The activation of mGluR4 rescues parallel fiber synaptic transmission and LTP, motor learning and social behavior in a mouse model of Fragile X Syndrome.

BACKGROUND: Fragile X syndrome (FXS), the most common inherited intellectual disability, is caused by the loss of expression of the Fragile X Messenger Ribonucleoprotein (FMRP). FMRP is an RNA-binding protein that negatively regulates the expression of many postsynaptic as well as presynaptic proteins involved in action potential properties, calcium homeostasis and neurotransmitter release. FXS patients and mice lacking FMRP suffer from multiple behavioral alterations, including deficits in motor learning for which there is currently no specific treatment. METHODS: We performed electron microscopy, whole-cell patch-clamp electrophysiology and behavioral experiments to characterise the synaptic mechanisms underlying the motor learning deficits observed in Fmr1KO mice and the therapeutic potential of positive allosteric modulator of mGluR4. RESULTS: We found that enhanced synaptic vesicle docking of cerebellar parallel fiber to Purkinje cell Fmr1KO synapses was associated with enhanced asynchronous release, which not only prevents further potentiation, but it also compromises presynaptic parallel fiber long-term potentiation (PF-LTP) mediated by ß adrenergic receptors. A reduction in extracellular Ca2+ concentration restored the readily releasable pool (RRP) size, basal synaptic transmission, ß adrenergic receptor-mediated potentiation, and PF-LTP. Interestingly, VU 0155041, a selective positive allosteric modulator of mGluR4, also restored both the RRP size and PF-LTP in mice of either sex. Moreover, when injected into Fmr1KO male mice, VU 0155041 improved motor learning in skilled reaching, classical eyeblink conditioning and vestibuloocular reflex (VOR) tests, as well as the social behavior alterations of these mice. LIMITATIONS: We cannot rule out that the activation of mGluR4s via systemic administration of VU0155041 can also affect other brain regions. Further studies are needed to stablish the effect of a specific activation of mGluR4 in cerebellar granule cells. CONCLUSIONS: Our study shows that an increase in synaptic vesicles, SV, docking may cause the loss of PF-LTP and motor learning and social deficits of Fmr1KO mice and that the reversal of these changes by pharmacological activation of mGluR4 may offer therapeutic relief for motor learning and social deficits in FXS.

Performance of the 2017 EULAR/ACR criteria for idiopathic inflammatory myopathies in a cohort of patients from Latin America.

We aimed to determine the performance of the 2017 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for idiopathic inflammatory myopathies (IIMs) in a cohort of Chilean patients. This single-center retrospective study included 151 patients with a clinical diagnosis of IIM. Patients were classified according to the 2017 EULAR/ACR classification criteria for IIM, and its performance was compared to the Bohan & Peter (B&P) classification criteria. A total of 135 patients (89.4%) met the EULAR/ACR criteria, and 140 (92.7%) patients met the B&P criteria. A total of 130 patients had IIM according to both the criteria; concordance rate was 29.2% for definite IIM, 6.2% for probable IIM, and 1.5% for possible IIM. The kappa coefficient of agreement was weak between the 2 classification criteria (κ = 0.39, SD 0.15-0.64). Against gold standard expert physician's diagnosis, sensitivity, and specificity of EULAR/ACR criteria was 0.86 and 0.85 to diagnose dermatomyositis, respectively, and 0.73 and 0.87 to diagnose polymyositis. The EULAR/ACR criteria showed good sensitivity and identified more patients with probable or definite IIM than the B&P criteria in a single-center cohort of patients with IIM in South America. The sensitivity of the EULAR/ACR criteria was slightly higher in patients with dermatomyositis, but lower in patients with polymyositis, than that of the B&P criteria.

Effective glutamate clearance from the systemic circulation by hemodialysis: Potential relevance for cerebral ischemia management.

High glutamate levels after head trauma or cerebral ischemia have neurotoxic effects. The objective of the present study was to evaluate the efficacy of hemodialysis to remove glutamate from the blood and to assess the behavior of this small molecule. Ten patients with end-renal disease on hemodialysis were included in the study. Glutamate clearance was evaluated within the first hour of hemodialysis on a midweek dialysis day on five patients who underwent low flux hemodialysis, whereas the other five patients underwent highly efficient hemodialysis (high flux hemodialysis on one day and online hemodiafiltration on another day). Glutamate clearance with hemodialysis was very effective and did not show any differences between the techniques (low flux: 214 [55], high flux: 204 [37], online hemodiafiltration: 202 [16], median (interquartile range), P = .7). Glutamate clearance was almost equivalent to vascular access plasma flow and it was not affected by dialyzer permeability or ultrafiltration rate. After a hemodialysis session, a significant decrease in glutamate blood level was observed (prehemodialysis: 59.7 [36.1], posthemodialysis 37.0 [49.2], P = .005). Dialysis performed under fasting condition showed higher glutamate reduction rate (60%) than that under feeding condition (20%). Hemodialysis may be an effective method to reduce glutamate blood levels, and the molecule clearance does not differ between the different techniques used. Considering previous results in experimental models, hemodialysis without hemodynamic stress, could be considered for reducing glutamate neurotoxic effects in acute ischemic strokes of patients in chronic hemodialysis programs.

Management of unexplained: poly-consultation and hyperfrequency on Primary Health Chilean Attention. A qualitative and exploratory study.

BACKGROUND: In Europe, Latin-America, and Asia, poly-consultation has become a complex problem for managing different healthcare systems. However, in the current literature, little attention has been paid to exploring territorial and critical analysis perspectives to manage unexplained symptoms. The purpose of this study is to analyze the socio-structural elements that underlie the users' phenomenon of poly-consultation or hyperfrequency in the Chilean primary healthcare system (PHCS). METHODS: This paper represents qualitative data collected as part of an exploratory study that used mixed methods across three metropolitan areas of Santiago, Valparaíso, and Concepción, Chile. The study involved a sample of 24 subjects from administrative and management positions in PHC who were recruited from Family Health Care Centers, considering urban municipalities from the low, medium, and high stratum. The study collected data using one set of semi-standardized interviews during a year-data analysis using qualitative content analysis. RESULTS: This article shows that poly-consultant patients provide a critical clinic category to management that cannot be cover by current biomedical models. Data showed the strain of a somatoform category, especially in the clinic and epistemological exercise. Precisely, the relevance of Chile's case, a mixed health system, and their effects: the naturalization of collective problems managed as individual problems. CONCLUSIONS: The study results can inform healthcare professionals and managers of developing practical and territorially based. We conclude that hyperfrequency and poly-consultation in Chile reveal relevant stratification in the territory. Those particularities open an opportunity to study quantitative methods, including current analysis categories, to develop new research.

Esclerodermia localizada en Coup de Sabre: a propósito de un caso / Localized Scleroderma en Coup de Sabre: a case report

INTRODUCCIÓN: La esclerodermia localizada o morfea corresponde a una patología idiopática autoinmune que produce cambios escleróticos subcutáneos, que presenta diferencias con respecto a la esclerosis sistémica o esclerodermia. Un tipo de morfea lineal es la morfea "En Coup de Sabre" que consiste en la contracción y rigidez de la piel que culmina con una depresión de parte de la mitad del rostro, que puede asociarse a síntomas oftalmológicos y neurológicos. Aquí se describe un caso en un hombre joven con este tipo de morfea lineal. PRESENTACIÓN DEL CASO: Hombre de 23 años presenta lesión cutánea de morfología triangular en región frontal izquierda, por lo que decide consultar a dermatología, dónde se maneja con corticoides tópicos. Dos años después, la lesión sigue creciendo y se asocia a cefalea occipital, sin otros síntomas sistémicos. Se decide estudiar con biopsia, ecografía de cuero cabelludo y resonancia nuclear magnética (RNM) cerebral con gadolinio. Se diagnostica morfea en coup de sabre e indica tratamiento inmunosupresor. DISCUSIÓN: Dado que la Morfea en Coup de Sabre es una patología que compromete el rostro, es relevante realizar una derivación al oftalmólogo para evaluación de compromiso ocular y realizar una RNM para evaluación neurológica, en este caso ambos estudios resultaron negativos. El estudio serológico no es siempre necesario y debemos ser cautelosos en el uso de esta herramienta. Cuando existen dudas diagnósticas, se puede recurrir a una biopsia del tejido comprometido, la que debe incluir grasa subcutánea. La biopsia también ayuda para ver el grado de compromiso cutáneo que presenta el paciente. Con respecto al manejo, los corticoides tópicos son la elección para el manejo de lesiones agudas. El Metotrexato ha demostrado ser útil en lesiones agudas y profundas, asociado o no a corticoides.

INTRODUCTION: Localized scleroderma or morphea is an idiopathic autoimmune disorder that causes subcutaneous sclerotic changes and is different from systemic sclerosis or scleroderma. The morphea in "coup de Sabre" is a subtype of linear morphea that usually involves the forehead and scalp causing contraction and stiffness of the skin that culminates in a depression and that may be associated with ocular and neurological symptoms. We present a case of a young male patient with morphea in coup de sabre. CASE PRESENTATION: A 23 years old male patient presents with a skin lesion of triangular morphology in the left-frontal region. He was initially treated with topical corticosteroids, but had persistent growing of the skin lesion associated with new onset occipital headache. Ultrasound of the lesion as well as skin biopsy were performed confirming morphea in coup de sabre. Brain magnetic resonance imaging with gadolinium was normal. Inmunosuppresive tratment was started. DISCUSSION: Morphea in Coup de sabre is an rare disease. It is more frequent in women and children. Because it involves the deep tissues of the face and forehead, it is relevant to rule out any ocular or neurological involvement. The serological study is usually not necessary and results are of uncertain interpretation. When the diagnosis is unclear, a biopsy of the compromised tissue may help to identify inflammation and/or atrophy and to evaluate the degree of activity of the lesion. Ultrasound is also an useful tool for evaluation of the activity of the skin lesion, comparable to biopsy. Regarding treatment, topical corticosteroids are the first line therapy for acute lesions. Methotrexate has proven to be useful in deeper active lesions, with or without corticosteroids. Finally, there is an important asociation between this type of lineal morphea and progressive hemifacial atrophy (Parry Romberg syndome), which may involve the brain and needs to be referred to the specialist as soon as possible.

ß-Adrenergic Receptors/Epac Signaling Increases the Size of the Readily Releasable Pool of Synaptic Vesicles Required for Parallel Fiber LTP.

The second messenger cAMP is an important determinant of synaptic plasticity that is associated with enhanced neurotransmitter release. Long-term potentiation (LTP) at parallel fiber (PF)-Purkinje cell (PC) synapses depends on a Ca2+-induced increase in presynaptic cAMP that is mediated by Ca2+-sensitive adenylyl cyclases. However, the upstream signaling and the downstream targets of cAMP involved in these events remain poorly understood. It is unclear whether cAMP generated by ß-adrenergic receptors (ßARs) is required for PF-PC LTP, although noradrenergic varicosities are apposed in PF-PC contacts. Guanine nucleotide exchange proteins directly activated by cAMP [Epac proteins (Epac 1-2)] are alternative cAMP targets to protein kinase A (PKA) and Epac2 is abundant in the cerebellum. However, whether Epac proteins participate in PF-PC LTP is not known. Immunoelectron microscopy demonstrated that ßARs are expressed in PF boutons. Moreover, activation of these receptors through their agonist isoproterenol potentiated synaptic transmission in cerebellar slices from mice of either sex, an effect that was insensitive to the PKA inhibitors (H-89, KT270) but that was blocked by the Epac inhibitor ESI 05. Interestingly, prior activation of these ßARs occluded PF-PC LTP, while the ß1AR antagonist metoprolol blocked PF-PC LTP, which was also absent in Epac2-/- mice. PF-PC LTP is associated with an increase in the size of the readily releasable pool (RRP) of synaptic vesicles, consistent with the isoproterenol-induced increase in vesicle docking in cerebellar slices. Thus, the ßAR-mediated modulation of the release machinery and the subsequent increase in the size of the RRP contributes to PF-PC LTP.SIGNIFICANCE STATEMENT G-protein-coupled receptors modulate the release machinery, causing long-lasting changes in synaptic transmission that influence synaptic plasticity. Nevertheless, the mechanisms underlying synaptic responses to ß-adrenergic receptor (ßAR) activation remain poorly understood. An increase in the number of synaptic vesicles primed for exocytosis accounts for the potentiation of neurotransmitter release driven by ßARs. This effect is not mediated by the canonical protein kinase A pathway but rather, through direct activation of the guanine nucleotide exchange protein Epac by cAMP. Interestingly, this ßAR signaling via Epac is involved in long term potentiation at cerebellar granule cell-to-Purkinje cell synapses. Thus, the pharmacological activation of ßARs modulates synaptic plasticity and opens therapeutic opportunities to control this phenomenon.

Predictors of Indwelling Pleural Catheter Removal and Infection: A Single-center Experience With 336 Procedures.

BACKGROUND: Indwelling pleural catheters (IPCs) offer ambulatory management of symptomatic persistent pleural effusions, but their widespread use is somewhat hampered by the risk of pleural infection and the inconvenience of carrying a catheter for a prolonged period of time. Factors associated with these 2 limitations were analyzed in this study. METHODS: Retrospective review of consecutive patients who had undergone IPC placement over a 5 ½-year period. Time to IPC removal was analyzed with the Fine and Gray competing risks survival model, with competing risk being death. A binary logistic regression method was used to evaluate factors influencing IPC-related pleural infections. RESULTS: A total of 336 IPCs were placed in 308 patients, mostly because of malignant effusions (83%). IPC removal secondary to pleurodesis was achieved in 170 (51%) procedures at a median time of 52 days. Higher rates of IPC removal were associated with an Eastern Cooperative Oncology Group (ECOG) grade of 0 to 2 [subhazard ratio (SHR)=2.22], an expandable lung (SHR=1.93), and development of a multiseptated pleural space (SHR=1.37). IPC-related pleural infections occurred in 8% of the cases, and were more often seen in hepatic hydrothoraces [odds ratio (OR)=4.75] and pleural fluids with a C-reactive protein <15 mg/L before the IPC insertion (OR=4.42). CONCLUSION: IPC removal is more likely to occur in patients with good performance status whose lungs fully expand after drainage. Hepatic hydrothorax is the most significant predictor of IPC-related infections.

Análisis de lesionología de una muestra de 353 autopsias de suicidios, Departamento de Medicina Legal, Costa Rica del 2010 al 2016 / Lesionology analysis of a sample of 353 suicide autopsies, Department of Legal Medicine, Costa Rica from 2010 to 2016

Resumen El presente trabajo corresponde a una investigación de la lesionología y antecedentes personales de las personas que han muerto de manera suicida en Costa Rica de 2010 a 2016. De los 2174 autopsias de suicidios que se realizaron en la Sección de Patología Forense del Departamento de Medicina Legal del Organismo de Investigación Judicial de Costa Rica, tomando como fuente de información la base de datos del Sistema de Automatización de Patología Forense del Departamento de Medicina Legal, se extrajo una muestra de 353 y a estos se les investigó información adicional en expediente y otros registros de poder judicial para obtener información relacionada con antecedentes patológicos personales, antecedentes sociales y mayores detalles del suicidio. Además, según el tipo de lesión que produjo la muerte, se caracteriza el tipo de asfixia, la localización del nudo, el lugar de ingreso del proyectil de arma de fuego o el tipo de sustancia usada para el suicidio.

Abstract The present work corresponds to research of the lesionology and personal antecedents of people that have died in a suicidal way in Costa Rica from 2010 to 2016. From the 2174 autopsies of suicides that were realized in the Section of Forensic Pathology of the Department of Legal Medicine of the Judicial Investigation Organization of Costa Rica, taking as a source of information the database of the Forensic Pathology Automation System of the Department of Legal Medicine, a sample of 353 was extracted and additional information was researched in the forensic file and other records of judicial system to obtain information related to personal pathological background, social background and more details of suicide. In addition, depending on the type of injury that caused the death, the type of asphyxia, the location of the knot, the place of entry of the firearm projectile or the type of substance used for suicide are characterized.

Suicidio en Costa Rica: Análisis de autopsias realizadas en el Departamento de Medicina Legal del 2010 al 2016 / Suicide in Costa Rica: Autopsy analysis performed in the Department of Legal Medicine from 2010 to 2016

Resumen El suicidio es un problema importante de salud pública. La presente investigación corresponde a un análisis estadístico descriptivo de los aspectos sociodemográficos de las personas que fallecen de manera suicida en Costa Rica durante el períodos de 2010 a 2016. Se toman los casos del Sistema de Automatización de Patología Forense del Departamento de Medicina Legal. Se hace un agrupamiento de datos según lugar de ocurrencia, edades, causa de muerte y ocupación. Se realiza la estadística descriptiva, se hace cruces de variables y se analizan las proporciones obtenidas mediante pruebas de Chi cuadrado de Pearson y Pruebas de Z con corrección de Bonferroni. Hubo 2174 casos, distribuidos usualmente en más de 300 casos por año. El suicidio es más frecuente en hombres, ente 19 y 44 años, solteros, no profesionales y la causa de muerte más común es asfixia por ahorcadura, luego intoxicación por agroquímicos y finalmente herida por arma de fuego.

Abstract Suicide is a major public health problem. The present investigation corresponds to a descriptive statistical analysis of the sociodemographic aspects of the people who died in a suicidal way in Costa Rica from 2010 to 2016. The cases were taken from the Forensic Pathology Automation System of the Department of Legal Medicine. A grouping of data is made according to place of occurrence, age, cause of death and occupation. Descriptive statistics are carried out, cross-data analysis are executed and the proportions obtained are analyzed by means of Pearson´s Chi-square test and Z-test with Bonferroni correction. There were 2174 cases, usually distributed in more than 300 cases per year. Suicide is more frequent in men, between 19 and 44 years of age, single, non-professional and the most common cause of death is asphyxia due to hanging, then intoxication by agrochemicals and finally wounding by firearm projectile.

The loss of ß adrenergic receptor mediated release potentiation in a mouse model of fragile X syndrome.

In fragile X syndrome, the absence of Fragile X Mental Retardation Protein (FMRP) is known to alter postsynaptic function, although alterations in presynaptic function also occur. We found that the potentiation of glutamate release induced by the ß adrenergic receptor (ßAR) agonist isoproterenol is absent in cerebrocortical nerve terminals (synaptosomes) from mice lacking FMRP (Fmr1 KO), despite the normal cAMP generation. The glutamate release induced by moderate stimulation of synaptosomes with 5 mM KCl was not potentiated in Fmr1 KO synaptosomes by isoproterenol, nor by stimulating the receptor associated signaling pathway with the adenylyl cyclase activator forskolin or with the Epac activator 8-pCPT. Hence, the impairment in the pathway potentiating release is distal to ßARs. Electron microscopy shows that Fmr1 KO cortical synapses have more docked vesicles than WT synapses, consequently occluding the isoproterenol response through which more SVs approach the active zone (AZ) of the plasma membrane. Weak stimulation of synaptosomes with the Ca2+ ionophore ionomycin recovered the release potentiation driven by forskolin and 8-pCPT but not with isoproterenol, revealing an impairment in the efficiency of receptor generated cAMP to activate the release potentiation pathway. Indeed, inhibiting cyclic nucleotide phosphodiesterase PDE2A with BAY 60-7550 reestablished isoproterenol mediated potentiation in Fmr1 KO synaptosomes. Thus, the lack of ß-AR mediated potentiation of glutamate release appears to be the consequence of an impaired capability of the receptor to mobilize SVs to the AZ and because of a decreased efficiency of cAMP to activate the signaling pathway that enhances neurotransmitter release.

Photoconversion of FM1-43 Reveals Differences in Synaptic Vesicle Recycling and Sensitivity to Pharmacological Disruption of Actin Dynamics in Individual Synapses.

The cycling of synaptic vesicles ensures that neurons can communicate adequately through their synapses on repeated occasions when activity is sustained, and several steps in this cycle are modulated by actin. The effects of pharmacological stabilization of actin with jasplakinolide or its depolymerization with latrunculin A was assessed on the synaptic vesicle cycle at individual boutons of cerebellar granule cells, using FM1-43 imaging to track vesicle recycling and its photoconversion to specifically label recycled organelles. Remarkable differences in the recycling capacity of individual boutons are evident, and their dependence on the actin cytoskeleton for recycling is clear. Disrupting actin dynamics causes a loss of functional boutons, and while this indicates that exo/endocytotic cycling in boutons is fully dependent on such events, this dependence is only partial in other boutons. Indeed, exocytosis and vesicle trafficking are impaired significantly by stabilizing or depolymerizing actin, whereas repositioning recycled vesicles at the active zone seems to be dependent on actin polymerization alone. These findings support the hypothesis that different steps of synaptic vesicle cycling depend on actin dynamics and that such dependence varies among individual boutons.

Síndrome de Capgras: una revision de la literatura / Capgras syndrome: a review of the literature

Los síndromes de falsa identificación delirante (DMS, por su sigla en inglés) son trastornos neuropsiquiátricos poco frecuentes que se caracterizan por tener ideas delirantes respecto a la propia identidad y la de otras personas, animales o lugares conocidos por el paciente. Los principales DMS son el Síndrome de Capgras (SC), el de Fregoli, el de doble subjetivo y el de intermetamorfosis. Se presentan en contexto tanto de enfermedades psiquiátricas como en cuadros orgánicos. Distintos modelos han tratado de encontrar una explicación a los DMS, con aportes tanto desde la psicología como de las neurociencias. Entre las causas están enfermedades neurodegenerativas, cuadros psiquiátricos, alteraciones estructurales, efecto de drogas, y alteraciones metabólicas. El manejo depende de la patología de base y las características clínicas específicas. Esta revisión se centra específicamente en el SC, ya que dentro de los DMS, es el más frecuente y estudiado

Delusional misidentification syndromes (DMS) are rare neuropsychiatric disorders that are characterized by having delirious ideas regarding one's and other people, animals or places identity known by the patient. The main DMS are the Capgras syndrome, the Fregoli syndrome, the subjective double syndrome and the intermetamorphosis syndrome. They appear in context of both psychiatric illnesses and organic disorders. Different models have tried to find an explanation to the DMS, with contributions from both psychology and neurosciences. Among the causes are neurodegenerative diseases, psychiatric symptoms, structural alterations, drug effects, and metabolic alterations. Management depends on the underlying pathology and the specific clinical characteristics. This review focuses specifically on the SC, since within the DMS, it is the most frequent and studied.

Bidirectional modulation of glutamatergic synaptic transmission by metabotropic glutamate type 7 receptors at Schaffer collateral-CA1 hippocampal synapses.

KEY POINTS: Neurotransmitter release is inhibited by metabotropic glutamate type 7 (mGlu7 ) receptors that reduce Ca2+ influx, yet synapses lacking this receptor also produce weaker release, suggesting that mGlu7 receptors may also prime synaptic vesicles for release. Prolonged activation of mGlu7 receptors with the agonist l-AP4 first reduces and then enhances the amplitude of EPSCs through a presynaptic effect. The inhibitory response is blocked by pertussis toxin, while the potentiating response is prevented by a phospholipase C inhibitor (U73122) and an inhibitor of diacylglycerol (DAG) binding (calphostin C), suggesting that this receptor also couples to pathways that generate DAG. Release potentiation is associated with an increase in the number of synaptic vesicles close to the plasma membrane, which was dependent on the Munc13-2 and RIM1α proteins. The Glu7 receptors activated by the glutamate released following high frequency stimulation provoke a bidirectional modulation of synaptic transmission. ABSTRACT: Neurotransmitter release is driven by Ca2+ influx at synaptic boutons that acts on synaptic vesicles ready to undergo exocytosis. Neurotransmitter release is inhibited when metabotropic glutamate type 7 (mGlu7 ) receptors provoke a reduction in Ca2+ influx, although the reduced release from synapses lacking this receptor suggests that they may also prime synaptic vesicles for release. These mGlu7 receptors activate phospholipase C (PLC) and generate inositol trisphosphate, which in turn releases Ca2+ from intracellular stores and produces diacylglycerol (DAG), an activator of proteins containing DAG-binding domains such as Munc13 and protein kinase C (PKC). However, the full effects of mGlu7 receptor signalling on synaptic transmission are unclear. We found that prolonged activation of mGlu7 receptors with the agonist l-AP4 first reduces and then enhances the amplitude of EPSCs, a presynaptic effect that changes the frequency but not the amplitude of the mEPSCs and the paired pulse ratio. Pertussis toxin blocks the inhibitory response, while the PLC inhibitor U73122, and the inhibitor of DAG binding calphostin C, prevent receptor mediated potentiation. Moreover, this DAG-dependent potentiation of the release machinery brings more synaptic vesicles closer to the active zone plasma membrane in a Munc13-2- and RIM1α-dependent manner. Electrically evoked release of glutamate that activates mGlu7 receptors also bidirectionally modulates synaptic transmission. In these conditions, potentiation now occurs rapidly and it overcomes any inhibition, such that potentiation prevails unless it is suppressed with the PLC inhibitor U73122.

Altered Synaptic Membrane Retrieval after Strong Stimulation of Cerebellar Granule Neurons in Cyclic GMP-Dependent Protein Kinase II (cGKII) Knockout Mice.

The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP)/cGMP-dependent protein kinase (cGK) signaling pathway regulates the clustering and the recruitment of proteins and vesicles to the synapse, thereby adjusting the exoendocytic cycle to the intensity of activity. Accordingly, this pathway can accelerate endocytosis following large-scale exocytosis, and pre-synaptic cGK type II (cGKII) plays a major role in this process, controlling the homeostatic balance of vesicle exocytosis and endocytosis. We have studied synaptic vesicle recycling in cerebellar granule cells from mice lacking cGKII under strong and sustained stimulation, combining imaging techniques and ultrastructural analyses. The ultrastructure of synapses in the adult mouse cerebellar cortex was also examined in these animals. The lack of cGKII provokes structural changes to synapses in cultured cells and in the cerebellar cortex. Moreover, endocytosis is slowed down in a subset of boutons in these cells when they are stimulated strongly. In addition, from the results obtained with the selective inhibitor of cGKs, KT5823, it can be concluded that cGKI also regulates some aspects of vesicle cycling. Overall, these results confirm the importance of the cGMP pathway in the regulation of vesicle cycling following strong stimulation of cerebellar granule cells.

CB1 receptors down-regulate a cAMP/Epac2/PLC pathway to silence the nerve terminals of cerebellar granule cells.

Cannabinoid receptors mediate short-term retrograde inhibition of neurotransmitter release, as well as long-term depression of synaptic transmission at excitatory synapses. The responses of individual nerve terminals in VGLUT1-pHluorin transfected cerebellar granule cells to cannabinoids have shown that prolonged activation of cannabinoid type 1 receptors (CB1Rs) silences a subpopulation of previously active synaptic boutons. Adopting a combined pharmacological and genetic approach to study the molecular mechanisms of CB1R-induced silencing, we found that adenylyl cyclase inhibition decreases cAMP levels while it increases the number of silent synaptic boutons and occludes the induction of further silencing by the cannabinoid agonist HU-210. Guanine nucleotide exchange proteins directly activated by cAMP (Epac proteins) mediate some of the presynaptic effects of cAMP in the potentiation of synaptic transmission. ESI05, a selective Epac2 inhibitor, and U-73122, the specific inhibitor of phospholipase C (PLC), both augment the number of silent synaptic boutons. Moreover, they abolish the capacity of the Epac activator, 8-(4-chlorophenylthio)-2'-O-methyladenosine 3',5'-cyclic monophosphate monosodium hydrate, to prevent HU-210-induced silencing consistent with PLC signaling lying downstream of Epac2 proteins. Furthermore, Rab3-interacting molecule (RIM)1α KO cells have many more basally silent synaptic boutons (12.9 ± 3.5%) than wild-type cells (1.1 ± 0.5%). HU-210 induced further silencing in these mutant cells, although 8-(4-chlorophenylthio)-2'-O-methyladenosine 3',5'-cyclic monophosphate monosodium hydrate only awoke the HU-210-induced silence and not the basally silent synaptic boutons. This behavior can be rescued by expressing RIM1α in RIM1α KO cells, these cells behaving very much like wild-type cells. These findings support the hypothesis that a cAMP/Epac/PLC signaling pathway targeting the release machinery appears to mediate cannabinoid-induced presynaptic silencing.

Brefeldin A sensitive mechanisms contribute to endocytotic membrane retrieval and vesicle recycling in cerebellar granule cells.

The recycling of synaptic vesicle (SV) proteins and transmitter release occur at multiple sites along the axon. These processes are sensitive to inhibition of the small GTP binding protein ARF1, which regulates the adaptor protein 1 and 3 complex (AP-1/AP-3). As the axon matures, SV recycling becomes restricted to the presynaptic bouton, and its machinery undergoes a complex process of maturation. We used the styryl dye FM1-43 to highlight differences in the efficiency of membrane recycling at different sites in cerebellar granule cells cultured for 7 days in vitro. We used Brefeldin A (BFA) to inhibit AP-1/AP-3-mediated recycling and to test the contribution of this pathway to the heterogeneity of the responses when these cells are strongly stimulated. Combining imaging techniques and ultrastructural analyses, we found a significant decrease in the density of functional boutons and an increase in the presence of endosome-like structures within the boutons of cells incubated with BFA prior to FM1-43 loading. Such effects were not observed when BFA was added 5 min after the end of the loading step, when endocytosis was almost fully completed. In this situation, vesicles were found closer to the active zone (AZ) in boutons exposed to BFA. Together, these data suggest that the AP-1/AP-3 pathway contributes to SV recycling, affecting different steps in all boutons but not equally, and thus being partly responsible for the heterogeneity of the different recycling efficiencies. Cover Image for this issue: doi. 10.1111/jnc.13801.

Intoxicación alcohólica / Alcohol intoxication

Resumen:La intoxicación se considera como una manifestación patológica definida por los signos y síntomas que secundarios a la acción de una o varias dosis de un agente tóxico y su evolución puede llevar al sujeto a un estado irreversible e incluso a la muerte. Cada año mueren alrededor de un millón de personas a consecuencia de diversos envenenamientos. La intoxicación alcohólica es causada por alcoholes, compuestos orgánicos que se derivan de los hidrocarburos y están formados por grupos hidroxilos. El etanol es el alcohol que con más frecuencia produce intoxicaciones ya que es el más común y el que más al alcance de la población se encuentra, este produce múltiples alteraciones a nivel del sistema nervioso y de otros sistemas del organismo.

Abstract:Intoxication is considered a pathological manifestation defined by the signs and symptoms secondary to the action of one or more doses of a toxic agent and its evolution may lead to an irreversible subject to state and even to death.Every year about a million people as a result of various poisonings. Alcohol intoxication is caused by alcohols, organic compounds derived hydrocarbons and consist of hydroxyl groups. Ethanol is the alcohol intoxication occurs more frequently because it is the most common and the most accessible to the population is, this results in multiple abnormalities in the nervous system and other body systems.

Cross-talk between metabotropic glutamate receptor 7 and beta adrenergic receptor signaling at cerebrocortical nerve terminals.

The co-existence of presynaptic G protein coupled receptors, GPCRs, has received little attention, despite the fact that interplay between the signaling pathways activated by such receptors may affect the neurotransmitter release. Using immunocytochemistry and immuhistochemistry we show that mGlu7 and ß-adrenergic receptors are co-expressed in a sub-population of cerebrocortical nerve terminals. mGlu7 receptors readily couple to pathways that inhibit glutamate release. We found that when mGlu7 receptors are also coupled to pathways that enhance glutamate release by prolonged exposure to agonist, and ß-adrenergic receptors are also activated, a cross-talk between their signaling pathways occurs that affect the overall release response. This interaction is the result of mGlu7 receptors inhibiting the adenylyl cyclase activated by ß adrenergic receptors. Thus, blocking Gi/o proteins with pertussis toxin provokes a further increase in release after receptor co-activation which is also observed after activating ß-adrenergic receptor signaling pathways downstream of adenylyl cyclase with the cAMP analog Sp8Br or 8pCPT-2-OMe-cAMP (a specific activator of the guanine nucleotide exchange protein directly activated by cAMP, EPAC). Co-activation of mGlu7 and ß-adrenergic receptors also enhances PLC-dependent accumulation of IP1 and the translocation of the active zone protein Munc13-1 to the membrane, indicating that release potentiation by these receptors involves the modulation of the release machinery.

The regulation of synaptic vesicle recycling by cGMP-dependent protein kinase type II in cerebellar granule cells under strong and sustained stimulation.

From the early periods of neurogenesis and migration, up until synaptogenesis, both nitric oxide (NO) and its downstream messenger, cGMP, are thought to influence the development of neurons. The NO/cGMP/cGMP-dependent protein kinase (cGK) pathway regulates the clustering and recruitment of synaptic proteins and vesicles to the synapse, adjusting the exoendocytic cycle to the intensity of activity and accelerating endocytosis following large-scale exocytosis. Here, we show that blockage of the N-methyl-D-aspartate receptor impairs the cycling of synaptic vesicles in a subset of boutons on cerebellar granule cells, an effect that was reversed by increasing cGMP. Furthermore, we demonstrate that presynaptic cGK type II (cGKII) plays a major role in this process. Using the FM1-43 dye to track vesicle recycling, we found that knockdown of cGKII and/or the application of a cGK inhibitor reduced the efficiency of synaptic vesicle recycling to a similar extent. Likewise, in cerebellar granule cells transfected with vGlut1-pHluorin to follow the exoendocytotic cycle, application of a cGK inhibitor slowed vesicle endocytosis when exocytosis was accelerated through strong and sustained stimulation. Additionally, ultrastructural analysis showed that cGKII knockdown or inhibition favored the formation of endosomal-like structures after strong and sustained stimulation. We conclude that cGKII controls the homeostatic balance of vesicle exocytosis and endocytosis in synaptic boutons of rat cerebellar granule cells.

Altered neuronal and endothelial nitric oxide synthase expression in the bladder and urethra of cyclophosphamide-treated rats.

Increased nitric oxide (NO) production seems to play a key role in cyclophosphamide (CYP)-induced cystitis, although the underlying mechanisms and the relative involvement of the different NO synthase (NOS) isoforms remain to be elucidated. Moreover, the role of the urethra in this process is also unclear. In this study, we have analyzed the changes in the expression and distribution of the inducible (iNOS), endothelial (eNOS) and neuronal (nNOS) isoforms of NOS, and the alterations in nerve-mediated contractility in the bladder and urethra of CYP-treated rats. Accordingly, Wistar rats were treated with 150 mg kg(-1) CYP for 4 (acute treatment) or 48 h (intermediate treatment), or with 70 mg kg(-1) CYP every 3 days for 10 days (chronic treatment), and the changes in protein expression were assessed by immunohistofluorescence and in Western blots, while mRNA expression was assessed by conventional and quantitative PCR. Similarly, nerve-mediated contractility was analyzed in vitro. Unexpectedly, no iNOS expression was detected in CYP-treated animals, while a transient downregulation of nNOS expression and a progressive upregulation of eNOS was observed, although the eNOS accumulated was not in the active phosphorylated form. Qualitative changes in mRNA expression were also observed in the bladder and urethra, although contractility only diminished in the bladder and this change was not dependent on NOS activity. These findings suggest that spatiotemporal alterations in NO production by constitutive NOS may be involved in the pathogenicity of CYP. Further studies will be necessary to understand the contribution of eNOS to the increases in NO associated with bladder inflammation, or that of free radicals.