What is the Origin of Growth Hormone Axis Sensitivity?

This term is rooted in the endocrinology of the somatotropic axis, specifically the negative feedback loop involving the hypothalamus, pituitary, liver, and peripheral tissues. The concept of 'sensitivity' gained prominence with the understanding that age-related decline in GH action is not solely due to decreased secretion but also due to post-receptor resistance, similar to insulin resistance. This understanding guides the nuanced treatment of adult growth hormone deficiency.

What is the Mechanism of Growth Hormone Axis Sensitivity?

The sensitivity is largely governed by the density and functionality of GH receptors on cell surfaces and the efficiency of the intracellular signaling pathways, such as the JAK-STAT pathway. Chronic inflammation, visceral adiposity, and high insulin levels are known to downregulate these receptors and impair post-receptor signaling, thereby reducing sensitivity. Strategies to improve sensitivity include optimizing body composition, enhancing mitochondrial function, and using GH secretagogues to restore more physiological, pulsatile GH release.

Growth Hormone Axis Sensitivity ∞ Area

Growth Hormone Axis Sensitivity

Meaning

Growth Hormone Axis Sensitivity refers to the degree of responsiveness of the peripheral tissues, primarily the liver and target cells, to the signaling cascade initiated by Growth Hormone (GH) and its downstream mediator, Insulin-like Growth Factor 1 (IGF-1). A decline in this sensitivity, often seen with age or metabolic syndrome, can impair GH’s anabolic, lipolytic, and tissue repair functions, even when circulating GH levels are adequate. Clinical interventions often focus on restoring this cellular responsiveness.