ACTH function

[dudewheresmymd]

Hey guys,
Can a med student or someone who's taken physiology comment on the role of ACTH? I've seen different workbooks say different things. Is the primary role of ACTH to stimulate the release of glucocorticoids from the adrenal cortex like cortisol? Can it also stimulate the release of mineral corticoids like aldosterone?

I asked my physician friend and they said that ACTH causes the release of cortisol only and that the mechanism for ACTH and aldosterone release should be kept separate? Why do the prep books disagree then?

Examkrackers says ACTH stimulates the adrenal cortex to only release glucocorticoids via cAMP 2nd messenger system, whereas TPR says ACTH stimulates release of both gluco and mineralcorticoids.

Thanks!

Reference question below:

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[mcloaf]

Is the primary role of ACTH to stimulate the release of glucocorticoids from the adrenal cortex like cortisol? Can it also stimulate the release of mineral corticoids like aldosterone?

Yes and yes. Cortisol and aldosterone share common precursors, and by ramping up synthesis of cortisol precursors ACTH ends up increasing the synthesis of both.

 

[dudewheresmymd]

Yes and yes. Cortisol and aldosterone share common precursors, and by ramping up synthesis of cortisol precursors ACTH ends up increasing the synthesis of both.

That makes sense. Thanks! I'm guessing MCAT wouldn't ask us to differentiate between primary/2ndary effect, just knowing that both can be released is good enuff?

 

[mcloaf]

That makes sense. Thanks! I'm guessing MCAT wouldn't ask us to differentiate between primary/2ndary effect, just knowing that both can be released is good enuff?

Knowing just ACTH --> cortisol was all I needed to be fine on the MCAT, and I'd expect that to still be true. I did take it a couple years ago though so my info isn't the most up to date.

 

[SurgeDO]

look at the word:

ACTH = Adreno Cortico Tropic Hormone

Adreno = adrenal gland
Cortico = cortex of adrenal gland
Tropic = a "tropin" is something that promotes the growth of something
Hormone = released into the blood stream

ACTH promotes the growth of the adrenal cortex. the (main) hormones of the adrenal cortex are aldosterone, cortisol, and the androgens.

ACTH's primary effect is on increasing cortisol (by acting on the zona fasciculata of the adrenal cortex). it also an effect on the zona glomerulosa and zona reticularis to increase the secretion of aldosterone and androgens, respectively. probably more than you need to know for the MCAT, so to keep it simpler.

increase in ACTH:

-increases cortisol
-increases androgen (slightly)
-increases aldosterone production

 

[dudewheresmymd]

look at the word:

ACTH = Adreno Cortico Tropic Hormone

Adreno = adrenal gland
Cortico = cortex of adrenal gland
Tropic = a "tropin" is something that promotes the growth of something
Hormone = released into the blood stream

ACTH promotes the growth of the adrenal cortex. the (main) hormones of the adrenal cortex are aldosterone, cortisol, and the androgens.

ACTH's primary effect is on increasing cortisol (by acting on the zona fasciculata of the adrenal cortex). it also an effect on the zona glomerulosa and zona reticularis to increase the secretion of aldosterone and androgens, respectively. probably more than you need to know for the MCAT, so to keep it simpler.

increase in ACTH:

-increases cortisol
-increases androgen (slightly)
-increases aldosterone production

thx for the clarification! 🙂 lmao i didnt' even know adrenal cortex secreted androgens thx tho.

 

[SurgeDO]

thx for the clarification! 🙂 lmao i didnt' even know adrenal cortex secreted androgens thx tho.

Very, very small amounts of androgen (~5% of total body androgens are made in the zona reticularis). It is important to remember in the event of tumors in the adrenal cortex. Pts. with adrenal tumors can sometimes present with heightened secondary masculine characteristics.

 

[dyspareunia]

look at the word:

ACTH = Adreno Cortico Tropic Hormone

Adreno = adrenal gland
Cortico = cortex of adrenal gland
Tropic = a "tropin" is something that promotes the growth of something
Hormone = released into the blood stream

ACTH promotes the growth of the adrenal cortex. the (main) hormones of the adrenal cortex are aldosterone, cortisol, and the androgens.

ACTH's primary effect is on increasing cortisol (by acting on the zona fasciculata of the adrenal cortex). it also an effect on the zona glomerulosa and zona reticularis to increase the secretion of aldosterone and androgens, respectively. probably more than you need to know for the MCAT, so to keep it simpler.

increase in ACTH:

-increases cortisol
-increases androgen (slightly)
-increases aldosterone production

ACTH does not have a significant effect on aldosterone production. Associate ACTH with cortisol only. Associate Angiotensin II with aldo.

Adrenocorticotropic hormone means adrenal corticoids, not adrenal cortex. Corticoids (corticosteroids) == cortisol.

 

[SurgeDO]

ACTH does not have a significant effect on aldosterone production. Associate ACTH with cortisol only. Associate Angiotensin II with aldo.

Adrenocorticotropic hormone means adrenal corticoids, not adrenal cortex. Corticoids (corticosteroids) == cortisol.

you are wrong. ACTH stimulates the production of all the hormones of the adrenal cortex. it is most noted for its effects on cortisol, but it also stimulates aldosterone and androgen production.

 

[dyspareunia]

you are wrong. ACTH stimulates the production of all the hormones of the adrenal cortex. it is most noted for its effects on cortisol, but it also stimulates aldosterone and androgen production.

Is this why people look down on DOs? Because they don't understand basic science?

As I said before, ACTH does not have a significant effect on aldo. This is why you don't see significant atrophy of the zona glomerulosa in hypopituitary patients (though you do see atrophy of ZF and ZR) and also why you don't include mineralocorticoids in HRT for hypopituitary patients (though you do include corticosteroids and sex steroids).

Aldo is primarily regulated by RAAS and also possibly ANP. ACTH is almost irrelevant.

 

[SurgeDO]

Is this why people look down on DOs? Because they don't understand basic science?

As I said before, ACTH does not have a significant effect on aldo. This is why you don't see significant atrophy of the zona glomerulosa in hypopituitary patients (though you do see atrophy of ZF and ZR) and also why you don't include mineralocorticoids in HRT for hypopituitary patients (though you do include corticosteroids and sex steroids).

Aldo is primarily regulated by RAAS and also possibly ANP. ACTH is almost irrelevant.

That's nice and all, but look at choice B in OPs original question.

I appreciate the science lesson though, bro.

EDIT:

ACTH does increase the secretion of aldosterone. its effect is significant enough that it should be noted and considered when answering a question.