Abstract
Background. Stretching of skeletal muscle induces expression of the genes which encode myogenic transcription factors or muscle contractile proteins and results in muscle growth. Anabolic steroids are reported to strengthen muscles. We have previously studied the effects of muscle stretching on gene expression. Here, we studied the effect of a combination of passive stretching and the administration of an anabolic steroid on mRNA expression of a muscle growth factor, insulin-like growth factor-I autocrine variant, or mechano-growth factor (MGF). Methods. Twelve 8-week-old male Wistar rats were used. Metenolone was administered and passive repetitive dorsiflexion and plantar flexion of the ankle joint performed under deep anesthesia. After 24 h, the gastrocnemius muscles were removed and the mRNA expression of insulin-like growth factor-I autocrine variant was measured using quantitative real-time polymerase chain reaction. Results. Repetitive stretching in combination with metenolone, but not stretching alone, significantly increased MGF mRNA expression. Conclusion. Anabolic steroids enhance the effect of passive stretching on MGF expression in skeletal muscle.
Highlights
The musculoskeletal system is a fundamental structure required for movement and daily living
The mechano-growth factor (MGF) expression ratio in the muscles of the unstretched side of the metenolone-treated rats was 0.83 ± 0.45, which did not differ significantly from both the stretched or the unstretched side of the control group not treated with metenolone
There was no significant difference in comparison with the unstretched side of the treated rats or with either side of the rats not treated with metenolone
Summary
The musculoskeletal system is a fundamental structure required for movement and daily living. Various factors are reported to enhance the growth of skeletal muscle tissue. Stretching of skeletal muscle induces expression of the genes which encode myogenic transcription factors or muscle contractile proteins and results in muscle growth. Anabolic steroids are reported to strengthen muscles. We have previously studied the effects of muscle stretching on gene expression. We studied the effect of a combination of passive stretching and the administration of an anabolic steroid on mRNA expression of a muscle growth factor, insulin-like growth factor-I autocrine variant, or mechano-growth factor (MGF). After 24 h, the gastrocnemius muscles were removed and the mRNA expression of insulin-like growth factor-I autocrine variant was measured using quantitative real-time polymerase chain reaction. Anabolic steroids enhance the effect of passive stretching on MGF expression in skeletal muscle
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