Dictionary > Steroidogenesis

Steroidogenesis

Definition
noun, plural: steroidogeneses
The biosynthesis of steroid hormones from cholesterol by various cells, such as those of adrenal glands, ovaries, testes, etc.
Supplement
Steroidogenesis is a biological process of steroid hormone production. Apart from the natural production by living organisms, various steroids are also produced synthetically for their medical uses. Steroidogenesis, though, is restricted to the biological production of steroids.
Human steroidogenesis, in particular, is the production of steroid hormones in humans. Steroid hormones include (1) sex steroids (hormones), (2) corticosteroids (e.g. glucocorticoids and mineralocorticoids), and (3) anabolic steroids. Sex steroid hormones are androgens (e.g. testosterone), estrogens (e.g. estradiol), and progestogens (e.g. progesterone).
All steroidogenic cells that produce steroids start with cholesterol being converted first into a C-21 steroid, pregnenolone, within the mitochondrion. The cholesterol may be produced within the cell from acetate or from stored cholesterol ester within the lipid droplet. The cholesterol may also come from the circulating cholesterol-containing LDL. The cholesterol is taken in by the cell and transported into the mitochondrion. The conversion of cholesterol into pregnenolone occurs in the inner membrane of mitochondrion by the aid of the enzyme called CYP11A1 (also called side-chain cleavage enzyme).
The pregnenolone is converted to either 17-hydroxypregnenolone or to progesterone. The enzyme CYP17 is the enzyme involved in the conversion of pregnenolone to 17-hydroxypregnenolone whereas the enzyme 3 beta-HSD is the enzyme involved in pregnenolone → progesterone.
The major pathways of steroidogenesis are as follows:
Androgen, particularly testosterone, biosynthesis:

  • Pregnenolone → Progesterone → 17-hydroxyprogesterone → Androstenedione ⇄ Testosterone
  • Pregnenolone → 17-hydroxypregnenolone → 17-hydroxyprogesterone → Androstenedione → Testosterone
  • Pregnenolone → 17-hydroxypregnenolone → Dehydroepiandrosterone → Androstenedione → Testosterone

Estrogen biosynthesis:

  • Pregnenolone → Progesterone → 17-hydroxyprogesterone → Androstenedione → Estrone Estradiol
  • Pregnenolone → 17-hydroxypregnenolone → 17-hydroxyprogesterone → Androstenedione → EstroneEstradiol
  • Pregnenolone → 17-hydroxypregnenolone → Dehydroepiandrosterone → Androstenedione → EstroneEstradiol
  • Pregnenolone → Progesterone → 17-hydroxyprogesterone → Androstenedione ⇄ Testosterone → Estradiol
  • Pregnenolone → 17-hydroxypregnenolone → 17-hydroxyprogesterone → Androstenedione → Testosterone → Estradiol
  • Pregnenolone → 17-hydroxypregnenolone → Dehydroepiandrosterone → Androstenedione → Testosterone → Estradiol
  • Progesterone biosynthesis:

    • Pregnenolone → Progesterone

    Corticosteroid biosynthesis:

  • Pregnenolone → Progesterone → 17-hydroxyprogesterone → 11-deoxycorstisol → Cortisol
  • Pregnenolone → 17-hydroxypregnenolone → 17-hydroxyprogesterone → 11-deoxycorstisol → Cortisol
  • Pregnenolone → Progesterone → Deoxycorticosterone → Corticosterone → Aldosterone
  • Word origin: steroid + Ancient Greek génesis (“origin”)
    See also:


    You will also like...

    green plant cells
    Plant Cells vs. Animal Cells

    Plant cells have plastids essential in photosynthesis. They also have an additional layer called cell wall on their cell..

    Buttress roots
    Roots

    This study guide tackles plant roots in greater detail. It delves into the development of plant roots, the root structur..

    Freshwater Ecology
    Freshwater Ecology

    Freshwater ecology focuses on the relations of aquatic organisms to their freshwater habitats. There are two forms of co..

    Sigmund Freud and Carl Gustav Jung
    Sigmund Freud and Carl Gustav Jung

    In this tutorial, the works of Carl Gustav Jung and Sigmund Freud are described. Both of them actively pursued the way h..

    Ecosystem Succession
    Ecosystem Succession

    If the balance of nature is left untouched, landscapes can change dramatically over time. A previous ecosystem is supers..

    Birth of a Human Baby
    Birth of a Human Baby

    Following nine months inside the mother's womb is the birth of the baby. Know the different stages of the birthing proce..

    Related Articles...

    No related articles found

    See all Related Topics