Steroid hormone

A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into 2 classes, corticosteroids (typically made in the adrenal cortex, hence cortico-) and sex steroids (typically made in the gonads or placenta). Within those 2 classes are 5 types according to the receptors to which they bind: glucocorticoids and mineralocorticoids (corticosteroids) and androgens, estrogens, and progestogens (sex steroids). Vitamin D derivatives are a sixth closely related hormone system with homologous receptors. They have some of the characteristics of true steroids as receptor ligands.

Steroid hormones help control metabolism, inflammation, immune functions, salt and water balance, development of sexual characteristics, and the ability to withstand illness and injury. The term steroid describes both hormones produced by the body and artificially produced medications that duplicate the action for the naturally occurring steroids.[1][2][3]

Synthesis

Further information: Steroidogenesis
Steroidogenesis with enzymes and intermediates

The natural steroid hormones are generally synthesized from cholesterol in the gonads and adrenal glands. These forms of hormones are lipids. They can pass through the cell membrane as they are fat-soluble,[4] and then bind to steroid hormone receptors (which may be nuclear or cytosolic depending on the steroid hormone) to bring about changes within the cell. Steroid hormones are generally carried in the blood, bound to specific carrier proteins such as sex hormone-binding globulin or corticosteroid-binding globulin. Further conversions and catabolism occurs in the liver, in other "peripheral" tissues, and in the target tissues.

Synthetic steroids and sterols

A variety of synthetic steroids and sterols have also been contrived. Most are steroids, but some non-steroidal molecules can interact with the steroid receptors because of a similarity of shape. Some synthetic steroids are weaker or stronger than the natural steroids whose receptors they activate.[5]

Some examples of synthetic steroid hormones:

Some steroid antagonists:

Effects

Steroids exert a wide variety of effects, mediated by slow genomic as well as by rapid nongenomic mechanisms. They bind to nuclear receptors in the cell nucleus for genomic actions. Membrane-associated steroid receptors activate intracellular signaling cascades involved in nongenomic actions.

Because steroids and sterols are lipid-soluble, they can diffuse fairly freely from the blood through the cell membrane and into the cytoplasm of target cells. This is in contrast to the actions of non-steroid hormones, which are water-soluble typically peptide hormones, acting through membrane bound receptors and intracellular second messenger systems to exert their effects. In the cytoplasm, the steroid may or may not undergo an enzyme-mediated alteration such as reduction, hydroxylation, or aromatization. In the cytoplasm, the steroid binds to the specific receptor, a large metalloprotein. Upon steroid binding, many kinds of steroid receptor dimerize: Two receptor subunits join together to form one functional DNA-binding unit that can enter the cell nucleus. In some of the hormone systems known, the receptor is associated with a heat shock protein, which is released on the binding of the ligand, the hormone. Once in the nucleus, the steroid-receptor ligand complex binds to specific DNA sequences and induces transcription of its target genes.[2][6][7][8]

See also

References

  1. ↑ Funder JW, Krozowski Z, Myles K, Sato A, Sheppard KE, Young M (1997). "Mineralocorticoid receptors, salt, and hypertension". Recent Prog Horm Res 52: 247–260. PMID 9238855.
  2. 1 2 Gupta BBP, Lalchhandama K (2002). "Molecular mechanisms of glucocorticoid action" (PDF). Current Science 83 (9): 1103–1111.
  3. ↑ Frye CA (2009). "Steroids, reproductive endocrine function, and affect. A review". Minerva Ginecol 61 (6): 541–562. PMID 19942840.
  4. ↑ Linda J. Heffner; Danny J. Schust (2010). The Reproductive System at a Glance. John Wiley and Sons. pp. 16–. ISBN 978-1-4051-9452-5. Retrieved 28 November 2010.
  5. ↑ Nahar L, Sarker SD, Turner AB (2007). "A review on synthetic and natural steroid dimers: 1997-2006". Curr Med Chem 14 (12): 1349–1370. doi:10.2174/092986707780597880. PMID 17504217.
  6. ↑ Moore FL, Evans SJ (1995). "Steroid hormones use non-genomic mechanisms to control brain functions and behaviors: a review of evidence". Brain Behav Evol 51 (4): 41–50. PMID 10516403.
  7. ↑ Marcinkowska E, Wiedłocha A (2002). "Steroid signal transduction activated at the cell membrane: from plants to animals". Acta Biochim Pol 43 (9): 735–745. PMID 12422243.
  8. ↑ Rousseau GG (2013). "Fifty years ago: The quest for steroid hormone receptors". Mol Cell Endocrinol 375 (1–2): 10–13. doi:10.1016/j.mce.2013.05.005. PMID 23684885.

Further reading

External links


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