Male mice (8 weeks old) underwent gonadectomy or sham surgery. Six weeks after surgery, a cohort of mice were subjected to skeletal muscle injury via intramuscular injection of cardiotoxin (CTX; 10 µM) in the gastrocnemius muscle. Cohorts (n=7-8) of animals were sacrificed at post CTX injury at day 1, 3, 5, 7, 14, 21, 28, 35. A. Body weight at time of sacrifice (grams), B. Gastrocnemius wet weight (mg), C-H. Gastroc muscle relative mRNA expression of HGF, IGF-1, FST, CXCR4, and TNF-α (normalized to PPIB) was measured via real-time PCR. Data are means ± SEM. Significance (*p<0.05) of CTX vs. Control (within Intact or GDX) was analyzed by ANOVA and Bonferonni’s posthoc analysis. H-I. Representative H&E cross-sectional images (20X) of myofibers and fatty infiltration in the H. Intact (androgen-normal) and I. GDX (androgen-depleted) gastrocnemius muscle at the 21 days post cardiotoxin time point.