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151 Cards in this Set

  • Front
  • Back
DURATION of a hormone’s effect depends on:
Most amino acid modifications have this action
Releasing or Inhibiting hormones are secreted from the
Type of mods:
a. N-acylation
b. N-formylation
c. Cyclization
Change the N-terminus
pyro-formation, via loss of a water molecule from the transition
state intermediate; symbol is < or “p”
symbol is < or “p”
Type of mods:
a. Convert the COOH to an amide (by adding NH2)
b. Convert the COOH to an ethylamide
c. Remove a terminal AA otherwise recognized by an exopeptidase: “des”AA
Change the C-terminus
how you form a "des"AA
remove a terminal AA
by removing a C-terminal Gly, the resulting peptide’s new name
starts with the phrase
Two things you can convert the COOH to when modifying a C-terminus
amide, ethylamide
Ways you can change the interior portion of a sequence
chemically modify, "des", replaced L with D
Three AAs of TRH
TRH half life
4 minutes
Active: at picogram levels. No commercial analogs are available.
Diagnostic only, for HYPOTHYROIDISM’s cause (& thus treatment)
Therapeutic use for TRH
After diagnosis with TRH, if a person has a primary problem, something is wrong with their
After diagnosis with TRH, if a person has a secondary problem, something is wrong with their
After diagnosis with TRH, if a person has a tertiary problem, something is wrong with their
Diagnostic use of TRH is in this manner
admin TRH IV wait, 15-30 minutes, take TRH levels
a 10 AA peptide
duration of action of GnRH
3-5 hours
Activity: Release LH & FSH from Anterior Pituitary
More than 3000 analogs tested
What TRH would look like if it were an unmodified Glu-His-Pro at physiological pH
Zwitterion at N-terminus and (-) at C-terminus
Actual TRH, at physiological pH
Pyroglutamate at N-terminus and C-terminus is amidated
Vasopressin and Oxytocin are secreted from this lobe of the pituitary
MSH is secreted from this lobe of the pituitary
Promote reproduction by enhanced follicle development/ovulation
GnRH or analog
Interfere with reproduction by RECEPTOR DOWN REGULATION
GnRH or analog
Diagnose potential cause of infertility (hypothalamic or pituitary)
GnRH or analog
How GnRH is used to treat endometriosis (by reducing levels of estrogen)
reducing levels of estrogen
Use of GnRH for palliative treatment of prostate cancer works by
reducing secretion of testosterone
Use of GnRH is palliative treatment of advanced metastatic breast cancer works by
reducing levels of estrogen
Used for chemical castration (as may be needed with advanced prostate cancer)
GnRH or analog
Used to suppress LH surges and increase chances of pregnancy
GnRH antagonists
aka Lutrepulse
route of Gonadorelin admin
IV, (not orally available)
AA #6 of Gonadorelin = D-Leu, not L-Gly
In Leuprolide, the #6 AA is also modified and the C-terminal GLY is replaced with
an N-ethylamide
15-50 x as potent as GnRH
Continuous dosage: shuts off production of estrogens or androgens.
Used with children in cases of premature puberty to stop menstruation or to control testosterone
AA #6 of Gonadorelin = modified D-Ser; C-terminal is also modified.
It is used to treat prostate and breast cancer, to treat endometriosis, or to help thin the endometrium
prior to a hysterectomy.
AA #6 of Gonadorelin is D-Ala conjugated to a naphthalene double ring structure.
Its advantage is that it is administered as a nasal spray.
Enhance fertilization: by BLOCKING the GnRH RECEPTORS they
prevent the LH surge that the anterior pituitary would otherwise induce.
GnRH antagonists
prevent ovulation and allow greater maturation of the egg in the ovary.
GnRH antagonists
Effective after only 5 days of treatment, rather than the 26 days required by leuprolide
GnRH antagonists
GnRH antagonist
aka CRH, or corticorelin, or Acthrel = ACTH releasing hormone
CRF - Corticotropin Releasing Factor
made of 41 aa's with a synthetic version also available
Smallest active peptide derivative of CRH is
38 AA long
As with TRH and GnRH, the C-terminal
COOH is “blocked” as an amide.
Conversion (CRF) of COOH is “blocked” as an amide back to COOH has this effect on its activity
drops significantly
CRH binds a receptor in the Anterior Pituitary. Signaling
involves adenylate cyclase, resulting in elevated levels of cAMP, then
ACTH release
Primary Use: Diagnostic, for cases of pituitary defects that present as Cushing’s
elevated levels of hydrocortisone that result from excess secretion of ACTH
Cushing’s Disease
Other tissues can also secrete ACTH (called __ secretion) and produce Cushing’s symptoms
44 AA, but only 1- 29 are required for activity (so can be produced synthetically).
causes release of human Growth Hormone (hGH) from Anterior Pituitary.
Diagnostic for kids with idiopathic (the cause is unknown) Growth Hormone
Deficiency (GHD)
for cases of GHD where the pituitary works fine, but hypothalamus is not working properly
Since GH promotes protein accumulation, __ is also approved as an “orphan drug” in AIDS to counteract protein (and associated weight) loss.
Dopamine and Somatostatin are both
inhibitory hypothalamic hormones
a catecholamine that can act both as a neurotransmitter and as a hormone
Dopamine receptors of type __, in which adenylate cyclase enzymes are inhibited
are those responsible for the inhibitory effect of DA at the pituitary
Dopamine D2 receptors
Uses for DA in hormone therapy
Two reasons DA is not used in hormone therapy
1.) peripheral effects of DA in vessels
2.) broken down by MAOs and others
dopamine agonist
In women with hyperprolactinemia and a pituitary tumor, treatment with __ led to disappearance of the tumor in
45% and stabilization in another 40% over a period of 8 years followup.
dopamine agonist with fewer side effects
Dopamine (DA), also known as
Prolactin-Release Inhibitory Factor, PRIF
Since elevated PRL (DA) can promote metastatic breast cancer, __
therapy used in conjunction with regular chemotherapy can be beneficial.
14-AA, cyclized peptide
inhibits release of Growth hormone from anterior pituitary
Activity requires that the peptide be cyclized
Parlodel is aka
If replace S-S bridge in somatostatin with an ___ the resulting
peptide has a half-life of 3 hours, instead of the 2-3 minutes exhibited by the native peptide.
ethylene bridge (-CH2-CH2-)
why replacement of S-S bridge in somatostatin with an ethylene bridge is so effective at increasing half-life
reducing agents such as Glutathione (Glu-Cys-Gly) cannot break ethylene bonds
somatostatin has several sources, not just
the hypothalamus
Spinal Cord somatostatin is a
a neurotransmitter, and it induces sedation and hypothermia.
brain somatostatin
inhibits the secretion of gastrin
gut somatostatin
inhibits the release of insulin and glucagon
pancreas somatostatin
reason native somatostatin is not used therapeutically
half-life is too short
therapeutic uses include diabetes, acromegaly, and cancer of the endocrine system
non-radioactive somatostatin analogs
reason non-radioactive somatostatin analogs have use for treatment of diabetes
inhibition of glucagon secretion by somatostatin is greater than its
inhibition of insulin secretion.
increases levels of blood sugar
lowers blood sugar by helping it get inside cells
inhibit the release of several
hormones that may be hypersecreted by endocrine tumors
somatostatin analogs
histamine, serotonin, bradykinin,
prostaglandins, vasoactive intestinal peptide
hormones that may be hypersecreted by endocrine tumors
use of non-radioactive somatostatin analogs in the treatment of eendocrine cancers is
palliative (to reduce diarrhea or e-lyte imbalances)
a condition in which too much growth hormone causes an enlargement of
large bones in the hands and feet and the face, along with an enlargement of the nose and lips
many tumor cell types express
use of radioactive somatostatin analogs for tumors
radioactivity is selectively delivered to kill the cells overexpressing somatostatin receptors
modified somatostatin analog which OVERALL most effectively inhibits the secretion of GH, insulin and glucagon
[D-Trp8] somatostatin
70 times more effective than native
modification of somatostatin with mirror images of aa's and COOH to OH yields
octreotide (70x more potent)
GH is this type of hormone
191 AA in length, with a MW of 22,000
GH is much larger than its active region, so the extra size
protects or shields the active region from enzymatic destruction
portion of GH which actually binds to the receptor
the C-terminal ¼ of the molecule
(somewhere within AA146-AA191)
The hormone does not move in the blood as a free molecule; rather, it travels
thru the circulatory system adsorbed onto plasma proteins.
has a lower rate of inactivation by proteolytic enzymes than does free GH
Adsorbed GH
instead of traveling freely, these three hormones extend their half-lives by adsorbing onto the surface of plasma proteins
ADH, oxytocin, and GH
Today's source of GH
recombinant DNA technology, probably within e.coli
somatropin is aka
Treatment for Children whose growth is abnormally slow
a. Due to lack of endogenous GH
b. Due to chronic renal failure
Neutropin and Serostim are aka
Treatment for adults with GH deficiency (due to pituitary or hypothalamic disease, radiation
therapy for cancer)
Treatment for girls with Turner’s syndrome (where one of the X-chromosomes is partially or
totally missing) – who are also unusually short
Treatment for body wasting (cachexia) due to HIV-1 or other disease
Treatment for cardiac insufficiency in patients (wall of the ventricle is too thin, or promote growth of useful cardiac tissue in some cases of cardiac hypertrophy
– where excess myocardial mass is nonproductive)
Although GH can increase skeletal mass and strength, why should athletes beware of use for muscle gain?
bizarre growth patterns
What could happen to an athlete who tries to use GH to gain rapid muscle mass?
acromegaly, esp. is those over 18 yrs.
Site of Production is primarily in the liver (but included since they work like GH)
somatomedins are similar to
IGFs (Insulin-like Growth Factors)
Quite similar to insulin (they have homologies with both the A-chain and the B-chain of
nature’s own “slow release formulation”
transport through blood via adsorption to plasma proteins
MW a bit larger than insulin with a half-life of about 20 hours
Act together with GH to promote cartilage growth, stimulate protein
synthesis, stimulate thymidine incorporation into DNA, and stimulate cell division (mitosis).
198 AA with a MW of about 23,000. Half-life is about 10 minutes. Neither
end of the peptide is blocked
similar in sequence to human GH (homology), and at sufficiently
high levels, bind to each others’ receptors
The best homology for GH and PRL is
only 16%
when only the first 50 AA in each GH and PRL sequence are considered
then the homology increases by half
Replacing only 8 AA from GH into
PRL makes a __ that readily binds the GH receptor.
mutant PRL
Thus, homology is important, but homology between __ is more important.
active site amino acids
increase stability (half-life)
facilitate secretion
create recognition sites
glycosylation - covalent attachment to sugars to N of Asn thru O of Ser or Thr or HyLys
–CH2-C(=O)-NH2 becomes –CH2-C(=O)-NH-sugar chain
which are less active glycosylated proteins are non-glycosylated ones?
glycosylated proteins are only 20-25% as active
prolactin and TSH are both
glycosylated hormones
Proteins that are secreted thru the plasma membrane are often
Prolactin has a synergistic action with __ to promote mammary
gland proliferation and milk let-down
helps release progesterone from luteal cells, which renders the uterus suitable for imbedding of the ovum
if fertilization occurs
also binds the lactogenic receptor (the receptor to which prolactin binds)
if GH binds to the lactogenic receptor instead of prolactin, will it stimulate lactation?
Excessive levels of GH may lead to
galactorrhea (xs milk production, even after nursing has stopped)
high levels of PRL binding to the GH
receptor causes
There is a synergistic relationship between prolactin and __ release for preparation of the uterus for implantation
The main characteristic of high levels of PRL is
How does xs PRL possibly cause infertility?
prolactin receptor desensitization
increases testosterone production levels that eventually down-regulate
testosterone receptors
have high levels of prolactin and are less able to become pregnant
New nursing mothers
This could be nature’s way of spacing the responsibilities for child-rearing
prolactin receptor desensitization
In the case of prolactinemia because of a pituitary tumor, __ may be administered to inhibit prolactin secretion.
dopamine agonists bromocriptine or cabergoline