Lecture 5:
Overview: hypothalamus->ant pituitary-> glands axes; hypothalamic hormones: GHRH somatostatin dopamine CRH TRH GnRH; anterior pituitary hormones; reflex and feed back regulation; primary secondary excess and deficiency
Hormones
· Prolactin: secreted by the lacotroph cells in the anteterior pituitary gland.
o Increase breast-> produce milk
o Increases in secretion during pregnancy and higher concentration during lactation
o Without prolactin breasts don’t produce milk
o It can act as a contraception
§ It is produced and secreted in males and females….?
§ During pregnancy there is no milk secretion but prolactin is still being secreted along with estrogen and progesterone
§ (Morning sickness is due to elevated estrogen)
§ estrogen and progesterone inhibit milk production
§ if women produces a baby but doesn’t feed the baby then milk production will stop… suclking of the nipples stimulate milk production
ú increase suckling->increase PRL secretion -> increase milk production
§ Prolactin receptors are cytokine group dimers, when it binds attack
ú Increase TYR kinase-> Jacob kinase-> increase stat k
§ Prolactin inhibits the secretion of GnRH. Therefore it acts like a contraceptive
o What is the role in men or in fetus or older women?? Still a mystery
§ Males can develop galactorreah
§ It can also decrease GnRH if they have overproduction of prolactin
o Hypothalamus’ role in secreting prolactin: regulates lactotrophes by secreting dopamine-> decrease prolactin secretion
§ Suckling can inhibit the hypothalamus’ secretion of dopamine-> increase PRL
o Pituitary tumor causes overproduction of hormones
§ Overproduction of prolactin will cause infertility effect.
ú To correct this one must increase levels of dopamine
· Growth Hormone: stimulates growth aka somatotropin
o Increases growth in long bones
o Increase amino acid uptake in cells
o Inhibit protein break down
o Increase protein synthesis
o Increase fat metabolism
o Decreases carbohydrate utilization/metabolism and uptake
§ Causes insulin resistance
o Gigantism is the opposite of dwarfism
§ Gigantism has increase of GH during the growth years
§ Dwarfism, if due to lack of GH, then administration of GH will grow the child to normal height
o Acromegaly- condition that comes from excess of growth horone after growing years
§ Thickness of fingers, frontal bone enlarges, nose becomes thicker, cheek bones become more prominent and does the jaw bones, thick skin
ú Jaws from 007 movies
o Hypothalamus secretion of GH
§ Hypoglycemia stimulates and hypoglycemia inhibits
§ Stresses and cold inhibit
§ Amino acids will stimulate particulary arginine
§ Increase nutrients after meal stimulates
§ Exercise and sleep both stimulates
o Hypothalamus has a double regulation on the somatotrophs
§ GHRH stimulates secretion and Somatostatin Inhibits secretion
§ Provides much more regulation
§ GH stimulates tissues and receptors in the liver
ú In the liver they synthesis and secrete insulin like growth factor 1 and they act on the tissues to stimulate them to grow
