Question

Which hormone stimulates the secretion of milk in a female?
(a)LH
(b)Prolactin
(c)Oxytocin
(d)Progesterone

Answer 1

Hint: This hormone is also called lactotropin. In mammals, this hormone is responsible for milk production whereas in fishes it is accountable for maintaining the salt and water balance.

Complete answer:
Lactation is the secretion of milk from the mammary glands and it is the time period during which a mother will lactate to feed her infant. Prolactin will stimulate the mammary glands to produce milk. The milk produced in the initial lactation days is called colostrum which has various antibodies that are crucial to developing resistance in the babies. The blood serum concentration of the prolactin will be increased during pregnancy, it causes the mammary gland enlargement and prepares the mammary gland for the milk production. The milk production starts when the progesterone level falls by the end of pregnancy and a stimulus for suckling will start. It is proved that lactation during pregnancy will cause premature birth. Thus, milk production is inhibited or stopped by the estrogen and the progesterone hormone which will block the prolactin secretion from the pituitary gland during pregnancy. After pregnancy, the estrogen and progesterone levels will decrease due to the expulsion of the placenta (which is the important site for these two hormone secretions). However, a sufficient amount of estrogen hormone will circulate in the blood to trigger the prolactin production from the pituitary gland.
So, the correct answer is ‘Prolactin’.

Note: The production of the prolactin must be regulated else it will lead to various diseases including cancer. Dopamine is another hormone that regulates the prolactin level. Increased prolactin level will stop the prolactin production. However, prolactin production will stimulate dopamine production. This type of regulation is called a “negative feedback loop’.