders. To address this question, we used a unique genetic model in which the brain-specific vesicular monoamine transporter-2 (VMAT2) gene expression was removed in NE-positive neurons disabling NE release in the entire brain. We engineered VMAT2 gene splicing and NE depletion by crossing floxed VMAT2 mice with mice expressing the Cre-recombinase under the dopamine β-hydroxylase (DBH) gene promotor. In this study, we performed a comprehensive behavioral and transcriptomic characterization of the VMAT2DBHcre KO mice to evaluate the role of central NE in behavioral modulations. We demonstrated that NE depletion induces anxiolytic and antidepressant-like effects, improves contextual fear memory, alters shifting behavior, decreases the locomotor response to amphetamine, and induces deeper sleep during the non-rapid eye movement (NREM) phase. In contrast, NE depletion did not affect spatial learning and memory, working memory, response to cocaine, and the architecture of the sleep-wake cycle. Finally, we used this model to identify genes that could be up- or down-regulated in the absence of NE release. We found an up-regulation of the synaptic vesicle glycoprotein 2c (SV2c) gene expression in several brain regions, including the locus coeruleus (LC), and were able to validate this up-regulation as a marker of vulnerability to chronic social defeat. The NE system is a complex and challenging system involved in many behavioral orientations given it brain wide distribution. In our study, we unraveled specific role of NE neurotransmission in multiple behavior and link it to molecular underpinning, opening future direction to understand NE role in health and disease.

Discontinuation of methylphenidate after long-term exposure in nonhuman primates

Attention-deficit hyperactivity disorder (ADHD) is a common human neurobehavioral disorder that usually begins in early childhood. Methylphenidate (MPH) has been used extensively as a first-line medicine for the treatment of ADHD. Since ADHD is often diagnosed in early childhood and can persist for the entire lifespan, individuals may take MPH for many years. Given that in the course of one's lifetime a person may stop taking MPH for periods of time, or may implement lifestyle changes that may reduce the need for MPH entirely, it is important to understand how cessation of MPH affects the adult brain following long-term use of MPH. The blockage of the dopamine transporter (DAT) and the norepinephrine transporter (NET) by MPH may help with ADHD symptoms by boosting monoamine levels in the synapse. In the present study, microPET/CT was used to investigate possible neurochemical alterations in the cerebral dopamine system after cessation of long-term MPH administration in nonhuman primates. MicroPET/CT images were collected from adult male rhesus monkeys 6 months after they stopped receiving vehicle or MPH following 12 years of chronic treatment. The neurochemical status of brain dopaminergic systems was evaluated using the vesicular monoamine transporter 2 (VMAT2) ligand [18F]-AV-133 and a tracer for imaging dopamine subtype 2 (D2) and serotonin subfamily 2 (5HT2) receptors, [18F]-FESP. Each tracer was injected intravenously and ten minutes later microPET/CT images were obtained over 120 min. The binding potential (BP) of each tracer in the striatum was obtained using the Logan reference tissue model with the cerebellar cortex time activity curve (TAC) as an input function. Brain metabolism was also evaluated using microPET/CT images of [18F]-FDG. [18F]-FDG was injected intravenously, and ten minutes later, microPET/CT images were obtained over 120 min. Radiolabeled tracer accumulation in regions of interest (ROIs) in the prefrontal cortex, temporal cortex, striatum, and cerebellum were converted into standard uptake values (SUVs). Compared to the vehicle control group, the BPs of [18F] AV-133 and [18F]-FESP in the striatum were not significantly altered in MPH treated groups. Additionally, no significant differences were detected in the SUVs of [18F]-FDG in the MPH treated group compared with control. This study demonstrates that 6 months after cessation of long-term, chronic MPH treatment, there are no significant neurochemical or neural metabolic changes in the central nervous system (CNS) of non-human primates (NHPs) and suggests that microPET imaging is helpful in assessing the status of biomarkers of neurochemical processes linked to chronic CNS drug exposure. (Supported by NCTR).

The Relationship between Rem Sleep Behaviour Disorder and Parkinson’s Disease Revisited – Are They One and the Same?

This paper reviews the relationship between RBD and PD and the pathophysiology. Most RBD patients develop PD within 14 years. PD pathophysiology is α-synucleinopathy with dopamine degeneration in nigrostriatal pathways. RBD pathology is poorly understood. Anomalies suggest RBD and PD are different, evidenced by smoking. RBD and PD are associated with glucocerebrosidase gene mutations (GBA gene), suggesting RDB with GBA gene mutation predicts PD. PET imaging, assessing vesicular monoamine transporter 2 (VMAT2), indexing nigrostriatal dopamine innervation, is lower in PD and RBD, in the putamen, ventral striatum and globus pallidus but not substantia nigra or subthalamus, compared with controls. VMAT2 may not contribute to pathophysiology of RBD in PD. Treatments for RBD and PD differ. PD with RBD had more depression, compared to PD without RBD. Only PD with RBD had statistically significant increased depression, compared with controls, and non-significant lowered cognition. PD patients, with and without RBD, had decreased ligand binding, compared to healthy controls, indicating no difference in VMAT2 within the caudate and putamen. Research showed differences in cholinergic levels, noradrenaline and glucose metabolism for PD with and without RBD. RBD with PD, is multi-systematic, affecting regions beyond dopaminergic pathways. Treatment of RBD does not affects PD neurodegeneration. Researchers continue to search for neuro-protective intervention. There is a relationship between PD and RBD but it is not absolute. PD nigrostriatal degeneration is independent of RBD. Pathophysiological differences may explain why treatment of RBD does not alter its natural history.

In vivo reduction of age-dependent neuromelanin accumulation mitigates features of Parkinson's disease.

Humans accumulate with age the dark-brown pigment neuromelanin inside specific neuronal groups. Neurons with the highest neuromelanin levels are particularly susceptible to degeneration in Parkinson's disease, especially dopaminergic neurons of the substantia nigra, the loss of which leads to characteristic motor Parkinson's disease symptoms. In contrast to humans, neuromelanin does not appear spontaneously in most animals, including rodents, and Parkinson's disease is an exclusively human condition. Using humanized neuromelanin-producing rodents, we recently found that neuromelanin can trigger Parkinson's disease pathology when accumulated above a specific pathogenic threshold. Here, by taking advantage of this newly developed animal model, we assessed whether the intracellular build-up of neuromelanin that occurs with age can be slowed down in vivo to prevent or attenuate Parkinson's disease. Because neuromelanin derives from the oxidation of free cytosolic dopamine, we enhanced dopamine vesicular encapsulation in the substantia nigra of neuromelanin-producing rats by viral vector-mediated overexpression of vesicular monoamine transporter 2 (VMAT2). This strategy reduced the formation of potentially toxic oxidized dopamine species that can convert into neuromelanin and maintained intracellular neuromelanin levels below their pathogenic threshold. Decreased neuromelanin production was associated with an attenuation of Lewy body-like inclusion formation and a long-term preservation of dopamine homeostasis, nigrostriatal neuronal integrity and motor function in these animals. Our results demonstrate the feasibility and therapeutic potential of modulating age-dependent intracellular neuromelanin production in vivo, thereby opening an unexplored path for the treatment of Parkinson's disease and, in a broader sense, brain ageing.

Whole genome sequencing revealed genetic diversity, population structure, and selective signature of Panou Tibetan sheep

BackgroundThe detection of selective traits in different populations can not only reveal current mechanisms of artificial selection for breeding, but also provide new insights into phenotypic variation in new varieties and the search for genes associated with important traits. Panou sheep is a cultivated breed of Tibetan sheep in China with stable genetic performance, consistent appearance and fast growth and development after decades of artificial selection and cultivation. Due to long-term adaptation to the high altitude, cold and hypoxic environment in the plateau area, they may have formed a unique gene pool that is different from other Tibetan sheep breeds. To explore the genetic resources of Panou sheep, we used next-generation sequencing technology for the first time to investigate the genome-wide population structure, genetic diversity, and candidate signatures of positive selection in Panou sheep.ResultsComparative genomic analysis with the closely related species Oula sheep (a native breed of Tibetan sheep in China) was used to screen the population selection signal of Panou sheep. Principal component analysis and neighbor joining tree showed that Panou sheep and Oula sheep had differences in population differentiation. Furthermore, analyses of population structure, they came from the same ancestor, and when K = 2, the two populations could be distinguished. Panou sheep exhibit genetic diversity comparable to Oula sheep, as shown by observed heterozygosity, expected heterozygosity and runs of homozygosity. Genome-wide scanning using the Fst and π ratio methods revealed a list of potentially selected related genes in Panou sheep compared to Oula sheep, including histone deacetylase 9 (HDAC9), protein tyrosine kinase 2 (PTK2), microphthalmia-related transcription factor (MITF), vesicular amine transporter 1 (VAT1), trichohyalin-like 1 (TCHHL1), amine oxidase, copper containing 3 (AOC3), interferon-inducible protein 35 (IFI35).ConclusionsThe results suggest that traits related to growth and development and plateau adaptation may be selection targets for the domestication and breeding improvement of Tibetan sheep. This study provides the fundamental footprints for Panou sheep breeding and management.