Which hormone is secreted from the adenohypophysis and stimulates milk production?

Prolactin is the hormone secreted from the adenohypophysis, which is the anterior lobe of the pituitary gland. Its primary function is to stimulate milk production in the mammary glands during lactation. Prolactin levels increase during pregnancy and after childbirth, promoting the development of mammary tissue and ensuring adequate milk supply for breastfeeding.

This hormone plays a crucial role in the lactation process, allowing for successful nursing of infants. It works synergistically with other hormones like oxytocin, which is responsible for milk ejection, to ensure that the breastfeeding process is effective.

The other options represent different hormones with distinct functions. Dopamine, for instance, acts as a neurotransmitter and has an inhibitory effect on prolactin secretion, while insulin is mainly involved in glucose metabolism and regulation, and cortisol is a steroid hormone involved in stress response and metabolism regulation. None of these hormones are responsible for stimulating milk production.