Insulin-like Growth Factor 1 (IGF-1)

Insulin-Like Growth Factor 1 (IGF-1): Overview and Functions

Insulin-like Growth Factor 1 (IGF-1) is a polypeptide hormone that plays a critical role in growth and development throughout life. It is primarily produced in the liver in response to growth hormone (GH) stimulation and has significant effects on various tissues and cellular functions.

Key Features of IGF-1

• Production and Regulation:

• IGF-1 is synthesized mainly in the liver, with production stimulated by growth hormone. It circulates in the bloodstream, mostly bound to insulin-like growth factor binding proteins (IGFBPs), which regulate its bioavailability and activity. The highest levels of IGF-1 occur during puberty, while levels decline with age .

• Biological Functions:

• Cell Growth and Differentiation: IGF-1 promotes cell proliferation, differentiation, and survival across various tissues, including muscle, cartilage, bone, and nerve cells. It is crucial for skeletal muscle development and maintenance, as it increases muscle mass and prevents atrophy .
• Metabolic Effects: IGF-1 influences glucose metabolism by enhancing glucose uptake in muscle and fat tissues while inhibiting hepatic glucose production. This regulation helps maintain energy homeostasis in the body .

• Mechanism of Action:

• IGF-1 exerts its effects primarily by binding to the IGF-1 receptor (IGF1R), a receptor tyrosine kinase that initiates intracellular signaling cascades involving pathways such as the Akt/mTOR pathway. This signaling promotes cell growth, protein synthesis, and inhibits apoptosis (programmed cell death) .

• Role in Aging:

• The levels of IGF-1 decline with age, which has been associated with age-related changes in body composition, muscle mass loss, and decreased metabolic function. Research suggests that maintaining optimal IGF-1 levels may have implications for longevity and healthspan .

• Clinical Relevance:

• Abnormal IGF-1 levels are linked to various health conditions:
  • Low IGF-1 Levels: Associated with growth hormone deficiency, malnutrition, and increased risk of cardiovascular diseases.
  • High IGF-1 Levels: Linked to an increased risk of certain cancers due to its role in promoting cell proliferation .
• IGF-1 is also studied for its potential therapeutic applications in treating muscle-wasting conditions and other disorders related to aging.

Conclusion

Insulin-like Growth Factor 1 (IGF-1) is a vital hormone involved in growth, metabolism, and cellular function. Understanding its mechanisms and effects can provide insights into health maintenance during aging and the management of various diseases.

References

1. Wikipedia contributors. (2023). “Insulin-like growth factor 1.” In Wikipedia, The Free Encyclopedia. Retrieved from Wikipedia.
2. Physiopedia. (n.d.). “Insulin Like Growth Factor-1 (IGF-1).” Retrieved from Physiopedia.
3. NCBI. (2020). “The Role of Insulin-like Growth Factor-1 (IGF-1) in the Control of Metabolism.” Retrieved from NCBI.
4. NCBI. (2017). “Insulin-Like Growth Factor-1 Physiology: Lessons from Mouse Models.” Retrieved from NCBI.
5. Assay Genie. (2023). “Guide to Understanding Th1 and Th2 Cells.” Retrieved from Assay Genie.