Unacylated Ghrelin Mitigates Skeletal Muscle Damage and Oxidative Stress in a Duchenne Muscular Dystrophy Models

Background: Duchenne muscular dystrophy (DMD) is a severe muscle disorder caused by mutations in the dystrophin gene, leading to progressive dysfunction and degeneration. DMD is caused by a mutation of dystrophin, a scaffolding protein of the sarcolemmal dystrophin-glycoprotein complex (DGC) which yields oxidative stress, damage, inflammation and fibrosis. Ghrelin is a 28-amino acid peptide hormone that circulates in acylated (AG) and unacylated (UAG) forms. While AG binds to the growth hormone secretagogue receptor (GHS-R), UAG could protect dystrophic muscle by mitigating damage, reducing oxidative stress, immune cell invasion, and thus damage and remodeling. Ghrelin analogs and UAG have mitigated in skeletal and heart muscle. Inhibition of NADPH oxidase-2 (Nox2), a primary source of oxidative stress in DMD pathology, has also mitigated DMD pathology. However, the redox mechanisms by which UAG affects DMD pathology are unknown. Objective: We propose that UAG treatment of DMD mice with UAG will mitigate damage, Nox2, oxidative stress, and pathology of muscles in dystrophic mice. Methods: In this experiment, 4 weeks C57BL10 (WT and mdx mice) are partitioned into three groups (n = 6/ group): (1) wild-type, (2) mdx mice, and (3) mdx mice + UAG (100µg/kg/day i.p.). After 10 days, Mice were euthanized, and the gastrocnemius muscles were dissected and frozen with O.C.T for subsequent analysis. Tissue analysis was conducted using H&E staining, immunoblotting, and immunofluorescence. Results: The mdx group gastrocnemius muscle mass was significantly higher than the mdx UAG group. Protein immunoblots and immunofluorescence revealed that UAG treatment significantly reduced tissue damage (IgG infiltration) was significantly greater in mdx vs. WT and was mitigated by UAG in mdx mice. H&E staining indicated improved regeneration in the mdx + UAG group vs. mdx mice. Furthermore, elevation of redox protein that contribute to pathology (e.g., Nox2, RANKL) was significantly reduced by UAG administration. Nrf2 was elevated in dystrophic muscle while sarcolemmal DGC proteins (a-syntrophin, a-dystrobrevin, dystrophin) were lost in mdx mice compared with wild-types, with modest recovery or protection by UAG. Conclusion: Our primary novel findings include protection against upregulation of Nox2 and RANKL by unacylated ghrelin, linked to reduced damage and improved muscle fiber regeneration. In addition, there appears to be partial protection of sarcolemmal DGC proteins by UAG. Future experiments will investigate the mechanisms by which UAG reduces Nox2 and RANKL in dystrophic muscle. Redox Biology & Cell Signaling Laboratory, Texas A&M University Department of Nutrition, Texas A&M University This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.