Mecanismos de modulación central del dolor: revisión de la literatura / Mechanisms of central pain modulation: literature review

RESUMEN: La percepción del dolor resulta de múltiples y dinámicos mecanismos en el sistema nervioso central (SNC) y periférico que inhiben o facilitan el estímulo y respuesta nociceptiva. Sin embargo, la principal capacidad de modulación esta a cargo del SNC. Los estímulos nociceptivos son detectados por terminaciones nerviosas libres de neuronas periféricas que sinaptan con neuronas aferentes secundarias de la médula espinal. Luego estas fibras decusan para formar las vías nociceptivas ascendentes. Una vez alcanzadas las estructuras subcorticales, se activan las neuronas del tálamo, quienes envían el estímulo hacia la corteza somatosensorial, desencadenando la percepción consciente del dolor y activando el sistema inhibitorio descendente. Para que la modulación nociceptiva se realice, es necesaria la participación de diversas sustancias o neurotransmisores que conectan áreas del SNC especializadas. Por lo tanto, el objetivo de este estudio fue realizar una revisión de la literatura respecto de los mecanismos que participan en los procesos de modulación central del dolor.

SUMMARY: Pain perception results from multiple and dynamic mechanisms in the central nervous system (CNS) and peripheral nervous system that inhibit or facilitate stimulation and nociceptive response. However, neuromodulation is mainly a function of the CNS. Nociceptive stimulus is detected by peripheral neurons receptors that synapse with the secondary afferent neurons of the spinal cord. These fibers cross to conform the ascending nociceptive pathways. Once the subcortical structures are reached, the thalamus`s neurons are activated; the thalamus send the stimulus to the somatosensory cortex, triggering the conscious perception of pain and activating the descending inhibitory system. For the nociceptive modulation to be carried out, the participation of various substances or neurotransmitters that connect specialized CNS areas is necessary. Therefore, the aim of this study was to review the literature regarding the mechanisms involved in central pain modulation processes.

Hierarchical Control of Drosophila Sleep, Courtship, and Feeding Behaviors by Male-Specific P1 Neurons / 神经科学通报·英文版

Animals choose among sleep, courtship, and feeding behaviors based on the integration of both external sensory cues and internal states; such choices are essential for survival and reproduction. These competing behaviors are closely related and controlled by distinct neural circuits, but whether they are also regulated by shared neural nodes is unclear. Here, we investigated how a set of male-specific P1 neurons controls sleep, courtship, and feeding behaviors in Drosophila males. We found that mild activation of P1 neurons was sufficient to affect sleep, but not courtship or feeding, while stronger activation of P1 neurons labeled by four out of five independent drivers induced courtship, but only the driver that targeted the largest number of P1 neurons affected feeding. These results reveal a common neural node that affects sleep, courtship, and feeding in a threshold-dependent manner, and provide insights into how competing behaviors can be regulated by a shared neural node.

Home-based nursing interventions improve knowledge of disease and management in patients with heart failure / Intervenções de enfermagem no domicílio melhoram conhecimento sobre a doença e tratamento em pacientes com insuficiência cardíaca / Intervenciones de enfermería en domicilio mejoran conocimiento sobre la enfermedad y tratamiento en pacientes con insuficiencia cardíaca

OBJECTIVE: to assess patient knowledge of heart failure by home-based measurement of two NOC Nursing Outcomes over a six-month period and correlate mean outcome indicator scores with mean scores of a heart failure Knowledge Questionnaire. METHODS: in this before-and-after study, patients with heart failure received four home visits over a six-month period after hospital discharge. At each home visit, nursing interventions were implemented, NOC outcomes were assessed, and the Knowledge Questionnaire was administered. RESULTS: overall, 23 patients received home visits. Mean indicator scores for the outcome Knowledge: Medication were 2.27±0.14 at home visit 1 and 3.55±0.16 at home visit 4 (P<0.001); and, for the outcome Knowledge: Treatment Regimen, 2.33±0.13 at home visit 1 and 3.59±0.14 at home visit 4 (P<0.001). The correlation between the Knowledge Questionnaire and the Nursing Outcomes Classification scores was strong at home visit 1 (r=0.7, P<0.01), but weak and non significant at visit 4. CONCLUSION: the results show improved patient knowledge of heart failure and a strong correlation between Nursing Outcomes Classification indicator scores and Knowledge Questionnaire scores. The NOC Nursing Outcomes proved effective as knowledge assessment measures when compared with the validated instrument. .

OBJETIVO: verificar o conhecimento dos pacientes sobre insuficiência cardíaca, por meio de dois Resultados de Enfermagem em ambiente domiciliar, durante um seguimento de seis meses e, correlacionar a média dos seus indicadores com um Questionário de Conhecimento sobre insuficiência cardíaca. MÉTODOS: neste estudo tipo antes-depois, pacientes com insuficiência cardíaca receberam quatro visitas domiciliares, durante seis meses, após a alta hospitalar. Em cada visita foram implementadas Intervenções de Enfermagem, mensurados os Resultados e aplicado o Questionário do Conhecimento. RESULTADOS: vinte e três pacientes receberam visitas em domicílio. Na visita um, o Resultado Conhecimento: Medicação obteve média de 2,27±0,14 e na visita quatro, 3,55±0.16 (P<0,001), e o Resultado Conhecimento: Regime Terapêutico 2,33±0,13 na visita um e 3,59±0,14 na visita quatro (P<0,001). A correlação entre o Questionário do Conhecimento e os escores da Classificação dos Resultados de Enfermagem foi de forte magnitude na visita domiciliar um (r=0.7, P<0,01), mas fraca e não significativa na visita quatro. CONCLUSÃO: os resultados indicaram progresso do conhecimento sobre insuficiência cardíaca e correlação forte entre a Classificação dos Resultados de Enfermagem e os escores do Questionário do Conhecimento. A Classificação dos Resultados de Enfermagem mostrou-se efetiva na avaliação do conhecimento quando comparada ao instrumento validado. .

OBJETIVO: verificar el conocimiento de los pacientes sobre insuficiencia cardíaca mediante dos Resultados de Enfermería en ambiente domiciliario durante un seguimiento de seis meses y correlacionar el promedio de sus indicadores con un Cuestionario de Conocimiento sobre insuficiencia cardíaca. MÉTODOS: en este estudio tipo antes-después, pacientes con insuficiencia cardíaca recibieron cuatro visitas en domicilio durante un período de seis meses tras el alta hospitalario. En cada visita fueron implementadas Intervenciones de Enfermería, mensurados los Resultados y aplicado el Cuestionario del Conocimiento. RESULTADOS: veinte y tres pacientes recibieron visitas en domicilio. En la visita 1, el Resultado Conocimiento: Medicación alcanzó promedio de 2,27±0,14 y, en la visita 4 3,55±0.16 (P<0,001), y el Resultado Conocimiento: Régimen Terapéutico 2,33±0,13 en la visita 1 y 3,59±0,14 en la visita 4 (P<0,001). La correlación entre el Cuestionario del Conocimiento y los scores de la Clasificación de los Resultados de Enfermería fue de magnitud fuerte en la visita en domicilio 1 (r=0.7, P<0,01), pero débil y no significativa en la visita 4. CONCLUSIÓN: los resultados indicaron mejora del conocimiento sobre insuficiencia cardíaca y correlación fuerte entre la Clasificación de los Resultados de Enfermería y los scores del Cuestionario del Conocimiento. La Clasificación de los Resultados de Enfermería se mostró efectiva en la evaluación del conocimiento cuando comparados al instrumento validado. .

Tuberculosis in renal transplant patients: The experience of a single center in Medellín-Colombia, 2005-2013 / Tuberculose em pacientes transplantados renais: experiência de um único centro em Medellín-Colômbia, 2005-2013

Introduction: Tuberculosis is a common opportunistic infection in renal transplant patients. Objective: To obtain a clinical and laboratory description of transplant patients diagnosed with tuberculosis and their response to treatment during a period ranging from 2005 to 2013 at the Pablo Tobón Uribe Hospital. Methods: Retrospective and descriptive study. Results: In 641 renal transplants, tuberculosis was confirmed in 12 cases. Of these, 25% had a history of acute rejection, and 50% had creatinine levels greater than 1.5 mg/dl prior to infection. The disease typically presented as pulmonary (50%) and disseminated (33.3%). The first phase of treatment consisted of 3 months of HZRE (isoniazid, pyrazinamide, rifampicin and ethambutol) in 75% of the cases and HZME (isoniazid, pyrazinamide, moxifloxacin and ethambutol) in 25% of the cases. During the second phase of the treatment, 75% of the cases received isoniazid and rifampicin, and 25% of the cases received isoniazid and ethambutol. The length of treatment varied between 6 and 18 months. In 41.7% of patients, hepatotoxicity was associated with the beginning of anti-tuberculosis therapy. During a year-long follow-up, renal function remained stable, and the mortality rate was 16.7%. Conclusion: Tuberculosis in the renal transplant population studied caused diverse nonspecific symptoms. Pulmonary and disseminated tuberculosis were the most frequent forms and required prolonged treatment. Antituberculosis medications had a high toxicity and mortality. This infection must be considered when patients present with a febrile syndrome of unknown origin, especially during the first year after renal transplant. .

Introdução: A tuberculose é uma infecção oportunista comum em pacientes transplantados renais. Objetivo: Oferecer uma descrição clínica e laboratorial de pacientes transplantados com diagnóstico de tuberculose e sua resposta ao tratamento durante o período entre 2005 e 2013 no Hospital Pablo Tobón Uribe. Métodos: Estudo retrospectivo descritivo. Resultados: Em 641 transplantes renais, a tuberculose foi confirmada em 12 pacientes. Destes, 25% tinham histórico de rejeição aguda e 50% apresentaram níveis de creatinina superiores a 1,5 mg/dl antes da infecção. A patologia geralmente se apresentava como pulmonar (50%) e disseminada (33,3%). A primeira fase do tratamento consistiu de três meses de HZRE (isoniazida, pirazinamida, rifampicina e etambutol) em 75% dos casos e HZME (isoniazida, pirazinamida, moxifloxacina e etambutol) em 25% dos pacientes. Durante a segunda fase do tratamento, 75% dos pacientes receberam isoniazida e rifampicina e 25% isoniazida e etambutol. A duração do tratamento variou entre seis e 18 meses. Em 41,7% dos pacientes, hepatotoxicidade foi associada ao início do tratamento da tuberculose. Durante o seguimento de um ano a função renal manteve-se estável e a taxa de mortalidade foi de 16,7%. Conclusão: A tuberculose foi responsável por diversos sintomas inespecíficos na população de transplantados renais estudada. Tuberculose pulmonar e disseminada foram as formas mais frequentes de acometimento e necessitaram de tratamento prolongado. Medicamentos contra a tuberculose apresentaram alta toxicidade e mortalidade. Esta infecção deve ser considerada quando o paciente apresenta síndrome febril de origem desconhecida, especialmente durante o primeiro ano após o transplante renal. .

GABA-induced inactivation of Cebus apella V2 neurons: effects on orientation tuning and direction selectivity

We investigated the GABA-induced inactivation of V2 neurons and terminals on the receptive field properties of this area in an anesthetized and paralyzed Cebus apella monkey. Extracellular single-unit activity was recorded using tungsten microelectrodes in a monkey before and after pressure-injection of a 0.25 or 0.5 M GABA solution. The visual stimulus consisted of a bar moving in 8 possible directions. In total, 24 V2 neurons were studied before and after blocker injections in 4 experimental sessions following GABA injection into area V2. A group of 10 neurons were studied over a short period. An additional 6 neurons were investigated over a long period after the GABA injection. A third group of 8 neurons were studied over a very long period. Overall, these 24 neurons displayed an early (1-20 min) significant general decrease in excitability with concomitant changes in orientation or direction selectivity. GABA inactivation in area V2 produced robust inhibition in 80% and a significant change in directional selectivity in 60% of the neurons examined. These GABA projections are capable of modulating not only levels of spontaneous and driven activity of V2 neurons but also receptive field properties such as direction selectivity.

Comparação de inibições medulares entre indivíduos com doença de Parkinson e saudáveis / Comparison of spinal inhibitions between parkisonian and helathy individuals

O objetivo do presente estudo foi comparar os níveis de inibição pré-sináptica (IPS) e inibição recíproca (IR) entre indivíduos com Doença de Parkinson e saudáveis e, a correlação entre essas inibições e a rigidez muscular e a severidade clínica de indivíduos com Doença de Parkinson (avaliadas através da Escala Unificada de Avaliação da Doença de Parkinson). Foram avaliados 11 indivíduos nos estágios 2 e 3 da doença e 13 indivíduos saudáveis pareados pela idade. A IPS foi menor em indivíduos com Doença de Parkinson (31,6%) do que em saudáveis (67,1%) (p = 0,02). A IR não diferiu entre indivíduos com Doença de Parkinson (26,9%) e saudáveis (27,6%) (p = 0,91). Adicionalmente, não foram detectadas correlações entre os níveis de IPS com a rigidez e a severidade clínica (p > 0,05). Portanto, mecanismos inibitórios não explicam totalmente a rigidez muscular e a severidade clinica da doença. Alterações entre ativação de músculos agonistas e antagonistas parecem estar relacionadas a influências supraespinhais anormais nos mecanismos espinhais decorrentes da doença...

The purposes of the present study were to compare presynaptic inhibition (PI) and disynaptic reciprocal inhibition (DRI) levels between parkinsonians and healthy individuals and to verify the correlation of such inhibitions with muscle rigidity and clinical severity (assessed by the Unified Parkinson Disease Rating Scale). We evaluated 11 parkinsonians in stages 2 and 3 of the disease and 13 healthy individuals matched for age. The PI was significant lower in parkinsonians (31.6%) than in healthy individuals (67.1%) (p = 0.02). The DRI did not differ between parkinsonians (26.9%) and healthy individuals (27.6%) (p = 0.91). Furthermore, no significant correlation was observed between PI with muscle rigidity and clinical severity (p > 0.05). Therefore, inhibitory mechanisms do not fully explain the cause of muscle rigidity and clinical severity of parkinsonians. Changes between the activation of agonist and antagonist muscles seem to be caused by abnormal supraspinal influence on spinal mechanisms...

Autonomic and cardiovascular effects of pentobarbital anesthesia during trigeminal stimulation in cats / 国际口腔科学杂志·英文版

Stimulation of the trigeminal nerve can elicit various cardiovascular and autonomic responses; however, the effects of anesthesia with pentobarbital sodium on these responses are unclear. Pentobarbital sodium was infused intravenously at a nominal rate and the lingual nerve was electrically stimulated at each infusion rate. Increases in systolic blood pressure (SBP) and heart rate (HR) were evoked by lingual nerve stimulation at an infusion rate between 5 and 7 mg·kg(-1)·h(-1). This response was associated with an increase in the low-frequency band of SBP variability (SBP-LF). As the infusion rate increased to 10 mg·kg(-1)·h(-1) or more, decreases in SBP and HR were observed. This response was associated with the reduction of SBP-LF. In conclusion, lingual nerve stimulation has both sympathomimetic and sympathoinhibitory effects, depending on the depth of pentobarbital anesthesia. The reaction pattern seems to be closely related to the autonomic balance produced by pentobarbital anesthesia.

Reduced hippocampal GABAergic function in Wistar audiogenic rats

Epilepsy is a neurological disorder associated with excitatory and inhibitory imbalance within the underlying neural network. This study evaluated inhibitory γ-amino-butyric acid (GABA)ergic modulation in the CA1 region of the hippocampus of male Wistar rats and Wistar audiogenic rats (aged 90 ± 3 days), a strain of inbred animals susceptible to audiogenic seizures. Field excitatory postsynaptic potentials and population spike complexes in response to Schaffer collateral fiber stimulation were recorded in hippocampal slices before and during application of picrotoxin (50 µM, 60 min), a GABA A antagonist, and the size of the population spike was quantified by measuring its amplitude and slope. In control audiogenic-resistant Wistar rats (N = 9), picrotoxin significantly increased both the amplitude of the population spike by 51 ± 19 percent and its maximum slope by 73 ± 21 percent. In contrast, in slices from Wistar audiogenic rats (N = 6), picrotoxin caused no statistically significant change in population spike amplitude (33 ± 46 percent) or slope (11 ± 29 percent). Data are reported as means ± SEM. This result indicates a functional reduction of GABAergic neurotransmission in hippocampal slices from Wistar audiogenic rats.

In vivo photorelease of GABA in the mouse cortex

Electrical stimulation has been used for more than 100 years in neuroscientific and biomedical research as a powerful tool for controlled perturbations of neural activity. Despite quickly driving neuronal activity, this technique presents some important limitations, such as the impossibility to activate or deactivate specific neuronal populations within a single stimulation site. This problem can be avoided by pharmacological methods based on the administration of receptor ligands able to cause specific changes in neuronal activity. However, intracerebral injections of neuroactive molecules inherently confound the dynamics of drug diffusion with receptor activation. Caged compounds have been proposed to circumvent this problem, for spatially and temporally controlled release of molecules. Caged compounds consist of a protecting group and a ligand made inactive by the bond between the two parts. By breaking this bond with light of an appropriate wavelength, the ligand recovers its activity within milliseconds. To test these compounds in vivo, we recorded local field potentials (LFPs) from the cerebral cortex of anesthetized female mice (CF1, 60-70 days, 20-30 g) before and after infusion with caged γ-amino-butyric-acid (GABA). After 30 min, we irradiated the cortical surface with pulses of blue light in order to photorelease the caged GABA and measure its effect on global brain activity. Laser pulses significantly and consistently decreased LFP power in four different frequency bands with a precision of few milliseconds (P < 0.000001); however, the inhibitory effects lasted several minutes (P < 0.0043). The technical difficulties and limitations of neurotransmitter photorelease are presented, and perspectives for future in vivo applications of the method are discussed.

Frontal stroke: problem solving, decision making, impulsiveness, and depressive symptoms in men and women

The present study compared men and women who suffered a frontal lobe stroke with regard to problem solving, decision making, impulsive behavior and depressive symptoms and also correlated these variables between groups. The sample was composed of 10 males and nine females. The study period was 6 months after the stroke. The following instruments were used: Wisconsin Card Sort Test (WCST), Iowa Gambling Task (IGT), Barrat Impulsiveness Scale (BIS11), and Beck Depression Inventory (BDI). For the exclusion criteria of the sample, the Mini International Psychiatric Interview (M.I.N.I Plus) and Mini Mental Stage Examination (MMSE) were used. To measure functional severity post-stroke, the Rankin Scale was used. The average age was 60.90 ± 8.93 years for males and 60.44 ± 11.57 years for females. In females, total impulsiveness (p = .013) and lack of planning caused by impulsiveness (p = .028) were significantly higher compared with males, assessed by the BIS11. These data indicate that females in the present sample who suffered a chronic frontal lesion were more impulsive and presented more planning difficulties in situations without demanding cognitive processing. These results that show gender differences should be considered when planning psychotherapy and cognitive rehabilitation for patients who present these characteristics.

Bases neurales del desarrollo de las funciones ejecutivas durante la infancia y adolescencia: una revisión / Neural basis of executive function development during childhood and adolescence: a review

Las funciones ejecutivas constituyen un controvertido constructo, bajo el cual se han agrupado diferentes procesos cognitivos asociadas al control consciente del pensamiento, comportamiento y afectividad. Gran parte de los mismos, comienzan su desarrollo en la infancia, culminando dicho proceso a fines de la adolescencia. A nivel anatómico, el funcionamiento ejecutivo (FE) ha sido vinculado a la actividad de la corteza prefrontal y la corteza cingulada, entre otras regiones cerebrales. El objetivo del presente artículo, es realizar una revisión de los cambios en la actividad cortical que han sido asociados a las mejoras en el FE durante la infancia y adolescencia. Para tal fin, se realizará una recopilación de diversos estudios con fMRI comparativos de la performance y actividad neuronal de infantes, adolescentes y adultos; durante la ejecución de tareas de FE. Se concluirá resaltando la necesidad de ampliar el número de estudios comparativos con tales características. Dichas investigaciones, podrían facilitar el diseño de estrategias preventivas y terapéuticas más específicas para el abordaje de las diferentes patologías asociadas al FE.

Executive functions is a controversial construct, under which are grouped different cognitive processes associated with conscious control of thought, behavior and emotion. Much of them, begin their development in childhood, finishing it in late adolescence. In the anatomical level, executive function (EF) has been linked to the activity of the prefrontal cortex and the cingulate cortex, among other brain regions. The purpose of this article is to review the changes in cortical activity that has been associated with improvements in EF during childhood and adolescence. To this goal, there will be a compilation of several fMRI studies that compare the performance and neuronal activity between infants, adolescents and adults during the performance of EF tasks. It will conclude by stressing the need to expand the number of comparative studies with such characteristics. Such research may facilitate the design of preventive and therapeutic strategies for addressing numerous pathologies associated with the FE.

Abnormalities of masseter inhibitory reflex in patients with episodic tension-type headache / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

<p><b>OBJECTIVE</b>To investigate the masseter inhibitory reflex (MIR) and its eventual changes in patients with episodic tension-type headache (TTH).</p><p><b>METHODS</b>MIR was studied in 21 patients with episodic TTH and 30 healthy subjects, with age and sex matched to the study cohort. Median age of patients was 17.0 years (ranged 16~49 years), median duration of disease 12 months (1~5 years), and median frequency of headache 7.5 d per month.</p><p><b>RESULTS</b>The second period of suppression (S2) of MIR was reduced in intensity and duration in 10% of controls and 66.7% (confidence interval (CI)=45.3%~85%; P<0.05) of patients with episodic TTH (chi(2)=74.9; P<0.001). In 3 (14.3%) of patients with episodic TTH, S2 was completely absent. No significant correlation between the duration of disease and headache frequency was found.</p><p><b>CONCLUSION</b>Our results confirm the link between episodic TTH and reduction or absence of S2. Teenage patients with episodic TTH may exhibit marked pathological changes in S2 in contrast to older individuals.</p>

Role of the caudal pressor area in the regulation of sympathetic vasomotor tone

It is well known that the ventrolateral medulla contains neurons involved in the tonic and reflex control of the cardiovascular system. Two regions within the ventrolateral medulla were initially identified: the rostral ventrolateral medulla (RVLM) and the caudal ventrolateral medulla (CVLM). Activation of the RVLM raises arterial blood pressure and sympathetic nerve activity, and activation of the CVLM causes opposite effects. The RVLM premotor neurons project directly to sympathetic preganglionic neurons and are involved in the maintenance of resting sympathetic vasomotor tone. A significant proportion of tonic activity in the RVLM sympathetic premotor neurons is driven by neurons located in a third region of the ventrolateral medulla denominated caudal pressor area (CPA). The CPA is a pressor region located at the extreme caudal part of the ventrolateral medulla that appears to have an important role controlling the activity of RVLM neurons. In this brief review, we will address the importance of the ventrolateral medulla neurons for the generation of resting sympathetic tone related to arterial blood pressure control focusing on two regions, the RVLM and the CPA.

The role and the mechanism of gamma-aminobutyric acid during central nervous system development / 神经科学通报·英文版

gamma -aminobutyric acid (GABA) is an inhibitory neurotransmitter in adult mammalian central nervous system (CNS). During CNS development, the role of GABA is switched from an excitatory transmitter to an inhibitory transmitter, which is caused by an inhibition of calcium influx into postsynaptic neuron derived from release of GABA. The switch is influenced by the neuronal chloride concentration. When the neuronal chloride concentration is at a high level, GABA acts as an excitatory neurotransmitter. When neuronal chloride concentration decreases to some degree, GABA acts as an inhibitory neurotransmitter. The neuronal chloride concentration is increased by Na+-K+-Cl(-)-Cl(-) cotransporters 1 (NKCC1), and decreased by K+-Cl(-) cotransporter 2 (KCC2).

Effects of ginkgolide B on neuronal discharges in paraventricular nucleus of rat hypothalamic slices / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To study the central role of ginkgolide B (BN52021) in regulating cardiovascular function of nerve center by examining the effects of ginkgolide B on the electrical activity of rat paraventricular nucleus (PVN) neurons in hypothalamic slice preparation and to elucidate the mechanism involved.</p><p><b>METHODS</b>Extracellular single-unit discharge recording technique.</p><p><b>RESULTS</b>(1) In response to the application of ginkgolide B (0.1, 1, 10 micromol/L; n = 27) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 26 (26/27, 96.30%) neurons were significantly decreased in a dose-dependent manner. (2) Pretreatment with L-glutamate (L-Glu, 0.2 mmol/L) led to a marked increase in the SDR of all 8 (100%) neurons in an epileptiform pattern. The increased discharges were suppressed significantly after ginkgolide B (1 micromol/L) was applied into the perfusate for 2 min. (3) In 8 neurons, perfusion of the selective L-type calcium channel agonist, Bay K 8644 (0.1 micromol/L), induced a significant increase in the discharge rates of 8 (8/8, 100%) neurons, while ginkgolide B (1 micromol/L) applied into the perfusate, could inhibit the discharges of 8 (100%) neurons. (4) In 8 neurons, the broad potassium channels blocker, tetraethylammonium (TEA, 1 mmol/L) completely blocked the inhibitory effect of ginkgolide B (1 micromol/L).</p><p><b>CONCLUSION</b>These results suggest that ginkgolide B can inhibit the electrical activity of paraventricular neurons. The inhibitory effect may be related to the blockade of L-type voltage-activated calcium channel and potentially concerned with delayed rectifier potassium channel (K(DR)).</p>

An intracellular study of pretectal influence on the optic tectum of the frog, Rana catesbeiana / 神经科学通报·英文版

<p><b>OBJECTIVE</b>A few investigations have been reported about pretectal suppressive influences on the optic tectum of frog, but characteristics of tectal activity to pretectal input are left unknown. We made intracellular recordings to demonstrate the unexpected complexity in synaptic mechanisms involved in the suppressive influences of pretecal stimulation on the tectal cells.</p><p><b>METHODS</b>In the present study, we investigated the neuronal activity evoked by pretectal (Lpd/P) nuclei stimulation using intracellular recording technique.</p><p><b>RESULTS</b>The pretectal stimulation mainly elicited two types of responses in the ipsilateral tectum: an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP) and a pure IPSP. The latter predominated in the tectal cells responding to pretectal stimulation. In a few cells, biphasic hyperpolarization appeared under stronger stimulus intensities. The spikes of tecto-pretectal projecting cells elicited by antidromical stimulation were recorded in the ipsilateral tectum, which revealed reciprocal connections between the tectum and particular pretectal nuclei. The synaptic natures underlying pretecto-tectal information transformation have also been demonstrated. EPSPs with short latencies were concluded to be monosynaptic. Most IPSPs were generated through polysynaptic paths, but monosynaptic IPSPs were also recorded in the tectum. Nearly 98% of impaled tectal cells (except for antidromically projecting cells) showed inhibitory responses to pretectal stimulation.</p><p><b>CONCLUSION</b>The results provide strong evidence that pretectal cells broadly inhibit tectal neurons as that has suggested by behavioral and extracellular recording studies.</p>

Modulation of the suppressive effect of corticosterone on adult rat hippocampal cell proliferation by paroxetine / 神经科学通报·英文版

<p><b>OBJECTIVE</b>The literature has shown that cognitive and emotional changes may occur after chronic treatment with glucocorticoids. This might be caused by the suppressive effect of glucocorticoids on hippocampal neurogenesis and cell proliferation. Paroxetine, a selective serotonin reuptake transporter, is a commonly used antidepressant for alleviation of signs and symptoms of clinical depression. It was discovered to promote hippocampal neurogenesis in the past few years and we wanted to investigate its interaction with glucocorticoid in this study.</p><p><b>METHODS</b>Adult rats were given vehicle, corticosterone, paroxetine, or both corticosterone and paroxetine for 14 d. Cell proliferation in the dentate gyrus was quantified using 5-bromo-2-deoxyuridine (BrdU) immunohistochemistry.</p><p><b>RESULTS</b>The corticosterone treatment suppressed while paroxetine treatment increased hippocampal cell proliferation. More importantly, paroxetine treatment could reverse the suppressive effect of corticosterone on hippocampal cell proliferation.</p><p><b>CONCLUSION</b>This may have clinic application in preventing hippocampal damage after glucocorticoid treatment.</p>

Inhibitory responses of parabrachial neurons evoked by taste stimuli in rat / 生理学报

In the present study, the responses of inhibitory gustatory neurons in the parabrachial nucleus (PBN) to four basic taste stimuli NaCl, HCl, quinine HCl (QHCl) and sucrose were examined using single-unit recording technique in anesthetized rats. A total of 18 inhibitory taste neurons in the PBN were obtained. Spontaneous firing rates of these inhibitory neurons were 0.2-5.5 Hz with mean firing rate of (2.15+/-0.31) Hz. Most of the neurons responded to more than one of the basic taste qualities. The inhibitory responses to taste occurred quickly and lasted 5-80 s in different PBN neurons. According to the responsive characteristics to the four basic taste stimuli, the neurons could be classified as NaCl-best (n=8), HCl-best (n=3), QHCl-best (n=3), and sucrose-best (n=4). The breadth of tuning of NaCl-best neurons was the highest (0.945). Inhibitory responsive neurons had feeble discrimination among sapid stimuli or aversive stimuli. These results suggest that there exist inhibitory taste neurons in the PBN. These neurons may play some useful roles in precise transmission of taste information and the taste coding for hedonic and aversive tastes.

Inhibiting effect of vagal nerve stimulation to seizures in epileptic process of rats / 神经科学通报·英文版

<p><b>OBJECTIVE</b>Our previous work suggested that sensitivity of hippocampal neurons is changed in process of epileptic activities, and closely parallel to the dynamic characteristic of epileptic activity of the neurons. This study investigated the sensitivity of epileptic brain to vagal nerve stimulation (VNS) in epileptic process.</p><p><b>METHODS</b>Epileptic model was evoked by penicillin. Left vagal nerves were stimulated to inhibit the seizures induced by penicillin. The electrocorticography (ECoG) and electromyography (EMG) were recorded to analyze inhibiting effect of VNS in epileptic process.</p><p><b>RESULTS</b>It was found that VNS could inhibit the seizures caused by penicillin, and the inhibiting effect of VNS to seizures increased as the vagal nerve stimulating time prolonged. It was also found that the inhibiting effect of VNS to seizures decreased in epileptic process.</p><p><b>CONCLUSION</b>The results suggested that the sensitivity of epileptic brain to VNS was different in epileptic process. The inhibiting effect of VNS to seizure decreased as the development of seizures.</p>

Gating of the dorsal penile nerve inputs by norepinephrine at the medial preoptic area in rats.

The medial preoptic area neurons related to male sexual behaviour in rats were identified by their responses to dorsal penile nerve stimulation. These neurons were further tested with norepinephrine applied iontophoretically. From the 21 medial preoptic area neurons recorded in urethane anaesthetized rats, 17 neurons responded to dorsal penile nerve stimulation. Excitatory and inhibitory responses were found in almost equal number of neurons. 14 neurons responded to norepinephrine application, out of which six neurons were excited and eight were inhibited. The direction of changes produced by dorsal penile nerve stimulation and norepinephrine application were similar in 10 neurons. The results suggest that the sensory inputs from the genitalia are possibly gated by norepinephrine at the level of the medial preoptic area. Afferent information from the genitalia carried by dorsal penile nerve and the availability of norepinephrine at the level of the medial preoptic area probably help in maintaining adequate level of sexual arousal.