Figure 7. Corticosterone administration exacerbates ischemia/reperfusion (IR) injury in female C57BL/6 mice in the proestrus phase of the estrus cycle.

Female C57BL/6 mice were administered regular water (RW) or corticosterone water (CW; 25 μg/mL) for 3 months and subjected to 60 minutes of ischemia and 48 hours of reperfusion at 2 different phases of the estrus cycle, estrus and proestrus. A, Serum levels of corticosterone in mice drinking RW or CW. B, Representative photographs of triphenyltetrazolium chloride heart sections harvested from sham and myocardial infarction (MI)/IR groups at 48 hours after surgery. The infarct areas (percentage) were quantified using ImageJ color threshold mode. C and D, Representative micrographs of hematoxylin‐eosin Masson trichrome–stained hearts harvested from water and corticosterone sham and MI/IR groups in the estrus and proestrus phases (scale bar=50 µm). See the Table for a full description. E and F, 5‐HTR2B mRNA levels in each experimental group. mRNA was normalized to cyclophillin B. Ordinary 1‐way ANOVA with Dunnett multiple comparisons analysis was used to evaluate differences among group treatments unless otherwise specified. The graphs show the mean±SEM for 3 to 4 repeated experiments performed in duplicate. ***P<0.001 vs sham in RW or CW controls.