An Atherogenic Paigen-Diet Aggravates Nephropathy in Type 2 Diabetic OLETF Rats.

Diabetic nephropathy develops in association with hyperglycemia, is aggravated by atherogenic factors such as dyslipidemia, and is sometimes initiated before obvious hyperglycemia is seen. However, the precise mechanisms of progression are still unclear. In this study, we investigated the influence of an atherogenic Paigen diet (PD) on the progression of nephropathy in spontaneous type 2 diabetic OLETF rats. Feeding PD to male OLETF rats for 12 weeks caused an extensive increase in excretion of urinary albumin and markers of tubular injury such as KIM-1 and L-FABP, accompanied by mesangial expansion and tubular atrophy. PD significantly increased plasma total cholesterol concentration, which correlates well with increases in urine albumin excretion and mesangial expansion. Conversely, PD did not change plasma glucose and free fatty acid concentrations. PD enhanced renal levels of mRNA for inflammatory molecules such as KIM-1, MCP-1, TLR4 and TNF-α and promoted macrophage infiltration and lipid accumulation in the tubulointerstitium and glomeruli in OLETF rats. Intriguingly, PD had little effect on urine albumin excretion and renal morphology in normal control LETO rats. This model may be useful in studying the complex mechanisms that aggravate diabetic nephropathy in an atherogenic environment.

Dietary cholesterol atherogenic changes in juvenile rabbits.

Atherosclerotic lesion formation starts during fetal development and progresses with age after adolescence. However, atherogenesis during the juvenile period has not been studied thoroughly. In this study, we examined the atherogenic susceptibility of juvenile rabbits to cholesterol feeding. Male New Zealand White rabbits aged 8 (younger group) and 12 (older group) weeks were fed a 0.5% cholesterol-containing diet for 8 weeks, and then their aortic atherosclerotic lesion areas were evaluated. Plasma concentrations of total cholesterol, triglycerides, and phospholipids did not differ between the two groups; however, plasma concentrations of high-density lipoprotein cholesterol were 23% lower in the younger than in the older group. Atherosclerotic lesion areas were significantly larger in the younger group (32±21%). However, only moderate changes were observed in these areas in the older group (3.3±0.3%). Histological examination showed marked intimal thickening and macrophage accumulation in the aortic lesions of rabbits in the younger group. To the best of our knowledge, this is the first study to show that dietary cholesterol-induced atherogenic changes markedly occur during a short period in juvenile rabbits.

Add-on effect of probucol in atherosclerotic, cholesterol-fed rabbits treated with atorvastatin.

OBJECTIVE: Lowering the blood concentration of low-density lipoprotein (LDL) cholesterol is the primary strategy employed in treating atherosclerotic disorders; however, most commonly prescribed statins prevent cardiovascular events in just 30% to 40% of treated patients. Therefore, additional treatment is required for patients in whom statins have been ineffective. In this study of atherosclerosis in rabbits, we examined the effect of probucol, a lipid-lowering drug with potent antioxidative effects, added to treatment with atorvastatin. METHODS AND RESULTS: Atherosclerosis was induced by feeding rabbits chow containing 0.5% cholesterol for 8 weeks. Probucol 0.1%, atorvastatin 0.001%, and atorvastatin 0.003% were administered solely or in combination for 6 weeks, beginning 2 weeks after the start of atherosclerosis induction. Atorvastatin decreased the plasma concentration of non-high-density lipoprotein cholesterol (non-HDLC) dose-dependently; atorvastatin 0.003% decreased the plasma concentration of non-HDLC by 25% and the area of atherosclerotic lesions by 21%. Probucol decreased the plasma concentration of non-HDLC to the same extent as atorvastatin (i.e., by 22%) and the area of atherosclerotic lesions by 41%. Probucol with 0.003% atorvastatin decreased the plasma concentration of non-HDLC by 38% and the area of atherosclerotic lesions by 61%. Co-administration of probucol with atorvastatin did not affect the antioxidative effects of probucol, which were not evident on treatment with atorvastatin alone, such as prevention of in vitro LDL-oxidation, increase in paraoxonase-1 activity of HDL, and decreases in plasma and plaque levels of oxidized-LDL in vivo. CONCLUSIONS: Probucol has significant add-on anti-atherosclerotic effects when combined with atorvastatin treatment; suggesting that this combination might be beneficial for treatment of atherosclerosis.

Cilostazol inhibits accumulation of triglyceride in aorta and platelet aggregation in cholesterol-fed rabbits.

Cilostazol is clinically used for the treatment of ischemic symptoms in patients with chronic peripheral arterial obstruction and for the secondary prevention of brain infarction. Recently, it has been reported that cilostazol has preventive effects on atherogenesis and decreased serum triglyceride in rodent models. There are, however, few reports on the evaluation of cilostazol using atherosclerotic rabbits, which have similar lipid metabolism to humans, and are used for investigating the lipid content in aorta and platelet aggregation under conditions of hyperlipidemia. Therefore, we evaluated the effect of cilostazol on the atherosclerosis and platelet aggregation in rabbits fed a normal diet or a cholesterol-containing diet supplemented with or without cilostazol. We evaluated the effects of cilostazol on the atherogenesis by measuring serum and aortic lipid content, and the lesion area after a 10-week treatment and the effect on platelet aggregation after 1- and 10-week treatment. From the lipid analyses, cilostazol significantly reduced the total cholesterol, triglyceride and phospholipids in serum, and moreover, the triglyceride content in the atherosclerotic aorta. Cilostazol significantly reduced the intimal atherosclerotic area. Platelet aggregation was enhanced in cholesterol-fed rabbits. Cilostazol significantly inhibited the platelet aggregation in rabbits fed both a normal diet and a high cholesterol diet. Cilostazol showed anti-atherosclerotic and anti-platelet effects in cholesterol-fed rabbits possibly due to the improvement of lipid metabolism and the attenuation of platelet activation. The results suggest that cilostazol is useful for prevention and treatment of atherothrombotic diseases with the lipid abnormalities.