Endothelial dysfunction and the development of renal injury in spontaneously hypertensive rats fed a high-fat diet

Abstract

Obesity and hypertension have been identified as cardiovascular risk factors that contribute to the progression of end-stage renal disease. To examine the mechanisms by which a high-fat diet and hypertension contribute to endothelial dysfunction and renal injury, 8-week-old male spontaneously hypertensive rats and Wistar rats were fed a high-fat (36% fat) or a normal-fat (7% fat) diet for 10 weeks. The high-fat diet increased body weight in Wistar and hypertensive rats by 25 and 31 g, respectively. Systolic blood pressure was higher in the hypertensive rats compared with Wistar rats; however, blood pressure was unaltered by the high-fat diet. Afferent arteriole response to acetylcholine was impaired in the high-fat groups after just 3 weeks. Renal macrophage infiltration was increased in the hypertensive high-fat group compared with others, and monocyte chemoattractant protein-1 excretion was increased in both of the high-fat-fed groups. Renal PCR arrays displayed significant increases in 2 inflammatory genes in hypertensive rats fed a normal diet, 1 gene was increased in high-fat-fed Wistar rats, whereas 12 genes were increased in high-fat-fed hypertensive rats. Urinary albumin excretion was increased in the hypertensive rats compared with the Wistar rats, which was further exacerbated by the high-fat diet. Glomerular nephrin expression was reduced and desmin was increased by the high-fat diet in the hypertensive rats. Our results indicate that endothelial dysfunction precedes renal injury in normotensive and spontaneously hypertensive rats fed a high-fat diet, and hypertension with obesity induces a powerful inflammatory response and disruption of the renal filtration barrier.

Figure 1

A: Body weight and B: Systolic blood pressure in the WKY and SHR animals fed a normal diet and a high fat diet at baseline and throughout the 10 weeks study. Values are mean ±SEM (n=5). *P<0.05 WKY vs SHR, †P<0.05 high fat diet vs normal diet.

Figure 2

A: Blood glucose levels in WKY and SHR fed a normal or high fat diet for up to 10 weeks. B: Plasma insulin levels in WKY and SHR fed a normal or high fat diet for 3, 6 or 10 weeks. C: Glucose infusion rates from hyperinsulinemic, euglycemic clamp experiments on WKY and SHR fed a normal or high fat diet for 10 weeks. D: Plasma leptin levels in WKY and SHR fed a normal or high fat diet for 3, 6 or 10 weeks. Values are mean ±SEM (n=5). *P<0.05 WKY vs SHR, †P<0.05 high fat diet vs normal diet.

Figure 3

Afferent arteriole vascular response to acetylcholine in WKY and SHR fed a normal or high fat diet for A: 3 weeks, B: 10 weeks. Values are mean ±SEM (n=5). *P<0.05 WKY vs SHR, †P<0.05 high fat diet vs normal diet.

Figure 4

A: Renal cortical immunohistochemistry in WKY and SHR showing ED-1 positive cells and mean positive cell counts, 400x magnification. B: Urinary monocyte chemoattractant protein-1 concentration in rats fed for 3 or 10 weeks. Values are mean ±SEM (n=5). †P<0.05 high fat diet vs normal diet.

Figure 5

Real-time PCR array data showing mean renal cortical mRNA expression of 84 inflammatory cytokines genes (n=3). A: WKY high fat (HF) vs WKY normal diet (ND) showing changes in gene expression as a result of 10 weeks high fat diet in normotensive rats. B: SHR ND vs WKY ND showing changes in gene expression as a result of hypertension. C: SHR HF vs WKY HF showing changes in gene expression as a result of 10 weeks high fat diet in hypertensive rats.

Figure 6

A: Urinary microalbumin excretion in WKY and SHR fed a normal or high fat diet for 3, 6 or 10 weeks. B: Urinary protein excretion in WKY and SHR fed a normal or high fat diet for 3, 6 or 10 weeks.

Figure 7

A: Immunofluorescence showing glomerular nephrin expression in WKY and SHR fed a normal or high fat diet for 10 weeks, 400x magnification. B: Western blot of glomerular nephrin protein expression in WKY and SHR fed a normal or high fat diet for 10 weeks. Values are mean ±SEM (n=5). †P<0.05 high fat diet vs normal diet. C: Immunofluorescence presenting glomerular desmin expression in WKY and SHR fed a normal or high fat diet for 10 weeks, 400x magnification. D: Western blot of glomerular desmin protein expression in WKY and SHR fed a normal or high fat diet for 10 weeks. Values are mean ±SEM (n=5). †P<0.001 high fat diet vs normal diet.