Histomorphometric analysis of the soleus muscle in different phases of ischemic stroke in an animal model

Abstract

Objective: To analyze the muscle mass and cross-sectional area of the muscular fiber of the hemiparetic soleus in an animal model, in order to identify the muscular adaptations that occur in ischemic stroke. Method: Twelve Rattus norvegicus were divided into 2 groups: stroke group (n=6) and control group (n=6). Each group was subdivided into two subgroups, with evaluations at 7 days (CG7 and SG7) and 21 days (CG21 and SG21) after the accident. Their soleus muscles were removed for muscle mass analysis and cross-sectional area of the muscular fibers (CSAMF) measurement. The adopted statistical significance was 5%. Result: Significant differences in the muscle mass were observed between CG7 (0.120 ± 0.005 g) vs. SG7 (0.100 ± 0.004 g; p=0.035), and between CG21 (0.130 ± 0.010 g) vs. SG21 (0.078 ± 0.006; p=0.012). Significant differences in the relative muscle mass were observed between CG7 (0.044 ± 0.002 g) vs SG7 (0.039 ± 0.003; p=0.025), and CG21 (0.044 ± 0.003) vs. SG21 (0.028 ± 0.002; p=0.011). The CSAMF showed significant differences between CG7 (2,322 μm2 [2312-2453]) vs. SG7 (2,056 μm2 [2,022-2,135]; p=0.012), and CG21 (2,667 μm2 [2,692-2,845]) vs. SG21 (2,050 μm2 [2,034-2,161]; p=0.006). Conclusion: In this study in animal models of ischemic stroke, there was a significant loss of muscle mass, and this loss was accentuated in the longer term of the injury, highlighting the importance of future research on types of muscle fibers and applicability in human patients.