Growth Hormone and Secretagogues Counter Steroid-Induced Muscle Wasting in Rats

Long-term corticosteroid treatment is a common therapy for various inflammatory and autoimmune conditions, but it often leads to severe side effects, including muscle wasting and negative nitrogen balance, a state where protein breakdown exceeds synthesis. This catabolic state can significantly impair patient recovery and quality of life. While growth hormone (GH) and growth hormone secretagogues (GHS) are known for their anabolic properties, their specific efficacy in mitigating the detrimental effects of steroid-induced catabolism on nitrogen balance and urea synthesis in an animal model has not been fully elucidated.

The study revealed significant improvements in nitrogen balance and reduced urea synthesis in the treated groups. Dexamethasone alone resulted in a negative nitrogen balance of -35 mg N/day, while the GH-treated group showed a remarkable positive nitrogen balance of +15 mg N/day, representing a 143% improvement compared to the dexamethasone-only group (p<0.001). Similarly, the GHS-treated group achieved a positive nitrogen balance of +10 mg N/day, a 129% improvement (p<0.01). The most striking finding was that both GH and GHS treatments effectively reversed the steroid-induced catabolic state, with GH leading to a 2.5-fold increase in nitrogen retention compared to the untreated catabolic group. Furthermore, plasma urea concentrations, an indicator of protein breakdown, were significantly reduced: the dexamethasone-only group exhibited 12.5 mmol/L, whereas GH treatment lowered it to 7.8 mmol/L (37.6% reduction, p<0.001), and GHS treatment reduced it to 8.5 mmol/L (32% reduction, p<0.01). These results demonstrate that both GH and GHS can effectively counteract the protein-wasting effects of corticosteroids.