Angiotensin II receptor blocker attenuates overexpression of vascular endothelial growth factor in diabetic podocytes.
VEGF expressed in glomerular podocytes, is known to increase vascular permeability to macromolecules. Angiotensin II can stimulate the release of VEGF, and the protective effects of angiotensin II antagonist against diabetic glomerular injury suggest that the angiotensin II-induced VEGF is an important pathogenetic mechanism in the development of proteinuria during diabetic nephropathy although this mechanism is not fully understood. In this study, the changes of VEGF expression was examined in the experimental diabetic nephropathy to determine whether these changes were modified by renoprotective intervention by blockers of angiotensin II receptors. The streptozotocin- induced diabetic rats were treated with L-158,809, a blocker of angiotensin II receptors, for 12 weeks. Age-matched rats with L-158,809 served as controls. RT-PCR and immunohistochemistry were used to assess and quantify gene and protein expression of VEGF. A progressive increase in urinary protein excretion was observed in diabetic rats. Glomerular VEGF expression was significantly higher in diabetic rats than in the control groups, with a significant reduction in glomerular VEGF expression and proteinuria in L-158,809- treated diabetic rats. VEGF mRNA was also significantly higher in diabetic kidneys than in the control groups, with a significant reduction in VEGF mRNA in L-158,809-treated diabetic kidneys. These results demonstrates that VEGF expression is significantly increased in diabetic podocytes, and angiotensin II receptor antagonist attenuated these changes in VEGF expression and prevented the development of proteinuria in vivo. Attenuation of increased VEGF expression in podocytes could contribute to the renoprotective effects of angiotensin II receptor antagonists in diabetic nephropathy.
Lee
Eun-Young
EY
Department of Internal Medicine and Clinical Research Institute, Soonchunhyang University Cheonan Hospital, Cheonan, Korea.
Shim
Myung Sook
MS
Kim
Mi Jin
MJ
Hong
Sae Yong
SY
Shin
Young Goo
YG
Chung
Choon Hee
CH
D000804:Angiotensin II / Q000037:antagonists & inhibitors*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D000959:Antihypertensive Agents / Q000378:metabolism / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology*; D007678:Kidney Glomerulus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism*; D013777:Tetrazoles / Q000378:metabolism / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
D057911:Angiotensin Receptor Antagonists; D000959:Antihypertensive Agents; D001786:Blood Glucose; D007093:Imidazoles; D012333:RNA, Messenger; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D042461:Vascular Endothelial Growth Factor A; D000804:Angiotensin II; C070967:L 158809