Biochem of steroid hormone

• what are the two types of steroid hormone?

  corticosteroids & sex steroids
• where are corticosteroids produced?


  adrenal cortex
• where are sex steroids produced


  gonads or placenta
• example of a corticosteroid = glucocorticoids, cortisol
• cortisol regulates metabolism
• example of sex steroids = androgens, testosterone
• hypothalamic hypophysiotropic hormones are produced in the neurosecretory cells of the hypothalamus
• steroid hormones are derived from cholesterol
• steroid hormones are synthesized in the liver
• cholesterol is amphipathic molecule
• Steroid Hormone Synthesis

  modification: shortening of hydrocarbon tail, hydroxylation of steroid nucleus
• key enzymes in steroid hormone synthesis

  cytochrome P450 (CYP)

  requires NADPH & Oxygen

  located in the endoplasmic reticulum & mitochondria of the adrenal gland
• first steps in steroid synthesis

  StAR (protein) that controls the uptake of cholesterol into the mitochondria

  cholesterol converted to pregnenolone

  catalysed by the enzyme, cytochrome P450

  NADPH & Oxygen are required,

  occurs in the adrenal gland, ovaries & testes
• Progesterone is synthesized from pregnenolone


  converts the 3-hydroxyl group to a 3-keto group
• function of cortisol


  enhances gluconeogenesis

  metabolism (increases blood glucose)

  immune response (suppresses inflammation)

  stress response (helps body manage stress)
• function of aldosterone


  salt & water balance - promotes sodium reabsorption in kidneys

  blood pressure regulation - increases blood volume & pressure
• gene expression alters the production of proteins which leads to cellular responses
• Cellular Mode of Action of Steroid Hormones

  1.Steroid hormones are lipophilic and diffuse across the cell membrane.

  2. Inside the cell, they bind to specific intracellular receptors.

  3.The hormone-receptor complex translocates to the nucleus and binds to hormone response elements (HREs) on DNA.

  4.This binding regulates gene transcription, leading to changes in protein synthesis that drive cellular responses.
• Glucocorticoid Deficiency

  •Condition: Addison's Disease

  •Causes: Insufficient cortisol production.

  •Symptoms:

  •Fatigue

  •Low blood pressure

  •Weight loss

  •Hyperpigmentation of the skin
• Mineralocorticoid Deficiency

  •Condition: Hypoaldosteronism

  •Causes: Insufficient aldosterone production.

  •Symptoms:

  •Dehydration

  •Low blood sodium levels (hyponatremia)

  •High potassium levels (hyperkalemia)

  Hypotension (low blood pressure)
• Congenital Adrenal Hyperplasia

  failure to secrete cortisol

  enlarged adrenal glands

  results in reduced levels of cortisol or aldosterone with overproduction of androgen