Phenobarbital ameliorates hyperglycemia-induced angiogenesis in diabetic nephropathy-possible intervention at the HIF-1α/VEGF axis

Abstract

Hyperglycemia contributes to a cascade of inflammatory responses in kidneys that result in the development of renal hypoxia and angiogenesis with subsequent chronic renal failure. As the hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) axis is a key pathway for neovascularization, the inhibition of this axis is a target for renal angiogenesis therapy. We speculate that Phenobarbital (PB) which has a potential to reduce vascularization in clinical settings might have an influence on the development of angiogenesis in diabetic kidney. The aim of the study was to explore the effects of PB on the HIF-1α and VEGF expression and angiogenesis in renal tissue of rats with hyperglycemia and diabetic nephropathy. Sixty-four male Wistar rats were devided into 4 groups: control group received a single intraperitoneal saline injection; PB group received 0.05% PB orally in drinking water; diabetic group received a single intra-peritoneal STZ (65 mg/kg) injection; PB-STZ group received 0.05% PB orally two weeks before STZ administration. At the end of the experiment period (8 weeks), the kidneys were removed and used for biochemical analyses. Serum glucose, urea and creatinine levels, IL-6 levels in kidney homogenate and changes in HIF-1α and VEGF gene expression were estimated. Hematoxylin-eosin staining was performed for histopathological exa­mination. The results obtained showed that both HIF-1α and VEGF gene expression and IL6 level in diabetic rat group were significantly elevated compared to that in control group, whereas in PB and PB-STZ groups, these indices were significantly down-regulated compared to the diabetic group. Abundant glomerular congestion and mesangial proliferation were detected in diabetic rat renal tissues. However, in PB-treated diabetic group, newly formed vessels were significantly decreased. These findings confirmed that phenobarbital, affecting the HIF-1α/VEGF signaling pathway, ameliorates angiogenesis after hyperglycemic kidney injury. Keywords: angiogenesis, HIF-1α, hyperglycemia, IL6, kidney injury, VEGF