#aldosterone

Part 3

ACTH & Adrenocortical hormones.

ACTH :

Polypeptide hormone produced and secreted by the anterior pituitary gland in the brain. ACTH regulates the levels of the hormones produced by the adrenal glands.

ACTH synthesis:

Preproopiomelanocortin -(cleaved)-> POMC -> (splits into many peptides one of them is ACTH)

ACTH release:

Pulsatile manner

Peaks in the morning.

ACTH role:

ACTH binds to its receptors and activates the release of cortico-steroid hormones:

Glucocorticoids : anti-inflammatory & metabolic effects

Mineralocarticoids: Electrolyte and water balance.

Adrenocortical Hormones:

Once ACTH binds to its receptors on the cells of the layers of the adrenal cortex it stimulates these cells to take cholesterol from the blood which is essential for adrenocortical hormones synthesis.

ACTH stimulates cholesterol desmolase enzyme inside these cells.

cholesterol desmolase converts:

Cholesterol -> pregnenolone

The adrenal cortex has 3 layers (as we mentioned in part 1)

Zona glomerulosa -> Aldosterone.

Zona fasciculata -> Cortisol

Zona reticularis -> Androgens.

The synthesis of Aldosterone: {image}

Aldosterone ⬆⬆ blood volume & ⬆⬆ blood pressure.

Pregnenolone --(3beta-HSD) → progesterone --(21beta-hydroxylase)

→ 11-DOC --(11 beta- hydroxylase)→ corticosterone -- (18 hydroxylase)

→ 18-hydroxy-corticosterone → ALDOSTERONE.

3beta-HSD= 3 Beta- hydroxysteroid dehydrogenase

11- DOC = 11- deoxycorticosterone

Aldosterone function:

Regulation of sodium concentration

⬆Blood volume → ⬆ blood pressure.

How?

Binds to receptors on the cells lining the distal tubule and collecting ducts → ⬆⬆ sodium/potassium pumps → ⬆⬆ sodium reabsorption into the blood → ⬆⬆ blood volume → ⬆⬆ blood pressure.

The synthesis of cortisol : {image }

1. Pregnenolone & progesterone -(17 alpha-hydroxylase)→

17 alpha- hydroxy-pregnenolone & 17 alpha-hydroxy -progesterone.

2. 17 alpha-hydroxy pregnenolone -(3beta-HSD) → 17 alpha-hydroxy -progesterone -(21beta-hydroxylase) → 11-Deoxycortisol → CORTISOL.

Cortisol function:

Cortisol is not stored but secreted once produced.

Pulsatile manner & peaks in the morning.

It is also secreted in stressful situations like - infections - caffeine - hypoglycemia (low blood sugar levels)

Cortisol is anti-inflammatory hormone and it inhibites: prostaglandin & leukotrienes.

Cortisol effects on the body:

Cortisol ⬆⬆ blood glucose & blood pressure

Fat → activates lipolysis → breaking down of fat in adipose tissue.

Liver → activates gluconeogenesis & glycogenolysis

⬆⬆ insulin resistance → diabetogenic

Muscles → activates proteolysis

⬆⬆Blood pressure

⬇⬇ bone formation

Poor wound healing.

What is cortisone?

Some tissues can convert cortisol to cortisone by the enzyme 11 beta- hydroxysteroid-dehydrogenase 2.

Cortisone has marginally reduced glucocorticoid activity compared to cortisol (80-90%), and thus, cortisone can be considered an active metabolite of cortisol.

Androgens : {image}

17 alpha-hydroxypregnenolone → DHEA → Androstenediol → Testosterone.

DHEA → Androstenedione → Testosterone

17 alpha hydroxyprogesterone → Androstenedione → Testosterone.

Testosterone → Estrogen by the enzyme Aromatase.

Note:

The amount of testosterone secreted by the adrenal glands is very small compared to the one produced by the testes.

Part 1 { here}

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The scientific Research Notes Of S. Sunkavally (years: 2002-2011).