What stimulates prolactin secretion?

Prolactin secretion is primarily stimulated by factors such as thyrotropin-releasing hormone (TRH) and serotonin. TRH is produced in the hypothalamus and promotes the release of prolactin from the anterior pituitary gland. This effect can be augmented by serotonin, particularly due to its role in the modulation of neuroendocrine functions.

Dopamine, on the other hand, acts as a prolactin-inhibiting factor; it inhibits prolactin secretion from the pituitary gland. Norepinephrine is involved in various regulatory mechanisms in the body but does not have a direct stimulating effect on prolactin release. While oxytocin is involved in stimulating breastmilk ejection during breastfeeding and may have some indirect effects on prolactin, it is not a primary stimulator of prolactin secretion.

Thus, TRH and serotonin serve as important stimulatory factors for prolactin secretion, which validates the choice indicating these substances as the correct answer.