RESUMO
After menopause, the incidence of cardiovascular disease rapidly rises in women. The disappearing protection provided by sex steroids is a consequence of the development of many risk factors. Preclinical studies are necessary to understand better the effects of ovarian hormones loss cardiac aging. To mimic menopause in mice and study its consequences, we delayed ovariectomy at 12 months and followed animals for 12 months. Using RNA sequencing, we investigated changes in the myocardial exome with aging. In addition, with four-core genotypes (FCG) transgenic mice, we studied sex chromosome effects on cardiac aging. Heart weight increased from 3 to 24 months (males + 35%, females + 29%). In males, 75% of this increase had occurred at 12 months; in females, only 30%. Gonadectomy of mice at 12 months blocked cardiac hypertrophy in both sexes during the second year of life. The dosage of the X chromosomes did not influence cardiac growth in young and older mice. We performed an RNA sequencing study in young and old mice. We identified new highly expressed genes modulated during aging (Bdh, Myot, Cpxm2, and Slc38a1). The myocardial exome in older animals displayed few differences related to the animal's sex or the presence or absence of sex steroids for a year. We show that the morphological evolution of the heart depends on the biological sex via gonadal sex hormone actions. The myocardial exome of old male and female mice is relatively similar. Our study emphasizes the need to consider sex steroid effects in studying cardiac aging.
Assuntos
Envelhecimento , Hormônios Esteroides Gonadais , Cromossomos Sexuais , Animais , Feminino , Masculino , Envelhecimento/genética , Camundongos , Hormônios Esteroides Gonadais/metabolismo , Cromossomos Sexuais/genética , Camundongos Transgênicos , Ovariectomia , Coração , Miocárdio/metabolismo , Miocárdio/patologia , Fatores Sexuais , Cardiomegalia/genéticaRESUMO
We propose a new mouse (C57Bl6/J) model combining several features of heart failure with preserved ejection fraction encountered in older women, including hypertension from Angiotensin II infusion (AngII), menopause, and advanced age. To mimic menopause, we delayed ovariectomy (Ovx) at 12 months of age. We also studied the effects of AngII infusion for 28 days in younger animals and the impact of losing gonadal steroids earlier in life. We observed that AngII effects on heart morphology were different in younger and adult mice (3- and 12-month-old; 20 and 19% increase in heart weight. P < 0.01 for both) than in older animals (24-month-old; 6%; not significant). Ovariectomy at 12 months restored the hypertrophic response to AngII in elderly females (23%, p = 0.0001). We performed a bulk RNA sequencing study of the left ventricle (LV) and left atrial gene expression in elderly animals, controls, and Ovx. AngII modulated (|Log2 fold change| ≥ 1) the LV expression of 170 genes in control females and 179 in Ovx ones, 64 being shared. In the left atrium, AngII modulated 235 genes in control females and 453 in Ovx, 140 shared. We observed many upregulated genes associated with the extracellular matrix regulation in both heart chambers. Many of these upregulated genes were shared between the ventricle and the atrium as well as in control and Ovx animals, namely for the most expressed Ankrd1, Nppb, Col3a1, Col1a1, Ctgf Col8a1, and Cilp. Several circadian clock LV genes were modulated differently by AngII between control and Ovx females (Clock, Arntl, Per2, Cry2, and Ciart). In conclusion, sex hormones, even in elderly female mice, modulate the heart's hypertrophic response to AngII. Our study identifies potential new markers of hypertensive disease in aging female mice and possible disturbances of their cardiac circadian clock.
Assuntos
Angiotensina II , Modelos Animais de Doenças , Hipertensão , Camundongos Endogâmicos C57BL , Ovariectomia , Animais , Feminino , Angiotensina II/farmacologia , Camundongos , Hipertensão/fisiopatologia , Envelhecimento/fisiologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Ventrículos do Coração/fisiopatologia , Menopausa , Humanos , Fator de Crescimento do Tecido Conjuntivo/genética , Fator de Crescimento do Tecido Conjuntivo/metabolismo , Átrios do Coração/fisiopatologia , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/patologia , Colágeno Tipo IIIRESUMO
Multiple factors cause heart failure with preserved ejection fraction (HFpEF) and involve various systems. HFpEF prevalence is rapidly rising, and its prognosis remains poor after the first hospitalization. Adopting a more active lifestyle has been shown to provide beneficial clinical outcomes for patients with HFpEF. Using a two-hit HfpEF murine model, we studied cardiac reverse remodeling (RR) after stopping the causing stress and introducing voluntary exercise (VE). We checked in 2-mo-old male and female C57Bl6/J mice the heart's response to angiotensin II (ANG II; 1.5 mg/kg/day for 28 days) fed or not with a high-fat diet (HFD). Then, ANG II and/or the HFD were stopped, and VE was started for an additional 4 wk. ANG II and ANG II + HFD (metabolic-hypertensive stress, MHS) caused cardiac hypertrophy (CH) and myocardial fibrosis, left ventricular (LV) concentric remodeling, atrial enlargement, and reduced exercise capacity. HFD alone induced CH and LV concentric remodeling in female mice only. CH and LV concentric remodeling were reversed 4 wk after stopping ANG II, starting VE, and a low-fat diet. Left atrial enlargement and exercise capacity were improved but differed from controls. We performed bulk LV RNA sequencing and observed that MHS upregulated 58% of the differentially expressed genes (DEGs) compared with controls. In the RR group, compared with MHS animals, 60% of the DEGs were downregulated. In an HfpEF mouse model, we show that correcting hypertension, diet, and introducing exercise can lead to extensive cardiac reverse remodeling.NEW & NOTEWORTHY Using a two-hit murine model of heart failure with preserved ejection fraction (HfpEF), combining elevated blood pressure, obesity, and exercise intolerance in male and female animals, we showed that correction of hypertension, normalization of the diet, and introduction of voluntary exercise could help reverse the remodeling of the left ventricle and double exercise capacity. We also identify genes that escape normalization after myocardial recovery and differences between males' and females' responses to stress and recovery.