Hypothalamus and Pituitary Overview Flashcards
What is the main role of the hypothalamic hormones?
Regulate adenohypophysis hormones
What does permissive action mean?
One hormone regulates the affect of another hormone
Down-regulation:
A decrease in density of receptors in response to chronic high concentrations of hormones
Up-regulation:
An increase in the density of receptors in response to chronic low concentrations of the hormone
What hormones are released from the hypothalamus?
GnRH GHRH SS TRH DA CRH PIH
What hormones are released from the anterior pituitary?
FSH LH Growth hormone TSH Prolactin ACTH
What does GnRH (gonadotropin releasing hormone) do?
Stimulates FSH and LH
What does GHRH (growth hormone releasing hormone) do?
Stimulates (GH) growth hormone
What does SS (somatostatin) do?
Inhibits (GH) growth hormone
What does TRH (thyrotropin-releasing hormone) do?
Stimulates TSH (thyroid stimulating hormone)
What is needed for GnRH to be released?
Kisspeptin
What does PIH and DA do?
Inhibits prolactin
What does CRH (corticotropin-releasing hormone) do?
Stimulates ACTH (adrenocorticotropic hormone)
What is the best way to test hormone levels?
Urine samples not blood samples due to diurnal cycle
How are peptide hormones translated?
They are translated on rough ER as inactive preprohormones and cleaved to prohormones
Where do prohormones go?
Packaged by the Golgi Apparatus for packing in secretory vesicles
What occurs to prohormones in vesicles?
They are cleaved to active hormone and pro-fragment
Where are the active hormones inside the vesicles stored?
In the cytoplasm
When does exocytosis of peptide hormones occur?
When the cell is stimulated and in many cases Ca2+ initiates the process
How are steroids made?
Rapidly from cholesterol and not stored
What is a primary disorder?
Target endocrine gland disorder
What is a secondary disorder?
Disorder on pituitary gland
What is a tertiary disorder?
Disorder on hypothalamus
What cascade does physical or emotional stress stimulate?
Stimulates hypothalamus to release corticotropin releasing hormone (CRH), CRH travels to adenohypophysis stimulating ACTH release, ACTH acts on the adrenal cortex to release cortisol
What is the two level hierarchical feedback of cortisol release?
Cortisol inhibiting hypothalamus from releasing CRH
Cortisol inhibiting ACTH release from anterior pituitary
What hormones are released from the posterior pituitary?
ADH
OT (oxytocin)
What does the paraventricular nucleus release?
CRH TRH SST DA AVP OT
What does the periventricular nucleus release?
SST
What does the Arcuate nucleus release?
GHRH
SST
DA
What does the preoptic nucleus release?
GnRH
What does the ventromedial nucleus release?
SST
What does the supraoptic nucleus release?
AVP (ADH)
OT (more so than AVP)
What does DA inhibit?
Somatostatin
What does somatostatin inhibit release of?
GHRH
What is the primary mediator of effects of GH?
IGF-1
What affect does IGF-1 have on GH pathway?
Inhibitory
What does IGF-1 affect on the hypothalamus?
SS release
What is SS effect on the GH?
Inhibitory
Ghrelin affect on hypothalamus?
Release of GHRH
What does GH effect?
Stimulation of IGF-1
Inhibits GHRH
What channel does ACTH work on in the adrenal gland?
MC2R (melanocortin receptor-2)
What is Pexacerfont?
A CRH-1 receptor antagonist
What is Pexacerfont being investigated for?
Use in anxiety disorder
What is high CRH found in?
Alzheimer’s
Major depression
Suicide victims
What stimulates release of TRH?
TSH
Low T3/T4 levels
What does GnRH do?
Stimulates LH and FSH release
What inhibits GnRH and LH/FSH release?
Testosterone
Estrogens/Progesterone
What does DA inhibit?
Lactotrophs from releasing Prolactin
What stimulates DA release?
Prolactin
What stimulates release of prolactin?
Breast suckling
What four disorders have links to dopamine?
- ) Parkinson’s disease: loss of dopamine
- ) Schizophrenia: altered levels
- ) RLS: decreased levels
- ) ADHD: decreased levels
What is used for a dopamine injection and why?
L-DOPA because it crosses the BBB
