14 research outputs found

    Calcium Handling Remodeling Underlies Impaired Sympathetic Stress Response in Ventricular Myocardium from <i>Cacna1c</i> Haploinsufficient Rats

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    CACNA1C encodes the pore-forming α1C subunit of the L-type Ca2+ channel, Cav1.2. Mutations and polymorphisms of the gene are associated with neuropsychiatric and cardiac disease. Haploinsufficient Cacna1c+/− rats represent a recently developed model with a behavioral phenotype, but its cardiac phenotype is unknown. Here, we unraveled the cardiac phenotype of Cacna1c+/− rats with a main focus on cellular Ca2+ handling mechanisms. Under basal conditions, isolated ventricular Cacna1c+/− myocytes exhibited unaltered L-type Ca2+ current, Ca2+ transients (CaTs), sarcoplasmic reticulum (SR) Ca2+ load, fractional release, and sarcomere shortenings. However, immunoblotting of left ventricular (LV) tissue revealed reduced expression of Cav1.2, increased expression of SERCA2a and NCX, and augmented phosphorylation of RyR2 (at S2808) in Cacna1c+/− rats. The β-adrenergic agonist isoprenaline increased amplitude and accelerated decay of CaTs and sarcomere shortenings in both Cacna1c+/− and WT myocytes. However, the isoprenaline effect on CaT amplitude and fractional shortening (but not CaT decay) was impaired in Cacna1c+/− myocytes exhibiting both reduced potency and efficacy. Moreover, sarcolemmal Ca2+ influx and fractional SR Ca2+ release after treatment with isoprenaline were smaller in Cacna1c+/− than in WT myocytes. In Langendorff-perfused hearts, the isoprenaline-induced increase in RyR2 phosphorylation at S2808 and S2814 was attenuated in Cacna1c+/− compared to WT hearts. Despite unaltered CaTs and sarcomere shortenings, Cacna1c+/− myocytes display remodeling of Ca2+ handling proteins under basal conditions. Mimicking sympathetic stress with isoprenaline unmasks an impaired ability to stimulate Ca2+ influx, SR Ca2+ release, and CaTs caused, in part, by reduced phosphorylation reserve of RyR2 in Cacna1c+/− cardiomyocytes

    Bipolar-associated miR-499-5p controls neuroplasticity by downregulating the Cav1.2 subunit CACNB2

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    Bipolar disorder (BD) is a chronic mood disorder characterized by manic and depressive episodes. Dysregulation of neuroplasticity and calcium homeostasis are frequently observed in BD patients, but the underlying molecular mechanisms are largely unknown. Here, we show that miR-499-5p regulates dendritogenesis and cognitive function by downregulating the BD risk gene CACNB2. miR-499-5p expression is increased in peripheral blood of BD patients, as well as in the hippocampus of rats which underwent juvenile social isolation. In rat hippocampal neurons, miR-499-5p impairs dendritogenesis and reduces surface expression and activity of the L-type calcium channel Cav1.2. We further identified CACNB2, which encodes a regulatory beta-subunit of Cav1.2, as a direct functional target of miR-499-5p in neurons. miR-499-5p overexpression in the hippocampus in vivo induces short-term memory impairments selectively in rats haploinsufficient for the Cav1.2 pore forming subunit Cacna1c. In humans, miR-499-5p expression is negatively associated with gray matter volumes of the left superior temporal gyrus, a region implicated in auditory and emotional processing. We propose that stress-induced miR-499-5p overexpression contributes to dendritic impairments, deregulated calcium homeostasis, and neurocognitive dysfunction in BD.ISSN:1469-221XISSN:1469-317

    Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data

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    Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers. Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0–1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0–2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4–6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903. Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10–2·03]; p=0·011), with low heterogeneity across studies (I 2=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05–1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06–2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4–6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52–1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03–4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [<1%], adjusted OR 5·58 [1·22–25·50]; p=0·024). Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death. Funding: None

    Functional Outcome of Intravenous Thrombolysis in Patients With Lacunar Infarcts in the WAKE-UP Trial

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    Importance: The rationale for intravenous thrombolysis in patients with lacunar infarcts is debated, since it is hypothesized that the microvascular occlusion underlying lacunar infarcts might not be susceptible to pharmacological reperfusion treatment. Objective: To study the efficacy and safety of intravenous thrombolysis among patients with lacunar infarcts. Design, Setting, and Participants: This exploratory secondary post hoc analysis of the WAKE-UP trial included patients who were screened and enrolled between September 2012 and June 2017 (with final follow-up in September 2017). The WAKE-UP trial was a multicenter, double-blind, placebo-controlled randomized clinical trial to study the efficacy and safety of intravenous thrombolysis with alteplase in patients with an acute stroke of unknown onset time, guided by magnetic resonance imaging. All 503 patients randomized in the WAKE-UP trial were reviewed for lacunar infarcts. Diagnosis of lacunar infarcts was based on magnetic resonance imaging and made by consensus of 2 independent investigators blinded to clinical information. Main Outcomes and Measures: The primary efficacy variable was favorable outcome defined by a score of 0 to 1 on the modified Rankin Scale at 90 days after stroke, adjusted for age and severity of symptoms. Results: Of the 503 patients randomized in the WAKE-UP trial, 108 patients (including 74 men [68.5%]) had imaging-defined lacunar infarcts, whereas 395 patients (including 251 men [63.5%]) had nonlacunar infarcts. Patients with lacunar infarcts were younger than patients with nonlacunar infarcts (mean age [SD], 63 [12] years vs 66 [12] years; P = .003). Of patients with lacunar infarcts, 55 (50.9%) were assigned to treatment with alteplase and 53 (49.1%) to receive placebo. Treatment with alteplase was associated with higher odds of favorable outcome, with no heterogeneity of treatment outcome between lacunar and nonlacunar stroke subtypes. In patients with lacunar strokes, a favorable outcome was observed in 31 of 53 patients (59%) in the alteplase group compared with 24 of 52 patients (46%) in the placebo group (adjusted odds ratio [aOR], 1.67 [95% CI, 0.77-3.64]). There was 1 death and 1 symptomatic intracranial hemorrhage according to Safe Implementation of Thrombolysis in Stroke-Monitoring Study criteria in the alteplase group, while no death and no symptomatic intracranial hemorrhage occurred in the placebo group. The distribution of the modified Rankin Scale scores 90 days after stroke also showed a nonsignificant shift toward better outcomes in patients with lacunar infarcts treated with alteplase, with an adjusted common odds ratio of 1.94 (95% CI, 0.95-3.93). Conclusions and Relevance: While the WAKE-UP trial was not powered to demonstrate the efficacy of treatment in subgroups of patients, the results indicate that the association of intravenous alteplase with functional outcome does not differ in patients with imaging-defined lacunar infarcts compared with those experiencing other stroke subtypes.status: publishe

    Interaction of the Psychiatric Risk Gene Cacna1c With Post-weaning Social Isolation or Environmental Enrichment Does Not Affect Brain Mitochondrial Bioenergetics in Rats

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    The pathophysiology of neuropsychiatric disorders involves complex interactions between genetic and environmental risk factors. Confirmed by several genome-wide association studies, Cacna1c represents one of the most robustly replicated psychiatric risk genes. Besides genetic predispositions, environmental stress such as childhood maltreatment also contributes to enhanced disease vulnerability. Both, Cacna1c gene variants and stressful life events are associated with morphological alterations in the prefrontal cortex and the hippocampus. Emerging evidence suggests impaired mitochondrial bioenergetics as a possible underlying mechanism of these regional brain abnormalities. In the present study, we simulated the interaction of psychiatric disease-relevant genetic and environmental factors in rodents to investigate their potential effect on brain mitochondrial function using a constitutive heterozygous Cacna1c rat model in combination with a four-week exposure to either post-weaning social isolation, standard housing, or social and physical environmental enrichment. Mitochondria were isolated from the prefrontal cortex and the hippocampus to evaluate their bioenergetics, membrane potential, reactive oxygen species production, and respiratory chain complex protein levels. None of these parameters were considerably affected in this particular gene-environment setting. These negative results were very robust in all tested conditions demonstrating that Cacna1c depletion did not significantly translate into altered bioenergetic characteristics. Thus, further investigations are required to determine the disease-related effects on brain mitochondria

    Dental Treatment of Snoring and Sleep Apnea

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    Quite often it is a source of amusement and quite often it is hushed up: SNORING! One third of the adult population snores and knows the problems in everyday life which result from snoring. However, what a lot of people do not know is that snoring can be one indication of a serious health problem called obstructive sleep apnea (OSA). This is the reason why more than 90% of the people with sleep apnea go undiagnosed.</p

    Cacna1c haploinsufficiency leads to pro-social 50-kHz ultrasonic communication deficits in rats

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    The cross-disorder risk gene CACNA1C is strongly implicated in multiple neuropsychiatric disorders, including autism spectrum disorder (ASD), bipolar disorder (BPD) and schizophrenia (SCZ), with deficits in social functioning being common for all major neuropsychiatric disorders. In the present study, we explored the role of Cacna1c in regulating disorder-relevant behavioral phenotypes, focusing on socio-affective communication after weaning during the critical developmental period of adolescence in rats. To this aim, we used a newly developed genetic Cacna1c rat model and applied a truly reciprocal approach for studying communication through ultrasonic vocalizations, including both sender and receiver. Our results show that a deletion of Cacna1c leads to deficits in social behavior and pro-social 50-kHz ultrasonic communication in rats. Reduced levels of 50-kHz ultrasonic vocalizations emitted during rough-and-tumble play may suggest that Cacna1c haploinsufficient rats derive less reward from playful social interactions. Besides the emission of fewer 50-kHz ultrasonic vocalizations in the sender, Cacna1c deletion reduced social approach behavior elicited by playback of 50-kHz ultrasonic vocalizations. This indicates that Cacna1c haploinsufficiency has detrimental effects on 50-kHz ultrasonic communication in both sender and receiver. Together, these data suggest that Cacna1c plays a prominent role in regulating socio-affective communication in rats with relevance for ASD, BPD and SCZ. This article has an associated First Person interview with the first author of the paper

    Downregulation of the psychiatric susceptibility gene Cacna1c promotes mitochondrial resilience to oxidative stress in neuronal cells

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    Affective disorders such as major depression and bipolar disorder are among the most prevalent forms of mental illness and their etiologies involve complex interactions between genetic and environmental risk factors. Over the past ten years, several genome wide association studies (GWAS) have identified CACNA1C as one of the strongest genetic risk factors for the development of affective disorders. However, its role in disease pathogenesis is still largely unknown. Vulnerability to affective disorders also involves diverse environmental risk factors such as perinatal insults, childhood maltreatment, and other adverse pathophysiological or psychosocial life events. At the cellular level, such environmental influences may activate oxidative stress pathways, thereby altering neuronal plasticity and function. Mitochondria are the key organelles of energy metabolism and, further, highly important for the adaptation to oxidative stress. Accordingly, multiple lines of evidence including post-mortem brain and neuro-imaging studies suggest that psychiatric disorders are accompanied by mitochondrial dysfunction. In this study, we investigated the effects of Cacna1c downregulation in combination with glutamate-induced oxidative stress on mitochondrial function, Ca2+ homeostasis, and cell viability in mouse hippocampal HT22 cells. We found that the siRNA-mediated knockdown of Cacna1c preserved mitochondrial morphology, mitochondrial membrane potential, and ATP levels after glutamate treatment. Further, Cacna1c silencing inhibited excessive mitochondrial reactive oxygen species formation and calcium influx, and protected the HT22 cells from oxidative cell death. Overall, our findings suggest that the GWAS-confirmed psychiatric risk gene CACNA1C plays a major role in oxidative stress pathways with particular impact on mitochondrial integrity and function.ISSN:2058-771

    Animal models of attention deficit/hyperactivity disorder (ADHD): A critical review

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    Position paper on the use of mandibular advancement devices in adults with sleep-related breathing disorders: A position paper of the German Society of Dental Sleep Medicine (Deutsche Gesellschaft Zahnaerztliche Schlafmedizin, DGZS)

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    Custom-made mandibular advancement devices are an effective treatment option for snoring, upper airway resistance syndrome, and obstructive sleep apnea (OSA). Evidence-based data indicates their efficacy, and international sleep societies recommend oral appliance (OA) therapy for patients with sleep-related breathing disorders. The following position paper by the German Society of Dental Sleep Medicine (DGZS) is to guide the interdisciplinary team (sleep physician and sleep disorder dentist) in detail when to prescribe oral appliances. This position paper supports the responsible use of OA as an effective treatment option for patients with sleep-related breathing disorders. The paper advises of proper indication regarding OSA severity, body mass index (BMI), and dentition. It emphasizes the interdisciplinary approach of oral appliance therapy and suggests treatment under the guidance of dentists trained in dental sleep medicine
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