A New Approach for the Development of Multiple Cardiovascular Risk Factors in Two Rat Models of Hypertension

Abstract

Cardiovascular disease (CVD) is the leading cause of death among non-communicable diseases. There is a lack of valid animal models that mimic associations among multiple cardiovascular risk factors in humans. The present study developed an animal model that uses multiple cardiovascular risk factors-namely, hypertension, hypothyroidism, and a high-fat diet (HFD). Two models of hypertension were used: renovascular hypertension (two-kidney, one clip [2K1C]) and spontaneously hypertensive rats (SHRs). The naive group was composed of normotensive rats. Twelve weeks after surgery to induce renovascular hypertension, rats in the 2K1C and SHR groups underwent thyroidectomy. The HFD was then implemented for 6 weeks. Renal function, serum redox status, biochemical CVD markers, electrocardiographic profile, blood pressure, mesenteric vascular bed reactivity, histopathology, and morphometry were investigated. Both experimental models induced dyslipidemia, renal function impairment, and hepatic steatosis, accompanied by higher levels of different inflammatory markers and serum oxidative stress. These alterations contributed to end-organ damage in all hypertensive rats. Our findings corroborate a viable alternative model that involves multiple cardiovascular risk factors and resembles conditions that are seen in humans. Both models mimicked CVD, but our data show that SHRs exhibit more significant pathophysiological changes.

Keywords: animal models; cardiovascular disease; dyslipidemia; renal impairment.

Figure 1

Oxidative/nitrosative stress markers in normotensive and hypertensive high-fat-fed rats. Serum nitrotyrosine (A), malondialdehyde (B), and oxidized low-density lipoprotein levels (C) are presented. The data are expressed as mean ± standard error of the mean. a p ≤ 0.05 when compared with naive; b p ≤ 0.05 when compared with 2K1C group. 2K1C: two-kidney-one-clip hypertension; MDA: malondialdehyde; NT: nitrotyrosine; oxLDL: oxidized low-density lipoprotein; SHR: spontaneously hypertensive rats.

Figure 2

Serum interleukins and soluble adhesion molecule levels in normotensive and hypertensive high-fat-fed rats. Serum sVCAM-1 (A), sICAM-1 (B), IL-6 (C), and L-1β (D) levels are shown. The data are expressed as mean ± standard error of the mean. a p ≤ 0.05 when compared with naive; b p ≤ 0.05 when compared with 2K1C group. 2K1C: two-kidney-one-clip hypertension; IL-1β: interleukin-1β; IL-6: interleukin-6; SHR: spontaneously hypertensive rats; sICAM-1: soluble intercellular adhesion molecule-1; sVCAM-1: soluble vascular cell adhesion molecule-1.

Figure 3

Representative histological sections of the liver (A), kidney (B), heart (C), and aorta artery (D) from normotensive and hypertensive high-fat-fed rats. The black arrows show micro and macro vacuolization and diffuse swelling of the hepatocyte’s cytoplasm. Empty-core arrows show necrosis in the liver. Empty-core arrowhead shows interstitial mononuclear inflammatory infiltrate. The black arrowhead shows thickening of the renal capsule in the remaining corpuscles and multifocal areas of calcification. H&E (40×). 2K1C: two-kidney-one-clip hypertension; SHR: spontaneously hypertensive rats.

Figure 4

Experimental design: 2K1C: two-kidney-one-clip; HFD: high-fat diet; BP: body pressure; ECG: electrocardiography; MVB: mesenteric vascular bed; SHR: spontaneously hypertensive rats; TX: thyroidectomy.