Dexmedetomidine Pretreatment Attenuates Kidney Injury and Oxidative Stress during Orthotopic Autologous Liver Transplantation in Rats

Abstract

This paper aims to explore whether pretreatment with dexmedetomidine (Dex) has antioxidative and renal protective effects during orthotopic autologous liver transplantation (OALT) and its impact on nuclear factor erythroid 2-related factor 2 (Nrf2) activation. Sprague-Dawley rats were randomized into groups that include sham-operated (group S), model (group M), low dose Dex (group D1), high dose Dex (group D2), atipamezole (a nonspecific α2 receptor blocker) + high dose Dex (group B1), ARC239 (a specific α2B/c receptor blocker) + high dose Dex (group B2), and BRL-44408 (a specific α2A receptor blocker) + high dose Dex (group B3). Then histopathologic examination of the kidneys and measurement of renal function, the renal Nrf2 protein expression, and oxidants and antioxidants were performed 8 hours after OALT. We found that pretreatment with Dex activated Nrf2 in glomerular cells and upregulated antioxidants but reduced oxidants (all P < 0.01, group D2 versus group M). Atipamezole and BRL-44408, but not ARC239, reversed these protective effects. In conclusion, pretreatment with Dex activates Nrf2 through α2A receptor, increases the antioxidant levels, and attenuates renal injury during OALT.

Figure 1

Remote kidney damage of rats in various groups after OALT. Kidney sections were stained with hematoxylin and eosin (HE) and visualized at ×400 magnification. (a) Group S; (b) group M; (c) group D1; (d) group D2; (e) group B1; (f) group B2; and (g) group B3.

Figure 2

Pathological scores of kidney tissue. A score from 0 to 3 was given for each tubular profile: 0 = normal histology; 1 = mild injury: tubular cell dilatation (expanded 50 times its normal size); 2 = moderate injury: epithelial cells which are flattened, moderate tubular dilatation, or partial nuclear condensation; 3 = severe injury: the shape of healthy cells lost, with severe tubular dilatation or nuclear condensation. The data were represented as mean ± standard deviation (SD), n = 8. ^▲ P < 0.01 versus group S; ^■ P < 0.01 versus group M; ^◆ P < 0.01 versus group D2.

Figure 3

Levels of Scr and BUN at various groups. (The blood samples were taken from the abdominal aorta 8 h after reperfusion. The data were represented as mean ± standard deviation (SD), n = 8. ^▲ P < 0.01, ^△ P < 0.05 versus group S; ^■ P < 0.01 versus group M; ^◆ P < 0.01 versus group D2.)

Figure 4

The expression of Nrf2 in kidney tissues of different groups was detected by immunofluorescence staining under a laser scanning confocal microscope (magnification 400x). (a) Group S; (b) group M; (c) group D1; (d) group D2; (e) group B1; (f) group B2; and (g) group B3. Positive Nrf2 cells were stained green, with the sections counterstained with 4,6-diamidino-2-phenylindole (DAPI) to visualize nuclei. Arrows indicate Nrf2 positive glomerular cells, while the triangle points at Nrf2 positive tubular epithelial cells.

Figure 5

The proportion of Nrf2 positive cells and semiquantitative immunofluorescence of Nrf2 in glomerular cells or tubular epithelial cells in kidney tissues of different groups. The cells were counted under a laser scanning confocal microscope (magnification 400x). (a) The proportion of Nrf2 positive cells in tubular epithelial cells; (b) the proportion of Nrf2 positive cells in glomerular cells; (c) semiquantitative immunofluorescence of Nrf2 in tubular epithelial cells; (d) semiquantitative immunofluorescence of Nrf2 in glomerular cells. Relative immunofluorescence intensities were normalized to that of group S. The data were represented as mean ± standard deviation (SD), n = 8. ^▲ P < 0.01 versus group S; ^■ P < 0.05 versus group M; ^◆ P < 0.05 versus group D2.

Figure 6

The antioxidants and oxidants of renal tissue. The data were represented as mean ± standard deviation (SD), n = 8. ^▲ P < 0.01, ^△ P < 0.05 versus group S; ^■ P < 0.01 versus group M; ^◆ P < 0.01 versus group D2.