Overexpression of endothelial β₃‐adrenergic receptor induces diastolic dysfunction in rats

Abstract

Aims Diastolic dysfunction is common in cardiovascular diseases, particularly in the case of heart failure with preserved ejection fraction. The challenge is to develop adequate animal models to envision human therapies in the future. It has been hypothesized that this diastolic dysfunction is linked to alterations in the nitric oxide (• NO) pathway. To investigate this issue further, we investigated the cardiac functions of a transgenic rat model (Tgβ 3) that overexpresses the human β 3-adrenoceptor (hβ 3-AR) in the endothelium with the underlying rationale that the • NO pathway should be stimulated in the endothelium. Methods and results Transgenic rats (Tgβ 3) that express hβ 3-AR under the control of intercellular adhesion molecule 2 promoter were developed for a specific expression in endothelial cells. Transcriptomic analyses were performed on left ventricular tissue from 45-week-old rats. Among all altered genes, we focus on • NO synthase expression and endothelial function with arterial reactivity and evaluation of • NO and O 2 •À production. Cardiac function was characterized by echocardiography, invasive haemodynamic studies, and working heart studies. Transcriptome analyses illustrate that several key genes are regulated by the hβ 3-AR overexpression. Overexpression of hβ 3-AR leads to a reduction of Nos3 mRNA expression (À72%; P < 0.05) associated with a decrease in protein expression (À19%; P < 0.05). Concentration-dependent vasodilation to isoproterenol was significantly reduced in Tgβ 3 aorta (À10%; P < 0.05), while • NO and O 2 •À production was increased. In the same time, Tgβ 3 rats display progressively increasing diastolic dysfunction with age, as shown by an increase in the E/A filing ratio [1.15 ± 0.01 (wild type, WT) vs. 1.33 ± 0.04 (Tgβ 3); P < 0.05] and in left ventricular end-diastolic pressure [5.57 ± 1.23 mmHg (WT) vs. 11.68 ± 1.11 mmHg (Tgβ 3); P < 0.05]. In isolated working hearts, diastolic stress using increasing preload levels led to a 20% decrease in aortic flow [55.4 ± 1.9 mL/min (WT) vs. 45.8 ± 2.5 mL/min (Tgβ 3); P < 0.05]. Conclusions The Tgβ 3 rat model displays the expected increase in • NO production upon ageing and develops diastolic dysfunction. These findings provide a further link between endothelial and cardiac dysfunction. This rat model should be valuable for future preclinical evaluation of candidate drugs aimed at correcting diastolic dysfunction.

Pharmacological Effects of Methotrexate and Infliximab in a Rats Model of Diet-Induced Dyslipidemia and Beta-3 Overexpression on Endothelial Cells

“…Also, other genetic interventions with the purpose of inducing co-morbidities in order to better mimic the development of complex diseases can be made [ 21 ]. The overexpression of beta-3 adrenoreceptors in endothelial cells can increase the risk of endothelial dysfunction and together with dyslipidemia may accelerate vascular modifications and lesions [ 22 ]. Chemically-induced atherosclerosis can be obtained with Triton WR-1339, bisphenol-A, and poloxamer 407 [ 29 , 30 ].…”

“…Several animal models of atherosclerosis have been developed [ 21 ], but the most reproducible are the ones using high lipid diets [ 21 ]. Although it is difficult to develop typical atherosclerosis in rats, studies show that a diet rich in lard and cholesterol administered to rats for more than 4 weeks can induce dyslipidemia, inflammation, and gradually lead to vascular modifications resulting in atherosclerosis-like lesions [ 22 ]. Atherosclerosis is associated with endothelial dysfunction and stiffening of the arterial wall.…”

“…Atherosclerosis is associated with endothelial dysfunction and stiffening of the arterial wall. Thus, the overexpression of beta-3 receptors at the endothelial level could lead to increased endothelial dysfunction [ 22 ], an enhanced vascular reactivity to hyperlipidemia, and vascular modifications indicative of atherosclerosis development.…”

Implications of a Soy-Based Diet for Animal Models

“…Using echocardiography, we show that the systolic function based on the ejection fraction shows no change during aging in male, female or ovariectomized (OVX) female rats whatever the diet or the genotype ( Figure 1 A–C). The diastolic function was affected as shown by an increase in the E/A ratio ( Figure 1 D) for male Tgβ 3 rats fed by soy-free diet only [ 7 ]. However, no changes in this parameter were observed in females, either OVX or not, fed with either soy-based or soy-free diets ( Figure 1 E,F).…”

“…We used a rodent model developed in our team: the transgenic (Tgβ 3 ) rats overexpressing human β 3 -adrenergic receptor in endothelial cells, and their control (WT) rats. The transgenic rat model overexpressing hβ 3 -AR in endothelial cells was generated by microinjection of a linearized plasmid consisting of the hβ 3 -AR cDNA under the control of the endothelial cell-specific intercellular adhesion molecule-2 (ICAM-2) promoter into Sprague-Dawley zygotes [ 7 ]. Both male and female (OVX or not) rats were analyzed.…”