![]() ![]() I) 17 a -Hydroxylase acts upon either progesterone or pregnenolone to form 17 a - hydroxyprogesterone and/or 17 a -hydroxypregnenolone. Ĭoncentration of receptors is "up-regulated" by high K +Īngiotensin II stimulates the conversion of cholesterol to pregnenolone,Īnd corticosterone to 18-hydroxycorticosterone and aldosterone via G p This conversion is regulated by renin-angiotensin and K +. V) The alcohol is oxidized to an aldehyde formingĪldosterone. Iv) 18-Hydroxylase acts on corticosterone to form I) Pregnenolone is converted to progesterone by Key to Figure, "Biosynthesis of Mineralo- and Gluco. Subcellular Compartmentalization of GlucocorticoidĬorisol (glucocorticoid) synthesis occurs in the ZFĪldosterone (mineralocorticoid) synthesis occurs in the ZG Reaction in Adrenal Steroid Hormone SynthesisĪll mammalian steroid hormones are formed from cholesterol In the mitochondria a cyctochrome P-450 cleavage enzyme (P-450 scc or 20,22-lyase) converts cholesterol to pregnenolone.Ĭholesterol Side-Chain Cleavage (SCC): A "Key" Adrenal hormones free#Zona glomerulosa (ZG) by angiotensin II (IP 3Įsterase is activated and the free cholesterol formed is transported into the (ZF) by ACTH (adrenocorticotropic hormone) (cAMP second messenger), or the adrenal Upon stimulation of the adrenal zona fasciculata ![]() Much of the cholesterol is esterified (by ACAT) and stored in lipid droplets. The adrenal steroid hormones are synthesized from cholesterol derived mostly from the plasma (some cholesterol is synthesized in situ from acetyl-CoA). Steroid hormones are classified according to their physiologicīiosynthesis of the Adrenal Steroid Hormones: If they are oriented below the plane (dashed line). If they are oriented above the plane (solid line). Often contain hydroxyl side chains -> sterols. Intact four ring system (except vitamin D where the B-ring General Structural Features for the Steroid Hormones: ![]()
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