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BACKGROUND: Spinal muscular atrophy (SMA) is a rare neuromuscular disorder leading to early death in the majority of affected individuals without treatment. Recently, targeted treatment approaches including Onasemnogene Abeparvovec (OA) were introduced. This study describes the first real-world experience with OA in Switzerland. METHODS: Prospective observational case series study using data collected within the Swiss Registry for Neuromuscular Disorders from SMA patients treated with OA. Development of motor, bulbar and respiratory function, appearance of scoliosis, and safety data (platelet count, liver function, and cardiotoxicity) were analyzed. RESULTS: Nine individuals were treated with OA and followed for 383 ± 126 days: six SMA type 1 (of which two with nusinersen pretreatment), one SMA type 2, and two pre-symptomatic individuals. In SMA type 1, CHOP Intend score increased by 28.1 from a mean score of 20.5 ± 7.6 at baseline. At end of follow-up, 50% of SMA type 1 patients required nutritional support and 17% night-time ventilation; 67% developed scoliosis. The SMA type 2 patient and two pre-symptomatically treated individuals reached maximum CHOP Intend scores. No patient required adaptation of the concomitant prednisolone treatment, although transient decrease of platelet count and increase of transaminases were observed in all patients. Troponin-T was elevated prior to OA treatment in 100% and showed fluctuations in 57% thereafter. CONCLUSIONS: OA is a potent treatment for SMA leading to significant motor function improvements. However, the need for respiratory and especially nutritional support as well as the development of scoliosis must be thoroughly evaluated in SMA type 1 patients even in the short term after OA treatment.
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Atrofia Muscular Espinal , Escoliose , Atrofias Musculares Espinais da Infância , Humanos , Atrofia Muscular Espinal/tratamento farmacológico , Doenças Raras , Respiração , Atrofias Musculares Espinais da Infância/tratamento farmacológico , Suíça/epidemiologiaRESUMO
Two-thirds of patients with Duchenne muscular dystrophy (DMD) have cognitive and neuropsychiatric problems. Concerning their quality of life, negative factors are the lack of qualifying education and social participation in sporting and leisure activities. Adapted assistance in education and participation in social life are thus important. During the coronavirus disease 2019 (COVID-19) pandemic, the pediatric population was less severely impacted by the disease, but by the restrictions associated. The aim of this study was to evaluate the impact of the COVID-19 pandemic regarding access to education and social participation for young patients with DMD in Switzerland. We conducted a survey study from May to August 2021 assessing the impact of the COVID-19 pandemic on access to education and social participation in 8 to 18 years old patients with DMD in Switzerland. Of 60 sent surveys, 40 were returned and included. Mean age of participants was 13.5 years (±3.1 standard deviation); 23/40 of the participants were wheelchair bound, 21/40 attended a special school, and 19/40 a regular school. Of the 22/40 participants receiving assistance at school, 7/40 reported a change caused by the pandemic: for 5/7, the assistance was paused. Of the 12 boys and adolescents attending sporting activities, 10 had to suspend these. Nine attended other leisure activities; for 3/9, these activities were paused. The COVID-19 pandemic had direct effects on school assistance, sporting, and leisure activities in young patients with DMD in Switzerland. It is important to ensure that school assistance and leisure activities are rapidly resumed.
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COVID-19 , Distrofia Muscular de Duchenne , Masculino , Humanos , Criança , Adolescente , Participação Social , Pandemias , Qualidade de Vida/psicologia , Distrofia Muscular de Duchenne/epidemiologia , Suíça/epidemiologiaRESUMO
BACKGROUND: Pediatric-onset inflammatory brain diseases are a group of potentially life-threatening central nervous system disorders. Overall, pediatric-onset inflammatory brain diseases are rare and therefore difficult to study. Patient registries are well suited to study the natural history of (rare) diseases and have markedly advanced the knowledge on pediatric-onset inflammatory brain diseases in other countries. Following their example, we established a national pediatric-onset inflammatory brain disease registry in Switzerland (Swiss-Ped-IBrainD). AIMS: The Registry aims to describe epidemiology, demographics, diagnostics, management, and treatment, since these areas remain understudied in Switzerland. Additionally, we want to promote research by fostering the knowledge exchange between study centers and setting up studies such as national quality of life surveys. We further aim to facilitate the access to national and international studies for patients with a pediatric-onset inflammatory brain disease living and/or treated in Switzerland. METHODS: The Swiss-Ped-IBrainD is a multicentric, population-based, observational cohort study (IRB number: 2019-00377) collaborating with 11 neuropediatric centers in Switzerland. Patient screening, information and recruitment is mainly conducted by the local principal investigators. The data collection is organized centrally by the Executive Office of the registry. The collected data is purely observational. Medical records are the primary data source. All patients who have been diagnosed with a pediatric-onset inflammatory brain disease since 2005 are eligible. We aim to include all pediatric-onset inflammatory brain disease patients living and/or treated in Switzerland who meet the inclusion criteria. Considering existing literature and our single-center experience we anticipate 300-400 eligible patients. STATUS: Currently, all 11 neuropediatric centers have been initiated and are recruiting. As of the first of May 2023, we have identified 275 eligible participants and obtained informed consent from 101 patients and/or families. None of the informed patients and/or families have refused participation.
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Encefalopatias , Qualidade de Vida , Humanos , Criança , Suíça/epidemiologia , Sistema de Registros , Coleta de Dados , Estudos Observacionais como AssuntoRESUMO
Background and Objectives: Chronic pain is a common symptom in various types of neuromuscular disorders. However, for patients with spinal muscular atrophy (SMA), the literature regarding chronic pain is scarce. Thus, this study assessed the prevalence of chronic pain in children, adolescents, and adults with SMA and investigated the influence of clinical characteristics on chronic pain. Materials and Methods: This study used data from 141 patients, which were collected by the Swiss Registry for Neuromuscular Disorders. Extracted data included information on pain (present yes/no, pain location, and pain medication) and clinical characteristics, such as SMA type, motor function, wheelchair use, scoliosis, and contractures. Results: The analyses revealed that the highest prevalence of chronic pain was observed in adolescents with 62%, followed by adults with 48%, children (6-12 years) with 39%, and children < 6 years with 10%. The legs, back, and hips were most frequently reported as pain locations. Sex (females), age (adolescents), and the presence of contractures and scoliosis (with surgery) were factors that were associated with chronic pain. Conclusions: These findings contribute to a better understanding of pain in SMA, shedding light on its prevalence and characteristics in different age groups, which underscores the importance of assessing and managing pain in patients with SMA.
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Cannabinoids are prescribed to children with cerebral palsy despite limited evidence. We aimed to assess cannabinoid prescribing practices in children with cerebral palsy, focusing on indications, types of preparations used, and tolerability. Furthermore, we investigated how physicians acquire knowledge about cannabinoid medication. We asked physicians with expertise in the care of children with cerebral palsy about their prescribing practices for cannabinoids. Data were collected through an online survey, which was distributed by email. In addition to the demographic information of participants, we also inquired about the indications for the prescription of cannabinoids, experiences regarding efficacy, and observed side effects of the therapy. Seventy physicians from Europe, North America, and Australia completed the survey. Forty-seven participants were experienced in treating of children with cerebral palsy with cannabinoids. The most common indication was epilepsy (69%), followed by spasticity (64%) and pain (63%). The preparations and doses prescribed varied considerably. Half of the participants evaluated the effect of the cannabinoids as moderate. Twenty-nine physicians reported side effects, most frequently, drowsiness (26%), somnolence (19%), fatigue (13%), and diarrhea (13%). Despite the lack of evidence to date, cannabinoids are used to treat children with cerebral palsy in a wide variety of indications. Randomized controlled trials in this vulnerable patient group are therefore of utmost importance.
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Network bursts and oscillations are forms of spontaneous activity in cortical circuits that have been described in vivo and in vitro. Searching for mechanisms involved in their generation, we investigated the collective network activity and spike discharge oscillations in cortical slice cultures of neonatal rats, combining multielectrode arrays with patch clamp recordings from individual neurons. The majority of these cultures showed spontaneous collective network activity [population bursts (PBs)] that could be described as neuronal avalanches. The largest of these PBs were followed by fast spike discharge oscillations in the beta to theta range, and sometimes additional repetitive PBs, together forming seizure-like episodes. During such episodes, all neurons showed sustained depolarization with increased spike rates. However, whereas regular-spiking (RS) and fast-spiking (FS) neurons fired during the PBs, only the FS neurons fired during the fast oscillations. Blockade of N-methyl-d-aspartate receptors reduced the depolarization and suppressed both the increased FS neuron firing and the oscillations. To investigate the generation of PBs, we studied the network responses to electrical stimulation. For most of the stimulation sites, the relationship between the stimulated inputs and the evoked PBs was linear. From a few stimulation sites, however, large PBs could be evoked with small inputs, indicating the activation of hub circuits. Taken together, our findings suggests that the oscillations originate from recurrent inhibition in local networks of depolarized inhibitory FS interneurons, whereas the PBs originate from recurrent excitation in networks of RS and FS neurons that is initiated in hub circuits.
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Potenciais de Ação/fisiologia , Animais Recém-Nascidos/fisiologia , Córtex Cerebral/citologia , Neurônios/fisiologia , Animais , Estimulação Elétrica , Eletrodos , Rede Nervosa/fisiologia , Inibição Neural/fisiologia , Neurônios/citologia , Técnicas de Patch-Clamp , Periodicidade , Ratos , Receptores de GABA-A/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Técnicas de Cultura de TecidosRESUMO
Spinal muscular atrophy (SMA) is an autosomal recessive disorder causing progressive proximal muscular, respiratory, and bulbar weakness. We present outcome data on motor function, ventilation, nutrition, and language development of SMA patients treated with nusinersen in Switzerland. This multicenter, observational study included 44 patients. At treatment initiation, after 2 months and then every 4 months we assessed motor function with the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), Hammersmith Functional Motor Scale expanded (HFMSE) and 6-Minute Walk Test (6MWT). At treatment initiation, patients were 0.1-44.6 years old, treatment duration ranged from 6 to 41 months. All 11 SMA type 1 children achieved higher CHOP-INTEND scores at the last assessment compared to treatment initiation, 4 acquired stable sitting. Six type 1 children were <18 months-old at treatment initiation. Two of them did not need ventilation or nutritional support at the last assessment; three had delayed language development and 3 articulation difficulties. 5/21 SMA type 2 patients achieved higher HFMSE scores. All ambulant type 3 patients showed a gain in the 6MWT. Nusinersen is an effective treatment, with gains in motor function occurring particularly in children and SMA type 1, but also in type 2 and 3, adolescents and adults.
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Atrofia Muscular Espinal , Atrofias Musculares Espinais da Infância , Adolescente , Adulto , Criança , Pré-Escolar , Humanos , Lactente , Oligonucleotídeos/uso terapêutico , Atrofias Musculares Espinais da Infância/tratamento farmacológico , Suíça , Adulto JovemRESUMO
BACKGROUND: Cerebral Palsy (CP) is a group of permanent disorders of movement and posture that follow injuries to the developing brain. It results in motor dysfunction and a wide variety of comorbidities like epilepsy; pain; speech, hearing and vision disorders; cognitive dysfunction; and eating and digestive difficulties. Central data collection is essential to the study of the epidemiology, clinical presentations, care, and quality of life of patients affected by CP. CP specialists founded the Swiss Cerebral Palsy Registry (Swiss-CP-Reg) in 2017. This paper describes the design, structure, aims and achievements of Swiss-CP-Reg and presents its first results. METHODS: Swiss-CP-Reg records patients of any age diagnosed with CP who are born, are treated, or live in Switzerland. It collects data from medical records and reports, from questionnaires answered by patients and their families, and from data linkage with routine statistics and other registries. The registry contains information on diagnosis, clinical presentation, comorbidities, therapies, personal information, family history, and quality of life. RESULTS: From August 2017 to August 2021, 546 participants (55% male, mean age at registration 8 years [interquartile range IQR: 5-12]), were enrolled in Swiss-CP-Reg. Most had been born at term (56%), were less than two years old at diagnosis (73%, median 18 months, IQR: 9-25), and were diagnosed with spastic CP (76%). Most (59%) live with a mild motor impairment (Gross Motor Function Classification System [GMFCS] level I or II), 12% with a moderate motor impairment (GMFCS level III), and 29% with a severe motor impairment (GMFCS level IV or V). In a subset of 170 participants, we measured intelligence quotient (IQ) and saw lower IQs with increasing GMFCS level. Swiss-CP-Reg has a strong interest in research, with four nested projects running currently, and many more planned. CONCLUSIONS: Swiss-CP-Reg collects and exchanges national data on people living with CP to answer clinically relevant questions. Its structure enables retrospective and prospective data collection and knowledge exchange between experts to optimise and standardise treatment and to improve the health and quality of life of those diagnosed with CP in Switzerland.
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Paralisia Cerebral , Paralisia Cerebral/diagnóstico , Paralisia Cerebral/epidemiologia , Paralisia Cerebral/terapia , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Masculino , Qualidade de Vida , Sistema de Registros , Estudos Retrospectivos , Índice de Gravidade de Doença , Suíça/epidemiologiaRESUMO
Although it is well established that low-voltage-activated T-type Ca(2+) channels play a key role in many neurophysiological functions and pathological states, the lack of selective and potent antagonists has so far hampered a detailed analysis of the full impact these channels might have on single-cell and neuronal network excitability as well as on Ca(2+) homeostasis. Recently, a novel series of piperidine-based molecules has been shown to selectively block recombinant T-type but not high-voltage-activated (HVA) Ca(2+) channels and to affect a number of physiological and pathological T-type channel-dependent behaviors. Here we directly show that one of these compounds, 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2), exerts a specific, potent (IC(50) = 22 nm), and reversible inhibition of T-type Ca(2+) currents of thalamocortical and reticular thalamic neurons, without any action on HVA Ca(2+) currents, Na(+) currents, action potentials, and glutamatergic and GABAergic synaptic currents. Thus, under current-clamp conditions, the low-threshold Ca(2+) potential (LTCP)-dependent high-frequency burst firing of thalamic neurons is abolished by TTA-P2, whereas tonic firing remains unaltered. Using TTA-P2, we provide the first direct demonstration of the presence of a window component of Ca(2+) channels in neurons and its contribution to the resting membrane potential of thalamic neurons and to the Up state of their intrinsically generated slow (<1 Hz) oscillation. Moreover, we demonstrate that activation of only a small fraction of the T-type channel population is required to generate robust LTCPs, suggesting that LTCP-driven bursts of action potentials can be evoked at depolarized potentials where the vast majority of T-type channels are inactivated.
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Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/fisiologia , Neurônios/fisiologia , Tálamo/fisiologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Gatos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Tálamo/efeitos dos fármacosRESUMO
Neuronal excitability contributes to rhythm generation in central pattern generating networks (CPGs). In spinal cord CPGs, such intrinsic excitability partly relies on persistent sodium currents (INaP), whereas respiratory CPGs additionally depend on calcium-activated cation currents (ICAN). Here, we investigated the contributions of INaP and ICAN to spontaneous rhythm generation in neuronal networks of the spinal cord and whether they mainly involve Hb9 neurons. We used cultures of ventral and transverse slices from the E13-14 embryonic rodent lumbar spinal cord on multielectrode arrays (MEAs). All cultures showed spontaneous bursts of network activity. Blocking synaptic excitation with the AMPA receptor antagonist CNQX suppressed spontaneous network bursts and left asynchronous intrinsic activity at about 30% of the electrodes. Such intrinsic activity was completely blocked at all electrodes by both the INaP blocker riluzole as well as by the ICAN blocker flufenamic acid (FFA) and the more specific TRPM4 channel antagonist 9-phenanthrol. All three antagonists also suppressed spontaneous bursting completely and strongly reduced stimulus-evoked bursts. Also, FFA reduced repetitive spiking that was induced in single neurons by injection of depolarizing current pulses to few spikes. Other antagonists of unspecific cation currents or calcium currents had no suppressing effects on either intrinsic activity (gadolinium chloride) or spontaneous bursting (the TRPC channel antagonists clemizole and ML204 and the T channel antagonist TTA-P2). Combined patch-clamp and MEA recordings showed that Hb9 interneurons were activated by network bursts but could not initiate them. Together these findings suggest that both INaP through Na+-channels and ICAN through putative TRPM4 channels contribute to spontaneous intrinsic and repetitive spiking in spinal cord neurons and thereby to the generation of network bursts.
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The manifestations of Parkinson's disease are caused by reduced dopaminergic innervation of the striatum. Loss-of-function mutations in the DJ-1 gene cause early-onset familial parkinsonism. To investigate a possible role for DJ-1 in the dopaminergic system, we generated a mouse model bearing a germline disruption of DJ-1. Although DJ-1(-/-) mice had normal numbers of dopaminergic neurons in the substantia nigra, evoked dopamine overflow in the striatum was markedly reduced, primarily as a result of increased reuptake. Nigral neurons lacking DJ-1 were less sensitive to the inhibitory effects of D2 autoreceptor stimulation. Corticostriatal long-term potentiation was normal in medium spiny neurons of DJ-1(-/-) mice, but long-term depression (LTD) was absent. The LTD deficit was reversed by treatment with D2 but not D1 receptor agonists. Furthermore, DJ-1(-/-) mice displayed hypoactivity in the open field. Collectively, our findings suggest an essential role for DJ-1 in dopaminergic physiology and D2 receptor-mediated functions.
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Dopamina/deficiência , Hipocinesia/fisiopatologia , Proteínas Oncogênicas/fisiologia , Transtornos Parkinsonianos/metabolismo , Substância Negra/metabolismo , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/farmacologia , Fatores Etários , Animais , Comportamento Animal , Southern Blotting/métodos , Western Blotting/métodos , Contagem de Células , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Modelos Animais de Doenças , Agonistas de Dopamina/farmacologia , Proteínas da Membrana Plasmática de Transporte de Dopamina , Estimulação Elétrica/métodos , Eletroquímica/métodos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Mutação em Linhagem Germinativa , Humanos , Imuno-Histoquímica/métodos , Técnicas In Vitro , Peptídeos e Proteínas de Sinalização Intracelular , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Neurônios/fisiologia , Transtornos Parkinsonianos/genética , Proteína Desglicase DJ-1 , Quimpirol/farmacologia , RNA Mensageiro/biossíntese , Ensaio Radioligante/métodos , Receptores de Dopamina D2/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Substância Negra/citologia , Substância Negra/efeitos dos fármacos , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Parkin is the most common causative gene of juvenile and early-onset familial Parkinson's diseases and is thought to function as an E3 ubiquitin ligase in the ubiquitin-proteasome system. However, it remains unclear how loss of Parkin protein causes dopaminergic dysfunction and nigral neurodegeneration. To investigate the pathogenic mechanism underlying these mutations, we used parkin-/- mice to study its physiological function in the nigrostriatal circuit. Amperometric recordings showed decreases in evoked dopamine release in acute striatal slices of parkin-/- mice and reductions in the total catecholamine release and quantal size in dissociated chromaffin cells derived from parkin-/- mice. Intracellular recordings of striatal medium spiny neurons revealed impairments of long-term depression and long-term potentiation in parkin-/- mice, whereas long-term potentiation was normal in the Schaeffer collateral pathway of the hippocampus. Levels of dopamine receptors and dopamine transporters were normal in the parkin-/- striatum. These results indicate that Parkin is involved in the regulation of evoked dopamine release and striatal synaptic plasticity in the nigrostriatal pathway, and suggest that impairment in evoked dopamine release may represent a common pathophysiological change in recessive parkinsonism.
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Corpo Estriado/metabolismo , Dopamina/metabolismo , Plasticidade Neuronal/fisiologia , Ubiquitina-Proteína Ligases/deficiência , Ubiquitina-Proteína Ligases/metabolismo , Animais , Corpo Estriado/fisiopatologia , Estimulação Elétrica , Feminino , Hipocampo/metabolismo , Hipocampo/fisiopatologia , Depressão Sináptica de Longo Prazo/genética , Depressão Sináptica de Longo Prazo/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Plasticidade Neuronal/genética , Membranas Sinápticas/genética , Membranas Sinápticas/metabolismo , Membranas Sinápticas/patologia , Ubiquitina-Proteína Ligases/genéticaRESUMO
DYT1 dystonia is caused by a deletion in a glutamic acid residue in the C-terminus of the protein torsinA, whose function is still largely unknown. Alterations in GABAergic signaling have been involved in the pathogenesis of dystonia. We recorded GABA- and glutamate-mediated synaptic currents from a striatal slice preparation obtained from a mouse model of DYT1 dystonia. In medium spiny neurons (MSNs) from mice expressing human mutant torsinA (hMT), we observed a significantly higher frequency, but not amplitude, of GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) and miniature currents (mIPSCs), whereas glutamate-dependent spontaneous excitatory synaptic currents (sEPSCs) were normal. No alterations were found in mice overexpressing normal human torsinA (hWT). To identify the possible sources of the increased GABAergic tone, we recorded GABAergic Fast-Spiking (FS) interneurons that exert a feed-forward inhibition on MSNs. However, both sEPSC and sIPSC recorded from hMT FS interneurons were comparable to hWT and non-transgenic (NT) mice. In physiological conditions, dopamine (DA) D2 receptor act presynaptically to reduce striatal GABA release. Of note, application of the D2-like receptor agonist quinpirole failed to reduce the frequency of sIPSCs in MSNs from hMT as compared to hWT and NT mice. Likewise, the inhibitory effect of quinpirole was lost on evoked IPSCs both in MSNs and FS interneurons from hMT mice. Our findings demonstrate a disinhibition of striatal GABAergic synaptic activity, that can be at least partially attributed to a D2 DA receptor dysfunction.
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Distúrbios Distônicos/fisiopatologia , Neurônios/fisiologia , Receptores de Dopamina D2/metabolismo , Transmissão Sináptica/fisiologia , Ácido gama-Aminobutírico/metabolismo , Análise de Variância , Animais , Modelos Animais de Doenças , Potenciais Pós-Sinápticos Excitadores , Ácido Glutâmico/metabolismo , Humanos , Técnicas In Vitro , Potenciais Pós-Sinápticos Inibidores , Camundongos , Camundongos Transgênicos , Potenciais Pós-Sinápticos em Miniatura , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Técnicas de Patch-ClampRESUMO
The striatum is richly innervated by serotonergic afferents from the raphe nucleus. We explored the effects of this input on striatal cholinergic interneurons from rat brain slices, by means of both conventional intracellular and whole-cell patch-clamp recordings. Bath-applied serotonin (5-HT, 3-300 microM), induced a dose-dependent membrane depolarization and increased the rate of spiking. This effect was mimicked by the 5-HT reuptake blockers citalopram and fluvoxamine. In voltage-clamped neurons, 5-HT induced an inward current, whose reversal potential was close to the K(+) equilibrium potential. Accordingly, the involvement of K(+) channels was confirmed either by increasing extracellular K(+) concentration and by blockade of K(+) channels with barium. Single-cell reverse transcriptase-polymerase chain reaction (RT-PCR) profiling demonstrated the presence of 5-HT2C, 5-HT6, and 5-HT7 receptor mRNAs in identified cholinergic interneurons. The depolarization/inward current induced by 5-HT was partially mimicked by the 5-HT2 receptor agonist 2,5-dimethoxy-4-iodoamphetamine and antagonized by both ketanserin and the selective 5-HT2C antagonist RS102221, whereas the selective 5-HT3 and 5-HT4 receptor antagonists tropisetron and RS23597-190 had no effect. The depolarizing response to 5-HT was also reduced by the selective 5-HT6 and 5-HT7 receptor antagonists SB258585 and SB269970, respectively, and mimicked by the 5-HT7 agonist, 5-CT. Accordingly, activation of either 5-HT6 or 5-HT7 receptor induced an inward current. The 5-HT response was attenuated by U73122, blocker of phospholipase C, and by SQ22,536, an inhibitor of adenylyl cyclase. These results suggest that 5-HT released by serotonergic fibers originating in the raphe nuclei has a potent excitatory effect on striatal cholinergic interneurons.
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Acetilcolina/metabolismo , Corpo Estriado/citologia , Interneurônios/efeitos dos fármacos , Receptores de Serotonina/metabolismo , Animais , Relação Dose-Resposta a Droga , Interações Medicamentosas , Estimulação Elétrica , Inibidores Enzimáticos/farmacologia , Masculino , Potenciais da Membrana/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos , Ratos Wistar , Serotonina/farmacologia , Serotoninérgicos/farmacologiaRESUMO
Adenosine and dopamine (DA) strongly modulate the neuronal activity in the striatum by pre- and postsynaptic mechanisms. As several behavioral and molecular studies indicate a functional antagonism between A2A adenosine and D2 DA receptors, compounds that are able to block A2A receptors are of particular interest as antiparkinsonian agents. To study the interaction of A2A and D2 receptors in the striatum, we performed intracellular recordings with sharp microelectrodes and whole-cell patch clamp recordings from spiny neurons in rat corticostriatal slices. The amplitude of the evoked excitatory postsynaptic potentials (EPSPs), as well as the frequency and the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs), were affected neither by the A2A receptor antagonists ST1535 and ZM241385, nor by the D2 receptor agonist quinpirole when applied in isolation. However, co-application of quinpirole and ST1535 or ZM241385 significantly reduced the EPSPs amplitude. This inhibitory effect was associated with an increased paired-pulse facilitation suggesting a presynaptic mechanism of action. Accordingly, whole-cell recordings showed that the concomitant activation of D2 receptors and the antagonism of A2A receptors decreased the frequency of sEPSCs without affecting their amplitude. These results suggest that A2A and D2 receptors converge in the control of corticostriatal glutamatergic transmission by exerting an opposite function.
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Córtex Cerebral/fisiologia , Corpo Estriado/fisiologia , Ácido Glutâmico/metabolismo , Neurônios/metabolismo , Receptor A2A de Adenosina/metabolismo , Receptores de Dopamina D2/metabolismo , Transmissão Sináptica/fisiologia , Adenina/análogos & derivados , Adenina/farmacologia , Adenosina/análogos & derivados , Adenosina/farmacologia , Animais , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Agonistas de Dopamina/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Masculino , Técnicas de Cultura de Órgãos , Técnicas de Patch-Clamp , Fenetilaminas/farmacologia , Quimpirol/farmacologia , Ratos , Ratos Wistar , Receptor A2A de Adenosina/efeitos dos fármacos , Receptores de Dopamina D2/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Triazinas/farmacologia , Triazóis/farmacologiaRESUMO
Clostridium botulinum neurotoxins (BoNTs) are the most poisonous naturally occurring protein toxins known to mankind and are the causative agents of the severe and potentially life-threatening disease botulism. They are also known for their application as cosmetics and as unique bio-pharmaceuticals to treat an increasing number of neurological and non-neurological disorders. Currently, the potency of biologically active BoNT for therapeutic use is mainly monitored by the murine LD50-assay, an ethically disputable test causing suffering and death of a considerable number of mice. The aim of this study was to establish an in vitro assay as an alternative to the widely used in vivo mouse bioassay. We report a novel BoNT detection assay using mouse embryonic stem cell-derived neurons (mESN) cultured on multi-electrode arrays (MEAs). After 21 days in culture, the mESN formed a neuronal network showing spontaneous bursting activity based on functional synapses and express the necessary target proteins for BoNTs. Treating cultures for 6 h with 16.6 pM of BoNT serotype A and incubation with 1.66 pM BoNT/A or 33 Units/ml of Botox® for 24 h lead to a significant reduction of both spontaneous network bursts and average spike rate. This data suggests that mESN cultured on MEAs pose a novel, biologically relevant model that can be used to detect and quantify functional BoNT effects, thus accelerating BoNT research while decreasing animal use.
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Presently there exists no cure for spinal cord injury (SCI). However, transplantation of embryonic tissue into spinal cord (SC) lesions resulted in axon outgrowth across the lesion site and some functional recovery, fostering hope for future stem cell therapies. Although in vivo evidence for functional recovery is given, the exact cellular mechanism of the graft support remains elusive: either the grafted cells provide a permissive environment for the host tissue to regenerate itself or the grafts actually integrate functionally into the host neuronal network reconnecting the separated SC circuits. We tested the two hypotheses in an in vitro SC lesion model that is based on propagation of activity between two rat organotypic SC slices in culture. Transplantation of dissociated cells from E14 rat SC or forebrain (FB) re-established the relay of activity over the lesion site and thus, provoked functional regeneration. Combining patch-clamp recordings from transplanted cells with network activity measurements from the host tissue on multi-electrode arrays (MEAs) we here show that neurons differentiate from the grafted cells and integrate into the host circuits. Optogenetic silencing of neurons developed from transplanted embryonic mouse FB cells provides clear evidence that they replace the lost neuronal connections to relay and synchronize activity between the separated SC circuits. In contrast, transplantation of neurospheres (NS) induced neither the differentiation of mature neurons from the grafts nor an improvement of functional regeneration. Together these findings suggest, that the formation of neuronal relays from grafted embryonic cells is essential to re-connect segregated SC circuits.
RESUMO
Spiral ganglion neurons (SGNs) participate in the physiological process of hearing by relaying signals from sensory hair cells to the cochlear nucleus in the brain stem. Loss of hair cells is a major cause of sensory hearing loss. Prosthetic devices such as cochlear implants function by bypassing lost hair cells and directly stimulating SGNs electrically, allowing for restoration of hearing in deaf patients. The performance of these devices depends on the functionality of SGNs, the implantation procedure and on the distance between the electrodes and the auditory neurons. We hypothesized, that reducing the distance between the SGNs and the electrode array of the implant would allow for improved stimulation and frequency resolution, with the best results in a gapless position. Currently we lack in vitro culture systems to study, modify and optimize the interaction between auditory neurons and electrode arrays and characterize their electrophysiological response. To address these issues, we developed an in vitro bioassay using SGN cultures on a planar multi electrode array (MEA). With this method we were able to perform extracellular recording of the basal and electrically induced activity of a population of spiral ganglion neurons. We were also able to optimize stimulation protocols and analyze the response to electrical stimuli as a function of the electrode distance. This platform could also be used to optimize electrode features such as surface coatings.
Assuntos
Técnicas de Cultura de Células , Eletrofisiologia , Gânglio Espiral da Cóclea , Bioensaio/métodos , Implantes Cocleares , Estimulação Elétrica , Humanos , NeurôniosRESUMO
OBJECTIVE: Cochlear implants (CIs) have become the gold standard treatment for deafness. These neuroprosthetic devices feature a linear electrode array, surgically inserted into the cochlea, and function by directly stimulating the auditory neurons located within the spiral ganglion, bypassing lost or not-functioning hair cells. Despite their success, some limitations still remain, including poor frequency resolution and high-energy consumption. In both cases, the anatomical gap between the electrode array and the spiral ganglion neurons (SGNs) is believed to be an important limiting factor. The final goal of the study is to characterize response profiles of SGNs growing in intimate contact with an electrode array, in view of designing novel CI devices and stimulation protocols, featuring a gapless interface with auditory neurons. APPROACH: We have characterized SGN responses to extracellular stimulation using multi-electrode arrays (MEAs). This setup allows, in our view, to optimize in vitro many of the limiting interface aspects between CIs and SGNs. MAIN RESULTS: Early postnatal mouse SGN explants were analyzed after 6-18 days in culture. Different stimulation protocols were compared with the aim to lower the stimulation threshold and the energy needed to elicit a response. In the best case, a four-fold reduction of the energy was obtained by lengthening the biphasic stimulus from 40 µs to 160 µs. Similarly, quasi monophasic pulses were more effective than biphasic pulses and the insertion of an interphase gap moderately improved efficiency. Finally, the stimulation with an external electrode mounted on a micromanipulator showed that the energy needed to elicit a response could be reduced by a factor of five with decreasing its distance from 40 µm to 0 µm from the auditory neurons. SIGNIFICANCE: This study is the first to show electrical activity of SGNs on MEAs. Our findings may help to improve stimulation by and to reduce energy consumption of CIs and thereby contribute to the development of fully implantable devices with better auditory resolution in the future.
Assuntos
Potenciais de Ação/fisiologia , Implantes Cocleares , Análise em Microsséries/instrumentação , Microeletrodos , Gânglio Espiral da Cóclea/citologia , Gânglio Espiral da Cóclea/fisiologia , Animais , Terapia por Estimulação Elétrica/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Camundongos , Camundongos Endogâmicos C57BL , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: One of the earliest neurochemical alterations observed in both Huntington's disease (HD) patients and HD animal models is the dysregulation of the endocannabinoid system, an alteration that precedes the development of identifiable striatal neuropathology. How this alteration impacts striatal synaptic transmission is unknown. METHODS: We measured the effects of cannabinoid receptor stimulation on gamma-aminobutyric acid (GABA)-ergic synaptic currents recorded from striatal neurons of R6/2 HD mice in the early phase of their disease. RESULTS: The sensitivity of striatal GABA synapses to cannabinoid receptor stimulation is severely impaired in R6/2 HD mice. In particular, whereas in control animals activation of cannabinoid CB1 receptors results in a significant inhibition of both evoked and spontaneous GABA-mediated synaptic events by a presynaptic mechanism, in R6/2 mice this treatment fails to reduce GABA currents but causes, in contrast, a slight increase of spontaneous inhibitory postsynaptic currents (sIPSCs). CONCLUSIONS: Experimental HD was also associated with enhanced frequency of sIPSCs, a result consistent with the conclusion that loss of cannabinoid-mediated control of GABA transmission might contribute to hyperactivity of GABA synapses in the striatum of HD mice. Accordingly, spontaneous excitatory postsynaptic currents, which were not upregulated in R6/2 mice, were still sensitive to cannabinoid receptor stimulation.