Steroids Flashcards
What are Anabolic Steroids?
Small cholesterol based drugs related to the endogenous androgenic endocrine hormones, including testosterone.
What are two main important actions of steroids?
- Androgenic. 2. Anabolic.
What is the androgenic action of steroids?
Promotes male characteristics.
What is the anabolic action of steroids?
Promotes protein synthesis/build lean muscle mass.
What are endogenous steroid hormones? How do they work?
Small lipid-based hormones based on cholesterol. They activate intracellular receptors that act as hormone regulated transcription factors.
What do Glucocorticoids do?
They regulate inflammation and metabolism.
What do Mineralocorticoids do?
They regulate fluid and salt balance.
What do sex steroids do?
They regulate reproductive physiology, bone density, muscle mass, etc.
Where is testosterone produced?
Leydig cells in the testes.
What part(s) of the brain regulate the production of testosterone and the creation of sperm?
Endocrine signals from the hypothalamus/anterior pituitary,
When do Leydig cells synthesize testosterone?
When LH binds to the extracellular LH receptor on the Leydig cell.
What are the metabolites of testosterone metabolized by?
By cytochrome p450 enzymes.
What is testosterone? What is it converted into and why?
The major form of androgen in circulation. It can be converted to dihydrotestosterone (DHT). It is 10x more potent and is converted to this form to target peripheral tissues.
What converts testosterone into DHT?
5-alpha-reductase.
How are testosterone concentrations kept up in the testis? Is testosterone converted into DHT in the testes.
By androgen binding proteins synthesized by Sertoli cells in the seminiferous tubes. It is not converted in the testes (thus, the concentration must be kept up).
What do Sertoli cells do?
They stimulate spermatogenesis.
How are hormones transported to their target tissues?
After synthesis, they diffuse into the plasma. Then they bind to carrier proteins including sex-hormone binding globulin (SHBG) and Albumin. They can diffuse out of the blood and cross freely into target tissues.
What are androgen receptors? What happens when an androgen binds?
An intracellular receptor that trans-locates into the nucleus, binds DNA, and alters transcription upon androgen binding.
What disorder is caused by mutations in androgen receptors?
Androgen Insensitivity Syndrome (AIS). Genetically XY, but are female.
What are reasons to antagonize androgen action? (Anabolic steroids would make them worse.)
Treatment of: prostate cancer, male pattern baldness, benign prostatic hyperplasia.
What are two ways to antagonize androgen?
- Use GnRH agonists. 2. Use GnRH receptor antagonists.
How does using GnRH agonists antagonize androgen activity?
They suppress the hypothalamus-pituitary-gonadal axis, which decreases the production of FSH and LH, which shuts down testosterone production.
What can GnRH agonists treat? How is it administered?
Prostate cancer and some breast cancers. It is administered continuously.
How does using GnRH receptor antagonist reduce androgen activity?
They block the release of FSH and LH.
