Lecture 12- Lactation

Question 1

Lactation: What two hormones lead to the development of alveoli in the mammary glands?

Answer 1

Estrogen and progesterone

Estrogen promotes duct growth via cell division. So if we get no estrogen we get impaired duct formation.

Progesterone is involved with branching off of the ducts. No progesterone = impaired alveolar development.

Question 2

What does estrogen do for lactation?

Answer 2

• Reduces dopamine-mediated inhibition of prolactin
• Increases number and size of prolactin-producing cells
• Makes genes required for prolactin production

Question 3

What is in milk?

Milk contents

Answer 3

• Lactose: sugar in milk
• Fat
• Casein: phosphoprotein that provides amino acids, carbohydrates, calcium and phosphorus

Question 4

Estrogen increases prolactin levels. But as a baby is born and the placenta (source of estrogen has the fetus is growing) is removed, how are prolactin levels affected?

Answer 4

Baby suckling on moms nipple will trigger prolactin to release and continue to make more milk.

Suckling feeds back to hypothalamus to reduce dopaminergic inhibition of prolactin-secreting neurons.

Question 5

Prolactin reduces the amount of FSH and LH released, so prolactin reduces the responsiveness of ovaries to gonadotropins(FSH & LH)

Answer 5

This causes ovulation to slow down/stop. Prolactin can act like a contraception. All this is happening around 6 months.

Question 6

Contraception with prolactin?

Answer 6

Once prolactin levels dip below a particular point, FSH and LH return to “pre-pregnancy” levels. Leading to follicular development