Dexmedetomidine alleviates cisplatin‑induced acute kidney injury by attenuating endoplasmic reticulum stress‑induced apoptosis via the α2AR/PI3K/AKT pathway

Abstract

Cisplatin (CP) is an effective antineoplastic agent; however, CP‑induced acute kidney injury (AKI) seriously affects the prognosis of patients with cancer. Endoplasmic reticulum (ER) stress (ERS)‑induced apoptosis serves a pivotal role in the pathogenesis of CP‑induced AKI. Dexmedetomidine (Dex), a potent α2 adrenergic agonist, has been reported to exert protective effects against AKI. However, the protective effects of Dex against CP‑induced AKI and the potential molecular mechanisms remain unknown. In the present study, male Sprague‑Dawley rats were divided into four groups (n=10/group), as follows: Control group; CP group, rats received an intraperitoneal (i.p.) injection of 5 mg/kg CP; Dex + CP group, rats received an i.p. injection of 25 µg/kg Dex immediately after CP treatment; and Dex + CP + atipamezole (Atip) group, rats received an i.p. injection of 250 µg/kg Atip, an α2 adrenoreceptor (α2AR) antagonist, and then received the same treatment as the Dex + CP group. Rats were anesthetized and sacrificed 96 h after CP injection. Subsequently, serum blood urea nitrogen (BUN) and serum creatinine (Scr) were analyzed, and kidney samples were collected for analyses. Pathological changes were examined using hematoxylin and eosin staining, and protein expression levels were assessed using western blotting and immunohistochemical staining. In addition, apoptosis was examined using a terminal deoxynucleotidyl transferase dUTP nick‑end labeling assay. The present results suggested that Dex protected against CP‑induced AKI by attenuating histological changes in the kidney, serum BUN and Scr production. Furthermore, the expression levels of 78‑kDa glucose‑regulated protein, C/EBP homologous protein and caspase‑12, and the apoptotic rate in the kidney were decreased following Dex treatment. In addition, the expression levels of phosphorylated (p)‑PI3K and p‑AKT in the Dex + CP group were significantly increased. Conversely, the renoprotective effects of Dex were attenuated following the addition of Atip. In conclusion, Dex may alleviate CP‑induced AKI by attenuating ERS‑induced apoptosis, at least in part, via the α2AR/PI3K/AKT signaling pathway.

Keywords: cisplatin; acute kidney injury; dexmedetomidine; endoplasmic reticulum stress; apoptosis.

Figure 1.

Effect of Dex on renal function and body weight. (A) Body weight, (B) RI, (C) BUN and (D) Scr. Data are presented as the mean ± SEM (n=10). **P<0.01, ***P<0.001 vs. Con; ^#P<0.05, ^##P<0.01 vs. Dex + CP. Atip, atipamezole; BUN, blood urea nitrogen; Con, control; CP, cisplatin; Dex, dexmedetomidine; Scr, serum creatinine; RI, renal index.

Figure 2.

Dex attenuates CP-induced kidney tubular damage. (A) Histological examination of sections stained with hematoxylin and eosin staining (magnification, ×400; scale bar, 50 µm). (B) Tubular damage scores. Data are presented as the mean ± SEM (n=10). ***P<0.001 vs. Con; ^#P<0.05 vs. Dex + CP. Atip, atipamezole; Con, control; CP, cisplatin; Dex, dexmedetomidine.

Figure 3.

Dex protects against proximal tubular cell apoptosis induced by CP. (A) TUNEL staining assay (magnification, ×400; scale bar, 50 µm). Green, TUNEL; blue, DAPI; red arrows, TUNEL-positive cells. (B) Quantification of TUNEL-positive cells. Data are presented as the mean ± SEM (n=10). ***P<0.001 vs. Con; ^#P<0.05 vs. Dex + CP. Atip, atipamezole; Con, control; CP, cisplatin; Dex, dexmedetomidine; HPF, high-power field; TUNEL, terminal deoxynucleotidyl transferase dUTP nick-end labelling.

Figure 4.

Western blot analysis and immunohistochemical staining of proteins in the kidney. (A) Western blot analysis, and semi-quantification of protein expression levels of (B) GRP78, (C) CHOP and (D) caspase-12. (E) Western blot analysis, and semi-quantification of protein expression levels of (F) p-PI3K/PI3K (G) and p-AKT/AKT relative to β-actin control. (H) Expression levels of GRP78 and caspase-12 detected in damaged tubules by immunohistochemistry (magnification, ×400; scale bar, 50 µm). (I) Semi-quantification of GRP78 in kidney sections. (J) Semi-quantification of caspase-12 in kidney sections. Data are presented as the mean ± SEM (n=3). *P<0.05, **P<0.01 vs. Con; ^#P<0.05, ^##P<0.01 vs. Dex + CP. Atip, atipamezole; CHOP, C/EBP homologous protein; Con, control; CP, cisplatin; Dex, dexmedetomidine; GRP78, 78-kDa glucose-regulated protein; p-, phosphorylated.