Involvement of catecholamines in the myocardium of rats submitted to experimental model of portal hypertension / Envolvimento das catecolaminas no miocárdio de ratos submetidos a modelo experimental de hipertensão portal

ABSTRACT Background: The role of autonomic nervous system in the development and maintenance of portal hypertension is not fully elucidated. It is known that the gene expression of norepinephrine in the superior mesenteric artery varies with time, and it may contribute for splanchnic vasodilation and its consequent hemodynamic repercussions. It is still not known exactly how the adrenergic expression behaves at the heart level in the initial stages of this process. Aim: To evaluate the immunohistochemical expression of the enzyme tyrosine hydroxylase (tyrosine 3-monooxygenase), involved in the synthesis of norepinephrine, in the myocardium of rats submitted to partial ligation of the portal vein. Methods: Twenty-four Wistar rats were divided into two groups: Sham Operated and Portal Hypertension. The partial ligation was performed in the Portal Hypertension group, and after 1/6/24 h and 3/5/14 days the animals were euthanized. Immunohistochemical analysis was performed to quantify the expression of the stained enzyme using the ImageJ program. Results: The Portal Hypertension group expressed percentages between 4.6-6% of the marked area, while the Sham Operated group varied between 4-5%. Although there was no statistical significance, the percentage stained in the Portal Hypertension group followed an increasing pattern in the first 6 h and a decreasing pattern after 24 h, which was not observed in the Sham Operated group. Conclusion: The expression of noradrenaline in rat myocardium during the first two weeks after partial ligation of the portal vein, with tyrosine hydroxylase as marker, did not show differences between groups over time.

RESUMO Racional: O papel do sistema nervoso autônomo na hipertensão portal não está completamente elucidado. Sabe-se que, nessa condição, a expressão gênica da norepinefrina na artéria mesentérica superior modifica-se com o tempo, podendo ser importante contribuinte para a vasodilatação esplâncnica e suas repercussões hemodinâmicas. Apesar dos estudos sobre as repercussões cardiovasculares na hipertensão portal, ainda não se sabe como a expressão adrenérgica se comporta a nível cardíaco nas etapas iniciais desse processo. Objetivo: Avaliar a expressão imunoistoquímica da enzima tirosina hidroxilase (tirosina 3-mono-oxigenase), relacionada à síntese da norepinefrina, no miocárdio de ratos submetidos à ligadura parcial da veia porta. Métodos: Foram utilizados 24 ratos, distribuídos em dois grupos: Sham Operated e Hipertensão Portal. A ligadura parcial da veia porta foi realizada apenas no grupo Hipertensão Portal e, após 1/6/24 h e 3/5/14 dias, os animais foram eutanasiados. Foi feita a análise imunoistoquímica para quantificar a expressão da enzima corada, utilizando o programa ImageJ. Resultados: No grupo Hipertensão Portal, o miocárdio expressou percentuais entre 4,6-6% de área marcada, enquanto que no grupo Sham Operated variou entre 4-5%, sem significância estatística. Apenas no grupo Hipertensão Portal, a porcentagem corada pela enzima seguiu padrão crescente nas primeiras 6 h e decrescente após 24 h. Conclusão: A expressão da noradrenalina no miocárdio de ratos durante as primeiras duas semanas após a ligadura parcial da veia porta, tendo como marcador a enzima tirosina hidroxilase, não apresentou diferenças entre grupos ao longo do tempo.

Adrenocorticotropic hormone-independent macronodular adrenal hyperplasia with abnormal cortisol secretion mediated by catecholamines

No abstract available.

Involvement of catecholaminergic medullary pathways in cardiovascular responses to acute changes in circulating volume

Water deprivation and hypernatremia are major challenges for water and sodium homeostasis. Cellular integrity requires maintenance of water and sodium concentration within narrow limits. This regulation is obtained through engagement of multiple mechanisms and neural pathways that regulate the volume and composition of the extracellular fluid. The purpose of this short review is to summarize the literature on central neural mechanisms underlying cardiovascular, hormonal and autonomic responses to circulating volume changes, and some of the findings obtained in the last 12 years by our laboratory. We review data on neural pathways that start with afferents in the carotid body that project to medullary relays in the nucleus tractus solitarii and caudal ventrolateral medulla, which in turn project to the median preoptic nucleus in the forebrain. We also review data suggesting that noradrenergic A1 cells in the caudal ventrolateral medulla represent an essential link in neural pathways controlling extracellular fluid volume and renal sodium excretion. Finally, recent data from our laboratory suggest that these structures may also be involved in the beneficial effects of intravenous infusion of hypertonic saline on recovery from hemorrhagic shock.

Influence of mode of delivery at term on the neonatal respiratory morbidity

Respiratory morbidity is an important complication of elective cesarean section. Our objective was to find out the incidence of respiratory distress in term neonates delivered by elective cesarean section and compare it with neonates delivered vaginally. We evaluated one thousands infants delivered by elective cesarean section and normal vaginal delivery for respiratory distress. Among 500 cesarean done, 27 [5.4%] neonates had respiratory distress and among 500 vaginal delivery infants, 8 [1.6%] developed respiratory Distress [P<0.001]. The odd ratio for neonatal respiratory distress was 3.38, almost threefold higher in cesarean section group than those delivered vaginally

Gordura visceral, subcutânea ou intramuscular: onde está o problema? / Visceral, subcutaneous or intramuscular fat: where is the problem?

O tecido adiposo é um órgão dinâmico que secreta vários fatores, denominados adipocinas. Eles estão relacionados, direta ou indiretamente, em processos que contribuem na aterosclerose, hipertensão arterial, resistência insulínica e diabetes tipo 2, dislipidemias, ou seja, representam o elo entre adiposidade, síndrome metabólica e doenças cardiovasculares. Na obesidade, os depósitos de gordura corporal estão aumentados, apresentando conseqüente elevação na expressão e secreção das adipocinas, proporcionalmente ao maior volume das células adiposas. Os diferentes depósitos de gordura, a saber: tecidos adiposos visceral, subcutâneo abdominal, subcutâneo glúteo-femural e intramuscular, possuem grau metabólico e endócrino diferenciados, podendo estar, portanto, interferindo de forma específica nos processos inerentes à adiposidade corporal em obesos e diabéticos. O presente trabalho visa discutir sobre o papel endócrino e metabólico de cada compartimento de tecido adiposo, de modo a avaliar a contribuição dos mesmos nas complicações inerentes à obesidade.

Role of catecholaminergic terminals in the preoptic area in behavioural thermoregulation in rats.

This study was conducted to find out the role of the catecholaminergic terminals in the preoptic area (POA) in selection of ambient temperature in rats. The adult male Wistar rats (n = 6) were allowed to choose between three ambient temperatures (24 degrees C, 27 degrees C and 30 degrees C). Rats could move about freely from one ambient temperature to another, in a specially designed environmental chamber having three interconnected compartments, which were maintained at the above mentioned temperature. The results show that the normal rats preferred to stay at 27 degrees C both during day and night. After the lesion of catecholaminergic terminals in the POA with 6-hydroxydopamine (6-OHDA), the animals preferred 24 degrees C on the third and seventh day and 27 degrees C on the fourteenth and twenty first day after lesion. The alteration in thermal preference was associated with an elevation of rectal temperature. The study suggests that the catecholaminergic terminals of the POA play an important role in integrating behavioural and non-behavioural thermoregulatory responses, but in its absence the rest of the brain takes over some of its functions.

Modificaçöes fisiológicas do aparelho cardiovascular / Physiological changes in cardiovascular system

As variaçöes circadianas säo conhecidas, há tempos, por influenciar os diversos sistemas fisiológicos, entre eles o cardiovascular. O estudo de mecanismos com variaçäo circadiana que alteram o funcionamento do sistema cardiovascular e suas doenças têm aumentado muito nos últimos anos devido à sua relevância clínica. Através desses trabalhos se pôde conhecer melhor a fisiopatologia, a epidemiologia e os fatores envolvidos nas doenças cardiovasculares. Dessa forma ficou evidente a maior incidência de eventos cardíacos pelas horas da manhä, assim como os possíveis mecanismos envolvidos nessa variaçäo durante as horas do dia. A pressäo arterial sanguínea, os níveis plasmáticos de catecolaminas e cortisol, a agregabilidade plaquetária e a açäo do sistema fibrinolítico säo os mecanismos que mais se destacam. Desse modo, tornou-se possível o desenvolvimento de novas estratégias terapêuticas, levando-se em consideraçäo o momento do dia de maior risco para o desenvolvimento das doenças cardiovasculares.

Neurobiología de los trastornos biopatográficos / Neurobiology of the biopathographics

Revisión de los cambios neurobiológicos que se producen como consecuencia de los trastornos de la biopatografía

Important recent advances in cardiovascular adrenergic mechanisms

Five sub-areas were taken into consideration: Adrenoceptor subclassification: Presently, 10 different adrenoceptor subtypes have been characterized by pharmacological and molecular biology studies: Ó1A-, Ó1B-, Ó1D-, Ó2A/D, Ó2B-, Ó2C-, ß1-, ß2-, ß3- and ß4-adrenoceptors. Intracellular signaling: the adrenoceptors are members of a large superfamily of receptors linked to guanine-nucleotide proteins (G proteins), Ó1-adrenoceptors are coupled to Gq proteins and activate phospholipases, especially phospholipase Cß, Ó2-adrenoceptors are coupled to G1 proteins and inhibit adenylyl cyclase and in some tissues regulate potassium and calcium channels. Both ß1 and ß2-adrenoceptors are preferentially coupled to adenylyl cyclase through GS proteins and ß3-adrenoceptors appear to be coupled to K+ channel through a pertussis toxin-sensitive G1 protein. ß4-Adrenoceptors appear to be coupled positively to a cyclic AMP-dependent cascade and can undergo desensitization. Influence of maturation and ageing: From birth to old age important changes occur in animal models as in humans at the receptor level, neurotransmitter process and catecholamine disposition. In general terms, one can say that maturation is associated with a gradual increase of adrenergic influence, while ageing is associated with a reduction in the role of the adrenergic system on the regulation of physiologic processes. Cotransmission: ATP and the neuropeptide Y are cotransmitters with noradrenaline. While noradrenaline is the main transmitter in vascular tissues, ATP has functional relevance in some vessels and neuropeptide Y is mainly a modulator of noradrenaline release; it seems that it has an increased role under pathophysiological conditions like ischemia. Role of endothelium on noradrenaline release: Many substances produced by the endotelium or acting through the endothelium are able to influence noradrenaline release from sympathetic nerve varicosities of the blood vessel wall: some of them, like bradykinin and angiotensin II, exert a facilitatory, while others like NO and endothelin have an inhibitory effect on noradrenaline release evoked electrical nerve stimulation.

Exercício físico e memória / Physical exercise and memory

A memória é susceptível às influências endógena, hormonal e neuro-humoral especialmente logo após a aquisiçäo da informaçäo. A amígdala, o septo medial, o hipocampo e o córtex entorrinal estäo envolvidos nos processos de consolidaçäo, armazenamento e evocaçäo. A resposta ao problema dos mecanismos de armazenamento podem encontrar-se tanto pelo caminho da potenciaçäo delonga duraçäo como pelo das redes neurais, através de uma interaçäo complementar. A modulaçäo da memória enfoca a atençäo na análise das condiçöes sob as quais a consolidaçäo da memória pode ser alterada. Uma informaçäo adquirida em um determinado contexto neuro-humoral será melhor evocada se durante o processo de evocaçäo o contexto neuro-humoral for similar ao do momento da aquisiçäo, caracterizando a existência de uma periférica pós-treino de hormônios normalmente liberados por experiências emocionais e estresses, tais como: catecolaminas, ACTH, vasopressina, além do peptídio opióide B-endorfina. Os hormônios e opióides envolvidos na regulaçäo da memória também estäo envolvidos na regulaçäo, homeostática do exercício. Estudos têm demonstrado que a liberaçäo das catecolaminas, vasopressina, ACTH e B-endorfina é estimulada pelo exercício, fazendo-se uma relaçäo do efeito do exercício na regulaçäo da memória, especialmente exercícios intensos e os moderados de longa duraçäo

Blood pressure control by the renin-angiotensin system and its interaction with the sympathetic nervous system in fish

The renin-angiotensin system (RAS) is from an evolutionary view-point a well-preserved regulatory system with many morphological and physiological similarities in all vertebrate groups from fish to mammals. Regulation by the RAS is often complicated, involving several other control systems and blood pressure is just one of many parameters controlled by this system. Control of cardiovascular functions by the RAS in fish has received some attention and both a direct action and modulation of adrenergic nerves by angiotensin II have been reported in most species studied. The interaction between the RAS and the adrenergic system in fish is not fully understood, but the facilitation of catecholamine release by angiotensin II is probably one of the more important mechanisms.

La atención selectiva I: teorías, estructurales cerebrales, y mecanismos neuroquímicos implicados / Selective attention I: theories, brain structures and neurochemical mechamisms implied

Para que el sistema nevioso central (SNC) puede procesar la gran cantidad de información sensorial a la cual está expuesto constantemente, debe efectuarse una selección de la información. Los procesos cerebrales que hacen posible esta selección se conocen como anteción selectiva. En esta revisión describimos las distintas etapas por las que ha transcurrido el concepto de atensión selectiva. Inicialmente, este concepto fue ignorado durante algún tiempo. Este olvido se debió, en parte, a la influencia dominante del análisis experimental de la conducta. Esta situación cambió con la descripción, en 1949, de la reacción de alertamiento producida por la estimulación eléctrica de la formación reticular del tallo cerebral. Recientmente, con la llegada de técnicas que permiten evaluar el funcionamiento del sistema nervioso con una alta resolución temporal y espacial, el estudio de las funciones cerebrales, en general, y de los procesos cognoscitivos, en particular, ha cobrado un nuevo impulso. Con base en las teorías del procesamiento de información, se han propuesto varios modelos para explicar cómo se efectúa la selección de estímulos sensoriales. Las teorías del "filtro" proponen que las señales irrelevantes deben ser excluidas del análisis con el fin de atender los mensajes de interés. Estas teorías difieren en el nivel del SNC, en el que ocurre la selección de la información. En un caso se propone que la selección de información importante ocurre en los primero relevos de la vía sensorial. Otras teorías sugieren que durante el procesamiento de información se establecen diferntes tipos de asociaciones de acuerdo con una jerarquía específica. De esta manera, la selección se llevaría a cabo en diferentes niveles. Se han desarrollado varias líneas de pensamiento que buscan el sitio en el cual ocurre la selección de información. Hay defensores de las teorías localizacionistas, globalistas o antilocalizacionistas, mientras que otros proponen la existencia de una jerarquía funcional o de sistemas distribuidos. Esta última idea deriva del concepto de ensamble neuronal propuesto por Hebb, el cual fue incorporado en la definición de Mountcastle de los módulos de procesamiento de información. Empleando técnicas de imagenología en pacientes con lesiones localizadas o en modelos animales, ha sido posible determinar las regiones cerebrales que participan en los procesos de atención. Se ha propuesto que estas regiones se encuentran en distintos niveles del sistema nervioso central Äen el tallo cerebral, el diencéfalo y la corteza cerebral- y presentan entre sí una gran interconectividad, formando circuitos o ensambles neuronales específicos relacionados con la atención. Recientemente, Posner sugirió que las funciones cognoscitivas están constituidas por ensambles de operaciones elementales que ocurren en regiones cerebrales específicas. Con el fin de determinar los mecanismos neuroquímicos relacionados con la atención selectiva, se han investigado sistemas específicos de neurotransmisión. Se ha puesto particular énfasis en el papel de las catecolaminas, ya que se ha observado que las neuronas que poseen estos neurotransmisiones muestran variaciones en sus niveles de activación relacionados con los distintos niveles de alertamiento o con la aplicación de estímulos sensoriales significativos. Así, el locus coeruleus, un núcleo norodrenérgico con proyecciones amplias hacia la corteza cerebral, ha sido asociado con los cambios ocurridos en la relación señal/ruido, lo cual permite que se haga la selección de estímulos relevantes entre las muchas señales que se encuentran en el ambiente. Más aún, se ha establecido que hay una relación entre los sitemas catecolaminérgicos y las alteraciones que se observan generalmente en la clínica. Además, lesionados estos sistemas es posible inducir déficits de atención. En la segunda parte de la revisión describimos los correlatos electrofisiológicos de la atención selectiva. Analizaremos los estudios en los que se registran los poptenciales provocados, la actividad unitaria y la respuesta otoacústica, y nos referiremos a las alteraciones de la atención más frecuente en el ser humano: la hemi-inatención, las alteraciones del aprendizaje y las ausencias de origen epiléptico

Stress-induced hyperglycemia and hypoinsulinemia are suppressed by sulfonylurea: predominant role of insulin

Based on the in vitro blockade of adrenal catecholamines release by sulfonylurea, we searched for an anti-stress activity of this drug. Stress-induced hyperglycemia and insulin inhibition were employed sadrenergic stress indicators. A standard dose of the oral sulfonylurea glipizide (200 micrograms/100 g), administered 15 min before a 1-h restraint stress to intact or 80 percent pancreatectomized rats, produced otalsuppression of the stress-induced hyperglycemia-hypoinsulinemia, an effect followed by a significant post-stress hypoglycemia of 1 h duration. The latter effect was elicited by all the sulfonylureas assayed. In the 80 percent pancreatectomized rats, glipizide nearly halved the increases in plasma catecholamines at 30 min of stress, but did not modify those attained at 60 min, when glycemia was decreasing and insulinemia was still increasing. Moreover, behavioral experiments in intact stressed rats showed that the adrenergic overt behavior inhibition caused by propranolol was not produced either by glipizide or insulin, reinforcing that glipizide affect was not mediated by catecholamine inhibition. These findings suggest a blockade of...

Reduction of experimental myocardial infarct size by pre-treatment with magnesium sulfate in rats.

Experimental myocardial infarction was induced in albino rats by administration of isoprenaline hydrochloride, 85 mg/kg, sc, daily for two consecutive days. Such rats were pretreated with either saline or magnesium sulfate (60 mg/kg) po, daily for three weeks, to serve as control or treated groups respectively. Heart specimens were taken for gross and histological examination at 24 hr, on 5th day, 12th day and 21st day. Infarct size was significantly reduced in the magnesium-treated group (P less than 0.05). We conclude that magnesium sulfate exerted a potent prophylactic effect in limiting infarct size in rats.

Suicídio, depressäo e atividade neurohumoral / Suicide, depression and neurohumoral activity

O autor apresenta uma revisäo dos principais achados das pesquisas referentes as alteraçöes na transmissäo nervosa relacionada ao suicídio e as depressöes. Säo apresentados e discutidos os principais modelos propostos para explicar o fenômeno da depressäo e os mecanismos de açäo dos diversos métodos terapêuticos antidepressivos. É dada ênfase especial ao modelo proposto por Crow e Deakin segundo o qual nas depressöes haveria uma hiperatividade serotoninérgica em associaçäo a desregulaçäo e hipoatividade no sistema catecolaminérgico