Somatotrophs are stimulated by: GHRH Somatostatin GH GnRH

Somatotrophs are specialized cells in the anterior pituitary gland responsible for the production and secretion of growth hormone (GH). The regulation of somatotroph activity is primarily influenced by specific releasing and inhibiting factors: 1. **GHRH (Growth Hormone-Releasing Hormone):** - **Stimulatory Effect:** GHRH is produced in the hypothalamus and directly stimulates somatotrophs to secrete growth hormone. It binds to receptors on somatotrophs, initiating a cascade that results in GH release. 2. **Somatostatin:** - **Inhibitory Effect:** Also produced in the hypothalamus, somatostatin acts to inhibit the secretion of growth hormone from somatotrophs. It serves as a regulatory mechanism to prevent excessive GH release. 3. **GH (Growth Hormone):** - **Negative Feedback:** While GH itself doesn’t stimulate somatotrophs, it participates in a negative feedback loop. Elevated levels of GH signal the hypothalamus and pituitary to reduce the release of GHRH and increase somatostatin, thereby decreasing further GH secretion. 4. **GnRH (Gonadotropin-Releasing Hormone):** - **No Direct Effect:** GnRH specifically targets gonadotrophs in the anterior pituitary to stimulate the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). It does not have a direct role in stimulating somatotrophs. **Summary:** - **Stimulates Somatotrophs:** GHRH - **Inhibits Somatotrophs:** Somatostatin - **No Direct Stimulation:** GH, GnRH **Correct Answer:** GHRH (Growth Hormone–Releasing Hormone) stimulates somatotrophs.