endocrinology

Question 1

How does Testosterone affect sexual function/arousal in females

Answer 1

Role in sexual function
* E2 and T directly enhance limbic system response to sexual stimuli
- Demonstrated through MRI studies of brain activation to sexual stimulus; given E2, T
* Androgen receptor present in vaginal mucosa
- Aromatase and 5-alpha-reductase enzymes in vaginal tissues
- T has vasodilatory effect  enhance blood flow and lubrication

Question 2

Role of oestrogen and progsterone in breast growth

Answer 2

• at puberty, increasing estrogen causes an increase in size and pigmentation of the areola and formation of a mass of breast tissue beneath the areola
• after this estrogen stimulates the ductal portion of the gland system
• progesterone in the presence of estrogen influences the growth of the alveolar components of the lobules that later become the milk producing structures

Question 3

Features of the prolactin receptor and prolactin hormone

Answer 3

Receptor:
Found on many tissues throughout the body, breast, endometrium, ovary, brain, heart, liver, immune cells, adrenal and pituitary gland.
Member of the cytokine receptor superfamily
Can be activated by PRL, GH, hPL

Prolactin:
Prolactin is a single chain polypeptide comprising 199 amino acids. It shares a high degree of homology with growth hormone and placental lactogen. Its most potent biological form (80–90%) is monomeric; 8–20% is dimeric and 1–5% is macroprolactin

Question 4

Lactogenesis physiology

Answer 4

Lactogenesis is the process of developing the ability to secrete milk and involves the maturation of alveolar cells. Two stages 1. Secretory initiation. 2. Secretory activation.

Stage 1 - secretory initiation.
Occurs during second half of pregnancy
Prolactin rises significantly in second half of pregnancy
* mechanism of increase in prolactin secretion believed to be estrogen suppression of dopamine and direct stimulation of prolactin gene transcription in the pituitary
* progesterone inhibits milk production by reducing PRL binding and antagonizing at PRL receptor.

Stage 2 - secretory activation.
Placenta removal at delivery leads to rapid drop in progesterone.
Elevated prolactin, cortisol and insulin help facilitate milk production but this process is delayed by 2-3 days due to the fall in progesterone levels taking a few days to result in milk increases and the signals from suckling causing an increase in prolactin take a few days for effect.
Lactation maintained by regular suckling/pumpnig - wtih regular emptying of the breast and stimulation of the nipple.
Causes further release of prolactin and also oxytocin.

Question 5

Initiating breast feeding

Answer 5

• 6 months prior to birth take COCP and 10mg domperidone 4 times a day, increasing to 20mg 4 times a day after a week
• Continue this regime until 6 weeks prior to due date when she should stop COCP and continue domperidone
• start using electric pump for 10 minutes every 3 hours then from 4 weeks prior to birth every 3 hours and once during the night
• (can also take other galactologues like fenugreek and oats)
• this combination of ceasing OCP, domperidone and pumping should cause a rapid drop in progesterone then increase in prolactin which attempts to mimic a pregnancy and birth
• once milk comes in but before baby arrives continue pumping and freeze the milk
• once the baby arrives, continue domperidone 20mg QID until substantial milk supply or ready to wean
• feed on demand as much as possible, pump for 10 mins after each feed to increase milk supply
• once milk supply well established may be able to wean off domperidone