Hypothalamic & Pituitary Hormones

Front 1

How are hypothalamic hormones released and regulated?

Back 1

released in a rhythmic/circadian pattern and regulated in a negative feedback loop.

Front 2

What are the hormones released from the hypothalamus?

Back 2

TRH; CRH; GnRH; GHRH; somatostatin; dopamine

Front 3

What are the hormones released from the anterior pituitary that are stimulated by the hypothalamus?

Back 3

TSH; ACTH; FSH/LH; GH

Front 4

What target organs and hormones are stimulated by the anterior pituitary?

Back 4

Thyroxine & T3 from thyroid
glucocorticoid from adrenals
androgens, estrogens & progestins from gonads
IGF-1 from liver

Front 5

what is the function of somatostatin?

Back 5

To inhibit GH release from the anterior pituitary.

Front 6

what is the function of dopamine?

Back 6

Inhibits prolactin release.

Front 7

Growth Hormone production

Back 7

most abundant hormone in AP.
1 gene produces a heterogenous mix of peptides, leads to several GH's of different AA combos.

Front 8

Growth Hormone control and release

Back 8

controlled Somatostatin and GHRH
Released by nurons in hypothalamus in pulsatile fashion therfore pulsatile stimulation of somatrophs in AP which release GH.

Front 9

Somatostatin receptors

Back 9

there are up to 5 SS receptors: SSTR2 and SSTR5 are the most important

Front 10

Somatostatin

Back 10

Decapeptide, inhibits GH, made in hypothalamus and pancreatic islets, also inhibits TSH, gonadotropins, insulin and glucagon release

Front 11

GH Regulation

Back 11

Negative Feedback loop
short loop- GH feedback to neurons of GnRH, inhibits GHRH's release
classic loop- end hormone (IGF-1)inhibits GH release of GHRH release

Front 12

What influences GH secretion?

Back 12

sleep, hypoglucemia, physical exertion, emotional excitement, drugs: increased by alpha agonists, L-dopa and amphetamines; decreased by Beta agonists and phenothiazines

Front 13

What is the insulin tolerance test?

Back 13

hypoclycemia increases GH release. Test: infuse insulin, blood gluc should dec, GH should inc, and cortisol should inc.

Front 14

pharmocodynamics of GH

Back 14

GH binds to cell surface receptors, and also circulates bound to extracellular protein domain of GH receptors

Front 15

Function of GH alone

Back 15

GH directly increases lipolysis and gluconeogenesis

Front 16

Function of GH through IGF-1

Back 16

anabolic and growth promoting effects (metab of proteins, fat, carbs, Ca) results in growth(increased cell number not size)

Front 17

Function of IGF's

Back 17

mediate most GH effects
IGF-2 activates intracellular mannose-6-phosphate receptor
IGF-1 binds receptors similar to insulin receptor

Front 18

Diseases of hypo GH secretion.

Back 18

dwarfism- in children
endocrinopathies in adults (including increased cardiovascular mortalities)

Front 19

Diseases of hyper GH secretion.

Back 19

Gigantism- in kids before epiphyseal plates close
acromegaly- after plates close

Front 20

symptoms of acromegaly

Back 20

visual problems from pituitary adenomas, bone overegrowth in hands, feet and face, headaches, sweating, diabetes, joint problems, colon cancer, cardiovascular disease

Front 21

prolactin

Back 21

structurally related to GH
secretion influenced by same factors as GH plus estrogen
role= lactation
receptors on other cells have unknown functions

Front 22

hyperprolactemia

Back 22

suppresses HPG-axis through actions on hypothalamus and gonads
Treatment= dopamine, bromocriptine, pergolide, cabergoline

Front 23

Octreotide

Back 23

SS analog,treats acromegaly, preferred because most specific for GH system, has modified Amino acid therefore longer t1/2 & greater selectivity,also used for metastatic carcinoid cancers, VIP secreting tumors, AIDS related diarrhea; SIDE EFFECTS: hypothyroidism, GI symptoms (loose stool, malabsorption, nausea and flatulence)

Front 24

Pegvisomant

Back 24

GH receptor antagonist, genetically engineered analog of human GH conjugated to polyethylene glycol= pegylation (reduces renal clearance and gives longer t1/2)
mech: blocks GH binding to receptor therefore decreases serum IGF-1 secretion but increases GH in serum
most effective for acromegegaly
SE: can develop auto GH Ab's leads to CV probs

Front 25

Bromocriptine

Back 25

dopamine agonist, treats acromegaly, hyperprolactinemia, amenorrhea, galactoffhea, infertility, hypogonadism, parkinson's; SE= HA, dizziness, nausea, HTN, postural hypotension, contraindicated in pts with sensitivity to ergot alkaloids

Front 26

Growth Hormone as a drug

Back 26

for dwarfism, chronic renal insufficiency, Turner's syndrome; can be prepared as hGH (somatropin)(encapsulated for monthly IM injections)or synthetic hGH with methionine removed (somatotrem)

Front 27

Dopamine

Back 27

inhibits prolactin release

Front 28

pergolide

Back 28

for hyperprolactinemia,

Front 29

cabergoline

Back 29

longer t1/2, more potent D2 selective, used once or twice a week
preferred over bromcriptine in acromegaly