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1.
J Sch Psychol ; 94: 49-65, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36064215

RESUMO

This study reviews findings for the first randomized controlled trial (RCT) on the Interconnected Systems Framework (ISF) for school mental health (SMH) and Positive Behavioral Interventions and Supports (PBIS). Since its development in the late 2000s, the ISF has been supported by federally funded centers for SMH and PBIS, and, guided by a national workgroup, is being implemented in >50 communities in the United States. This experimental evaluation of the ISF involved an RCT implemented in 24 schools in two southeastern states, with the ISF implemented in eight schools, PBIS alone implemented in eight schools, and typically co-located PBIS+SMH implemented in eight schools. Related to very poor implementation, documented by two sources of fidelity data, two ISF schools were dropped from major analyses; hence, the study used a treatment on the treated (ToT; Rubin, 1974) as compared to a more traditional Intent-to-Treat approach (ITT; Lachin, 2000). This is the first paper from this large study, with emphasis here on proximal variables and school discipline. Within schools' multi-tiered systems of support (MTSS), ISF schools delivered more Tier 2 (early intervention) and Tier 3 (treatment) interventions to a greater proportion of students than the other two conditions by the second year of the intervention. There was also a dramatic difference in the provision of interventions by community mental health clinicians in ISF schools (almost half of interventions delivered) as compared to PBIS+SMH schools (around 3% of interventions delivered), underscoring the critical role of the ISF in integrating clinicians into MTSS teams and core school functions in SMH. As compared to the other two conditions, ISF schools also had reduced office discipline referrals (ODRs) and in-school suspensions, as well as reduced ODRs and out-of-school suspensions for African American students. Findings are discussed in relation to future directions of education-mental health system partnerships in improving the delivery and impact of SMH programs and services, demonstrated in the ISF.


Assuntos
Saúde Mental , Instituições Acadêmicas , Terapia Comportamental , Humanos , Serviços de Saúde Escolar , Estudantes/psicologia , Suspensões
2.
Artigo em Inglês | MEDLINE | ID: mdl-37383298

RESUMO

African American adolescent girls have evidenced higher levels of disruptive behavior than girls from other ethnic groups. However, most research focused on understanding disparities in these outcomes has been conducted without consideration of gender or has focused exclusively on boys. Yet, prior research suggests that anger and aggression are less gender-typed in African American youth than they are among youth from other ethnic backgrounds. The purpose of this preliminary investigation was to examine the extent to which ethnic-specific gender schemas about anger mediated the relationship between ethnicity and girls' disruptive behavior. Participants were 66 middle school girls (24.1 % African American, 46.3 % European American; Mage= 12.06). They completed measures of ethnic-specific gender schemas about anger, reactive and instrumental aggression, and classroom disruptive behavior. Results indicated that relative to girls from other ethnic groups, African American girls had higher levels of reactive aggression and classroom disruptive behavior, both of which are rooted in anger. In contrast, no ethnic difference was found for instrumental aggression, which is not connected to anger. Ethnic-specific gender schemas about anger at least partially accounted for ethnic differences in reactive aggression and classroom disruptive behavior. Findings highlight the importance of examining gender schemas specific to ethnicity as factors in ethnic disparities in behavioral outcomes among adolescent girls.

3.
Rev Neurosci ; 28(8): 869-892, 2017 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-28779572

RESUMO

Mutant mice deficient in hyaluronan (HA) have an epileptic phenotype. HA is one of the major constituents of the brain extracellular matrix. HA has a remarkable hydration capacity, and a lack of HA causes reduced extracellular space (ECS) volume in the brain. Reducing ECS volume can initiate or exacerbate epileptiform activity in many in vitro models of epilepsy. There is both in vitro and in vivo evidence of a positive feedback loop between reduced ECS volume and synchronous neuronal activity. Reduced ECS volume promotes epileptiform activity primarily via enhanced ephaptic interactions and increased extracellular potassium concentration; however, the epileptiform activity in many models, including the brain slices from HA synthase-3 knockout mice, may still require glutamate-mediated synaptic activity. In brain slice epilepsy models, hyperosmotic solution can effectively shrink cells and thus increase ECS volume and block epileptiform activity. However, in vivo, the intravenous administration of hyperosmotic solution shrinks both brain cells and brain ECS volume. Instead, manipulations that increase the synthesis of high-molecular-weight HA or decrease its breakdown may be used in the future to increase brain ECS volume and prevent seizures in patients with epilepsy. The prevention of epileptogenesis is also a future target of HA manipulation. Head trauma, ischemic stroke, and other brain insults that initiate epileptogenesis are known to be associated with an early decrease in high-molecular-weight HA, and preventing that decrease in HA may prevent the epileptogenesis.


Assuntos
Encéfalo/metabolismo , Epilepsia/metabolismo , Espaço Extracelular/metabolismo , Hialuronan Sintases/genética , Ácido Hialurônico/metabolismo , Animais , Encéfalo/fisiopatologia , Epilepsia/tratamento farmacológico , Epilepsia/genética , Hialuronan Sintases/metabolismo , Ácido Hialurônico/uso terapêutico , Camundongos
4.
Environ Sci Pollut Res Int ; 23(22): 23195-23202, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27604124

RESUMO

Vermicomposting (VC) has proven to be a promising method for treating garden, household, and municipal wastes. Although the VC has been used extensively for converting wastes into fertilizers, pathogens such as Escherichia coli (E. coli) survival during this process is not well documented. In this study, both lab and field scale experiments were conducted assessing the impacts of earthworms in reducing E. coli concentration during VC of food waste. In addition, other pertinent parameters such as temperature, carbon and nitrogen content, moisture content, pH, volatile solids, micronutrients (P, K, Ca, Mg, and S), and heavy metals (Zn, Mn, Fe, and Cu) were monitored during the study. The lab and field scale experiments were conducted for 107 and 103 days, respectively. The carbon to nitrogen ratio (C/N) decreased by 54 % in the lab scale study and by 36 % in the field study. Results showed that VC was not significantly effective in reducing E. coli levels in food waste under both lab and field scale settings. The carbon to nitrogen ratio (C/N) decreased by 54 % in the lab scale study and by 36 % in the field study.


Assuntos
Escherichia coli , Alimentos , Eliminação de Resíduos , Solo , Animais , Carbono/análise , Carbono/metabolismo , Metais Pesados/análise , Nitrogênio/análise , Nitrogênio/metabolismo , Oligoquetos , Eliminação de Resíduos/métodos , Solo/química , Instalações de Eliminação de Resíduos
5.
Home Healthc Now ; 33(1): 20-6, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25654342

RESUMO

Technology holds potential to improve the quality of healthcare delivery. The use of remote patient monitoring, or telehealth (TH), has been widely adopted by many home care agencies to facilitate early identification of disease exacerbation, particularly for patients with chronic diseases such as heart failure. TH has been successfully used to improve symptom detection and potentially reduce rehospitalization rates. Quantifying program effectiveness through data analysis is a critical step for program improvement, resource allocation, and future strategic planning. Using the Outcome and Assessment Information Set-C database, a retrospective analysis was conducted examining 22 months of heart failure patient data from one home care agency in southern California. Seventy patients receiving TH were compared to patients who received usual home care nursing services. No major differences in baseline socio-demographics were found between the 2 groups. While receiving home healthcare services, the non-TH patients had a 21% all-cause hospital readmission rate, compared to the home TH patients with a 10% all-cause readmission rate. Statistical differences were found between groups on the variables of fall risk, vision, smoking, shortness of breath, the ability to bathe and take oral meds, along with having been discharged from a skilled nursing facility in the last 2 weeks. These results indicate that aggregate data analysis is useful in providing insight into program effectiveness. This study suggests TH programs have the potential to reduce the burden associated with rehospitalizations in the heart failure population.


Assuntos
Serviços de Assistência Domiciliar/organização & administração , Avaliação de Resultados em Cuidados de Saúde , Readmissão do Paciente/estatística & dados numéricos , Telemedicina/métodos , Idoso , Idoso de 80 Anos ou mais , California , Bases de Dados Factuais , Feminino , Humanos , Masculino , Melhoria de Qualidade , Estudos Retrospectivos
6.
J Neurosci ; 34(18): 6164-76, 2014 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-24790187

RESUMO

Hyaluronan (HA), a large anionic polysaccharide (glycosaminoglycan), is a major constituent of the extracellular matrix of the adult brain. To address its function, we examined the neurophysiology of knock-out mice deficient in hyaluronan synthase (Has) genes. Here we report that these Has mutant mice are prone to epileptic seizures, and that in Has3(-/-) mice, this phenotype is likely derived from a reduction in the size of the brain extracellular space (ECS). Among the three Has knock-out models, namely Has3(-/-), Has1(-/-), and Has2(CKO), the seizures were most prevalent in Has3(-/-) mice, which also showed the greatest HA reduction in the hippocampus. Electrophysiology in Has3(-/-) brain slices demonstrated spontaneous epileptiform activity in CA1 pyramidal neurons, while histological analysis revealed an increase in cell packing in the CA1 stratum pyramidale. Imaging of the diffusion of a fluorescent marker revealed that the transit of molecules through the ECS of this layer was reduced. Quantitative analysis of ECS by the real-time iontophoretic method demonstrated that ECS volume was selectively reduced in the stratum pyramidale by ∼ 40% in Has3(-/-) mice. Finally, osmotic manipulation experiments in brain slices from Has3(-/-) and wild-type mice provided evidence for a causal link between ECS volume and epileptiform activity. Our results provide the first direct evidence for the physiological role of HA in the regulation of ECS volume, and suggest that HA-based preservation of ECS volume may offer a novel avenue for development of antiepileptogenic treatments.


Assuntos
Encéfalo/patologia , Epilepsia/patologia , Espaço Extracelular/metabolismo , Glucuronosiltransferase/deficiência , Ácido Hialurônico/deficiência , Neurônios/fisiologia , Potenciais de Ação/genética , Animais , Estimulação Elétrica , Eletroencefalografia , Epilepsia/genética , Antagonistas de Aminoácidos Excitatórios/farmacologia , Espaço Extracelular/genética , Glucuronosiltransferase/genética , Hialuronan Sintases , Técnicas In Vitro , Camundongos , Camundongos Knockout , Modelos Neurológicos , Mutação/genética , Rede Nervosa/metabolismo , Rede Nervosa/patologia , Neurônios/efeitos dos fármacos , Fosfopiruvato Hidratase/metabolismo , Quinoxalinas/farmacologia
7.
PLoS Genet ; 10(4): e1004285, 2014 04.
Artigo em Inglês | MEDLINE | ID: mdl-24743323

RESUMO

Invasive lobular breast cancer (ILC) accounts for 10-15% of all invasive breast carcinomas. It is generally ER positive (ER+) and often associated with lobular carcinoma in situ (LCIS). Genome-wide association studies have identified more than 70 common polymorphisms that predispose to breast cancer, but these studies included predominantly ductal (IDC) carcinomas. To identify novel common polymorphisms that predispose to ILC and LCIS, we pooled data from 6,023 cases (5,622 ILC, 401 pure LCIS) and 34,271 controls from 36 studies genotyped using the iCOGS chip. Six novel SNPs most strongly associated with ILC/LCIS in the pooled analysis were genotyped in a further 516 lobular cases (482 ILC, 36 LCIS) and 1,467 controls. These analyses identified a lobular-specific SNP at 7q34 (rs11977670, OR (95%CI) for ILC = 1.13 (1.09-1.18), P = 6.0 × 10(-10); P-het for ILC vs IDC ER+ tumors = 1.8 × 10(-4)). Of the 75 known breast cancer polymorphisms that were genotyped, 56 were associated with ILC and 15 with LCIS at P<0.05. Two SNPs showed significantly stronger associations for ILC than LCIS (rs2981579/10q26/FGFR2, P-het = 0.04 and rs889312/5q11/MAP3K1, P-het = 0.03); and two showed stronger associations for LCIS than ILC (rs6678914/1q32/LGR6, P-het = 0.001 and rs1752911/6q14, P-het = 0.04). In addition, seven of the 75 known loci showed significant differences between ER+ tumors with IDC and ILC histology, three of these showing stronger associations for ILC (rs11249433/1p11, rs2981579/10q26/FGFR2 and rs10995190/10q21/ZNF365) and four associated only with IDC (5p12/rs10941679; rs2588809/14q24/RAD51L1, rs6472903/8q21 and rs1550623/2q31/CDCA7). In conclusion, we have identified one novel lobular breast cancer specific predisposition polymorphism at 7q34, and shown for the first time that common breast cancer polymorphisms predispose to LCIS. We have shown that many of the ER+ breast cancer predisposition loci also predispose to ILC, although there is some heterogeneity between ER+ lobular and ER+ IDC tumors. These data provide evidence for overlapping, but distinct etiological pathways within ER+ breast cancer between morphological subtypes.


Assuntos
Neoplasias da Mama/genética , Carcinoma in Situ/genética , Carcinoma Lobular/genética , Predisposição Genética para Doença/genética , Estudos de Casos e Controles , Feminino , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética
8.
Maturitas ; 75(3): 232-40, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23664318

RESUMO

DietCompLyf is a multi-centre prospective study designed to investigate associations between phytoestrogens - naturally occurring plant compounds with oestrogenic properties - and other diet and lifestyle factors with breast cancer recurrence and survival. 3159 women with grades I-III breast cancer were recruited 9-15 months post-diagnosis from 56 UK hospitals. Detailed information on clinico-pathological, diet, lifestyle and quality of life is collected annually up to 5 years. Biological samples have also been collected as a resource for subsequent evaluation. The characteristics of the patients and associations between pre-diagnosis intake of phytoestrogens (isoflavones and lignans; assessed using the EPIC-Norfolk UK 130 question food frequency questionnaire) and breast cancer (i) risk factors and (ii) prognostic factors are described for 1797 women who had complete data for all covariates and phytoestrogens of interest. Isoflavone intakes were higher in the patients who were younger at diagnosis, in the non-smokers, those who had breast-fed and those who took supplements. Lignan intakes were higher in patients with a higher age at diagnosis, in ex-smokers, those who had breast-fed, who took supplements, had a lower BMI at diagnosis, lower age at menarche and were nulliparous. No significant associations between pre-diagnosis phytoestrogen intake and factors associated with improved breast cancer prognosis were observed. The potential for further exploration of the relationship between phytoestrogens and breast cancer recurrence and survival, and for the establishment of evidence to improve dietary and lifestyle advice offered to patients following breast cancer diagnosis using DietCompLyf data is discussed.


Assuntos
Neoplasias da Mama , Isoflavonas/farmacologia , Lignanas/farmacologia , Fitoestrógenos/farmacologia , Extratos Vegetais/farmacologia , Sobreviventes , Adulto , Fatores Etários , Aleitamento Materno , Neoplasias da Mama/diagnóstico , Inquéritos sobre Dietas , Suplementos Nutricionais , Feminino , Humanos , Menarca , Pessoa de Meia-Idade , Paridade , Prognóstico , Estudos Prospectivos , Recidiva , Fumar , Inquéritos e Questionários , Reino Unido
9.
Epilepsy Res ; 94(3): 163-76, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21353480

RESUMO

Application of 4-aminopyridine (4-AP, 100µM) in a solution containing 0.6mM Mg(2+) and 1.2mM Ca(2+) to hippocampal-entorhinal-perirhinal slices of adult rat brain induced ictal-like epileptiform activity in entorhinal and perirhinal cortices as revealed by electrophysiological field potential recordings. The ictal-like activity persisted after washing out the 4-AP. This persistence indicated that a change had occurred in the slice so that it was now "epileptic" in the absence of the convulsant 4-AP. Induction of persistent ictal-like activity was dependent upon the concentration of divalent cations during 4-AP exposure; that is, although 4-AP caused ictal-like activity in approximately half the slices in solution containing 1.6mM Mg(2+) and 2.0mM Ca(2+), this ictal-like activity did not persist upon washout of the 4-AP. Expression of the persistent ictal-like epileptiform activity required ionotropic glutamate-mediated synaptic transmission: application of the AMPA/kainate receptor antagonist NBQX after 4-AP washout reduced persistent ictal-like activity, and the combined application of NBQX and the NMDA receptor antagonist d-AP5 completely blocked it. In order to investigate the mechanism of induction of persistent ictal-like activity, several agents were applied before the introduction of 4-AP. Application of d-AP5 did not block the onset of ictal-like activity upon introduction of 4-AP but did prevent the persistence of the ictal-like activity upon washout of the 4-AP. In contrast, induction of persistent ictal-like activity was not prevented by simultaneous application of the group I metabotropic glutamate receptor (mGluR) antagonists LY 367385 and MPEP or by application of the protein synthesis inhibitor cycloheximide. In conclusion, we have characterized a new in vitro model of epileptogenesis in which induction of ictal-like activity is dependent upon NMDA receptor activation but not upon group I mGluR activation or protein synthesis.


Assuntos
4-Aminopiridina/farmacologia , Córtex Entorrinal/efeitos dos fármacos , Potenciais Evocados/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/farmacologia , Animais , Cálcio/farmacologia , Cicloeximida/farmacologia , Eletrofisiologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Técnicas In Vitro , Magnésio/farmacologia , Inibidores da Síntese de Proteínas/farmacologia , Ratos , Ratos Sprague-Dawley
10.
Breast Cancer Res Treat ; 128(2): 473-82, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21221774

RESUMO

The diagnosis of cancer can motivate survivors to alter their lifestyle habits. Healthcare providers need to be aware of what changes patients are likely to make in order to derive more pertinent recommendations; however, few studies have reported pre- and post-diagnostic lifestyle behaviours. Semi-quantitative food frequency questionnaires (FFQs) completed approximately 1 year after diagnosis were used to evaluate dietary intake and supplement use before and after diagnosis in a cohort of 1,560 breast cancer patients participating in the UK, prospective DietCompLyf study. Intake of fruit and vegetables, wholegrains and lean sources of protein increased significantly post-diagnosis (P < 0.05, each). Conversely, after diagnosis consumption of high-fat, high-sugar products, red meat, coffee, some alcoholic drinks and refined grains significantly decreased (P < 0.05, each). Post-diagnostic changes in diet were accompanied by changes in the intake of macronutrients and a number of vitamins and minerals. Supplement use was highly prevalent (56.1%) pre-diagnosis, increasing to 62.8% after diagnosis (P = 0.001). Fish oils, multivitamin and minerals, and evening primrose oil were most often used and the proportion of users significantly increased (P < 0.05, each) after diagnosis. The percentage of women using oestrogenic botanical supplements (OBSs) was small but more than doubled to 8.4% after diagnosis (P < 0.05). British women participating in the DietCompLyf study reported significant changes in dietary intake and supplement use after their breast cancer diagnosis. These findings contribute to our understanding of female cancer survivors' dietary behaviours which is crucial for developing and implementing recommendations.


Assuntos
Neoplasias da Mama/dietoterapia , Neoplasias da Mama/psicologia , Dieta/psicologia , Suplementos Nutricionais , Sobreviventes/psicologia , Idoso , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/epidemiologia , Estudos de Coortes , Dieta/tendências , Feminino , Seguimentos , Promoção da Saúde , Humanos , Estilo de Vida , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Inquéritos e Questionários , Reino Unido/epidemiologia
11.
Science ; 322(5902): 682-3, 2008 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-18974334
12.
Neuropharmacology ; 55(1): 47-54, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18538357

RESUMO

Co-application of the convulsant 4-aminopyridine (4-AP) and the GABA(B) receptor antagonist CGP 55845 to adult guinea pig hippocampal slices elicits giant GABA-mediated postsynaptic potentials (GPSPs) and epileptiform discharges. Here we tested the effects of the group I metabotropic glutamate receptor (mGluR) subtype-selective antagonists LY 367385 (mGlu1, 100 microM), MPEP (mGlu5, 10 microM), and MTEP (mGlu5, 500 nM) on this synchronous activity. Electrophysiological field recordings were performed in the CA3 region of hippocampal slices from adult guinea pigs. The mGlu5 receptor antagonists increased GPSP rate, but the mGlu1 receptor antagonist did not. This ability of mGlu5 receptor antagonists to increase the rate of GPSPs indicates that enough endogenous glutamate is released under these conditions to activate group I mGluR; nevertheless, co-application of a mGlu1 receptor antagonist (LY 367385 or JNJ 16259685) and MPEP did not decrease pre-existing epileptiform activity. Furthermore, co-application of LY 367,385 and MPEP did not prevent the emergence of epileptiform activity. When ionotropic glutamate receptor (iGluR) antagonists were present, neither MPEP nor the group I mGluR agonist DHPG changed GPSP rate, suggesting that pyramidal cell-to-interneuron iGluR-mediated synaptic connections are involved in the rate change mechanism. In contrast to the lack of effect of group I mGluR antagonists on epileptiform activity in the 4-AP/CGP 55845 model, group I mGluR antagonists blocked the emergence of longer epileptiform events and decreased the overall amount of synchronous activity in the GABA(A) antagonist/4-AP model. In conclusion, in the 4-AP/CGP 55845 model, enough glutamate was released to activate group I mGluRs and affect GPSP rate via mGlu5 receptors; however, this group I mGluR activation was not required for the generation of the epileptiform activity.


Assuntos
4-Aminopiridina/farmacologia , Potenciais de Ação/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas GABAérgicos/farmacologia , Hipocampo/efeitos dos fármacos , Ácidos Fosfínicos/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Propanolaminas/farmacologia , Animais , Combinação de Medicamentos , Interações Medicamentosas , Cobaias , Técnicas In Vitro
13.
J Neurosci Methods ; 154(1-2): 1-18, 2006 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-16554092

RESUMO

Cell-attached recording provides a way to record the activity of - and to stimulate - neurons in brain slices without rupturing the cell membrane. This review uses theory and experimental data to address the proper application of this technique and the correct interpretation of the data. Voltage-clamp mode is best-suited for recording cell firing activity, and current-clamp mode is best-suited for recording resting membrane potential and synaptic potentials. The magnitude of the seal resistance determines what types of experiments can be accomplished with a cell-attached recording: a loose seal is adequate for recording action potential currents, and a tight seal is required for evoking action potentials in the attached cell and for recording resting and synaptic potentials. When recording action potential currents, if the researcher does not want to change the firing activity of the cell, then it is important that no current passes from the amplifier through the patch resistance. In order to accomplish this condition, the recording pipette should be held at the potential that gives a holding current of 0. An advantage of cell-attached current-clamp over whole-cell recording is that it accurately depicts whether a synaptic potential is hyperpolarizing or depolarizing without the risk of changing its polarity.


Assuntos
Encéfalo/fisiologia , Técnicas de Patch-Clamp/métodos , Potenciais de Ação/fisiologia , Algoritmos , Animais , Estimulação Elétrica , Eletrofisiologia , Espaço Extracelular/fisiologia , Cobaias , Técnicas In Vitro , Potenciais da Membrana , Técnicas de Patch-Clamp/instrumentação , Sinapses/fisiologia
14.
J Neurophysiol ; 93(5): 2656-67, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15590725

RESUMO

In the presence of 4-aminopyridine, interneurons fire synchronously, causing giant GABA-mediated postsynaptic potentials (GPSPs; GPSCs in voltage clamp) in CA3 pyramidal cells in hippocampal slices from adult guinea pigs. These triphasic GPSPs are composed of a GABA(A)-mediated hyperpolarizing component, a depolarizing component, and a GABA(B)-mediated hyperpolarizing component. We propose that GABA(B) receptors exert control over the postsynaptic depolarizing GABA response. Microelectrode and cell-attached recordings demonstrated that the mean number of action potentials during the depolarizing component of the GPSP increased dramatically in the presence of the GABA(B) receptor antagonist (2S)-3-[[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2- hydroxypropyl](phenylmethyl) phosphinic acid (CGP 55845A; P = 0.003 and 0.0005, respectively). Whole cell voltage-clamp recordings showed that the postsynaptic GABA(B) and depolarizing GABA components of the GPSC overlap substantially, allowing the GABA(B)-mediated hyperpolarization to suppress the excitation mediated by the depolarizing GABA component. Further voltage-clamp recordings showed that CGP 55845A increased the duration of the depolarizing GABA component of the GPSC even when the GABA(B) component had already been blocked by internal QX-314, suggesting that CGP 55845A also increased the duration of GABA release. When glutamatergic transmission is intact, GPSPs directly precede epileptiform afterdischarges. We hypothesize that the depolarizing component of the GPSP triggers the epileptiform events and show here that enhancement of the depolarizing component with CGP 55845A increased epileptiform activity. CGP 55845A increased the likelihood of a GPSP triggering an epileptiform event from 32 to 99% (P = 0.0000001), and significantly increased the number of afterdischarges per epileptiform event (P = 0.001). Loss of GABA(B) receptor function is associated with temporal lobe epilepsy in rodents and humans. We show here that GABA(B) receptors exert control over the synaptic depolarizing GABA response and that block of GABA(B) receptors makes the depolarizing GABA response excitatory and proconvulsive.


Assuntos
Hipocampo/citologia , Lidocaína/análogos & derivados , Inibição Neural/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Receptores de GABA-A/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologia , 4-Aminopiridina/farmacologia , Anestésicos Locais/farmacologia , Animais , Interações Medicamentosas , Estimulação Elétrica/métodos , Antagonistas GABAérgicos/farmacologia , Ácido Glutâmico/farmacologia , Cobaias , Técnicas In Vitro , Lidocaína/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/efeitos da radiação , Neurônios/fisiologia , Neurônios/efeitos da radiação , Técnicas de Patch-Clamp/métodos , Ácidos Fosfínicos/farmacologia , Bloqueadores dos Canais de Potássio/farmacologia , Propanolaminas/farmacologia , Piridazinas/farmacologia
15.
J Neurophysiol ; 87(3): 1404-14, 2002 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11877515

RESUMO

Whole cell voltage-clamp recording and focal application of the neurotransmitter gamma-aminobutyric acid (GABA) were used to investigate the ability of exogenous GABA applied to different locations within the guinea pig hippocampal slice to trigger a giant GABA-mediated postsynaptic current (GPSC) in pyramidal cells. A GPSC reflects the synchronous release of GABA from a group of interneurons. Recordings were done in the presence of 4-aminopyridine (4-AP) and blockers of ionotropic glutamatergic synaptic transmission. Spontaneous GPSCs occurred rhythmically in pyramidal cells under these conditions. Brief focal pressure application of GABA (500 microM; 30-200 ms) to CA3 stratum lacunosum-moleculare (SLM) or to the border between CA3 s. radiatum (SR) and SLM triggered an "all-or-none" GPSC in CA3 and CA1 pyramidal cells that looked like the spontaneous GPSCs. During the refractory period following a spontaneous GPSC, application of GABA could not trigger a GPSC. Both spontaneous GPSCs and GPSCs triggered by exogenous GABA were blocked by suppressing synaptic transmission with high Mg(2+)/low Ca(2+) bath solution. On the other hand, focal application of GABA to CA3 s. oriens (SO) or to proximal SR did not trigger a GPSC in the CA3 pyramidal cell; instead it produced a graded response. Focal application of GABA to regions other than CA3 was also tested. Focal application of GABA to CA1 SLM always triggered a GPSC in the CA3 pyramidal cell. Focal application of GABA within the outer two-thirds of the dentate molecular layer often elicited a GPSC in the CA3 pyramidal cell. In contrast, focal application of GABA to CA1 SO, to CA1 SR, or to the hilus elicited no current response in the CA3 pyramidal cell. These data indicate that the GPSC recorded in pyramidal cells that was triggered by focal GABA application resulted from the synchronous synaptic release of GABA from activated interneurons rather than from the binding of exogenous GABA to receptors on the pyramidal cell. Furthermore, the "all-or-none" nature of the response to SLM GABA applications of different durations indicates that the exogenous GABA was exciting (directly or indirectly) some members of a network of interneurons, which in turn recruited the rest of the network, rather than individually activating each interneuron that contributed to the GPSC. Interestingly, the effective sites of GABA application--CA3 SLM, CA1 SLM, and the outer two-thirds of the dentate molecular layer--are also the sites which receive direct innervation from the entorhinal cortex in an intact animal.


Assuntos
Hipocampo/citologia , Hipocampo/fisiologia , Interneurônios/fisiologia , Ácido gama-Aminobutírico/farmacologia , Animais , Giro Denteado/citologia , Giro Denteado/fisiologia , Cobaias , Interneurônios/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Técnicas de Cultura de Órgãos , Técnicas de Patch-Clamp , Células Piramidais/efeitos dos fármacos , Células Piramidais/fisiologia , Período Refratário Eletrofisiológico/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos
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