Effects of nitric oxide on magnocellular neurons of the supraoptic nucleus involve multiple mechanisms

Physiological evidence indicates that the supraoptic nucleus (SON) is an important region for integrating information related to homeostasis of body fluids. Located bilaterally to the optic chiasm, this nucleus is composed of magnocellular neurosecretory cells (MNCs) responsible for the synthesis and release of vasopressin and oxytocin to the neurohypophysis. At the cellular level, the control of vasopressin and oxytocin release is directly linked to the firing frequency of MNCs. In general, we can say that the excitability of these cells can be controlled via two distinct mechanisms: 1) the intrinsic membrane properties of the MNCs themselves and 2) synaptic input from circumventricular organs that contain osmosensitive neurons. It has also been demonstrated that MNCs are sensitive to osmotic stimuli in the physiological range. Therefore, the study of their intrinsic membrane properties became imperative to explain the osmosensitivity of MNCs. In addition to this, the discovery that several neurotransmitters and neuropeptides can modulate their electrical activity greatly increased our knowledge about the role played by the MNCs in fluid homeostasis. In particular, nitric oxide (NO) may be an important player in fluid balance homeostasis, because it has been demonstrated that the enzyme responsible for its production has an increased activity following a hypertonic stimulation of the system. At the cellular level, NO has been shown to change the electrical excitability of MNCs. Therefore, in this review, we focus on some important points concerning nitrergic modulation of the neuroendocrine system, particularly the effects of NO on the SON.

Efeito da indução de obesidade neuroendócrina sobre a hemodinâmica sistêmica e a função ventricular esquerda de ratos normotensos / Effects of neuroendocrine obesity induction on systemic hemodynamics and left ventricular function of normotensive rats

O objetivo do estudo foi avaliar o efeito da obesidade induzida pela administração neonatal de glutamato monossódico (MSG) sobre o peso corporal, a pressão arterial de cauda, a hemodinâmica sistêmica e a função ventricular esquerda de ratos Wistar. Dois grupos de ratos Wistar foram preparados: a)18 animais foram tornados obesos por meio da administração de 2 mg/kg/SC de MSG durante os 11 primeiros dias do período neonatal e b)16 animais controles (que receberam o veículo do MSG pelo mesmo período). Animais adultos foram acompanhados dos três aos seis meses de vida e tiveram pressão arterial e peso corporal medidos duas vezes por semana. Ao final desse período, em parte dos animais dos dois grupos, avaliou-se a função ventricular por intermédio da preparação do coração isolado de Langerdorff, e os animais restantes foram usados para o estudo da hemodinâmica sistêmica por meio de um método de termodiluição. Resultados: Nos animais MSG houve aumento da gordura epididimal relativa (WST = 2,076 ± 0,622; MSG = 2,731 ± 0,722 g/100 g), aumento significante da freqüência cardíaca (WST = 235,0 ± 35,1; MSG = 312,0 ± 90,8 bpm), da resistência periférica total (WST = 0,312 ± 0,100; MSG = 0,535 ± 0,195 mmHg.ml-1.min), e diminuição do volume sistólico (WST = 1,020 ± 0,364; MSG = 0,748 ± 0,455 µl/bat). No estudo hemodinâmico, também detectou-se nos animais obesos aumento da pressão arterial média. Os aumentos da FC e da RPT e a diminuição do VS sugerem que houve aumento da atividade simpática nos ratos normotensos com obesidade associado ao aumento da deposição de gordura visceral.

The aim of this study was to evaluate the effects of obesity induced by neonatal Monosodium Glutamate (MSG) administration upon body weight, tail blood pressure, systemic hemodynamics and left ventricular function of Wistar rats. Two groups of Wistar rats were prepared: a) 18 animals made obese through the administration of 2mg/Kg/SC of MSG during the first 11 days of the neonatal period and b)16 control animals (vehicle treated for the same period). Adults animals were followed from the 3rd up the 6th month of life with blood pressure and body weight being measured twice a week. At the end of this period, in part of animals from both groups, we evaluated the left ventricular function through the Langendorff isolated heart preparation whereas the remainders were used to evaluate the systemic hemodynamics through a termodilution method. Results: MSG animals showed significant increases in heart rate (WST = 235,0 ± 35,1; MSG = 312,0 ± 90,8 bpm), total peripheral resistance (WST = 0,312 ± 0,100; MSG = 0,535 ± 0,195 mmHg.ml-1.min) and in relative epididymal adipose tissue content (WST = 2,076 ± 0,622; MSG = 2,731 ± 0,722 g/100g) and a reduction of systolic volume (WST = 1,020 ± 0,364; MSG = 0,748 ± 0,455 ml/bat). An increase in mean arterial pressure was also detected in obese animals during the hemodynamic evaluation. The increases in HR and TPR and the reduction in SV suggest an augmentation in the sympathetic activation of those obese normotensive rats associated with an increased visceral fat deposition.

Aspectos neuroendócrinos e nutricionais em atletas com overtraining / Neuroendocrine and nutritional aspects of overtraining

A síndrome de overtraining tem sido caracterizada por um excesso de treinamento responsável pelo surgimento de diversos efeitos adversos, sendo o principal deles a diminuição do desempenho. Sua incidência entre atletas de elite vem aumentando significativamente nos últimos anos, fato este responsável pelo crescente interesse de pesquisadores em buscar medidas capazes de prevenir ou tratar tal síndrome; porém, para tanto, torna-se necessário que se esclareçam os possíveis mecanismos responsáveis pelo desenvolvimento do overtraining. Diversas hipóteses têm sido propostas no intuito de desvendar esses mecanismos, tais como a maior ativação do sistema nervoso autônomo e do eixo hipotálamo-hipófise-adrenal e supressão do eixo hipotálamo-hipófise-gonadal, porém alguns estudos têm proposto que a modulação desses sistemas seria uma conseqüência da síndrome de overtraining e não necessariamente a sua causa. Desta forma, novas hipóteses relacionadas à liberação de citocinas, à fadiga central, à depleção do glicogênio muscular e hepático, e à diminuição da disponibilidade de glutamina durante a atividade física têm sido levantadas.

Mechanisms for the environmental regulation of gene expression: ecological aspects of animal development.

The environment can play a significant role in the production of phenotypes. However, the developmental mechanisms by which the environmental agents effect normal development are just becoming known. At least three paths have been found through which the environment can modify gene activity. The first is the neuroendocrine route. Here, the nervous system monitors the environment and transfers signals to the endocrine system. The endocrine hormones can then alter gene expression. The second route involves environmental factors that change the methylation pattern of genes, thereby altering their transcriptional capabilities. The third route involves the direct induction of gene expression in the host by microbial symbionts. The normal regulation of phenotype production by the environment should be considered a normal component of development and developmental biology.

Aspectos neuroendocrinos de la obesidad / Neuroendocrine aspects of obesity

En la fisiopatología de la obesidad intervienen factores genéticos, sociales, metabólicos, endocrinos y neurológicos. Esta multifactoriedad junto al hecho que estos factores se interrelacionan a través de mecanismos muy complejos, que son sólo parcialmente conocidos, ha llevado a que la comprensión íntima de este trastorno resulte una tarea sumamente ardua. Por estos motivos, el conocimiento integral de esta afección plantea un desafío al que actualmente están abocados numerosos grupos de investigadores. El análisis de la obesidad como un trastorno neuroendocrino, propone el estudio de este fenómeno desde una visión particular que implica disfunciones en casi todos los órganos endocrinos y en el sistema nervioso central, fundamentalmente en la actividad hipotalámica. Estas alteraciones afectan principalmente a los ejes neuroendocrinos hipotálamo-hipofiso-adrenal, adipo-insular y al control hipotalámico, tanto de la ingesta de alimento como del almacenamiento y gasto energético. Este artículo plantea una actualización en este campo; en primer lugar, se realiza una breve descripción, en forma independiente, de los principales sistemas antes mencionados y luego una descripción de su funcionamiento normal integrado. Finalmente, se describen desregulaciones de estos mecanismos y se discute como ellas contribuirían al desarrollo y/o mantenimiento de la obesidad.

Changes in the neurosecretory cells of the brain and thoracic ganglion of male crab, Uca (celuca) lactea annulipes with respect to seasons.

The change in the neurosecretory cells with males with respect to seasons was investigated. The brain is provided with three types of neurosecretory cells namely A, B and C and thoracic ganglion with four types of neurosecretory cells A, B, C and D. They vary in number and neurosecretory activity according to seasons which may be responsible for the increase in the size and development of the reproductive and associated structures.

¿Es la obesidad el resultado de un epigenotipo equivocado? / Is obesity the consequence of an inadequate epigenotype?

Los individuos con obesidad asociada a sobrenutrición, manifiestan características genotípicas que modifican diversas funciones: Ingesta de alimentos condicionada por el ingreso calórico, composición de los macronutrientes, patabilidad, y control neuroendócrino del hambre y la saciedad; asimismo muestran una disminución en el egreso calórico producido por el metabolismo basal, el efecto térmico de los alimentos, el gasto calórico en ejercicio y la regulación de la termogénesis en situaciones de estrés. Existen además diferencias en la velocidad de oxidación de los nutrientes, tanto para cubrir las necesidades energéticas como para mantener la forma y la función. Es probable que muchos obesos, por seleción natural, presenten diferncias funcionales, algunas ocacionadas por mutaciones géneticas, que desde el punto de vista filogenético hayan facilitado la supervivencia de poblaciones nómadas y cazadoras con consumos alimentarios irregulares e inconstantes, pero que en la actualidad no sólo son innecesarias, sino que su asociación con sobrenutrición aumenta la morbimortalidad

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

Neuropeptídios e dermatologia / Neuropeptides and dermatology

Os autores apresentam novos conceitos científicos dosneuropeptídeos, que atuam como neurotransmissores, neuro moduladores e neuro hormônios. Sua participaçäo na imunidade cutânea, nos processos de cicatrizaçäo e doenças crônicas da pele, säo evidentes. Os neuropeptídeos agem como mensageiros químicos, interligando o cérebro com os receptores da pele. Existem mais de cinqüenta neuropeptídeos envolvidos na transmissäo de sinais entre as células nervosas e o sistema auto-imune. Säo produzidos na pele neuropeptídeos opióides, que atuariam nas dores e emoçöes, promovendo a integraçäo do sistema neuroimunocutâneo. Uma das propostas do trabalho é uma visäo integrativa da Dermatologia na medicina geral.

ANP as a neuroendocrine modulator of body fluid homeostasis

The role played by the central nervous system (CNS) in the control of body fluid homeostasis has been demonstrated by several authors. The AV3V plays a key role in central control of sodium excretion since its cholinergic, adrenergic, angiotensinergic and osmotic stimulation enhances and its destruction blocks sodium excretion in rats and goats. Cholinergic stimulation of the AV3V induced an increase in plasma ANP as well as a marked elevation in content of the peptide in medial basal hypothalamus, neuro and adenohypophysis. On the other hand, a decline in plasma ANP after AV3V lesions was accompanied by dramatic declines in content of ANP in these same structures. Our previous work has also indicated the essential role of the AV3V region and its ANPergic neurons in the control of ANP release in response to volume expansion (BVE) and indicated that alpha-adrenergic and muscarinic receptors are critical in mediating these responses. Lesions of the AV3V region, or of the median eminence or posterior lobe of pituitary gland blocked the increase in plasma ANP concentration in response to BVE. That this effect is related to blockage of the activity of the brain ANPergic neurons is supported by fyndings in sheep and in rats that the injection of the antiserum directed against ANP into the AV3V region at least partially blocked the BVE-induced release of ANP. We and others have also previously shown that denervation of baroreceptors inhibits ANP release induced by BVE. Activation of the ANP neurons also cause release of ANP from the anterior and neural lobe of pituitary gland. ANP neurons may activate oxytocinergic neurons in the supraoptic and paraventricular, which projects to neural lobe. Oxytocin would circulate to the atria and may directly activate release of ANP from the atrial myocytes, since i.v. or i.p. injection of oxytocin increases sodium excretion as well as elevates plasma ANP. Oxytoxin is present in the neural lobe in large quantity, which could reach the atria myocytes in high concentration and release ANP that circulate to the kidneys and evokes natriuresis to return circulating blood volume to normal.

Thermoregulatory spectrum in vertebrates.

Thermoregulatory mechanisms and control of homeothermy are quite recent from evolutionary stand point. Animals have either simply recruited or modified other regulatory systems for the purpose of thermoregulation. The degree of such recruitments or modifications vary among different class of vertebrates thus giving rise to a relative diversity in the spectrum of thermoregulatory control and mechanisms. The review briefly summarizes the evidence showing that body temperature control is not an isolated regulated system in vertebrates, rather, a hierarchically integrated multiple system. The available information shows that pineal transduces environmental cues for photoperiodic and seasonal adjustments to the preoptic area of anterior hypothalamus via its primary secretory product, melatonin. The hypothalamus integrates the information and then sets the effector recruitment for each control system consistent with the metabolic rate of the animal taking into considerations the cost and benefit of the action taken. The overwhelming similarity in response to different constituents of the thermoregulatory spectrum contradicts the aphorism that cold-blooded animals are dependent on ambient temperature. It is our collective view that there is no fundamental difference between ectotherms and endotherms since the two vary only in the degree of their ability to maintain thermal homeostasis.

Melatonina / Melatonin

Se revisan las principales acciones fisiológicas de la melatonina, destacando sus efectos metabólicos y endocrinológicos y sus influencias sobre el sistema nervioso y el inmunológico. Se señalan los factores que estimulan la secreción de la melatonina en la glándula pineal. Entre ellos destaca la oscuridad, por lo que la melatonina ha sido considerada como el mensajero de la noche y la reguladora de los ritmos circadianos. Se señalan igualmente los posibles usos terapéuticos de la melatonina, de los cuales el más importante hasta ahora es la regulación del ciclo vigilia-sueño y la prevención del jet-lag. Por el momento se discuten sus eventuales proyecciones terapéuticas derivadas de efectos antioxidantes; inmunomoduladores y cardioprotectores. Los efectos laterales indeseables son muy escasos con la dosis habituales de 3 a 10 mg

La melatonina en el sistema inmunoneuroendocrino / Melatonin in the immuno-neuro-endocrine system

El conocimiento actual de las relaciones neuroendocrinas e inmunológicas confiere un rol importante a la melatonina (MT) en la regulación de los ritmos circadianos de los mamíferos. La función de la glándulapinela en todas las especies es traducir información del ciclo luz/oscuridad a los ritmos fisiológicos del organismo. La MT es producida casi exclusivamente en la oscuridad. En los humanos la secreción ocurre en correspondencia a la edad, disminuyendo en la vejez; guarda relación inversa con la temperatura del cuerpo; evidencia un efecto anti-estrés, posiblemente a través del sistema opioide; favorece la respuesta inmunológica y protege frente al daño tisular que provocan los radicales libres, por su fuerte acción antioxidante. La MT ha sido usada con éxito en la inducción del sueño en personas que ven perturbado su ritmo habitual de sueño por trabajos nocturnos, el síndrome de jet-lag u otras causas. No se ha logrado beneficio en el tratamiento de trastornos mayores del sueño, ni en la depresión ni en otros trastornos psiquiátricos. La presencia de receptores para la MT en múltiples órganos y sistemas estimula actualmente la investigación clínica sobre estas funciones posibles de la melatonina

Stress, steroids, and "ojas": neuroendocrine mechanisms and current promise of ancient approaches to disease prevention.

Recent research on causes of disease and aging has increasingly supported the importance of stress. One theory of the relationship between stress and disease is based on the concept of homeostasis, a term coined by Cannon over 50 years ago to signify those states and mechanisms responsible for the "staying power of the body". Bernard, Cannon, Selye and other leading researchers held that full, normal function of the self-regulating or homeostatic power of the body maintains the balanced, integrated condition we recognize as health. Failures in this capacity, such as those produced by frequent stressful experiences, can result in disease or death. Theories of health and disease surprisingly similar to this have existed since ancient times, and in widely different cultures. This review discusses both the fundamental elements of these theories and the current neuroendocrine research supporting their validity and immediate relevance. The connections between ancient and modern knowledge described herein were made possible largely by the work of Maharishi Mahesh Yogi, a scholar and teacher of the ancient vedic tradition of India. A key part of Ayurveda that has been obscure to modern science is the substance "ojas", which the classical texts say maintains balance of the physiology. In this article, specific steroids or steroid classes are proposed as likely candidates for both the "ordinary" and the "superior" types of ojas described in Ayurveda. Current evidence for the functions of these steroids, as well as their role in stress, disease and the maintenance of health, is reviewed. The knowledge of Ayurveda, as recently brought to light by Maharishi, includes methods for recovering and maintaining optimal function of steroidal systems. Such effects may help mediate the improvements in health and increased longevity attributed to Ayurveda and other ancient methods.

Dimensiones biológicas de la ansiedad infantil / Biological dimension of childhood anxiety

Se presenta una breve revisión de la literatura sobre los factores psicobiológicos asociados con la ansiedad infantil. Se exploran los conocimientos actuales en los campos genético, neuroendocrinológico, neurofisiológico, neuroinmunológico y algunas hipótesis sobre los factores prenatales

Respuesta metabólica ante la cirugía: modificaciones sistémicas (segunda de tres partes) / Metabolic response to surgery: systemic changes. (seconf o three parts)

En respuesta a la cirugía se producen cambios vasculares periféricos que aseguran una composición corporal, concentración electrolítica, volumen vascular, tonicidad y metabolismo ácido-base adecuados tanto para el trauma quirúrgico como para las características de salud o enfermedad del paciente. Estos cambios están modulados por factores neuroendocrinos hipotálamo-hipofisiarios, renales, suprarrenales y cardiacos

Interaçäo imunoneuropsicoendócrina / Immunoneuropsychoendocrinological interaction

Os autores discutem a inter-relaçao entre os sistemas imunitário, neuropsíquico e endócrino. As diferentes origens de peptídeos/proteínas, originários de diferentes sistemas, com estruturas químicas semelhantes, porém com atuaçao fisiológica em órgaos-alvos diferentes, efetivam a intercomunicaçao entre os sistemas, formando "rede integradora" no nosso organismo, correlacionando os sistemas imunoneuropsicoendócrino com a reproduçao, envelhecimento e o câncer.

Hormonas tímicas como mediadoras de la integración inmunogonadotropa / Thymic hormones as mediators of the inmunogonadotroph integration

Existe significativa evidencia sobre la existencia de un eje timo-hipofiso-gonadal. En razón de que estudios previos de los autores habían demostrado que la Hormona Homeostática Tímica, un dímero de histonas H2A y H2B, posee múltiples efectos in vivo sobre la secreción de hormonas hipofisarias, resultó de interés evaluar el efecto in vitro de distintas preparaciones tímicas y proteínas nucleares relacionadas, sobre la liberación de prolactina (Prl), hormona foliculoestimulante (FSH) y hormona luteinizante (LH). Células hipofisarias frescas de ratas hembras se dispersaron con colagenasa y se empaquetaron en una columna de Biogel P-2 mantenida a 37oC. Las células se perifundieron continuamente con medios EBSS, o,5 por ciento de BSA, 1 por ciento de ácido ascórbico y 50 IU de aprotinina/ml (medio de perifusión, MP). Las sustancias a ser testeadas (estímulos) se disolvieron en MP, perifundiéndose en un volumen de 1,5 ml por estímulo a través del circuito de perifusión, al final del cual se recogieron fracciones de 1 ml. Las hormonas liberadas se dosaron por radioinmunoensayo. La viabilidad de las células dispersas osciló entre 84 y 96 porciento. Distintas diluciones de extractos de eminencia media de rata generaron, para cada hormona, una respuesta estimulatoria dosis-dependiente. En general, tanto las preparaciones de histona H2A como las de nucleohistona (ambas a una concentración de 500 µg/ml) indujeron picos secretorios significativos de LH, FSH y Prl, siendo los más elevados los correspondientes a Prl. Asimismo, la hormona tímica timulina y sobrenadantes provenientes de cultivo de células epiteliales tímicas de rata y ratón, pero no la timosina fracción ÷ o el péptido tímico MB-35, resultaron estimulatorios. Los resultados del presente trabajo sugieren que ciertos productos tímicos podrían participar en la integración inmuno-gonadotropa, actuando como señales hipofisotropas