Anterior pituitary hormones

PRL acts on the mammary glands (breasts) to stimulate lactation;

TSH indirectly increases the basal metabolic rate (BMR) – by stimulating the synthesis of the thyroid hormones, thyroxine and triiodothyronine, from thyroglobulin in the thyroid follicles;

ACTH indirectly elevates the plasma glucose concentration and triggers cell differentiation – by stimulating the synthesis of the glucocorticoid steroid, cortisol.  (In addition, ACTH can also promote the development of secondary sexual characteristics – by stimulating the synthesis of the adrenal androgen, dehydroepiandrosterone [DHEA] in the adrenal cortex);

GH stimulates growth and development indirectly (via hepatic insulin-like growth factors [IGF’s]) and through direct actions (e.g. on bone);

FSH promotes the formation of second sexual characteristics in females – by stimulating the growth of ovarian follicles and then stimulating them to synthesise estradiol (via actions on granulosa cells).  In males, FSH indirectly promotes spermatogenesis – by stimulating the Sertoli cells of the testis that line the seminiferous tubules;

LH indirectly regulates female sexual receptivity (estrus / ‘heat’) in mammals – by acting on ovarian theca and granulosa cells to stimulate estradiol synthesis and to release the mature germ cells (oocytes) at ovulation.  In addition, LH is necessary to stimulate progesterone synthesis (for pregnancy) by the post-ovulatory ovarian corpus luteum and to promote fertility in males – by stimulating testis Leydig cells to synthesise testosterone.