Lec 3 - Control of release of APG hormones Flashcards
3 common pathways for anteriori pituitary cells
Ca2+
Pi
cAMP
receptor for corticotropin reeasing hormone
CRH-R1
a GPCR (Gs)
what pathway CRH-R1
adenylate cyclase
= cAMP= PKA
creates POMC gene product
which is processed and stored as ACTH
what other hormone released from hypothal that potentiates ACTH release
ADH/vasopressin
what receptor does vasopressin act on
V2
what pathway does vasopressin trigger
PKA
what hormone negatively feedbacks to reduce ACTH
cortisol (released from adrenal cortex)
this is the short loop feedback
which enzymes porcess POMC
prohormone convertases (PCs) 1 and 2
converts to ACTH
long loop feedback in ACTH release
cortisol will act on hypothalamus to reduce CRH release
ultra short loop feedback in ACTH release
CRH acts on the neurons that release them
inhibit themselves
where is the SCN
anterior hypothalamus
peak cortisol release time
8am
most cardiovasc events happen at this time, thought to be a contributing factor
when is ACTH release
little bit earlier than cortisol
when is CRH released
earlier that ACTH lol
how do the diurnal cycles govern recpetors
peak time of release, means peak no. receptors
what hormone released from hypothalamus negatively inhibits GH release from somatotropes
somatostatin
trophic action of GH
acts on liver to release IGF-1
3 things that affect GH release
- sleep = increases GHRH
- Free Fatty Acids = increases somatostatin
- oestrogen = increases somatotrope sensitivity to GHRH
difference in release of PRL compared to other horomones
default is to be released
must be inhibited
(no hormone from hypothal that triggers its release)
what hormone inhibits secretion of prolactin
dopamine
which is reduced in pregnancy to increase prolactin
when is TRH released normally
diurnal release (inccreases overnight)
what environmental can reduce release of TRH
mental, phsyical, starvation, infection stresses
what do LH and FSH control in testes
testosterone biosynthesis
spermatogenesis
what do LH and FSH control in ovaries
oestrogen, prgesterone synthesis
menstrual cycle
what negatively inhibits FSH LH in men
testosterone (also inhibits GnRH) and inhibin
PRL role in FSH LH release in men
negatively inhibits hypothalamus (less GnRH) and gonadotropes (less FSH and LH)
