Hypothalamic and Pituitary Agents
1. Growth Hormone
- Somatropin
- Octreotide – somatostatin analogue
- hMG/Menotropins (LH/FSH)
- hCG/Chorionic Gonadotropin (LH)
- Oxytocin
- Desmopressin
- Bromocryptine -Dopamine agonist used paradoxically in Acromegaly treatment; Prolactinemia
Growth Hormone
- Secretion
Ø stimulated by GHRH
Ø inhibited by somatostatin
- Effects
Ø Direct: plasma membrane receptors triggers kinase cascade (the JAK-STAT system) that eventually alters gene transcription
- effects carbohydrate, fat, and protein metabolism
- initially, “insulin-like” effect and later on “anti-insulin like” effect
Ø Indirect
- due to the actions of insulin-like growth factors (somatomedians)
- stimulate: collagen biosynthesis, production of chondroitin sulfate
- Therapeutic Uses:
1) GH deficiency: some resistance occurs
- Use of Bromocryptine in Acromegaly
Ø Normally, Dopamine agonists increase GH secretion
Ø BUT, for some freak of nature reason, Bromocryptine depresses it.
Somatostatin
- naturally occuring – too short t1/2 to be useful
- Octreotide – somatostatin analogue
Ø used to suppress GH secretion
- Acromegaly treatment
- Also used to treat several types of hormone-secreting tumors
Prolactin
- PRL itself is not used therapeutically
- Treatment of hyperprolactinemia
Ø dopamine agonists – Bromocriptine
ACTH
- no use because glucocorticoids are readily available
TSH
- no widespread use because of thyroid hormones
- occasional for diagnostic purposes
Gonadotropins – (human menotropins – hMG) = LH + FSH mixture; hCG has similar activity to LH
- limited use
- may be used in female infertility to induce ovulation
- hMGs- usually given to stimulate follicular development
- hCG- given to simulate the LH surge and trigger ovulation
Oxytocin
- direct effects on uterine myometrium to produce contractile activity
- used to induce or augment labor
- other uses: control of post-partum bleeding; increase in milk ejection in nursing women
Vasopressin (ADH, antidiuretic hormone)
- pressor effects on smooth muscle and ADH effects on the collecting ducts of the kidney
- 1o use – treatment of diabetes insipidus
- also – DDAVP – enuresis
Tags: antidiuretic hormone, chorionic villi, Gonadotropins, Growth Hormone, menotropins, octreotide, Somatostatin, somatropin, Vasopressin
