High Susceptibility of Obese Hypertensive SHRSP.Z-Leprfa/IzmDmcr Rats to Lipid Deposition in the Mesenteric Artery

1. Atherosclerosis is commonly observed in obesity. Obese atherosclerosis-prone animals may be a promising tool for understanding the pathophysiology of obesity-associated atherosclerosis. However, most rat strains are resistant to atherosclerosis. The aim of the present study was to assess the susceptibility of two obese hypertensive rat models, namely SHRSP.Z-Lepr(fa) /IzmDmcr rats (SHRSP-fatty) and SHR.Cg-Lepr(cp) /NDmcr rats (SHR-cp), to arterial lipid deposition, an initial stage of atherosclerosis, by comparing these strains with non-obese stroke-prone spontaneously hypertensive rats (SHRSP). 2. Eight-week-old male SHRSP, SHRSP-fatty and SHR-cp were fed a high-fat and high-cholesterol diet containing 20% palm oil, 5% cholesterol and 2% cholic acid for 5weeks. Bodyweight, blood pressure and fasting serum levels of total cholesterol and triglycerides were measured in 12-week-old rats. Oil red O staining was used to visualize lipid deposition in the mesenteric artery. 3. The bodyweight of 12-week-old SHRSP-fatty and SHR-cp was higher than that of SHRSP (P<0.005). Systolic blood pressure in SHRSP and SHRSP-fatty was higher than in SHR-cp (P<0.005). Serum total cholesterol and triglyceride levels were elevated in SHRSP-fatty (P<0.005) and SHR-cp (P<0.05) compared with levels in SHRSP. Lipid deposition in the mesenteric artery was significantly greater in SHRSP-fatty than in SHRSP (37.7±4.9 vs 13.1±2.8%, respectively; P<0.005), but markedly reduced in SHR-cp (1.8±0.4%; P<0.05). 4. The results of the present study indicate that SHRSP-fatty are highly susceptible to arterial lipid deposition, whereas SHR-cp are resistant. Thus, SHRSP-fatty may be a useful obese rat model in which to investigate atherosclerotic processes.