Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

Orientador: Ana Paula Couto Davel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T14:07:47Z (GMT). No. of bitstreams: 1 Victorio_JamairaAparecida_M.pdf: 1155350 bytes, checksum: eab5bb2760f0d9abd7c5e93ac2b95b51 (MD5) Previous issue date: 2014 / Resumo: A hiperativação dos receptores ß-adrenérgicos (ß-AR) tem importante papel na patogênese de doenças cardiovasculares que cursam com hiperatividade simpática. Dentre os seus efeitos, sugere-se a indução da síntese e liberação de angiotensina II e de aldosterona sistemicamente. A hiperativação dos receptores ß-AR pode ser mimetizada pelo tratamento crônico com isoproterenol (ISO). Já foi demonstrado que o antagonismo do receptor AT1 de angiotensina II ou do receptor de mineralocorticoides (MR) previne parcialmente o remodelamento cardíaco induzido pelo ISO. Entretanto, ainda não está elucidado o envolvimento da angiotensina II e da aldosterona nos efeitos vasculares causados pela hiperativação dos receptores ß-AR. Assim, o objetivo do presente estudo foi investigar as vias de sinalização dos receptores AT1 e MR nas alterações vasculares causadas pelo tratamento por 7 dias com ISO em aorta de ratos, assim como os mecanismos envolvidos. Ratos Wistar (3 meses) foram tratados com ISO (0,3 mg/kg/dia, s.c.) ou veículo (CT) e co-tratados ou não com o antagonista do receptor AT1 losartan (LOS; 40 mg/kg/dia) ou com o antagonista do receptor MR espironolactona (ESP; 200 mg/kg/dia). O tratamento com ISO causou hipertrofia ventricular sem alterações hemodinâmicas, e o co-tratamento com LOS ou ESP atenuaram o remodelamento ventricular observado. Na aorta do grupo ISO observou-se um aumento da resposta máxima à fenilefrina associado à redução da biodisponibilidade de óxido nítrico (NO) e aumento de ânion superóxido, os quais foram prevenidos pelo co-tratamento com ESP, mas não com LOS. O efeito preventivo da ESP sobre a reatividade vascular da aorta dos ratos ISO foi acompanhado de aumento da expressão proteica da HSP90, a qual foi reduzida no grupo ISO. Além disso, a ESP preveniu o aumento da expressão proteica de ß-arrestina, Gai, p-Src, ERK1/2, p- ERK1/2 e gênica de osteopontina na aorta deste grupo. As concentrações plasmáticas de corticosterona ou aldosterona não foram alteradas entre os grupos avaliados. Em conjunto, os dados sugerem que o antagonismo do receptor MR com o uso de espironolactona previne o aumento da resposta contrátil à fenilefrina observada em aorta de ratos tratados com ISO, associado a: aumento da biodisponibilidade de NO e redução do estresse oxidativo; aumento da expressão de HSP90, a qual estabiliza a forma dimérica da eNOS; e prevenção do aumento da expressão proteica de ß- arrestina, Gai1,2, p-Src, ERK1/2 e p-ERK1/2 e gênica de osteopontina, vias de sinalização de estresse oxidativo e prejuízo da função endotelial / Abstract: ß-adrenergic (ß¿AR) receptors overstimulation plays an important role in the pathogenesis of cardiovascular diseases concurrent with sympathetic overactivity. It has been suggested to increase plasma levels of angiotensin II and aldosterone. In line with this, angiotensin II/AT1 receptor or mineralocoticoid (MR) receptor antagonism partially prevents the cardiac remodeling induced by ß-AR overstimulation mediated by isoproterenol (ISO) administration. However the implication of angiotensin II or aldosterone on vascular effects provoked by ß¿AR overstimulation is not yet elucidated. So, the aim of the present study was to investigate the AT1 and MR receptor signaling pathway on vascular alterations caused by 7-day ISO treatment on rat aorta, as well as the mechanisms involved. For this, male Wistar rats (3-month-old) were treated with ISO (0.3 mg/kg/day, s.c.) or vehicle (CT) and co-treated or not with AT1 antagonist losartan (LOS; 40 mg/kg/day, v.o.) or MR receptor antagonist spironolactone (ESP; 200 mg/kg/day, v.o.). The ISO treatment resulted in ventricular hypertrophy without hemodynamic alterations, and LOS or ESP co-treatment attenuated the ventricular remodeling of ISO group. ISO aorta showed an increased phenylephrine maximum response associated with a decreased nitric oxide (NO) bioavailability and an increased in superoxide anion; both effects were prevented by ESP co-treatment, but not by LOS. Beneficial effects of ESP on vascular reactivity of aorta from ISO-treated rats were accompanied by an increased HSP90 protein expression, which was reduced in ISO group. Moreover, ESP prevented the increased protein expression of ß-arrestin, Gai, p- Src, ERK1/2 and p-ERK1/2 and osteopontina gene expression in the aorta from ISO group. Plasma corticosterone and aldosterone were not changed between the groups. In conclusion, our results suggest that spironolactone, an MR receptor antagonist prevented the increased phenylephrine contractile response in aorta from ISO-treated rats, associated with increased NO bioavailability and decreased oxidative stress; increased expression of HSP90 and; prevented the increase of ß-arrestin, Gai1,2, p-Src, ERK1/2 and p-ERK1/2 and osteopontin induced by ß-adrenergic overstimulation. These results suggest that the vascular effects induced by ISO in aorta are mediated by a MR activation / Mestrado / Fisiologia / Mestra em Biologia Funcional e Molecular

Orientador: Heitor Moreno Júnior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-19T19:14:14Z (GMT). No. of bitstreams: 1 Faria_AnaPaulaCabralde_M.pdf: 1479802 bytes, checksum: 020b8c9f4ab7e6ccb0f7ba9946157d2c (MD5) Previous issue date: 2012 / Resumo: A Hipertensão Arterial Resistente (HAR) é uma condição na qual sobrepeso e obesidade estão correlacionados devido à influência no controle da pressão arterial (PA). Embora ambos os subgrupos resistentes não controlados (HARNC) e controlados (HARC) são, frequentemente, obesos, estudos recentes demonstram que o primeiro apresenta maior índice de massa corporal (IMC) comparados com o segundo subgrupo. A redução de adiponectina plasmática, um hormônio produzido pelo tecido adiposo, tem sido correlacionada ao desenvolvimento da hipertensão e foi considerada um dos fatores de risco independente para essa doença. Entretanto, é desconhecida se essa adipocina está associada com o não controle de PA nestes pacientes. O total de 96 pacientes foi dividido em dois subgrupos: HARNC (n=44) e HARC (n=52) e distribuído controlando idade, gênero e IMC. Foram avaliados os níveis plasmáticos de aldosterona e adiponectina (enzyme-linked immunosorbent assay - ELISA), medidas da PA de consultório e da Monitoração Ambulatorial de PA (MAPA), a resposta dependente do endotélio (vasodilatação mediada por fluxo - VMF), índice de massa ventricular esquerda (IMVE) e velocidade de onda de pulso (VOP). As idades foram 57±1,6 e 59±1,5 em HARNC (26M/18H) e HARC (35M/17H), respectivamente, e todos os pacientes tinham sobrepeso. Os pacientes HARNC apresentaram maiores níveis de aldosterona (12,6±1,4 vs. 8,9±0,8 ng/dL, p=0,02), assim como, IMVE (142,2±6,0 vs. 122,9±4,3 g/m², p=0,02) e VOP (12,0 ± 1,8 vs. 9,2 ± 1,7 m/s, p<0,0001). Por outro lado, foram encontrados no mesmo subgrupo menores níveis de adiponectina (6,9±0,7 vs. 9,5±0,8 ?g/mL, p=0,01) e prejuízo da resposta no teste da VMF (6,6±0,3 vs. 7,5±0,3%, p=0,001). A análise de correlação indicou que as pressões de pulso braquial e da MAPA foram inversamente correlacionadas com a adiponectina plasmática (r = - 0,45, p=0,002; r= - 0,33, p=0,03, respectivamente), assim como, a aldosterona e VOP (r = - 0,38, p=0,01; r = - 0,36, p=0,02, respectivamente) nos sujeitos HARNC. A regressão linear multivariada demonstrou que a VOP somente foi influenciada significativamente pelos níveis de adiponectina nos pacientes HARNC (?= - 0,16, SE= 0,05, p=0,01). A adiponectina não se correlacionou com os mesmos parâmetros no subgrupo HARC. Nossos resultados sugerem que a hipoadiponectinemia e níveis elevados de aldosterona estão implicados na rigidez arterial e podem ser responsáveis pela resistência à terapia anti-hipertensiva / Abstract: Resistant hypertension (RHTN) is a condition in which overweight and obesity were shown to influence in blood pressure (BP) control. Although both uncontrolled (UCRHTN) and controlled (CRHTN) resistant hypertensive subjects are frequently obese, recent studies have shown that the former group has higher body mass index (BMI) compared to the latter. Low plasma levels of adiponectin, a hormone produced by adipose tissue, seems to be related to the development of hypertension and it is considered one of independent risk factor for this disorder. However, it is unknown if this adipokine is associated with the lack of BP control in these patients. Ninety-six patients were divided in two subgroups: UCRHTN (n=44) and CRHTN (n=52) and were matched for age, gender and BMI. Adiponectin and aldosterone levels, office BP and ABPM, determination of brachial artery responses to endothelial-dependent (flow-mediated dilation - FMD), left ventricular mass index (LVMI) and pulse wave velocity (PWV) were evaluated. Mean ages were 57±1.6 and 59±1.5 years in UCRHTN (26 F/ 18 M) and CRHTN (35 F/ 17 M) subgroups, respectively. All patients were overweight. UCRHTN patients had increased aldosterone levels (12.6 ± 1.4 vs. 8.9 ± 0.8 ng/dL, p=0.02) as well as LVMI (142.2 ± 6.0 vs. 122.9 ± 4.3 g/m², p=0.02) and PWV (12.0 ± 0.3 vs. 9.2 ± 0.2 m/s, p<0.0001). On the other hand, lower levels of adiponectin (6.9 ± 0.7 vs. 9.5 ± 0.8 ?g/mL, p=0.01) and impaired FMD test response (6.6 ± 0.3 vs. 7.5 ± 0.3%, p=0.001) were found in this same subgroup. Correlation analysis indicated that brachial and ABPM pulse pressures were inversely associated with plasma adiponectin levels (r = - 0.45, p=0.002; r= - 0.33, p=0.03, respectively) as well as aldosterone and PWV (r = - 0.38, p=0.01; r = - 0.36, p=0.02, respectively) in UCRHTN subjects. Multivariate linear regression analysis showed that PWV was only significantly influenced by adiponectin levels in UCRHTN patients (?= - 0.16, SE= 0.05, p=0.01). Plasma adiponectin levels did not correlate to the same parameters in the CRHTN subgroup. Taken together, our results suggest that hypoadiponectinemia and high aldosterone levels are implicated in arterial rigidity, and may be responsible for antihypertensive therapy resistance / Mestrado / Farmacologia / Mestre em Farmacologia

Na+ sensitive hypertension in Dahl salt sensitive rats (Dahl S) or spontaneously hypertensive rats (SHR) is linked to intrinsic changes in the brain that favour increased Na+ entry into the cerebrospinal fluid (CSF) followed by increases in sympathetic hyperactivity and hypertension (Huang et al 2004). Similar responses are observed in salt resistant and Wistar rats that receive an intracerebroventricular (icv) infusion of Na+ rich artificial cerebrospinal fluid (aCSF) (Huang et al 2001, 2006). Downstream to increased CSF[Na+], a pathway has been described involving mineralocorticoid receptors (MRs), benzamil sensitive Na+ channels, “ouabain”, and angiotensin II type 1 receptors (AT1-R) (Huang et al 1998, Zhao et al 2001, Wang and Leenen 2003, Huang et al 2008). Blood pressure (BP) responses to increased CSF[Na+] may involve activation of AT1-R in the subfornical organ (SFO) as the BP response to injection of NaCl into a lateral ventricle can be blocked by AT1-R blockade in the SFO (Rohmeiss et al 1995a). The role of aldosterone and AT1-R in the SFO was investigated in mediating the BP and heart rate (HR) response to increases in CSF[Na+] and local [Na+]. Results show that infusion of 0.45M and 0.6M Na+ rich aCSF into the SFO increases BP but not HR. The BP is unchanged by infusion of a mannitol solution osmotically equivalent to 0.6M Na+ rich aCSF indicating that the SFO is Na+ sensitive. The BP response to a lower concentration of Na+ (0.45M) is enhanced by prior infusion of aldosterone while BP response to 0.6M is not further enhanced suggesting that the SFO may have maximal responsiveness to acute increases in [Na+] at 0.6M. The BP responses to Na+ rich aCSF in the SFO and the enhancement of those responses by aldosterone can be blocked by infusion of the AT1-R blocker Candesartan in the SFO. This response appears therefore to be mediated in the SFO through AT1-R activation, likely through Ang II release in the SFO. ICV infusion of Na+ rich aCSF increases BP but not HR and this response is partially blocked by infusion of the AT1-R blocker Candesartan in the SFO. This indicates that nearly half the BP responses to icv infusion of Na+ rich aCSF is mediated through AT1-R activation in the SFO. Lastly, contrary to icv, PVN and MnPO studies (Huang and Leenen 1996, Budzikowski and Leenen 2001, Gabor and Leenen 2009) ouabain in the SFO does not increase BP or HR. In conclusion, these results show that the SFO is Na+ sensitive and mediates half the BP responses to changes in CSF[Na+] through a mechanism that involves AT1-R activation. The SFO is further sensitized to Na+ by aldosterone presumably through its genomic effects. Lastly, ouabain in the SFO does not increase BP or HR suggesting that endogenous ouabain in the SFO is not involved in modulating BP or HR responses.

Abstract Statement of problem Plasma angiotensin II (Ang II) increases blood pressure (BP) through the activation of brain angiotensinergic pathways and the aldosterone-mineralocorticoid receptors (MR)- epithelial Na+ channel (ENaC)-endogenous ouabain (EO) pathway. The response of BP to circulating Ang II is enhanced by high salt intake, but the central mechanisms mediating this elevated response are not known. Methods of investigation Study 1) Male Wistar rats were divided into 4 groups and treated with regular salt diet (0.4% NaCl), high salt diet (2% NaCl), sc Ang II infusion (150 ng/kg/min), or sc Ang II infusion together with 2% salt diet for 14 days; plasma aldosterone and corticosterone levels, CYP11B2 mRNA in adrenal cortex and the mRNA levels of Ang II type 1 receptors (AT1R), CYP11B1 (11-β hydroxylase), CYP11B2 (aldosterone synthase), MR, 11βHSD2, ENaC α, ENaC β and ENaC γ in the subfornical organ (SFO), paraventricular nucleus (PVN), supraoptic nucleus (SON) and rostral ventrolateral medulla (RVLM) were measured. Study 2) MR blockers (eplerenone, spironolactone), ENaC blocker (benzamil), AT1R blocker (losartan) or vehicles were centrally infused in rats treated with Ang II plus high salt, and BP and heart rate (HR) were recorded by telemetry; plasma aldosterone and corticosterone levels and CYP11B2 mRNA expression in adrenal cortex were measured. Major findings Ang II alone caused a small increase in BP. Ang II together with 2% salt diet markedly increased the BP and plasma aldosterone level. Sc Ang II decreased 11βHSD2 and MR mRNA expression in the PVN, increased AT1R and ENaC γ expression in the PVN, and increased AT1R mRNA expression in the RVLM. Other genes tested in the four brain nuclei were not affected by sc Ang II or high salt diet. BP and plasma aldosterone increases in response to Ang II and salt, as well as CYP11B2 mRNA expression in adrenal cortex, were largely prevented by central infusion of eplerenone, spironolactone, benzamil or losartan. Main conclusion BP and plasma aldosterone responses to Ang II-salt are under the control of central mechanisms, and MR-AT1R activation in the brain plays a critical role in Ang II-salt induced hypertension.

Understanding the physiological response of marine mammals to anthropogenic stressors can inform marine ecosystem conservation strategies. Stress stimulates release of glucocorticoid (GC) hormones, which increase energy substrate availability while suppressing energy-intensive processes. Exposure to repeated stressors can potentially affect an animal’s ability to respond to and recover from subsequent challenges. To assess the endocrine response of a marine mammal to repeated stressors, we administered adrenocorticotropic hormone (ACTH) to free-ranging juvenile northern elephant seals (Mirounga angustirostris; n=7) once daily for four days. ACTH administration induced significant, but transient (<24 h) elevation in circulating cortisol levels (p < 0.0001). These increases did not vary in magnitude between the first ACTH challenge on day 1 and the last challenge on day 4. In contrast, aldosterone levels remained elevated above baseline for at least 24 hours after each ACTH injection (p < 0.001), and responses were greater on day 4 than day 1 (p < 0.01). Total triiodothyronine (tT3) levels were decreased on day 4 relative to day 1 (p < 0.01), while reverse triiodothyronine (rT3) concentrations increased relative to baseline on days 1 and 4 (p < 0.001) in response to ACTH, indicating a suppression of thyroid hormone secretion. There was no effect of ACTH on the sex steroid dehydroepiandrosterone (DHEA). These results suggest that elephant seals are able to mount adrenal responses to multiple ACTH challenges. However, repeated stress results in facilitation of aldosterone secretion and suppression of tT3, which may impact osmoregulation and metabolism. We propose that aldosterone and tT3 are informative additional indicators of repeated stress in marine mammals.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第13206号 / 論医博第2160号 / 新制||医||1031(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 木村 剛, 教授 岩田 想, 教授 秋山 芳展 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21677号 / 医博第4483号 / 新制||医||1036(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 中山 健夫, 教授 木村 剛, 教授 湊谷 謙司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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