Peptide Hormones Flashcards
What nucleus in the brain produces dopamine
Arcuate nucleus
What stimulates production of prolactin
High oestrogen at end of pregnancy
Growth Hormone polypeptide
Single Chain 191 AA polypeptide
What form of growth hormone dominates
Pituitary, GH-N
What two transcription factors are involved in development of somatotrophs
Prop1 and then Pit 1
What nuclei in hypothalamus releases GHRH
Arcuate nucleus
What enhances GH secretion
Starvation
Glucocorticoids
Ghrelin
Estradiol
What blunts GHRH secretion
Insulin
Glucose
Obesity
Somatostatin
Age
Why is Ghrelin synergistic with GHRH
It is a natural ligand of Growth Hormone Secretagogue Receptor
Where is somatostatin made in the hypothalamus
SST 14 in the PVN
What hormones or chemicals are suppressed by SST
Insulin
GH and TSH
What does the Phosphorylation cascade for GHR involve
JAK/SKAT
What proteins are IGF-1 bound to and what is increased by what hormone
IGFBP 1-6, IGFBP3 increased by GH
What pathway(s) does ligand binding of IGF-1 result in
AKT and MAPK
Is GH or IGF-1 involved in retention of ions and what ions
Sodium water and phosphate
Does IGF 1 or GH inhibit proteolysis
IGF 1
What stimulates protein synthesis
Both GH and IGF 1
Effect of IGF-1 OR GH on glucose
IGF-1 decreases blood glucose and improves insulin sensitivity
What effect does IGF-1 have on protein synthesis
Reversed catabolic effects of glucocorticoids
What three diseases can stimulate GH
Renal Failure
Liver Cirrhosis
Type 1 diabetes
What is Laron Syndrome due to
Problems with GHR
How are levels of GH, GHBP and IGF-1 in Laron Syndrome
GH normal but GHBP and IGF-1 low
Symptoms of Laron Syndrome
Short limbs, mean high 119F 124 M, small head circumference, saddle nose, prominent forehead, delayed skeletal maturation, osteopenia and obesity
What stimulatory test used for GH deficiency
GHRH-arginine test
IGF-1 lower than reference range confirms diagnosis in adults with pit disease
Most common cause of acromegaly
- what disease
75% somatotroph macroadenomas
What are the classical clinical features of acromegaly
Facial changing, sweating, headache
Sleep apnoea, diabetes, hypertension
Treatment of acromegaly
Pituitary surgery for adenoma as first line in most
SST analogues like lanreotide to inhibit release of GH
GHR antagonist like pegvisomant which improves binding in site 1 and impairs binding on site 2 so no downstream signalling on IGF-1
Where are the most powerful effects of ADH- what happens?
Collecting ducts, resorption of water due to opening of aquaporin channels
Where else does ADH work on in kidney
Thick ascending limb and loop of Henle by increasing NaCl and ureas absorption respectively. Na and K/H is reciprocal
What are the 4 V receptors and thjr functions
V1a - Vasopressor effects at vascular or cardiac muscle(egm splanchnic beds in abdomen)
V2- Water retention in distal nephron
V1b- Role in ACTH/stress receptors in Anterior Pituitary
OT- Uterine contraction at birth at Myometrium
Two main types of vaptans and their effects
V2- selective (tol, lixi, sata)
V1a+ V2 eg. Conivaptan
What nucleus links to SON and PVN and what does it link to
Posteriomedial nucleus- links to VLM for SNS and pain, and NTS for baroreceptor
How does BP change as AVP/ Osmolality increase
BP decreases
Should random GH be used for Acromegaly
No, used OGTT
