What is the Origin of Somatostatin Feedback?

The term is derived from the hormone's original name, Growth Hormone Inhibiting Hormone (GHIH), and its action of providing "feedback" to the endocrine glands. Somatostatin itself was first isolated from the hypothalamus, demonstrating its central role in neuroendocrine control. The term highlights the intricate, self-regulating nature of the body's hormonal systems.

What is the Mechanism of Somatostatin Feedback?

Somatostatin binds to specific somatostatin receptors (SSTRs) located on the surface of secretory cells, such as the somatotrophs in the anterior pituitary. Receptor binding activates inhibitory G-proteins, which in turn reduce intracellular cyclic AMP (cAMP) levels and inhibit voltage-gated calcium channels. This sequence of events hyperpolarizes the cell and reduces the exocytosis of pre-formed hormone vesicles, thereby rapidly and effectively halting the release of GH and other target hormones.

Somatostatin Feedback

Meaning

A critical inhibitory mechanism within the neuroendocrine system where the peptide hormone somatostatin acts to suppress the secretion of various other hormones, particularly Growth Hormone (GH) and Thyroid-Stimulating Hormone (TSH). This negative feedback loop ensures hormonal levels remain within a tight physiological range, preventing overproduction. In the context of the hypothalamic-pituitary axis, hypothalamic somatostatin release is stimulated by high circulating GH and IGF-1 levels, completing the feedback loop to reduce GH secretion from the pituitary. This regulatory system is vital for maintaining metabolic and growth homeostasis.