Abstract: BACKGROUND: In sarcopenic osteoporosis, muscle loss and osteoporosis often coexist, leading to a significant increase in the risk of falls and fractures. Gushukang Granules are clinically used for the treatment of osteoporosis; however, the mechanism of action on myogenic and osteogenic factors in muscle and bone remains unclear.
OBJECTIVE: To investigate the effects of Gushukang Granules on myogenic and osteogenic factors in the muscles and bones of rats.
METHODS: Thirty-six healthy Sprague-Dawley rats were randomly divided into a control group, a model group, and a Gushukang Granules group, with 12 rats in each group. Osteoporosis was induced in the latter two groups via ovariectomy. Four weeks after surgery, drug administration began. The Gushukang Granules group was given 1.05 mL/kg of Gushukang Granules solution by gavage daily, while the other groups received an equal volume of normal saline, once a day for 12 consecutive weeks. General conditions of the rats in each group were observed. Hematoxylin-eosin staining was used to examine morphological changes in the bone and muscle tissues. Real-time quantitative polymerase chain reaction was performed to measure mRNA expression levels of interleukin-6, tumor necrosis factor-α, osteocalcin, and insulin-like growth factor-1 in the muscle tissues. Immunohistochemistry was used to observe the expression of interleukin-6, tumor necrosis factor-α, insulin-like growth-1, and osteocalcin in the muscle and bone tissues. Western blot was used to detect the protein expression levels of interleukin-6, tumor necrosis factor-α, insulin-like growth 1, and osteocalcin in the muscle and bone tissues. 
RESULTS AND CONCLUSION: (1) Compared with the control group, the model group exhibited typical sarcopenic osteoporosis phenotypes: In muscle tissue, muscle fibers were sparsely and disorderly arranged with widened spacing, accompanied by significant atrophy. In bone tissue, the number of trabeculae decreased, with sparse arrangement, widened spacing, visible fractures, and poor connectivity. mRNA and protein expression of interleukin-6 and tumor necrosis factor-α were significantly increased (P < 0.01), while mRNA and protein expression of insulin-like growth 1 and osteocalcin were significantly decreased (P < 0.01) in both muscle and bone tissues. (2) Compared with the model group, the Gushukang Granules group showed significant improvements in the above indicators: In muscle tissue, the arrangement of muscle fibers tended to be more orderly, with obvious interstitial fibrosis. In bone tissue, the number of trabeculae increased, and connectivity improved (though still relatively loose). mRNA and protein expression of interleukin-6 and tumor necrosis factor-α were significantly decreased (P < 0.01), while mRNA and protein expression of insulin-like growth-1 and osteocalcin were significantly increased (P < 0.01) in both muscle and bone tissues. (3) Western blot results were consistent with the immunohistochemistry trends. Overall, these findings suggest that Gushukang Granules can improve muscle atrophy and trabecular sparseness in ovariectomized rats by downregulating the abnormally high expression of interleukin-6 and tumor necrosis factor-α and upregulating the expression of insulin-like growth-1 and osteocalcin in muscle and bone tissues. Its effects may be related to regulating the muscle-bone interaction signaling pathway and balancing inflammatory and growth-promoting factors, providing experimental support for the clinical application of Gushukang Granules in sarcopenic osteoporosis. 

Key words: Gushukang Granules, sarcopenic osteoporosis, interleukin-6, tumor necrosis factor-α, insulin-like growth factor-1, osteocalcin