6979 Effect of Orchiectomy on Muscle Growth and Differentiation Factors in Male Mice With Kidney Disease

Abstract Disclosure: O. Marks: None. J. Bruno: None. D. Wu: None. A. Patwardhan: None. Y. Komaru: None. G. Ling: None. E. Kefalogianni: None. R. Aurora: None. S.S. Dhindsa: None. A. Herrlich: None. Background: Sarcopenia and frailty are major clinical concerns in participants with chronic kidney disease (CKD). In males, an additional factor contributes to the development of sarcopenia. Around half of the men with CKD have subnormal serum testosterone (T) concentrations. The mechanisms that underlie the effect of low T concentrations on muscle growth in CKD are not known. In this study, we performed orchiectomy in male mice with kidney disease and evaluated the expression and protein content of the following muscle growth and differentiation factors. Methods: Forty mice were divided into 4 groups: 1) renal injury, induced by ischemia-induced reperfusion (IRI, N=11) at 2 months of age; 2) orchidectomy (ORX), performed 4 weeks after IRI (IRI + ORX, N=9); 3) sham-IRI and ORX (sham-ORX, N=8); and 4) sham-sham surgery (N=12). The mice were sacrificed when they were ∼7 months old (mean age 206±13 days). Gastrocnemius and levator ani muscles were harvested to measure expression by RT-qPCR of muscle catabolism markers (Atrogin-1 and ubiquitin ligase MuRF1), muscle growth inhibitors, myostatin and myogenic regulatory factor (Mrf4), fibroblast growth factor-2 (FGF2, a stimulator of satellite stem cells) and its receptor FGFR2, androgen receptor (AR) and IGF-1. Results: The mean BUN (blood urea nitrogen) at the time of sacrifice was higher in the IRI/ORX (32±4 mg/dl) and IRI/Sham (26±5 mg/dl) groups as compared to sham-sham (21±5 mg/dl, p