Isoproterenol Induces Cardiac Injury and Senescence in Sprague–Dawley Rats: A Cost-Effective Pharmacological Model

Figures

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  Figure 1. ISO induces inflammatory cellular infiltration and collagen deposition in the apex of the young adult rat. (A) 10–12-week-old rats were administered 100 mg/kg ISO or saline for five days, and then apexes were collected on days 10 and 28. (B) H&E-stained cardiac sections. Black arrows indicate areas of inflammatory cell infiltration. (C) Quantification of the injured area. (D) MT-stained cardiac sections. Black arrows indicate areas of collagen deposition. (E) Quantification of collagen-positive area. Scale bars = 50 µm. Data are expressed as the mean ± S.D. Statistical analysis was performed using two-way ANOVA followed by Šídák’s multiple comparisons test. n = 5 per group. Panel (A) was created using BioRender (As Sobeai, H. (2026). https://biorender.com/q0u7o5z, accessed on 21 May 2026).

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  Figure 2. ISO increases hypertrophy in the apex of the young adult rat. 10–12-week-old rats were administered 100 mg/kg ISO or saline for five days, and then apexes were collected on days 10 and 28. (A) Representative images of WGA and DAPI staining. (B) Quantification of cardiomyocyte cross-sectional area. (C) Quantification of heart weight/body weight ratio. Scale bars = 100 µm. Data are expressed as the mean ± S.D. Statistical analysis was performed using two-way ANOVA followed by Šídák’s multiple comparisons test. n = 5 per group for cross-sectional area measurements, and n = 10 per group for HW/BW measurements.

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  Figure 3. ISO induces senescence in the apex of the young adult rat. 10–12-week-old rats were administered 100 mg/kg ISO or saline for five days, and then apexes were collected on days 10 and 28. (A) Representative SA-β-gal staining images (blue; black arrows). (B) Quantification of SA-β-gal-positive area. (C) Representative p16 staining images (green; yellow arrows). (D) Quantification of p16-positive cells. (E) Representative p21 staining images (green; yellow arrows). (F) Quantification of p21-positive cells. Scale bars = 100 µm. Data are expressed as the mean ± S.D. Statistical analysis was performed using two-way ANOVA followed by Šídák’s multiple comparisons test. n = 5 per group.

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  Figure 4. Changes in senescence markers and SASP factors in the apex of the young adult rat after ISO or saline. 10–12-week-old rats were administered 100 mg/kg ISO or saline for five days and then apexes were collected on days 10 and 28. RT-qPCR analysis of (A) p16, (B) p21, (C) IL-1β, (D) MMP12, (E) TNF-α, (F) CCL2, (G) IL-6, and (H) MMP9. The mRNA levels were normalized to Actb mRNA levels within the same samples and then expressed as the fold change in the experimental group relative to the equivalent control group using the ΔΔCt method. Data are expressed as the mean ± S.D. Statistical analysis was performed using two-way ANOVA followed by Šídák’s multiple comparisons test. n = 5 per group.

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  Figure 5. ISO induces DNA damage in the apex of the young adult rat. 10–12-week-old rats were administered 100 mg/kg ISO or saline for five days, and then apexes were collected on days 10 and 28. (A) Representative γH2AX staining images (green; yellow arrows). (B) Quantification of γH2AX-positive cells. Scale bars = 100 µm. Data are expressed as the mean ± S.D. Statistical analysis was performed using two-way ANOVA followed by Šídák’s multiple comparisons test. n = 5 per group.