Impact of DNA interference targeting myostatin on selected muscle growth-related gene expression in a rat model

Abstract Myostatin (MSTN), a protein synthesized by muscle cells, plays a crucial role in regulating muscle growth and development. Its inhibition has been identified as a potential therapeutic strategy to enhance muscle mass and strength. DNA interference (DNAi) is a gene-silencing strategy that employs short DNA oligonucleotides designed to target promoter regions or transcription factor binding sites, thereby repressing gene transcription at the DNA level. In the present study, we investigated the effects of DNA interference (DNAi) molecules on the expression of MSTN, MyoD, and FSTL1 genes in the gastrocnemius muscle of male Wistar rats in combination with resistance training. The DNAi molecules consisted of synthetic DNA oligonucleotide targeting the promoter region of the rat MSTN gene. Five distinct rat groups underwent various interventions. Group PTO3, the first cohort, received 10 µg/kg of DNAi intraperitoneally, a treatment repeated three times weekly for seven weeks. Another group, PTO1, received the same DNAi dosage but on a weekly basis over seven weeks. Meanwhile, the NPTO3 group was administered 10 µg/kg of none-modified DNAi three times weekly. The fourth group acted as a control, receiving no DNAi intervention. Lastly, the fifth group, dedicated to exercise, participated in resistance training on a treadmill and their weekly weights were recorded. All groups engaged in this treadmill routine, adhering to the set protocol, with their progress monitored through weekly weight measurements. Group differences were assessed by one-way ANOVA, and Tukey’s post hoc test was used for multiple comparisons. This study revealed that rats administered with three weekly doses of none-modified DNAi showed the highest weight gain. Furthermore, a notable decrease in triglyceride levels was detected in the blood of rats treated with DNAi, coupled with resistance training. Both the weight of the gastrocnemius muscle and its relative weight were significantly influenced by the experimental treatments, with the highest value observed in the group receiving injections of modified DNAi per week (P-value = 0.008 and 0.024 respectively). Histological analysis revealed a higher cell count in the muscle tissue of the group received none-modified DNAi compared to the other groups. A significant reduction in myostatin gene expression was observed in muscle tissue after treatment with DNAi, as indicated by qPCR analysis (P-value = 0.004). This effect was accompanied by an intriguing upregulation of FSTL1 and a decrease in MyoD genes, both of which are known to influence muscle development. These results highlight the potential of DNAi-based myostatin inhibition, coupled with resistance training, as a powerful strategy to promote muscle growth and strength. This study opens new possibilities for designing innovative treatments for various muscle disorders.