Pregnancy Protects Hyperandrogenemic Female Rats from Postmenopausal Hypertension

Polycystic ovary syndrome, the most common endocrine disorder in women of reproductive age, is characterized by hyperandrogenemia, obesity, insulin resistance, and elevated blood pressure. However, few studies have focused on the consequences of pregnancy on postmenopausal cardiovascular disease and hypertension in polycystic ovary syndrome women. In hyperandrogenemic female (HAF) rats, the hypothesis was tested that previous pregnancy protects against age-related hypertension. Rats were implanted with dihydrotestosterone (7.5 mg/90 days, beginning at 4 weeks and continued throughout life) or placebo pellets (controls), became pregnant at 10 to 15 weeks, and pups were weaned at postnatal day 21. Dams and virgins were then aged to 10 months (still estrous cycling) or 16 months (postcycling). Although numbers of offspring per litter were similar for HAF and control dams, birth weights were lower in HAF offspring. At 10 months of age, there were no differences in blood pressure, proteinuria, nitrate/nitrite excretion, or body composition in previously pregnant HAF versus virgin HAF. However, by 16 months of age, despite no differences in dihydrotestosterone, fat mass/or lean mass/body weight, previously pregnant HAF had significantly lower blood pressure and proteinuria, higher nitrate/nitrite excretion, with increased intrarenal mRNA expression of endothelin B receptor and eNOS (endothelial nitric oxide synthase), and decreased ACE (angiotensin-converting enzyme), AT1aR (angiotensin 1a receptor), and endothelin A receptor than virgin HAF. Thus, pregnancy protects HAF rats against age-related hypertension, and the mechanism(s) may be due to differential regulation of the nitric oxide, endothelin, and renin-angiotensin systems. These data suggest that polycystic ovary syndrome women who have experienced uncomplicated pregnancy may be protected from postmenopausal hypertension.Fil: Shawky, Noha M.. University Of Mississippi Medical Center; Estados UnidosFil: Patil, Chetan N.. Medical College Of Wisconsin; Estados UnidosFil: Dalmasso, Carolina. University of Kentucky; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Grupo Vinculado Centro de Investigación en Medicina Traslacional Severo R. Amuchástegui - Cimetsa | Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Grupo Vinculado Centro de Investigación en Medicina Traslacional Severo R. Amuchástegui - Cimetsa | Instituto de Investigación Médica Mercedes y Martín Ferreyra. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Grupo Vinculado Centro de Investigación en Medicina Traslacional Severo R. Amuchástegui - Cimetsa; ArgentinaFil: Marañón, Rodrigo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Romero, Damián Gastón. University Of Mississippi Medical Center; Estados UnidosFil: Drummond, Heather. University Of Mississippi Medical Center; Estados UnidosFil: Reckelhoff, Jane F.. University Of Mississippi Medical Center; Estados Unido

Antidiuretic Effects of the Endothelin Receptor Antagonist Avosentan

Several clinical studies have investigated the potential benefits of endothelin receptor antagonism in chronic pathologies such as diabetic kidney disease. However, fluid retention and edema have been identified as major side effects of endothelin receptor antagonists. In the present study we hypothesized that avosentan which was described as a predominant ETA receptor antagonist would produce fluid retention at high concentrations where non-specific blockade of ETB receptors may occur. Incremental doses of the predominant ETA receptor antagonist SPP301 (0.003; 0.03; 3 mg/kg) were administered intravenously to anesthetized Sprague-Dawley rats undergoing saline diuresis. Diuresis, glomerular filtration rate, and blood pressure (BP) were monitored. SPP301 decreased urine output (5.6; 34.8; 58.8% decrease from vehicle) and fractional excretion of water (5.7; 31.7; 56.4% decrease from vehicle) in a concentration-dependent manner. Glomerular filtration rate was unchanged while BP was reduced by 10 mmHg only by the highest dose of SPP301. Administration of the ETB selective receptor antagonist BQ-788 (3 mg/kg) following SPP301 3 mg/kg did not further decrease urine output or water excretion and was without effect on glomerular filtration rate. These data indicate that increasing concentrations of SPP301 may also block ETB receptors and cause antidiuresis. This effect could explain why fluid retention and edema occur during treatment with predominant ETA receptor blockers

Animal models of hypertension: a scientific statement from the American Heart Association

Hypertension is the most common chronic disease in the world, yet the precise cause of elevated blood pressure often cannot be determined. Animal models have been useful for unraveling the pathogenesis of hypertension and for testing novel therapeutic strategies. The utility of animal models for improving the understanding of the pathogenesis, prevention, and treatment of hypertension and its comorbidities depends on their validity for representing human forms of hypertension, including responses to therapy, and on the quality of studies in those models (such as reproducibility and experimental design). Important unmet needs in this field include the development of models that mimic the discrete hypertensive syndromes that now populate the clinic, resolution of ongoing controversies in the pathogenesis of hypertension, and the development of new avenues for preventing and treating hypertension and its complications. Animal models may indeed be useful for addressing these unmet needs

Strategies and methods to study sex differences in cardiovascular structure and function: a guide for basic scientists

<p>Abstract</p> <p>Background</p> <p>Cardiovascular disease remains the primary cause of death worldwide. In the US, deaths due to cardiovascular disease for women exceed those of men. While cultural and psychosocial factors such as education, economic status, marital status and access to healthcare contribute to sex differences in adverse outcomes, physiological and molecular bases of differences between women and men that contribute to development of cardiovascular disease and response to therapy remain underexplored.</p> <p>Methods</p> <p>This article describes concepts, methods and procedures to assist in the design of animal and tissue/cell based studies of sex differences in cardiovascular structure, function and models of disease.</p> <p>Results</p> <p>To address knowledge gaps, study designs must incorporate appropriate experimental material including species/strain characteristics, sex and hormonal status. Determining whether a sex difference exists in a trait must take into account the reproductive status and history of the animal including those used for tissue (cell) harvest, such as the presence of gonadal steroids at the time of testing, during development or number of pregnancies. When selecting the type of experimental animal, additional consideration should be given to diet requirements (soy or plant based influencing consumption of phytoestrogen), lifespan, frequency of estrous cycle in females, and ability to investigate developmental or environmental components of disease modulation. Stress imposed by disruption of sleep/wake cycles, patterns of social interaction (or degree of social isolation), or handling may influence adrenal hormones that interact with pathways activated by the sex steroid hormones. Care must be given to selection of hormonal treatment and route of administration.</p> <p>Conclusions</p> <p>Accounting for sex in the design and interpretation of studies including pharmacological effects of drugs is essential to increase the foundation of basic knowledge upon which to build translational approaches to prevent, diagnose and treat cardiovascular diseases in humans.</p

Reproducibility in animal models of hypertension: a difficult problem

Abstract In 2016, the National Institutes of Health mandated that all grant proposals enhance reproducibility through rigor and transparency. In the past few years, physiological outcomes in established animal models of hypertension, in particular in regard to sex differences, have varied from study to study or laboratory to laboratory. The aim of this commentary is to increase investigator awareness of caveats related to animal models that may be sensitive to vendor-, barrier-, or diet-specific changes that result in an inability to sustain the genotype and/or phenotype of well-established experimental models. These considerations are critical in order for investigators to make informed and educated decisions in regard to their hypothesis-driven research, in particular as it relates to experimental design and interpretation, and the reporting of results