3.1.1 Growth Hormone and Prolactin Physiology Flashcards
What are some conditions that increase the amount of GHRH, which upreagulates somatotrophs?
GalphaS (adenylate cyclase and cAMP)
Ca++
What is used to sequester IGF1? In what form does IGF interact with target tissues?
IGFBP; unbound
What are some mutations that can alter the axis of GH?
What are some other mutations within the GH axis that can lead to growth abnormalities?
Describe the positive and negative feedback loops mediated by IGF-1 throughout the GH cascade.
What role do estrogens/androgens play in the regulation of growth?
Positive via the induction of GH and IGF-1
Negative via epiphyseal plate closure
Describe the regulation of prolactin and its unique characteristic within the anterior pituitary.
Prolactin is upregulated by PRH and downregulated by dopamine. It is unique in that it is under dominant negative regulation.
Prl secretion can lead to what condition?
Amenorrhea
What are three possible treatment mechanisms for GH excess?
Dopamine agonists
Somatostatin analogs
GH antagonists
What stimulates milk production? propels milk?
Production: Prl
Propels milk: Oxytocin
What role do glucocorticoids play in the regulation of growth?
Necessary for growth
Regulates the synthesis of GH and GHRH-R
Excess can lead to growth inhibition (directly at the level of cartilage and bone synthesis) and a catabolic state
What pathway acts downstream of the GH receptor which ultimately leads to activation of transcription factors?
Jak/Stat pathway
Describe the mechanism of how the hypothalmus can stimulate the somatotroph leading to increased IGF-1
What are some of the diabetogenic effects of GH?
Name the three sites of action of GH and its effects on those sites.
Name the three sites of action of IGF1 and its effects on those sites.
IGF1 can interact with this molecule’s receptor. As can this molecule interact with the receptor for IGF1. What molecule is this?
Insulin
What protein has the same number of AAs and only varies in 29 AA locations?
Chorionic Somatomammotropin 1 and 2
How do you feel about all of the endocrine cascades and feedback loops? Let’s check in on Holla
You aren’t alone….
Compare GH and IGF-1: their structure, half-life, and activation pathway.
Through what type of cells does prolactin upregulate dopamine?
Tuberoinfundibular Dopaminergic Neurons (TIDA)
Describe the differentiation steps that lead to the 5 different cell types present in the anterior pituitary. What is the POU1F1 and GATA status of each cell type?
What is different about the growth of rats when administered GH?
The bones of rats continue growing due to non-closure of the epiphysis.
What are some characteristics that differentiate b/t acromegaly and giantism? What are some of the treatment options for either?
How many AAs are in the GH peptide?
191 AAs
What role does thyroid hormone play in the regulation of growth?
Plays a permissive role
Hypothyroidism can cause growth retardation or dwarfism
Name 3 external factors that alter the regulation of prolactin.
Sleep, suckling stimulus, stress
(The triple S)
Identify the positive and negative regulators of somatotrophs
Positive: GHRH
Negative: SRIF
Describe the pathway leading to the induction of GH to the main effector of GH
Use one word to describe the secretion of GH.
Pulsatile/episodic
What are some conditions that upregulate SRIF, which downregulates the action of somatotrophs?
Galphai (decreased cAMP and decreased Ca++)
Describe the positive and negative feedback loops mediated by GH throughout the GH cascade.
How role does insulin play in the regulation of growth?
Deficiency has catabolic effects
Very important in utero (maternal diabetes => fetal macrosomy, insulin resistance => leprechaunism)
Describe the cascade leading to prolactin production and the feedback loops.
What are some of the mutations associated with panhypopituitarism and dwarfism? What are some treatment methods?
Identify some of the trophic hormones and feedback mechanisms.
