8 Questions
Which enzyme is responsible for the oxidative fission and removal of the two-carbon side chain from 17-hydroxypregnenolone in the adrenal cortex?
17,20-lyase enzyme
What is the major androgen produced by the zona reticularis of the adrenal cortex?
Dehydroepiandrosterone (DHEA)
What is DHEA converted into by the actions of 3 β-OHSD and ∆514 isomerase?
Androstenedione
Which hormone is considered a prohormone in the context of adrenal androgen synthesis?
Dehydroepiandrosterone (DHEA)
Which pathway is the major pathway in the adrenal cortex for the conversion of pregnenolone to androgens?
∆5 pathway
What is the fate of most 17-hydroxypregnenolone in the adrenal cortex?
Follows the glucocorticoid pathway
Which of the following statements concerning adrenal steroidogenesis is true?
All reactions involved are irreversible.
Which androgen is produced in small amounts in the adrenal cortex by the same pathway as in the gonads?
Testosterone
Study Notes
Androgens Synthesis
- The zona reticularis and, to a lesser extent, the zona fasciculata of the adrenal cortex produce dehydroepiandrosterone (DHEA) and androstenedione, with androstenedione being the more potent androgen.
Steps of Androgens Synthesis
- 17-hydroxypregnenolone undergoes oxidative fission and removal of the two-carbon side chain by the 17, 20-lyase enzyme, producing DHEA.
- DHEA is converted into androstenedione by the actions of 3β-OHSD and Δ5-4 isomerase.
- A small amount of androstenedione is formed in the adrenal cortex by the action of 17,20 lyase on 17-hydroxyprogesterone.
- A small amount of testosterone is produced in the adrenal cortex through the same pathway as in the gonads.
Adrenal Steroidogenesis
- The pathway of pregnenolone conversion into 17-hydroxypregnenolone and DHEA is called the Δ5 pathway, which is the major pathway.
- The pathway of progesterone conversion into 17-hydroxyprogesterone and androstenedione is called the Δ4 pathway, which is the minor pathway.
- All reactions involved in adrenal steroidogenesis are irreversible.
Learn about the synthesis of androgens in the adrenal cortex, including the roles of zona reticularis and zona fasciculata, and the production of DHEA and androstenedione.
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