Fig. 2

Expression of profibrotic transcription factors due to chronic increased or decreased medullary solute concentration in rats. a Compared to control rats, water restriction increased the medullary expression of Egr-1 mRNA and protein, while furosemide treated rats had similar expression levels to controls. b The Egr-1 overexpression was confirmed by immunohistochemistry, depicting a significant amount of Egr-1 positive tubular cell nuclei in water restricted rats (arrows), as compared to both control and furosemide treated rats. c Interestingly, apart of the tubular staining (arrows), we also found Egr-1 positive interstitial cells only in the medulla of water restricted rats (asterisk). d Water restriction significantly increased the mRNA expression of the AP-1 component cFos. The expression of the AP-1 component cJun did not change due to increased medullary solute concentration, but decreased by 50% after furosemide treatment. e Increased medullary osmolarity had no effect on the mRNA expression of collagen-III, but it was reduced by furosemide treatment. As compared to controls, the medullary TIMP-1 expression was almost 2-fold elevated after chronic water restriction, and furosemide did not alter TIMP-1. Data are presented as mean ± SEM, n = 6/group. * p < 0.05, ** p < 0.01, *** p < 0.001 (Kruskal-Wallis test with Dunn’s post-hoc test)