Blood pressure, renal biochemical parameters and histopathology in an original rat model of essential hypertension (SHRSP/Kpo strain)

Hypertensive nephropathy, a consequence of chronic high blood pressure, is increasingly a cause of end-stage renal diseases and its correct management is very important for clinical outcome. Spontaneously hypertensive rat (SHR/Kpo) and stroke-prone SHR (SHRSP/Kpo) strains represent models of human essential hypertension. However, the kidney injuries in SHR/Kpo and SHRSP/Kpo are not well defined. We therefore characterized the renal pathophysiology of SHR/Kpo and SHRSP/Kpo compared with normotensive control (WKY/Kpo) rats. The SHRSP/Kpo exhibited increased systolic blood pressure at 10 weeks of age, and proteinuria and increased blood urea nitrogen (BUN) and serum creatinine levels at 20 weeks. We simultaneously detected mononuclear cell infiltration, tubular injuries, accumulation of extracellular matrix and marked expression of α-SMA in the tubulointerstitium. Additionally, TGF-β1 and CTGF were up-regulated in the kidney of SHRSP/Kpo. We lastly focused on changes in glomerular cells of SHRSP/Kpo. Nestin, a podocyte marker, was detected but decreased slightly in 20-week-old SHRSP/Kpo. PECAM-1 expression was increased in SHRSP/Kpo glomeruli, indicating the thickening of glomerular endothelial cells. Moreover, we found that α-SMA, a myofibroblast marker, was also upregulated in the glomeruli of SHRSP/Kpo at 20 weeks. These findings suggest that SHRSP/Kpo could be a valuable animal model for human hypertensive nephropathy.