Breast development extension adrenocorticotropic hormone (ACTH)), and thyroid hormones such as thyroxine (and by extension thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH)) also play permissive but less well-understood/poorly-characterized roles in breast development during both puberty and pregnancy, and are required for full functional development. Leptin has also been found to be an important factor in mammary gland development, and has been found to promote mammary epithelial cell proliferation. In contrast to the female-associated sex hormones, estrogen and progesterone, the male-associated sex hormones, the androgens, such as testosterone and dihydrotestosterone (DHT), powerfully suppress the action of estrogen in the breasts. At least one
Trophic hormone causes hyperplasia of enterochromaffin cells which may transform into carcinoid tumors. Trophic hormone Trophic hormone is a hormone that has a growth effect, hyperplasia or hypertrophy, on the tissue it is stimulating. The term "trophic" is from Ancient Greek τροφικός ("trophikós") meaning "pertaining to food or nourishment", here used to mean "growth"; this is the same origin as "atrophy." This should not be confused with "tropic," as in the similar-sounding tropic hormone – the words and concepts are both unrelated. A key example of this is thyroid-stimulating hormone stimulating the thyroid; excess thyroid-stimulating hormone can create a goitre. Trophic hormones