ENDO CH 5

hypothalamus

Regulates secretion of endocrine glands, especially anterior pituitary, part of dicenphelon

hypothalamo-hypophyseal system

made of Two capillaries median eminence and Paris distalis

hypothalamus releases

stimulatory and inhibitory factors- hypophysiotropic hormones made of proteins

large size

magnocellular nuclei (supraoptic, para)

small ones

parvocellular nuclei (preven, preop, arcutate)

Ectopic pituitary graft

refraction of secretory pars distalis due to lack of stimulus provided by hypthamaloc release factors

hypothalamic nuclear areas

paraventricular and acructate nuclei

hypo-physio hormones

TRH-thyroid,
CRH-corticopin
GnRh-gonadotropin
GHRH-growth hormone
SRF/SST-somatostatin inhibiting
PIF-Prolactin release inhibiting factor

TRH hormone

hypothalamus control of thyroid
smallest hormone, a tripeptide discovered by Guillemin and Schally (pig and sheep)
expressed in paraventricular nuclei as preproTRH-then proTRH

Function of TRH

secretion is inhibited by T3, Nueropteptide Y, and AgRp
secretion is simulated by norepinephrine and alpha MSH, leptin
receptors (THR 1 AND TRH 2)
Binding to G protein (gqr) triggers PKC and increases Calcium
TRH increases TSH (thyrotropin) secretion
• TRH----PRL, GH
TRH acts though GQ-R to TSH
TSH acts on thyroud using Gs

CRH: Corticotrophin

Hypothalamic control of adrenal cortex
CRH is secreted by placenta and plays a role in childbirth, contractions and stress using DHEA
secrets ACTH *Gs type in adrenal cortex, which secretes cortisol DHEA

Function of CRH

binds to CRH –R1 andCRH R2 receptors (gq receptor) (release ACTH)
secretion stimulated via noradrenic/glutamergic
secretion decreased by negative feedback from ACH

simulates secretion of ACH Adrenocoritcosteriods and POMC
inhibit secretion of ACTH

Gonadotropin releasing hormone (GnRH)

pituitary of gonads
Decapeptide found by gulimen and Schally (mouse without gnrh)
Expressed by paraventricular neurons
role in rep cycle by secretion of FSH and LH
LH(high fre)/ FSH secretion(low fre) same cell/are dimeric

function of GnRH

binds to Gq protein coupled receptors, ligand binding using Phoslopoase C, IP3 and PKC
FSH and Lh use Gs receptors
Secreted by preoptic neuorns known as KNDy neuorns in paraventricular
secretion influenced byneuropeptides, kisspeptin neurokin dynorphon, Camp and calcium

GHRH: Growth hormone releasing hormone

Hypothalamic control of growth
expressed in arcuate nuclei, pulsatile
GHRH somatotropin proliferator occurs using the MAP pathway

function of GHRH

GHRH receptors are G protein coupled and produce CAMP in responds to ligand binding
secretion stimulated by Calcium and K channels
GHRH secretes HGH insulin, somatostatin, glucagon, gastrin
inhibited by SST/SRIF

Somatotropin release inhibiting factor (SRF/SST

tetra decapeptides expressed by periventricular nuclei
Secreted by D cells of pancreas, stomach and intestine
inhibits GH release by decreasing camp levels in g coupled receptors, closing Calcium chanels, opening K channels (prevents exocytosis of hormone)
decreases amyloid-B peptide in brain of Alzheimer patiens
Inhibits insulin and glucagon

Prolactin release inhibiting factor (PIF)

Hypothalamic control of Lactation
PIF is dopamine secreted by actuate and ventromedial nuclei
Ectopic pituitary grafts: PIF missing
reduce PRL synthesis and stops growth of lactoropes
made of dopamine

PIF function

inhibit PRL through D2Rreceptors, increases K in lacotopes and blocks calcium which [prevents exocytosis of hormones

secretion stimulated by TRH, OT and VIP
Suckling: triggers PRL and inhibits PIF

diseases

DA: schizophrenia and Parkinson
GnRh deficiency: anemia in females
Oglisermia and hypogonadotropic hypogonadism in males

PRF

release hormone for PRL

ectopic location

NO INHIBiTION