Skeletal muscle atrophy is characterized by a reduction in both the size and quantity of skeletal muscle fibers, resulting in impaired muscle strength and function. It mainly includes disuse muscle atrophy, aging muscle atrophy, denervated muscle atrophy and muscle atrophy caused by disease <i>etci>. As a cost-effective way, exercise has been widely used in the prevention and treatment of skeletal muscle atrophy, but its mechanism for improving skeletal muscle atrophy remains unclear. Recent studies have indicated that insulin-like growth factor 1 (IGF-1) plays an important role in improving muscle atrophy through exercise, in addition to promoting the survival of neurons, lowering blood sugar, and anti-inflammation. This article reviews recent findings on the mechanisms by which IGF-1 mediates exercise-induced improvement in skeletal muscle atrophy, providing a theoretical basis for the prevention and treatment of this disease.
Insulin-Like Growth Factor I/physiology* ; Muscular Atrophy/therapy* ; Humans ; Exercise/physiology* ; Muscle, Skeletal ; Animals ; Insulin-Like Peptides

The maintenance of skeletal muscle quality involves various signal pathways that interact with each other. Under normal physiological conditions, these intersecting signal pathways regulate and coordinate the hypertrophy and atrophy of skeletal muscles, balancing the protein synthesis and degradation of muscle. When the total rate of protein synthesis exceeds that of protein degradation, the muscle gradually becomes enlarged, while when the total rate of protein synthesis is lower than that of protein degradation, the muscle shrinks. Myocyte atrophy mainly involves two protein degradation pathways, namely ubiquitin-proteasome and autophagy-lysosome. Protein degradation pathway is activated during muscle atrophy, resulting in the loss of muscle mass. Muscle atrophy can occur under various conditions such as malnutrition, aging and cachexia. Skeletal muscle atrophy caused by orthopedic diseases mainly includes disuse muscular atrophy caused by fracture and denervation muscular atrophy. The signal pathways that control and coordinate protein synthesis and degradation in skeletal muscle include insulin-like growth factor 1 (IGF1)-Akt-mammalian target of rapamycin (mTOR), myostatin-activin A-Smad, G protein α inhibitory peptide 2 (Gαi2)-PKC, nuclear factor κB (NF-κB), ectodysplasin A2 receptor (EDA2R)-NF-κB inducing kinase (NIK) and mitogen-activated protein kinase (MAPK) pathways. This paper provides a comprehensive review of the protein degradation pathways in skeletal muscle atrophy and the associated signal pathways regulating protein degradation in muscular atrophy.
Humans ; Muscular Atrophy/etiology* ; Muscle, Skeletal/pathology* ; Signal Transduction ; Animals ; Insulin-Like Growth Factor I/metabolism* ; Myostatin/physiology* ; TOR Serine-Threonine Kinases/metabolism* ; Autophagy/physiology* ; NF-kappa B/metabolism* ; Proteolysis ; Proteasome Endopeptidase Complex/physiology*

To explore the effect and mechanism of Zuogui Pills in promoting neural tissue recovery and functional recovery in mice with ischemic stroke. Male C57BL/6J mice were randomly divided into a sham group, a model group, and low-, medium, and high-dose Zuogui Pills groups(3.5, 7, and 14 g·kg~(-1)), with 15 mice in each group. The ischemic stroke model was established using photochemical embolization. Stiker remove and irregular ladder walking behavioral tests were conducted before modeling and on days 7, 14, 21, and 28 after medication. Triphenyl tetrazolium chloride(TTC) staining was performed on day 3 after modeling, and T2-weighted imaging(T2WI) and diffusion-weighted imaging(DWI) were performed on day 28 after medication to evaluate the extent of brain injury. Hematoxylin-eosin(HE) staining was performed to observe the histology of the cerebral cortex. Axonal marker proteins myelin basic protein(MBP), growth-associated protein 43(GAP43), mammalian target of rapamycin(mTOR), and its downstream phosphorylated s6 ribosomal protein(p-S6), as well as mechanism-related proteins osteopontin(OPN) and insulin-like growth factor 1(IGF-1), were detected using immunofluorescence and Western blot. Zuogui Pills had a certain restorative effect on the neural function impairment caused by ischemic stroke in mice. TTC staining showed white infarct foci in the sensory-motor cortex area, and T2WI imaging revealed cystic necrosis in the sensory-motor cortex area. The Zuogui Pills groups showed less brain tissue damage, fewer scars, and more capillaries. The number of neuronal axons in those groups was higher than that in the model group, and neuronal activity was stronger. The expression of GAP43, OPN, IGF-1, and mTOR proteins in the Zuogui Pills groups was higher than that in the model group. In summary, Zuogui Pills can promote the recovery of neural function and axonal growth in mice with ischemic stroke, and its mechanism may be related to the activation of the OPN/IGF-1/mTOR signaling pathway.
Mice ; Animals ; Male ; Ischemic Stroke ; Recovery of Function/physiology* ; Insulin-Like Growth Factor I/pharmacology* ; Mice, Inbred C57BL ; TOR Serine-Threonine Kinases/metabolism* ; Stroke/drug therapy* ; Brain Ischemia/drug therapy* ; Mammals/metabolism*

PURPOSE: MicroRNAs are small non-coding RNAs that play important roles in vascular smooth muscle cell (VSMC) function. This study investigated the role of miR-379 on proliferation, invasion, and migration of VSMCs and explored underlying mechanisms thereof. MATERIALS AND METHODS: MicroRNA, mRNA, and protein levels were determined by quantitative real-time PCR and western blot. The proliferative, invasive, and migratory abilities of VSMCs were measured by CCK-8, invasion, and wound healing assay, respectively. Luciferase reporter assay was used to confirm the target of miR-379. RESULTS: Platelet-derived growth factor-bb was found to promote cell proliferation and suppress miR-379 expression in VSMCs. Functional assays demonstrated that miR-379 inhibited cell proliferation, cell invasion, and migration. Flow cytometry results further showed that miR-379 induced apoptosis in VSMCs. TargetScan analysis and luciferase report assay confirmed that insulin-like growth factor-1 (IGF-1) 3'UTR is a direct target of miR-379, and mRNA and protein levels of miR-379 and IGF-1 were inversely correlated. Rescue experiments showed that enforced expression of IGF-1 sufficiently overcomes the inhibitory effect of miR-379 on cell proliferation, invasion, and migration in VSMCs. CONCLUSION: Our results suggest that miR-379 plays an important role in regulating VSMCs proliferation, invasion, and migration by targeting IGF-1.
Apoptosis ; Cell Movement/*physiology ; Cell Proliferation/*physiology ; Humans ; Insulin ; Insulin-Like Growth Factor I/*physiology ; MicroRNAs/*physiology ; Muscle, Smooth, Vascular/*cytology ; Proto-Oncogene Proteins c-sis/*physiology ; RNA, Messenger/metabolism ; Real-Time Polymerase Chain Reaction ; Sincalide/physiology ; Wound Healing/physiology

BACKGROUND: Despite many ongoing, prospective studies on the topic, sepsis still remains one of the main causes of death in hospital. The hormone insulin-like growth factor 1 (IGF-1) has a similar molecular structure to that of insulin. IGF-1 exerts anabolic effects and plays important roles in both normal physiology and pathologic processes. Previous studies have observed low serum IGF-1 level in patients with critical illnesses. Here, we evaluated changes in IGF-1 level based on survival of septic patients. METHODS: We evaluated 140 patients with sepsis and septic shock (21 with sepsis and 119 with septic shock) admitted to the intensive care unit of a university-affiliated hospital in Korea. Serum IGF-1 level was measured on days 0, 1, 3, and 7. Patients with liver disease were excluded from this study. All data were analyzed using SPSS version 20 (SPSS Inc., Chicago, IL, USA). RESULTS: Patients with septic shock had significantly lower serum IGF-1 level on days 1 and 3 than patients without septic shock (p = 0.002 and p = 0.007, respectively). Generally, there was a negative relationship between IGF-1 and serum cortisol levels; however, this relationship was only significant on day 3 (p = 0.029). Furthermore, renin showed significantly negative correlation with IGF-1 on day 3 (p = 0.038). IGF-1 level did not show significant difference between survivors and non-survivors. CONCLUSIONS: Our results showed that IGF-1 was associated with septic shock, and that the IGF-1 axis is severely disrupted in septic patients. Additionally, serum cortisol and renin levels were associated with IGF-1 level.
Anabolic Agents ; Cause of Death ; Critical Illness ; Humans ; Hydrocortisone ; Insulin ; Insulin-Like Growth Factor I ; Intensive Care Units ; Korea ; Liver Diseases ; Molecular Structure ; Pathologic Processes ; Physiology ; Prospective Studies ; Renin ; Sepsis* ; Shock, Septic* ; Survivors

BACKGROUND: Despite many ongoing, prospective studies on the topic, sepsis still remains one of the main causes of death in hospital. The hormone insulin-like growth factor 1 (IGF-1) has a similar molecular structure to that of insulin. IGF-1 exerts anabolic effects and plays important roles in both normal physiology and pathologic processes. Previous studies have observed low serum IGF-1 level in patients with critical illnesses. Here, we evaluated changes in IGF-1 level based on survival of septic patients. METHODS: We evaluated 140 patients with sepsis and septic shock (21 with sepsis and 119 with septic shock) admitted to the intensive care unit of a university-affiliated hospital in Korea. Serum IGF-1 level was measured on days 0, 1, 3, and 7. Patients with liver disease were excluded from this study. All data were analyzed using SPSS version 20 (SPSS Inc., Chicago, IL, USA). RESULTS: Patients with septic shock had significantly lower serum IGF-1 level on days 1 and 3 than patients without septic shock (p = 0.002 and p = 0.007, respectively). Generally, there was a negative relationship between IGF-1 and serum cortisol levels; however, this relationship was only significant on day 3 (p = 0.029). Furthermore, renin showed significantly negative correlation with IGF-1 on day 3 (p = 0.038). IGF-1 level did not show significant difference between survivors and non-survivors. CONCLUSIONS: Our results showed that IGF-1 was associated with septic shock, and that the IGF-1 axis is severely disrupted in septic patients. Additionally, serum cortisol and renin levels were associated with IGF-1 level.
Anabolic Agents ; Cause of Death ; Critical Illness ; Humans ; Hydrocortisone ; Insulin ; Insulin-Like Growth Factor I ; Intensive Care Units ; Korea ; Liver Diseases ; Molecular Structure ; Pathologic Processes ; Physiology ; Prospective Studies ; Renin ; Sepsis ; Shock, Septic ; Survivors

Mechano growth factor (MGF) is an autocrine/paracrine factor and sensitive to mechanical stimulation. MGF can be highly expressed in various soft tissues under physical stimuli, biochemistry stimuli or in damaged situation. MGF may "compensate" the stress for tissue in the processing of tissue repair. MGF can effectively accelerate the repair of the soft tissue by promoting the proliferation, migration and differentiation of cells. This paper summarizes the MGF expressions in different soft tissues and their functions in soft tissue repair. The paper also discusses current problems and challenges in using MGF to repair the soft tissue.
Cell Differentiation ; Cell Proliferation ; Humans ; Insulin-Like Growth Factor I ; physiology ; Soft Tissue Injuries ; Wound Healing

The type 1 insulin-like growth factor receptor (IGF-1R) and its downstream signaling components have been increasingly recognized to drive the development of malignancies, including non-small cell lung cancer (NSCLC). This study aimed to investigate the effects of IGF-1R and its inhibitor, AG1024, on the progression of lung cancer. Tissue microarray and immunohistochemistry were employed to detect the expressions of IGF-1 and IGF-1R in NSCLC tissues (n=198). Western blotting was used to determine the expressions of IGF-1 and phosphorylated IGF-1R (p-IGF-1R) in A549 human lung carcinoma cells, and MTT assay to measure cell proliferation. Additionally, the expressions of IGF-1, p-IGF-1R and IGF-1R in a mouse model of lung cancer were detected by Western blotting and real-time fluorescence quantitative polymerase chain reaction (FQ-PCR), respectively. The results showed that IGF-1 and IGF-1R were overexpressed in NSCLC tissues. The expression levels of IGF-1 and p-IGF-1R were significantly increased in A549 cells treated with IGF-1 as compared to those treated with IGF-1+AG1024 or untreated cells. In the presence of IGF-1, the proliferation of A549 cells was significantly increased. The progression of lung cancer in mice treated with IGF-1 was significantly increased as compared to the group treated with IGF-1+AG1024 or the control group, with the same trend mirrored in IGF-1/p-IGF-1R/IGF-1R at the protein and/or mRNA levels. It was concluded that IGF-1 and IGF inhibitor AG1024 promotes lung cancer progression.
Adult ; Aged ; Animals ; Carcinoma, Non-Small-Cell Lung ; metabolism ; pathology ; Cell Proliferation ; Disease Models, Animal ; Disease Progression ; Female ; Humans ; Insulin-Like Growth Factor I ; metabolism ; Lung Neoplasms ; metabolism ; pathology ; Male ; Mice ; Middle Aged ; Receptor, IGF Type 1 ; antagonists & inhibitors ; physiology ; Tyrphostins ; pharmacology

Since its discovery in 1921, insulin has been considered to be the most important hormone in the regulation of glucose and fat metabolism. In recent years, studies have revealed that besides metabolism regulation, insulin can also act as a growth factor like hormone in regulating multiple processes and various cellular activities in the process of wound healing. This review summarizes the role of insulin in wound healing and its underlying mechanism.
Glucose ; metabolism ; Growth Hormone ; metabolism ; physiology ; Humans ; Insulin ; physiology ; Insulin-Like Growth Factor I ; physiology ; Insulin-Like Growth Factor II ; physiology ; Wound Healing ; physiology

OBJECTIVETo observe the effect of the postpone in skeletal muscle aging process of D-galactose rats by weight training and soy polypeptide supplement in 6 weeks, and discuss the initial mechanism.

METHODSixty male SD rats (three month old)were randomly assigned: 6 week control (C6,) and 6 week model (M6) 6 for each group, 12 week model (M12), big load (B12), small load (S12), peptide (P12), peptide + big load (PB12) and peptide + small load group (PS12) 8 for each group, eight fourteen month rats were taken in the natural aging group. The rats were killed by the end of 6th week and 12th week, tested the indicators.

RESULTCompare with group C6, the indicators in group M6 showed aging in different levels; Compare with group M12, weight training or soy polypeptide supplement in all intervention groups could increase the content of skeletal muscle superoxide dismutase (SOD), SOD/MDA, the serum growth hormone(GH), insulin-like growth factor-1 (IGF-I)and skeletal muscle IGF-I mRNA, decreased the malondialdehyde (MDA) content of skeletal muscle, and they had notable interaction.

CONCLUSIONRat skeletal muscle aging model can be copied successfully by D-galactose hypodermic, and go on with 6-week weight training or soy polypeptide supplement, they can postpone the skeletal muscle aging process of D-galactose rats, and the two interference way united can have more obvious effect. Its preliminary mechanism may be related to the reduction of skeletal muscle oxidative stress and lipid peroxidation, the correction of hormones and related factors metabolic disorders, the elevation of skeletal muscle IGF-I mRNA expression and so on.

Aging ; physiology ; Animals ; Galactose ; Growth Hormone ; blood ; Insulin-Like Growth Factor I ; metabolism ; Male ; Malondialdehyde ; metabolism ; Muscle, Skeletal ; drug effects ; physiology ; Physical Conditioning, Animal ; physiology ; Rats ; Rats, Sprague-Dawley ; Soybean Proteins ; pharmacology ; Soybeans ; chemistry ; Superoxide Dismutase ; metabolism