Telmisartan ameliorates nephropathy and restores the hippo pathway in rats with metabolic syndrome

The main objective of this study was to determine if the telmisartan-ameliorative effects of metabolic syndrome (MetS)-evoked nephropathy are attributed to the Hippo pathway. A secondary objective was to investigate the potential of vitamin D3 to enhance telmisartan-favourable effects. A diet composed of 24% fat and 3% salt, along with drinking water containing 10% fructose, was administered for 12 weeks to induce MetS. MetS-rats were given telmisartan (5 mg/kg/day), vitamin D3 (10 μg/kg/day) or both by gavage, starting in the sixth week of experimental diet administration. Assessments performed at closure included renal function, histological examination, catalase, malondialdehyde (MDA), nuclear factor kappa-B (NF-κB), interleukin-6 (IL-6), peroxisome proliferator-activated receptor-γ (PPAR-γ), phosphatase and tensin homolog (PTEN), and transforming growth factor-β (TGF-β). Matrix metalloproteinase-9 (MMP-9) immunostaining was conducted. The expression of the Hippo pathway components, as well as that of angiotensin II type 1 and type 2 (AT1 and AT2), receptors was evaluated. Telmisartan attenuated MetS-evoked nephropathy, as demonstrated by improvement of renal function and histological features, enhancement of catalase, reduction of MDA, inflammation (NF-κB, IL-6), and renal fibrosis (increased PPAR-γ and PTEN and reduced MMP-9 and TGF-β). Telmisartan downregulated AT1-receptor, upregulated AT2-receptor and restored the Hippo pathway. Vitamin D3 replicated most of the telmisartan-elicited effects and enhanced the antifibrotic actions of telmisartan. The alleviative effects of telmisartan on MetS-evoked nephropathy may be related to the restoration of the Hippo pathway. The combination of vitamin D3 and telmisartan exerted more favourable effects on metabolic and nephropathic biomarkers compared with either one administered alone.