Zachow - GH Flashcards
How does GH get secreted?
Initial signal is from ventromedial nucleus. It secreted GHRH, GH secretagogue, and somatostatin. From there the signal goes to the anterior pituitary.
What things upregulate GH secretion and what down regulates it?
Up: hypoglycemia, dopamine, serotonin
Down: somatostatin
Within the SNS, what will upregulate GH and which will down regulate it? How???
Alpha 2 - upregulate by either up regulating serotonin or inhibiting somatostatin.
Beta 2 - down regulates GH through the up regulation of somatostatin.
How does IGF-1 get made?
One of the major targets of GH is the liver where it causes the creation of IGF-1, which btw causes negative feedback on GH.
What are GHBP? IGFBP?
GHBP - binds to GH in order to increase half life and lower renal clearance.
IGFBP - same thing as GHBP but for IGF-1.
How does. GH. Impact insulin?
Blocks The activity of insulin.
How do we treat excess GH?
Somatostatin agonists
GH receptor antagonists
(Sometimes dopamine agonists for random reasons)))
Sings and symptoms of low GH in kids? Adults?
Kids - short, obese, high pitched voice
Adults - decreased bone density, obesity, dyslipidemia.
How we we test for GH deficiency? GH excess?
Deficiency - stimulation testing - force GH secretion through arginine, exercise, GHRH, or insulin. Then measure GH.
Excess - suppression testing - you would give a glucose load and see how quickly the GH levels come down at certain timed intervals. If the GH levels don’t reach a certain threshold then there is said To be excess GH.
How do you treat GH deficiency?
Give them GH
What are some things the combo of GH and IGF-1 do?
Muscle - anabolism, glucose uptake, metabolism
Bone - growth at the epiphyseal plate and remodeling
Kidney - RAAS
Heart - ventricular remodeling, inotropy, chronotropy
Ovaries and testis
Thyroid - TH synthesis
Pancreus - has impact on insulin secretion and glycemic status
Liver - IGF-1 production and glucose uptake
What is somatostatins affect on GH release?
It will inhibit GH release.
How does GH affect lipolysis? Proteolysis? Glycolysis?
Lipolysis - will be upregulated because GH helps triglycerides be broken down into FFA’s.
Proteolysis - will be down regulated because GH inhibits this process.
Glycolysis - will be down regulated because GH prevents the breakdown of glycogen into glucose.
What is the name of the disease that is when you have too much GH?
In kids - gigantism
In adults - acromegaly.
- in adults they will have high glucose levels because GH causes insulin resistance. They will have bone overgrowth because GH causes bone minerlaziation - because of this you will see their hands, feet, and face grow. They will have dislipidemia and abnormal menses.
Why does excess GH cause high BP?
1) Because GH causes an increase in lean body mass as well as extracellular H20. With extracellular H20 comes high BP.
2) Additionally, GH stimulates the secretion of aldosterone, which pumps up BP even more.
3) GH also causes unfavorable remodeling of vascular smooth muscle.
