Uraemic Cardiomyopathy in Different Mouse Models

Abstract

Uraemic cardiomyopathy (UCM) is one of the most common complications in chronic kidney disease (CKD). Our aim was to compare characteristics of various UCM mouse models. Mice were assigned to the following groups: the pole ligation group, 5/6 nephrectomy group (5/6Nx), uninephrectomy plus contralateral ischemia followed by reperfusion group (IR), adenine group, and sham group. Mice were sacrificed at 4, 8, and 16 weeks after surgery in the pole ligation, 5/6Nx, and IR groups, respectively. In the adenine group, mice were sacrificed at 16 weeks after the adenine diet. The structure and function of the heart and the expression of fibroblast growth factor 23 (FGF-23) and growth differentiation factor 15 (GDF-15) in hearts were assessed. The mortality in the 5/6 Nx group was significantly higher than that in the pole ligation, IR, and adenine groups. Echocardiogram and histological examination showed cardiac hypertrophy in the adenine,5/6Nx, ligation group, and IR group. In addition, cardiac fibrosis occurred in all CKD modeling groups. Interestingly, cardiac fibrosis was more serious in the IR and adenine groups. FGF-23 expression in sham mice was similar to that in modeling groups; however, the GDF-15 level was decreased in modeling groups. Our results suggest that the four models of UCM show different phenotypical features, molding time and mortality. GDF-15 expression in the hearts of UCM mice was downregulated compared with sham group mice.

Keywords: FGF-23; GDF-15; adenine; mouse models; surgical method; uraemic cardiomyopathy.

Figure 1

Protocols for the induction of UCM. (A) Diagrammatic drawing of surgery of the 5/6 nephrectomy group (5/6Nx), pole ligation group, and uninephrectomy plus contralateral ischemia followed by reperfusion group (IR). (B) Eight-week-old C57BL/6J male mice were randomly allocated to the sham (n = 14), 5/6th nephrectomy group (5/6Nx) (n = 45), pole ligation group (n = 34), uninephrectomy plus contralateral ischemia followed by reperfusion group (IR) (n = 20), and adenine group (n = 15). Mice were killed at 4, 8, and 16 weeks after surgery in the pole ligation, 5/6th nephrectomy, and uninephrectomy plus contralateral ischemia followed by reperfusion (IR) groups, respectively. In the adenine group, mice were killed at 16 weeks after the adenine diet (0.20%).

Figure 2

(A–C) Between-group comparisons of survival rate, kidney pathology, and renal function. (A) Comparisons of survival rates in the sham group, adenine group, 5/6 nephrectomy group (5/6Nx), pole ligation group, and uninephrectomy plus contralateral ischemia followed by reperfusion group (IR). (B) Comparisons of renal pathology in different models. (C) The mean BUN and Cr in the sham group and modeling groups. Data are presented as the mean ± SEM (n = 14–22). ^&P < 0.05, vs. 5/6Nx group; *P < 0.01, vs. Sham; **P < 0.01, vs. IR group; ^#P < 0.05, vs. Sham; ^##P < 0.05, vs. pole ligation group. (D) Between-group comparisons of body weight, heart weight, and heart weight-to-body weight ratio. (D) The mean body weight, heart weight, and heart weight-to-body weight ratio in the sham, adenine group, 5/6 nephrectomy group (5/6Nx), pole ligation group, and uninephrectomy plus contralateral ischemia followed by reperfusion group (IR). Data are presented as the mean ± SEM (n = 14–22). *P < 0.01, vs. Sham; ^#P < 0.05, vs. Sham.

Figure 3

Comparisons of cardiac histology changes in different models in CKD mice. (A) Representative micrographs of transverse sections (HE). (B) Representative micrographs of left ventricular sections (Masson). *P < 0.001, vs. Sham; ^#P < 0.01 vs. adenine group; ^##P < 0.001 vs. IR group.

Figure 4

Between-group comparisons of cardiac characteristics in echocardiography. (A) Representative M-mode echocardiograms from the sham, adenine group, 5/6th nephrectomy group (5/6Nx), pole ligation group, and uninephrectomy plus contralateral ischemia followed by reperfusion group (IR); (B) The mean LVAWS, LVPWs, LVPWs, LVPWd, RWT, LVEF, and LVFS in the five groups. Data are presented as the mean ± SEM (n = 14–22). (C) The mean LVAWs/BW, LVPWs/BW, LVPWs/BW, and LVPWd/BW in the sham and adenine groups. Data are presented as the mean ± SEM (n = 14–15). *P < 0.001, vs. Sham; **P < 0.01, vs. Sham; ^#P < 0.05, vs. Sham.

Figure 5

Between-group comparisons of left ventricular diastolic function assessed by echocardiography and Doppler. (A) Representative M-mode echocardiograms from the sham, adenine group, 5/6th nephrectomy group (5/6Nx), pole ligation group, and uninephrectomy plus contralateral ischemia followed by reperfusion group (IR). (B) The mean E/A in the sham, adenine group, 5/6th nephrectomy group (5/6Nx), pole ligation group, and uninephrectomy plus contralateral ischemia followed by reperfusion group (IR). Data are presented as the mean ± SEM (n = 14–22). *P < 0.001, vs. Sham.

Figure 6

Comparisons of myocardial FGF-23 and GDF-15 protein expression. (A) Representative immunohistochemical staining of FGF-23. (B) Relative values of FGF-23 optical density according to groups. (C) Representative immunohistochemical staining of GDF-15. (D) Relative values of GDF-15 optical density according to groups. *P < 0.001, vs. Sham.