Aldosterone secretion from the zona glomerulosa is stimulated by angiotensin II. The post-receptor signaling mechanism in zona glomerulosa cells predominantly involves:

• A Gαs → adenylyl cyclase → cAMP → PKA → StAR protein phosphorylation
• B JAK-STAT pathway activation leading to nuclear translocation of STAT5
• C Gαq → PLCβ → IP₃ → intracellular Ca²⁺ rise → CaMK II activation → StAR synthesis and CYP11B2 induction ✓
• D β-arrestin recruitment causing receptor internalization and ERK1/2 activation only

Explanation

Angiotensin II AT1 receptors couple to Gαq, activating phospholipase Cβ → IP₃ + DAG. IP₃ releases intracellular Ca²⁺, raising [Ca²⁺]i and activating CaMKII. This increases expression of StAR (steroidogenic acute regulatory protein, which shuttles cholesterol into mitochondria — the rate-limiting step) and induces CYP11B2 (aldosterone synthase) transcription. Cortisol synthesis in the zona fasciculata uses ACTH → Gαs → cAMP → PKA pathway. The distinction is functionally important as ACTH does not drive aldosterone secretion at physiological concentrations.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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