Expression of proinflammatory cytokines and Hsp70 in rat kidney at an early stage of experimental diabetes induced by streptozotocin

PAGOTTO, MELINA; MOLINAS, SARA M.; ROLDÁN, LORENA; GARCÍA, VERÓNICA; TRUMPER, LAURA; MONASTEROLO, LILIANA; ELÍAS, M. MÓNICA

Rio de Janeiro. Brasil

Congreso; World Congress of Nephrology 2007; 2007

International Society of Nephrology

Expression of proinflammatory cytokines and Hsp 70 in rat kidney at an early stage of experimental diabetes induced by streptozotocin. M.A. Pagotto1, S. M. Molinas1,M. L. Roldán, L. Trumper2, L. A. Monasterolo1, M. M. Elías11Farmacología-IFISE CONICET, Facultad de Cs. Bioquímicas y Farmacéuticas. Universidad Nacional de Rosario. 2 CIUNR , Rosario, Argentina. World Congress of Nephrology 2007. Del 21 al 25 de abril de 2007. Rio de Janeiro. Brasil Introduction: Proinflammatory citokynes and other molecules with relevant role within the inflammatory process may be critical factors in the  pathogenesis of diabetes and in the development of microvascular diabetic complications, including diabetic nephropathy.  Heat shock proteins (Hsp) play essencial role in folding, assembly, traslocation of polypeptides and  also act as molecular chaperones. The levels of Hsp 70 are proved to be altered during the course of diabetic disease in different tissues resulting in an impairment of their cytoprotective ability (1). Our objective was to evaluate the expression of different inflammatory mediators and Hsp 70 levels in kidney tissue at an early stage of streptozotocin-induced diabetes. Methods: Male adult Wistar rats received a single injection of streptozotocin (STZ)  (50 mg/kg) i.v., while a group of control animals (C) received only the vehicle. After seven days, kidneys were excised and cortex was separated from medullary tissue. The expression  of the proinflammatory cytokines TNF-a, IL-1b and IL-6 were evaluated by semiquantitative RT-PCR , co-amplifying b-actin as internal control. PCR products were electrophoresed on a 1.0% agarose gel, stained with etidium bromide.  Hsp 70 levels were detected in cortical and medullary homogenates by Western Blotting. Data were analysed with GelPro program. Results: In diabetic rats glucose plasma level was 3.76±0.82 g/l; and insulin was decreased (C: 16.3±2.3, STZ: 7.5±2.2 µU/ml*). In STZ kidneys there were no changes in the mRNA levels of TNF-a. There was an increase in the mRNA levels of IL-1b  in the diabetic group both in cortical tissue (arbitrary units) (C: 0.54±0.07, STZ: 1.22±0.23*) and in renal medulla (C: 0.72±0.04, STZ: 0.99±0.11*). mRNA levels of IL-6 were increased in cortical tissue (C:0.77±0.08 STZ:1.51±0.21*). The levels of Hsp 70 decreased in cortical homogenates (C:51.4±0.6 STZ:38.9±4.6*) while there were no changes in medullary tissue (*p<0.05).Conclusion: This results indicate the activation of inflammmatory processes in an early stage of diabetes. IL-1b induction (2) and diminished insulin levels (3) could be responsible for the observed decrease in Hsp70 expression. Further investigations are required to fully understand the relationship between inflammatory mediators and the stress response. References: 1)Life Sci. 2001;69(22):2603-9 2)J. Immunol. 1997; 159(6):2886-92 3)J. Endocrinol. 2006; 190(2):433-40