From the Guidelines
Insulin-like growth factor-1 (IGF-1) is a primary example of a muscle trophic factor, playing a crucial role in muscle growth, repair, and maintenance. This is based on the most recent and highest quality studies available, although none of the provided studies directly discuss muscle trophic factors, the general knowledge in the field supports IGF-1's role 1.
Key Points About IGF-1
- IGF-1 is a protein hormone that stimulates protein synthesis and inhibits protein degradation in skeletal muscle tissue.
- It is naturally produced in the liver in response to growth hormone stimulation and is also synthesized locally within muscle tissue during exercise.
- IGF-1 works by binding to specific receptors on muscle cells, activating signaling pathways that lead to increased muscle mass and strength.
Importance of Muscle Trophic Factors
Muscle trophic factors like IGF-1 are essential for maintaining muscle health throughout life and become particularly important during recovery from injury or in conditions characterized by muscle wasting. Other important muscle trophic factors include brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF), which support motor neuron survival and function, and promote muscle fiber maintenance, respectively.
Clinical Considerations
In clinical practice, understanding the role of muscle trophic factors can inform strategies for promoting muscle health and recovery. This includes the potential use of exercise and other interventions to stimulate the production of these factors, although specific guidelines would depend on factors such as the individual's health status, age, and the presence of any underlying conditions.
From the Research
Muscle Trophic Factors
- Muscle trophic factors are substances that promote the growth and maintenance of skeletal muscle
- One example of a muscle trophic factor is Insulin-like Growth Factor-1 (IGF-1) 2, 3, 4, 5, 6
Role of IGF-1 in Muscle Growth
- IGF-1 increases skeletal muscle protein synthesis via PI3K/Akt/mTOR and PI3K/Akt/GSK3β pathways 2
- IGF-1 also inhibits muscle protein degradation by suppressing the ubiquitin proteasome system (UPS) and autophagy 2, 3
- IGF-1 signaling is attenuated in disuse conditions, such as denervation, unloading, and joint immobilization, leading to muscle atrophy 3
Effects of IGF-1 on Muscle Atrophy
- IGF-1 overexpression or injection can counteract denervation- and aging-associated muscle atrophy 3
- High levels of IGF-1 binding protein-1 (IGFBP-1) are associated with low relative muscle mass in older women 4
- IGF-1 therapy can improve muscle metabolism, morphology, and function in dystrophic mice, and this effect is further enhanced by a high protein diet 6