INTRODUÇÃO: O consumo moderado de vinho tinto está inversamente associado ao desenvolvimento de doença cardiovascular. Efeitos do vinho tinto no sistema nervoso simpático e na reatividade vascular não estão totalmente esclarecidos. MÉTODOS: Foi avaliada a atividade simpática do nervo muscular e a dilatação mediada pelo fluxo na artéria braquial por ultrassom em 10 indivíduos hipercolesterolêmicos, 9 hipertensos e 7 controles antes e após o consumo de vinho tinto durante 15 dias. Medidas hemodinâmicas foram realizadas com Finometer: pressão arterial sistólica, diastólica, freqüência cardíaca, débito cardíaco e resistência vascular sistêmica foram calculados continuamente durante a microneurografia. Para avaliação da atividade simpática, utilizou-se punção de nervo fibular - esta foi medida como bursts/min durante período basal, teste do gelo e exercício estático com 30% da contração voluntária máxima. RESULTADOS: Após 15 dias de vinho tinto, a atividade simpática aumentou de forma significante em hipertensos e hipercolesterolêmicos (p < 0,05); porém, a dilatação mediada pelo fluxo aumentou somente em hipercolesterolêmicos (p < 0,05). As pressões arteriais sistólica e diastólica não apresentaram mudança significante. Não houve mudança na freqüência cardíaca. Houve aumento do débito cardíaco em controles, diminuição da resistência arterial sistêmica durante o gelo em controles no período basal. CONCLUSÃO: O consumo de vinho tinto aumentou a atividade simpática em hipertensos e hipercolesterolêmicos; porém, somente estes experimentaram melhoria da função endotelial, o que sugere diferentes mecanismos na regulação da função endotelial. / Introduction: Moderate red wine intake is inversely associated with development of cardiovascular disease. Red wine effects in sympathetic activity and vascular reactivity are not fully understood. Methods: Muscle sympathetic nerve activity and flow mediated dilatation of brachial artery by ultrasound were evaluated in 10 hypercholesterolemic, 9 hypertensive, and 7 controls subjects before and after red wine intake during 15 days. Hemodynamic measures were done with Finometer: arterial blood pressure, heart rate, cardiac output, and systemic vascular resistance were assessed during mycroneurography. The sympathetic activity was evaluated during baseline, cold test and isometric exercise. Results: After 15 days of red wine intake, sympathetic activity increased significantly in hypertensives and hypercholesterolemics (p < 0.05). On the other hand, flow mediated dilation increased after red wine only in hypercholesterolemics (p < 0.05). Systolic and diastolic blood pressure as well as heart rate did not change significantly. Cardiac output increased in controls and systemic vascular resistance decreased during cold test in controls. Conclusion: There were similar increases in sympathetic activity in hypertensive and hypercholesterolemic subjects; however, endothelial function was restored only in the latter group, which suggests different mechanisms regulating endothelial function.

I ntrodução: A insuficiência cardíaca é uma síndrome clínica caracterizada por anormalidades da função do ventrículo esquerdo e regulação neurohormonal, associadas a hipertrofia cardíaca (HC). Dentre as vias intracelulares envolvidas na HC, a via dependente de cálcio calcineurina tem se demonstrado importante. O treinamento físico tem sido utilizado como tratamento coadjuvante de pacientes com IC, mas seu papel sobre a atividade da via da calcineurina relacionado a HC na IC ainda não foi estabelecido. Portanto, neste estudo avaliamos o efeito do treinamento físico sobre a via da calcineurina e sobre a HC em um modelo genético de IC induzida por hiperatividade simpática. Métodos: Estudamos camundongos controle (WT) e com inativação gênica para os receptores adrenérgicos 2A e 2C (2A/2CARKO) dos 5 aos 7 meses, que foram divididos nos grupos WT (n=19), 2A/2CARKO (n=26) e 2A/2CARKO treinados (n=31). O treinamento físico aeróbico em esteira foi realizado durante 8 semanas, 5 vezes por semana por 1 hora. Foi avaliada a tolerância ao esforço pela distância total percorrida em um teste máximo até a exaustão em esteira, a função cardíaca pela fração de encurtamento por meio do ecocardiograma, a estrutura cardíaca pela massa cardíaca das câmaras cardíacas, diâmetro transverso dos cardiomiócitos por microscopia óptica, expressão gênica da -MHC por RT-PCR, a expressão das proteínas calcineurina, NFATc3 e GATA-4 nos extratos citoplasmáticos e nucleares por meio do Western blot, e a localização sub-celular das proteínas NFATc3 e GATA-4 por microscopia confocal. Resultados: Os camundongos 2A/2CARKO apresentaram intolerância ao esforço, prejuízo na função cardíaca e alterações estruturais cardíacas observadas pelo aumento na massa do ventrículo esquerdo, do diâmetro transverso dos cardiomiócitos e da expressão gênica da -MHC. Além disso, os camundongos 2A/2CARKO não apresentaram diferenças na expressão da proteína calcineurina, mas apresentaram aumento na expressão das proteínas NFATc3 e GATA-4 nos extratos nucleares, como também um aumento na localização nuclear das proteínas NFATc3 e GATA-4 quando comparados ao grupo WT. Após o treinamento físico, os camundongos 2A/2CARKO apresentaram aumento na tolerância ao esforço e na função cardíaca, reversão parcial das alterações cardíacas observadas que foram acompanhadas por uma redução na expressão das proteínas NFATc3 3 GATA-4 nos extratos nucleares, como também uma redução na localização das proteínas NFATc3 e GATA-4 no núcleo por microscopia confocal. Conclusão: Os resultados sugerem que o treinamento físico é capaz de promover remodelamento cardíaco reverso com redução na participação da via intracelular da calcineurina e um menor agravamento da IC neste modelo genético de IC. / I ntroduction: Heart failure (HF) is a clinical syndrome characterized by cardiac dysfunction associated with neuro-hormonal hyperactivity, which culminates in cardiac hypertrophy (CH). Among the intracellular pathways involved in CH associated with HF, the calcium-dependept calcineurin pathway has been demonstrated to take an important role. Exercise training has been used as adjuvant treatment of patients with IC, but its role on cardiac remodeling related with calcineurin pathway in CH of HF has not yet been studied yet. Therefore, in the present study we evaluated the effect of exercise training on the calcineurin pathway and on CH in a genetic model of sympathetic hyperactivity induced HF. Methods: A cohort of male congenic 2A/2C-ARKO mice in a C57BL6/J genetic background and their wild-type controls (WT) were studied from 5 to 7 months of age, and were randomly assigned into WT (n=19), 2A/2C-ARKO (n=26) and 2A/2C-ARKO trained (n=31) groups. Treadmill aerobic exercise training was performed over 8 wk, 5 times per wk for 1 hour. Exercise tolerance was evaluated by total distance covered in treadmill maximal test until exhaustion, fractional shortening by echocardiogram, cardiac structure by mass of cardiac cardiac mass, and cardiomyocyte cross-sectional diameter by optical microscopy. -MHC mRNA levels were evaluated by RT-PCR, and expression of calcineurin, NFATc3 and GATA-4 in cytoplasmatic and nuclear extracts were evaluated by Western blot. Indeed sub-cellular localization of NFATc3 and GATA-4 proteins were studied by confocal microscopy. Results: 2A/2C-ARKO mice displayed exercise intolerance, cardiac dysfunction and structural cardiac alterations, which included increased left ventricle mass, myocyte crosssectional diameter and increased -MHC expression when compared to WT group. In addition, we observed alteration in calcineurin pathway associated with CH of 2A/2C-ARKO mice, named increased NFATc3 and GATA-4 expression in nuclear extracts paralleled by increased nuclear localization of NFATc3 and GATA-4 by confocal microscopy when compared to WT group. Exercise training in 2A/2CARKO mice improved exercise tolerance and cardiac function with a partial reversion of CH associated with reduced nuclear expression and localization of NFATc3 and GATA-4 when compared with WT mice. Conclusions: These data provide evidences for the anticardiac remodeling effect of exercise training in HF associated with reduced activation of calcineurin intracellular pathway

Sympathetic nerves are important for renal physiology and sepsis pathophysiology. A recent study showed sprouting of sympathetic nerves in spleen of septic mice. This study was done to test if renal sprouting of sympathetic nerves also happens and to investigate renal morphology in septic mice. Cecal ligation and puncture (CLP) was used to induce sepsis and kidneys were removed for evaluation. Bowman’s space was diminished with cortical bubble cells present suggestive of acute renal pathology, however, renal function was unchanged. Acute sepsis did not affect either renal sympathetic innervation or non-neuronal cholinergic cells. Mouse kidneys had more epinephrine (EPI) than norepinephrine (NE) in both groups. This is most likely due to uptake of epinephrine by renal sympathetic nerves and may have no correlation with sepsis. In conclusion, septic mice showed minor renal pathology and no evidence of acute sympathetic nerve sprouting. Further studies are needed to understand the mechanism and consequences of elevated EPI in mice kidney.

The mammalian target of rapamycin complex 1 (mTORC1) is an evolutionary conserved serine/threonine kinase regulating diverse cellular functions, including cell growth, protein synthesis and sensing nutrients and energy status. Prior studies have identified the involvement of hypothalamic mTORC1 in the control of energy balance, renal sympathetic activation and blood pressure regulation. Hypothalamic insulin receptor signaling through the phosphatidylinositol 3-kinase (PI3K) is known to regulate energy homeostasis and sympathetic nerve activity (SNA). We examined the role of hypothalamic mTORC1 in the anorectic and sympathetic effects of central insulin. mTORC1 inhibition by rapamycin or PI3K mutation resulted in blunted regional SNA responses to insulin. Rapamycin also blunted appetite-suppressing and body weight-reducing effects of insulin. Furthermore, biochemical analyses revealed PI3K-dependent activation of mTORC1 pathway by insulin in the arcuate nucleus of hypothalamus (ARC), where insulin initiates its central actions. These results indicate the significant contribution of mTORC1 pathway in the ARC to the central action of insulin on the regulation of energy homeostasis and SNA. Angiotensin II (Ang II) is a vasoconstrictive and anti-diuretic peptide produced in the renin-angiotensin system (RAS). Local brain RAS plays an important role in the control of blood pressure, electrolyte and fluid balance. Stimulation of Ang type 1 receptor (AT1R) by Ang II in the cardiovascular brain nuclei triggers drinking and pressor responses. Chronic Ang II action in CNS leads to transcriptional neuromodulation, which in turn, contributes to the development and maintenance of hypertension. Intracellular signaling cascades responsible for neuronal Ang II's actions include PI3K and extracellular signal-regulated kinase (ERK) pathways, which are known upstream effectors of mTORC1 in peripheral tissues. We investigated the involvement of mTORC1 signaling in the brain Ang II actions. Ang II was capable of activating mTORC1 in neuronal cell line and mouse brain, however mTORC1 inhibition had no influence on the drinking and pressor responses to Ang II. Moreover, we found an upregulated mTORC1 activity in the SFO of hypertensive transgenic mice with overactive brain RAS (sRA mice). Importantly, mTORC1 inhibition normalized systolic blood pressure in sRA mice. These results support a potential role of mTORC1 in the maintenance of neurogenic hypertension. Overall, data presented in this thesis provide a better understanding of neuronal mTORC1 function as a key effector component of insulin or Ang II-mediating regulation of physiological and pathophysiological processes.

Abstract not available

Doctor of Philosophy(PhD) / This thesis addresses the neurochemistry and function of specific nuclei in the autonomic nervous system that are crucial mediators of cardiorespiratory regulation. The primary aim is to build on previous knowledge about muscarinic cholinergic mechanisms within cardiorespiratory nuclei located in the ventrolateral medulla oblongata. The general focus is characterisation of gene expression patterns of specific muscarinic receptor subtypes in central nuclei involved in blood pressure control and respiratory control in normal rats. The findings were subsequently extended by characterisation of muscarinic receptor gene expression patterns in 1) a rat model of abnormal blood pressure control (hypertension) (Chapter 3) 2) a rat model of cholinergic sensitivity (Chapter 5) 3) the rat ventral respiratory group (Chapter 6) The results of a series of related investigations that ensued from the initial aims more finely characterise the neurocircuitry of the ventrolateral medulla, from a specifically cholinoceptive approach. All five muscarinic receptor subtypes are globally expressed in the ventrolateral medulla but only the M2R mRNA was significantly elevated in the VLM of hypertensive animals compared to their normotensive controls and in the VLM of animals displaying cholinergic hypersensitivity compared to their resistant controls. Surprisingly, M2R mRNA is absent in catecholaminergic cell groups but abundant in certain respiratory nuclei. Two smaller projects involving gene expression of other neurotransmitter / neuromodulators expressed in cardiorespiratory nuclei were also completed during my candidature. Firstly, the neurochemical characterisation of enkephalinergic neurons in the RVLM, and their relationship with bulbospinal, catecholaminergic neurons in hypertensive compared to normotensive animals was carried out (Chapter 4). A substantial proportion of sympathoexcitatory neurons located in the RVLM were enkephalinergic in nature. However, there was no significant difference in preproenkephalin expression in the RVLM in hypertensive compared to normotensive animals. Secondly, the identification and distribution of components of the renin-angiotensin aldosterone system (RAAS) within the brainstem, and differences in gene expression levels between hypertensive and normotensive animals was also investigated. The RAAS data was not included in this thesis, since the topic digresses substantially from other chapters and since it is published (Kumar et al., 2006). The mRNA expression aldosterone synthase, mineralocorticoid receptor (MR1), 12-lipoxygenase (12-LO), serum- and glucocorticoid- inducible kinase and K-ras) were found to be present at all rostrocaudal levels of the ventrolateral medulla. Expression of MR1 mRNA was lower in the RVLM of SHR compared with WKY rats and 12-LO mRNA levels were lower in the CVLM in SHR compared with WKY rats. Otherwise, there was no difference in gene expression level, or the method of detection was not sensitive enough to detect differences in low copy transcripts between hypertensive and normotensive animals.

The hypothalamic paraventricular nucleus (PVN) is known to be a major integrative region within the forebrain. It is composed of functionally different subgroups of neurons, including the parvocellular neurons that project to important autonomic targets in the brainstem e.g. the rostral ventrolateral medulla (RVLM) and the intermediolateral cell column (IML) of the spinal cord, where the sympathetic preganglionic motor-neurons are located. These regions are critical in cardiovascular regulation; hence, these projections are likely to mediate the effects of the PVN on sympathetic nerve activity and hence may contribute to the cardiovascular changes induced by physiological stimuli such as elevations in body temperature. The neurotransmitter such as nitric oxide (NO) is important in cardiovascular regulation and it is now emerging as a major focus of investigation in thermoregulation. One of the most striking accumulations of NO containing-neurons is in the PVN where it appears to be playing an important role in cardiovascular regulation and body fluid homeostasis. The results of the work show; 1. That spinally-projecting and nitrergic neurons in the PVN may contribute to the central pathways activated by exposure to a hot environment. 2. Suggests that nitrergic neurons and spinally- projecting neurons in the brainstem may make a small contribution to the central pathways mediating the reflex responses initiated by hyperthermia. 3. The present study also illustrates that these PVN neurons projecting to the RVLM may make a smaller contribution than the spinal-projecting neurons in the PVN to the cardiovascular responses initiated by heat. 4. The results of my studies showed that the microinjection of muscimol to inhibit the neuronal activity in the PVN abolished the reflex decrease in renal blood flow following an elevation of core body temperature. In addition, this effect was specific to the PVN, since microinjections of muscimol into areas outside the PVN were not effective. These findings demonstrate that the PVN is critical for this reflex cardiovascular response initiated by hyperthermia. In conclusion, PVN is critical for the reflex decrease in renal blood flow during elevations in core body temperature. We hypothesise that projections from the PVN to the spinal cord and the RVLM contribute to the reflex cardiovascular responses. Additionally, nitrergic neurons in the PVN may contribute but the physiological role of those neurons in the reflex responses elicited by hyperthermia needs to be investigated.

Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2007.

Brown adipose tissue (BAT) is a critical organ for non-shivering thermogenesis, which is under control of both sympathetic and sensory neural innervation. We utilized both a retrograde sympathetic nerve tract tracer pseudorabies virus and an anterograde sensory tract tracer the H129 strain of herpes simplex virus-1 to locate individual neurons across the neuroaxis that are part of the SNS outflow from brain to interscapular BAT and are part of the sensory input to the brain. We found specific neuronal phenotype of the double-infected neurons distributed from the hindbrain to the forebrain with highest densities in several discrete brain regions: the paraventricular hypothalamus (PVH), lateral hypothalamus (LHA), parabrachial nucleus (PB) and raphe pallidus (RPa). The neuroanatomical reality of the SNS-sensory feedback loops suggests coordinated control of BAT thermogenesis at several sites and indicates plasticity of SNS-sensory crosstalk.

No description available.