Submitted on May 2, 2006
Accepted on October 16, 2006
Transcriptome-based identification of pro- and anti-oxidative gene expression in kidney cortex of nitric oxide depleted rats
Sebastiaan Wesseling1, Jaap A. Joles1, Harry van Goor2, Hans A. Bluyssen1, Patrick Kemmeren3, Frank C. Holstege3, Hein A Koomans1, and Branko Braam4*
1 Nephrology and Hypertension - F03.223, Univ. Med. Center Utrecht, Utrecht, Netherlands
2 Pathology, Univ. Med. Center Groningen, Groningen, Netherlands
3 Genomics Lab, Univ. Med. Center Utrecht, Utrecht, Netherlands
4 Nephrology and Immunology, University of Alberta, Edmonton, Canada; Nephrology and Hypertension - F03.223, Univ. Med. Center Utrecht, Utrecht
* To whom correspondence should be addressed. E-mail: bbraam{at}gmail.com.
Nitric oxide (NO) depletion in rats induces severe endothelial dysfunction within 4 days. Subsequently, hypertension and renal injury develop, which are ameliorated by alpha-tocopherol (VitE) co-treatment. The hypothesis of the present study was that NO synthase (NOS) inhibition induces a renal cortical anti-oxidative transcriptional response, and invokes pro-oxidative and pro-inflammatory gene expression due to elimination of dampening effects of NO and enhanced oxidative stress. Male Sprague-Dawley (SD) rats received NOS inhibitor L-NNA (500 mg/L water) for 4 (4d-LNNA), 21 (21d-LNNA) or 21 days with VitE in chow (0.7 g/kg BW/day). Renal cortical RNA was applied to oligonucleotide rat arrays. In 4d-LNNA, 21d-LNNA and 21d-LNNA+VitE, 120, 320 and 184 genes were differentially expressed, respectively. Genes related to glutathione and bilirubin synthesis were suppressed during 4d and 21d-LNNA and not corrected by VitE. Proteinuria, tubulointerstitial macrophages and HO-1 expression were strongly correlated. Remarkably, pro-oxidative genes were not induced. Inflammation- and injury related genes, including kidney injury molecule-1 and osteopontin, were unchanged at day 4, induced at 21d and partly corrected by VitE. Superimposing HO-1 inhibition on NOS inhibition had no impact on the development of hypertension. Summarizing, renal expression of genes involved in synthesis of the antioxidants glutathione and bilirubin seemed directly NO dependent, but there were no direct effects of NO depletion on pro-oxidant systems. This indicates that renal transcriptional regulation of two defense systems, glutathione and bilirubin syntheses, seems to depend upon adequate NO synthesis. Interaction between NO synthesis and heme degradation pathways for blood pressure regulation was not found.
