Block 8: Week 1: Sex Steroids/PBL

what is the role of cytoplasmic enzyme 5α-reductase?

reduces free testosterone to 5α-dihydrotestosterone (DHT)

how is 5α-dihydrotestosterone (DHT) different from free testosterone?

has greater affinity than testosterone for androgen receptors,

hence it has 2.5 times greater androgenic potency as compared to T.

what happens to the testosterone receptor of DHT to act on androgen receptors?

The T receptor of the DHT complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to the specific nucleotide sequences of the chromosomal DNA.

what are Hormone Response Elements (HREs)?

areas of binding that testosterone acts on:

they influence transcriptional activity of certain genes, producing androgen affects.

what is nandrolone?

is an anabolic steroid that occurs natural in the human body, however in small quantities.

what is the function of nandrolone?

• increases the production and urinary excretion of erythropoietin. possible indirect action on bone marrow.

• binds to the androgen receptor to a greater degree than testosterone, however has less effect on muscle growth.

what is the most commonly seen sexual disorder?

hypoactive sexual desire disorder.

what are the 3 substypes of hypoactive sexual desire disorder?

lifelong/generalised.

acquired/situational.

acquired/generalised.

what is lifelong Hypoactive sexual desire disorder?

Little/no desire for sexual stimulation with/without partner and never had

what is acquired/situational Hypoactive sexual desire disorder?

Previously had sexual interest in current partner but no longer has sexual interest in them.

Has desire for sexual stimulation (with someone else other than current partner or by themself).

what is acquired/generalised Hypoactive sexual desire disorder?

Previously had sexual interest in partner but no longer does.

Lacks interest in sexual activity alone or with a partner.

what are common causes of hypoactive sexual desire disorder?

- Partner factors: Partner’s sexual problems or health status

- Relationship factors: Poor communication, relationship discord

- Individual vulnerability factors: Depression or anxiety, poor body image

- Cultural/religious factors: Restrictive upbringing

- Medical factors: Illness, medication

- Physical factors: Post-surgery, cancer, vulvodynia

how does sildenfail work?

Selective inhibitor of phosphodiesterase in the corpus cavernosum:

In normal erection, nitric oxide is released into the corpus cavernosum. This causes increased cGMP and relaxes smooth muscle to allow inflow of blood. 

Less cGMP breakdown and therefore increased blood flow.

what is the drug class of sildenafil?

Phosphodiesterase type-5 inhibitors