What is the Origin of IGF-I Axis?

The axis was identified in the mid-20th century following the discovery that the effects of GH were largely mediated indirectly by a circulating factor, later identified as IGF-I. The term 'axis' reflects the sequential and regulatory nature of the hormonal cascade, originating in the pituitary (GH) and acting primarily via the liver (IGF-I) to affect target tissues.

What is the Mechanism of IGF-I Axis?

Growth Hormone is released from the pituitary and travels to the liver, where it stimulates the synthesis and secretion of IGF-I. Circulating IGF-I, largely bound to IGF-binding proteins (IGFBPs), then acts on IGF-I receptors in various tissues, initiating intracellular signaling pathways. These pathways promote protein synthesis, inhibit apoptosis, and stimulate cell growth and differentiation. The tight regulation by IGFBPs ensures a stable, controlled delivery of the growth factor to its target cells.

IGF-I Axis

Meaning

The IGF-I Axis refers to the critical endocrine signaling cascade involving Insulin-like Growth Factor I (IGF-I), its binding proteins, and its specific receptors. This axis is primarily regulated by Growth Hormone (GH) and plays a fundamental role in mediating the anabolic and growth-promoting effects of GH in peripheral tissues. It is essential for cell proliferation, tissue repair, bone density maintenance, and overall metabolic health throughout the lifespan. Clinical monitoring of IGF-I levels is a standard proxy for assessing GH status and the effectiveness of growth hormone-related therapies.

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