The anterior pituitary gland secretes
- 6 peptide hormones,
- in response to excitatory or inhibitory factors from the hypothalamus (via the hypothalamic-hypophyseal portal system)
- under negative feedback
ACTH
- Cell: corticotrope
- Excretion: \(\uparrow\) by \(\uparrow\) CRH; \(\downarrow\) by \(\uparrow\) cortisol
- Effects on adrenal cortex: \(\uparrow\) androgen and glucocorticoid release; adrenal cortex hypertrophy
TSH
- Cell: thyrotrope
- Excretion: \(\uparrow\) by \(\uparrow\)TRH, \(\downarrow\) by \(uparrow\)T3/T4/cortisol
- Effects on thyroid gland: \(\uparrow\) T3/4 secretion, size, vascularity
FSH and LH
- Cell: gonadotrope
- Excretion: \(\uparrow\) by \(\uparrow\)GnRH, \(\downarrow\) by \(\uparrow\) testosterone. Low levels of oestrogen suppress FSH/LH, high levels stimulate release
- In males, LH \(\to\) testosterone release from testes, FSH \(\to\) spermatogenesis
- In females, LH \(\to\) oestrogen and progesterone from ovary, FSH \(\to\) ovarian follicle development. When oestrogen reaches threshold and becomes positive feedback on LH \(\to\) LH surge \(\to\) ovulation.
Growth hormone
- Cell: somatotrope
- Excretion: \(\uparrow\) by GHRH, \(\uparrow\) by starvation, especially protein deficiency
- Effects: IGF1 release from liver. Metabolic changes to burn lipids, conserve protein, and reserve glucose for CNS. \(\uparrow\) protein anabolism, \(\uparrow\) fat catabolism, insulin resistance (so skeletal muscle must use fat). Stimulates osteoblasts \(\to\) net bone formation.
Prolactin
- Cell: Lactotrope
- Excretion: \(\downarrow\) by dopamine from hypothalamus (suckling / pregnancy \(\to\) disinhibition). \(\uparrow\) by oestrogen.
- Effects: Milk production, mammary gland hypertrophy