Growth Hormone

In the short term what will be the primary regulators of the GH release?

Releasing hormones

In the long term what will the primary regulators that control of GH release?

Nutritional state

Particularly protein nutrition

Where is GHRH released from?

Medial pre optic area and arcuate/ infundibular nucleus of the hypothalamus

Emotions stress, and trauma will have what affect of GHRH?

Inhibit

Catacholamines, dopamine and serotonin will have what affect on GHRH?

Increase

Hypothalamic signaling of somatotrophs will involve what two opposing hormones?

GHRH,

GHIH

What does PIT1 do?

Regulates genes involved w/ growth and development

How is GH synthesized?

Using Pre-prohormone mRNA as the template

What kind of hormone is GH?

Peptide

What is dual control of GH secretion?

Adenylyl cycles -> PKA -> Ca2+ influx

GH increases after what?

Exercise w/ food restriction and during sleep

Serum GH is not a good indicator of what?

Pituitary somatotropin function

What are indirect effect of GH?

Stimulates liver to promote growth positive effects via insulin-like growth factor

What is the direct effect of growth hormone?

Controls intermediary fuel metabolism that bind to GHR in tissue

GH and IGF will have a ___ feedback on the HP axis to cause an ___GHRH and ____ somatostatin?

Negative

Decrease GHRH, Increase somatostatin

What are the effects of GH on BG?

decrease glucose uptake by muscles

Increase glucose sparing

What are effects of GH on muscle protein?

Increase protein synthesis

Decrease protein degredation

Increase DNA & RNA synthesis

In a fed state w/ ample protein and energy what will happen?

Protein synthesis will be favored resulting in increases in GH, IGF, and insulin

In times where protein synthesis is favored what will happen to caloric storage?

Little to no changes

In a fed state w/ carbohydrates only what will happen?

Energy storage is favored, GH will decrease, IGF wont see a change, Insulin will increase

Hyperglycemia is going to do what to GH or Insulin?

Suppress GH,

promomtes Insulin to increase storage of CHO

What is favored during fasting states?

Glucose sparing is favored,

GH will increase and IGF-1 and insulin will decrease.

What happens during fasting states to protein anabolism and our caloric stores?

Growth and protein anabolism will be reduced and the calorie stores will be moved.

During hypoglycemia GH will be secreted, what will it do?

enhance lipolysis and hepatic glucoeogenesis and decrease peripheral glucose uptake, increase BG

What is ghrelin?

A signaling in the pituitary that will trigger GH due to nutritional deprivation to prevent hypoglycemia

What other two hormones will be triggered by fasting?

Glucagon and cortisol will increase production

What will GH and cortisol do?

Promote synthesis of IGF-BP3 - neutralizing IGF-1 (glucose uptake into cells is inhibited)

IGF-1 is a type of what?

Somatomedins

GH/IGF-1 will promote what?

Long bone growth when the epiphyseal plate remains cartilaginous

At the end of adolescents what will stimulate the ossification of epiphyseal plates?

Sex steroids

What is giantism?

Excessive stimulation of epiphyseal plates

What is acromegaly?

Increased growth after fusion of epiphyseal plates

What are some problems w/ acromegaly?

Bone and soft tissue deformities

Enlarged feet

thick skin

increased protein and decreased fat,

Vission changes

PU/PD

DM type 2

heart failure

What is the primary cause of acromegaly?

Somatotrope adenomas,

What are some ways you could dx acromegaly?

MRI of the pituitary

IGF-1 of the serum

BG check

How does insulin affect Growth?

May promote growth via protein synthesis

Looks like IGF and can bind to IGF receptors

How do glucocorticoids affect growth?

Required for proper GH signalling but in excess will inhibit through somatostatin

What is required for growth in children?

T3/T4

In the absents of ____ growth will halt even if GH is present

T3/4

What are growth effects of T3/T4?

Linear bone growth, increases chondrocyte activity in growth plates

What are maturation effects of T3/T4?

Bone remodeling - osteoblasts

Tooth development and eruption

Hair and nail growth

Alters sq tissue

T3 will activate genes related to growth and turnover? What are these?

IL6, PGE2

IGF1 receptors

At low stress levels what will se see in regards to GH secretion?

Low GH and GHRH (less stimulus)

At high stress levels what will se see in regards to GH secretion?

Somatostatin will increase,

GHRH and GHRP decreases