the zona fasciculata of the adrenal glands secretes the hormone

Key intracellular signaling molecules, including second messengers and downstream transcription factors, are reviewed. This chapter highlights the regulation of adrenal steroidogenesis. The remaining steps of steroidogenesis take place in the endoplasmic reticulum and mitochondria. To initiate steroidogenesis, cholesterol undergoes facilitated transport from a replenishable pool in the outer mitochondrial membrane to the inner mitochondrial membrane, where CYP11A1 catalyzes the conversion of cholesterol to pregnenolone. Cholesterol can be liberated from stored CEs by hormone-sensitive lipase, an enzyme activated in response to Ang II or ACTH or stimulation. The resultant-free cholesterol can be re-esterified by sterol O-acetyltransferase and stored in lipid droplets. In late endosomes, LDL-derived cholesteryl esters (CEs) are hydrolyzed by lysosomal acid lipase. Most of the cholesterol used for the biosynthesis of adrenal steroids is derived from receptor-mediated endocytosis of plasma low-density lipoproteins (LDL). Angiotensin II (Ang II) and extracellular K + are the principal stimuli of aldosterone secretion, whereas adrenocorticotropic hormone (ACTH) is the main stimulus of cortisol and C 19 steroid production. The human adrenal cortex is divided into concentric zones: the zona glomerulosa produces aldosterone, the zona fasciculata secretes cortisol, and the zona reticularis synthesizes 19-carbon (C 19) androgen precursors.

The zona fasciculata of the adrenal glands secretes the hormone