Mne Lecture 20 - Hormones

Front 1

Number it !!

Back 1

Front 2

List the classes of hormones.

Back 2

1. Isoprene derivatives
a. Steroids
b. Vitamin D
c. Retinoids

2. Thyroid Hormones

3. Proteins, glycoproteins, peptides

4. Amino acid derivatives

5. Eicosanoids

Front 3

Give examples of Isoprene derivatives

Back 3

1. Cortisol
2. 1,25 dihydroxy-vitamin D
3. All trans retinoic acid
4. 9-cis retinoic acid

Front 4

Give examples of thyroid hormones

Back 4

Thyroxine (T4) and triiodthyronine (T3)

Front 5

Give examples of proteins, glycoproteins, and peptide hormones

Back 5

1. Insulin
2. Thyroid stimulating hormone
3. Vasopresin

Front 6

Give examples of amino acid derivatives as hormones

Back 6

1. histamine
2. epinephrine

Front 7

Give examples of eicosanoids

Back 7

Prostaglandins and thromboxanes made from arachidonic acid via the cyclooxygenase pathway

Front 8

Number of carbons in

Cortisol

Back 8

21 carbons

Front 9

Number of carbons in

Aldosterone

Back 9

21 carbons

Front 10

Number of carbons in

Progesterone

Back 10

21 carbons

Front 11

Number of carbons in

Testosterone (DHT)

Back 11

19 carbons

Front 12

Number of carbons in

Estradiol

Back 12

18 carbons

Front 13

Back 13

Cortisol

(21 carbons)

Hint 13

-Stress
-->bug bite, gives itches. otherwise turns down immune system
-Lung development
*give glucocorticoids to premies and they develop lung surfactant
-Carbohydrate metabolism

Front 14

Back 14

Aldosterone

**anything on 18 position, should be aldosterone!
(21 carbons)

Hint 14

-Salt/water balance

Front 15

Back 15

Progesterone

-one of least substituted, no hydroxygroups
(21 carbons)

Hint 15

-Female sex tissue function

Front 16

Back 16

Testosterone (DHT)

*no substitutions except for hydroxy group on 17 position
(19 carbons)

Hint 16

-male urogenital development
-male secondary sexual characteristics
-aggression (males and females)
-bone maintenance

*although testosterone is the main male sex hormone and estrogen the main female sex hormone, testosterone is important in females and estrogen is important in males

Front 17

Back 17

Estradiol

(18 carbons)

Hint 17

-Female sex tissue function
-Male brain development
-Male fertility
-Bone maintenance
-Cardiovascular protection

*although testosterone is the main male sex hormone and estrogen the main female sex hormone, testosterone is important in females and estrogen is important in males

Front 18

What steroid hormone is this?

Back 18

this is 1,25 dihydroxyvitamin D3, but while this fat soluble molecule looks like a steroid, IT IS NOT A STEROID BC RING STRUCTRE IS BROKEN (Blue). DOES NOT HAVE 3 six membered rings and one 5 membered rings

Front 19

How do we make this molecule?

Back 19

1,25 Dihydroxyvitamin D3 (cholecalciferol) synthesis Illustrates how we make all hormones!!
Almost every hormone is made as a precursor and then activated. Not all but many

-all forms of vitamin D are bound to a vitamin d-binding protein in the circulation

Vitamin d is actual made from 7-dehydrocholesterol -- (note dbl bond in 7 position) –
This molecule is found in skin
UV radiation of skin results in formation of vitamin D3. This is why it is important to get some sunlight. 
THEN vitamin d3 can be converted to 25 hydroxyvitamin D3 in liver through 25-hydroxylase
Then it can be activated in the kidney to 1,25 dihydroxyvitamin D3
There is an inactivation step, and that is 24 hydroxylation is on the left of the image. 

Things that turn on degradation turn off synthesis and visa versa.
When one is turned no the other is turned off.

This is 1,25 Dihydroxyvitamin D3, the active form, and the 24 hydroxyl group added is inactive.

This cycling of events makes it look as though it HAS to go from the skin to the liver to the kidney, and that is the main route, in fact, the skin is the only organ that has all enzymes necessary to produce active vitamin d3, so you can form the whole thing in the skin without going through this process.

-1 a-hydroxylase is the major control point of the pathway, it is controled by 1,25-dihydroxyvitamin D3 itself (downregulates), parathyroid hormone (upregulates), and low serum phosphate (upregulates)

-1, 25-dihydroxyvitamin D3 increases 24-hhydroxylase activity

-the enzymes involved are NADPH-dependent cytochrome P-450s

Front 20

Besides finding 7-dehydrocholestrol in the body, where else can you find it?

Back 20

You can also find 7-dehydrocholesterol in other sources like MILK. One way of increasing vitamin D levels in milk is to irradiate with light. Can also feed cows with yeast extract (ergosterol can be used to make a form of Vitamin D which is active in humans). Feed cows this then shine UV light on milk and it gives you higher levels of active form vitamin D3.

Front 21

What is vitamin D important for?

Back 21

vitamin d important for bones, cell differentiation but actually the most direct effect is on CALCIUM UPTAKEto take up Calcium up in intestine need vitamin D3

Front 22

What is the main controlling point in the synthesis of vitamin D?

Back 22

1 alpha hydroxylase is thought to be the main controlling point in the synthesis of vitamin d synthesis.
-it is controlled by 1,25 dihydroxyvitamin D3 itself (downregulates), parathryoid hormone (upregulates), and low serum phosphate (upregulates)

also note that 1,25 dihydroxyvitamin D3 increases 24-hydroxylase activity

Front 23

Back 23

man – no vitamin d3 get rickets – note bow legs in this image but can also have knocked knees. In this case the bones do not develop properly because you’re not taking up calcium. The bones remain soft and when you start putting weight on them they bend one way or the other.

Front 24

Bonus: why doesn't this individual have hair?

Back 24

Particularly severe form of vitamin d3 deficiency simple hereditary resistance to vitamin d3 meaning vitamin d3 has no effect on this individual. This person has Alopecia (no hair) and oligodenentia (malformed teeth). May think the reason there is no hair because there is not enough calcium, but animal models have shown that is not the case. If you knock out vitamin d receptors in mice and make sure they have enough calcium in their blood stream find that it does correct a number of problems with vitamin d deficiency but it does NOT cure hair loss. It turns out that in those mice you can bring back hair growth by putting in a vitamin d receptor. That vitamin d receptor does NOT need to bind hormone. Idea that receptors can have effects bound to hormone and receptors can have effects not bound to hormone. It looks like hairloss here, ability of vitamin d to stimulate hair growth needs the receptor molecule but does not ligand vitamin d.

Front 25

Retinoids

Back 25

Retinoids
-all trans retinoic acid and 9-cis-retinoic acid
-made from b-carotene

important because there are 2 types of retinoic acid receptors:
1. all-trans retinoic acid binds to the retinoic acid receptor (RAR)
*involved in differentiation

2. 9-cis retinoic acid binds to the retinoic acid X receptor (RXR)
-->RXR heterodimerizes with other nuclear receptors and controls their activity
-->it is a MASTER REGUALTOR that regulates other receptors, including vitamin d receptor

Front 26

Proteins and amino acid derivatives

-list the four types

Back 26

-There is no clear distinction between peptides and proteins except when a protein consists of more than one polypeptide.
-In general, peptide hormones refer to short peptides such as somatostatin that is 14 amino acids long
-They all bind to membrane receptors on the outside of cells
-Only insulin-like growth factor 1 (IGF1), thyroid hormones, and the isoprene derivatives bind to carrier proteins
-Lack of carrier protein association leads to a shorter half life (seconds/minutes)
-Bring about immediate short term effects
-Although thyroid hormones are amino acid derivatives, they are generally classified separately

Front 27

proteins

Back 27

large polypeptides or multiple polypeptides joined together

eg.
growth hormone
insulin

Hint 27

growth hormone -- 191 amino acids, 2 disulfide bond

insulin -- 2 subunits joined together 2 disulfide bonds

Front 28

peptides

Back 28

eg. somatostatin

Hint 28

somatostatin -- 14 amino acids, generally an inhibitory hormone (main inhibitory hormone in humans)

Front 29

glycoproteins

Back 29

eg.
thyroid stimulating hormone (TSH) 
leuteinizing hormone (LH)
chorionic gonadotropin (CG)
Follide stimulating hormone (FSH)

Hint 29

activate cAMP

pitutary and placental hormone

two subunits:
-alpha subunits are the same, beta subunits are different
-specificity of action resides not in the alpha subunit which is the same but in the beta subunit which is different.
-if you have an Ab against the alpha subunit if you did an assay you'd measure everything with an alpha subunit, which is all of these hormones.

Front 30

amino acid derivatives

Back 30

eg.
dopamine
thyroxine (T4)

Hint 30

both of these examples are made from tyrosine

Front 31

Growth Hormone

polypeptide/bond number

Back 31

Single Polypeptide, 1 disulphide bond

Front 32

Insulin

polypeptide/bond number?

Back 32

2 polypeptides, 2 disulphide bonds

Front 33

What is detected in home pregnancy test kits?
error rates?

Back 33

hCG is the molecule to detect pregnancy in pregnancy test kits

has a and b subunits

ab used to test control red bar and then other bar comes up if hCG is present in the urine you're adding to the test

Test kit error rates:
96-98.5%
-->this is with skiled technicians doing test
-->average population doing test has error rate or 25% because people don’t follow directions.. Don’t leave it long enough or let it develop too long see bands that aren't there (evaporation)

Front 34

Catecholamines

pathway of synthesis?
location of synthesis?
rate limiting step?
released in response to?
degradation?

Back 34

-amino acid derivatives

Synthesized:
-Adrenal medulla
-Sympathetic & parasympathetic nervous system.
-What is made in a tissue is determined by what enzymes are present.Have a tissue with PNMT, going to be able to make epinephrine, don’t have it make Norepinephrine.

Rate limiting step:
-Tyrosine hydroxylase

Epinephrine:
-Made mainly in the adrenal medulla
-PNMT converts norepinephrine to epinephrine
-PNMT also found in other tissues e.g. heart
-Fight or flight response!

Stress Response
-Catecholamines are released from the adrenal medulla
-Catecholamines increase ACTH production
-Glucocorticoids increase dopamine ß-hydroxylase synthesis

Degraded by deamination
-catechol-O-methyltransferase (COMT)
-monoamine oxidase

Pheochromocytomas
Tumors of the adrenal medulla, overproduce epinephrine and norepinephrine!

Front 35

Eicosanoids

Back 35

-Made from arachidonic acid (20 carbons: 4 double bonds)

Arachidonic acid can be converted into prostaglandin H2 by prostaglandin synthase

Prostaglandin synthase:
-Cyclooxygenase
-Hydroperoxidase

Prostaglandin H2 (PGH2) is the precursor to
-Prostacyclin
-thromboxanes
-other prostaglandins.

Aspirin irreversibly inhibits the cyclooxygenase (asprin aka acetylsalicylate acetylates tyrosine residue, releases salicylate and have inactive enzyme)
-Anti-inflammatory
-Antithrombotic

Inhibits platelet thromboxane A2 synthesis
-Prevents positive feedback on clotting
-Lasts the lifetime of the platelet (10 days)

Ecosanoids can bind to multiple receptors!
Have receptors on the cell surface, but these molecules are very hydrophobic so you'd expect them to go straight into cells but on the way they can bind to these cell surface receptors. Can also bind to nuclear receptors

Front 36

What are these two molecules??

What are they made of?
Where are they made?
What happens if you don't have them?

Back 36

-hydrophobic
-partially lipid soluble
-made from tyrosine (linkage of two together)

-made in thyroid not as two tyrosines being linked together but as tyrosines being linked together in protein (thyroglobulin)
-the only hormones that contain iodide
-enter the cells and bind to an intracellular receptor
-play a role in growth and development

- can make 2 forms: t4 and t3
- t4 has 4 iodines (thyroxine)
- t3 has 3 iodines (triiodothyronine)
*T3 is the active form!!
*T4 is precursor for t3 !

If you don’t have thryoid hormone at birth you develop incorrectly. Look like image --> short, short because thyroid hormone controls growth hormone activity. This reduces level of growth hormone so you’re short. You also have mental retardation because thyroid hormone is essential for mentation and development of the brain.

Front 37

glucocorticoids produced in the

Back 37

adrenal corex act on the

Hint 37

liver

(classical endocrine)

Front 38

vitamin d is produced in the

Back 38

kidney acts on the

Hint 38

intestine

(classical endocrine)

Front 39

insulin produced in the

Back 39

pancreas (b-cells) acts on

Hint 39

adipose tissue

(classical endocrine)

Front 40

TSH produced in the

Back 40

anterior pitutary acts on the

Hint 40

thryoid 

(classical endocrine)

Front 41

glucagon produced in the

Back 41

pancreas (a-cells) acts on the

Hint 41

liver 

(classical endocrine)

Front 42

norepinephrine produced in the

Back 42

adrenal medulla acts on the

Hint 42

heart

(classical endocrine)

Front 43

Classical endocrine

v. Paracrine

v. Autocrine

Back 43

Classical endocrine:
"hormones are chemicals secreted by specific tissues into the blood stream that then act on target organs."
-hormone, an active molecule, which is made by one tissues travels through the bloodstream binds to another tissue and brings about an effect

Paracrine:
"Hormones act on an adjacent cell type to the one that produced the hormone. All chemical classes of hormone can potentially act in a paracrine manner."

Autocrine:
"Hormones act on the cells that produce the hormone. This is a much rarer event than paracrine or endocrine action. It requires that the hormone producing cells have the receptor for that hormone. It is not thought to occur with steroid or thyroid hormones."
-proteins/peptides
-eicosanoids

Front 44

Testosterone synthesized in the

Back 44

Leydig cells acts on

Hint 44

seminiferous tubules

(paracrine)

-can also act in classical endocrine manner, go through circulation and cause facial hair growth for instance
-have paracrine action in testes

Front 45

Insulin produced in

Back 45

B-cells acting on

Hint 45

a- cells

(paracrine)

Front 46

Histamine released by

Back 46

mast cells acts locally on

Hint 46

blood vessels, neurotransmitter, and neuromodulators

(paracrine)

Front 47

Prostaglandins released in

Back 47

inflammation

(paracrine)

-dont have to go into blood stream and travel, can act locally

Front 48

Examples of autocrine hormones

Back 48

1. proteins / peptides
-eg. growth factors
-can use conditioned media (media thats been used to grow other cells to help cells grow)

2. Eicosanoids
-eg. prostaglandins
or thromboxane acting on platelets

Front 49

Examples of hormones secreted in the active form

Back 49

1. hydrocortisone
2. Aldosterone
3. T3
4. Estradiol
5. Catecholamines

Front 50

Examples of hormones that have to undergo intracellular processing before being secreted

Back 50

eg.
1. Tissue specific processing of the 285 amino acid polypeptide pro-opiomelanocortin (POMC) to ACTH, b-lipotropin, B-endorphiin, aMSH, bMSH

2. Prosinulin
3. Preproparathryoid hormone
4. Thryoglobuln to T3 and T4

Front 51

Examples of hormones that are activated peripherally in target tissues

Back 51

eg.
1.Thyroxine (T4) to triiodothyronine (T3)
2. Testosterone to dihydroxytestosterone
3. Testpsterone to 17b-estradiol

testosterone  direct action, through circulation affecting hair growth, spermatogenesis, can be activated to two other hormones  DHT (dihydrotestoseterone the main one that causes pattern baldness in males, also important in the prostate) also 17 beta estradiol – 17 beta estradiol is the main FEMALE sex hormones. Females make testosterone first, then converting very efficiently to estradiol. Make too much testosterone then you’ll start seeing effects of testosterone like facial hair growth, acne. Males can make estradiol, through testosterone. This is an inefficient conversion.

Front 52

Examples of hormones that are activated peripherally in target and/or non-target tissues

Back 52

1. dehydroepiandrosterone (adrenal) to androstenedione (liver), to testosterone or estradiol in fat, liver, or skin

2. Vitamin D3 from skin to 25- hydroxycholecalciferol in liver, to 1,5-dihydroxycholecaliciferol in kidney

Front 53

Aldosterone


Primary Binding Protein?

Back 53

Albumin

Front 54

Cortisol


Primary Binding Protein?

Back 54

CBG

CBG = corticosteroid binding globulin

Front 55

Estrogen


Primary Binding Protein?

Back 55

TeBG

TeBG = testosterone binding globulin

Front 56

Testosterone


Primary Binding Protein?

Back 56

TeBG/albumin


TeBG = testosterone binding globulin

Front 57

Vitamin D


Primary Binding Protein?

Back 57

D-binding protein

Front 58

Retinoic acid


Primary Binding Protein?

Back 58

Albumin

Front 59

Triiodothyronine (T3)


Primary Binding Protein?

Back 59

TBG

(thyroid hormone binding globulin)

Front 60

Thryoxine (T4)


Primary Binding Protein?

Back 60

TBG

(thyroid hormone binding globulin)

Front 61

IGF1


Primary Binding Protein?

Back 61

IGF-Binding proteins

Front 62

ACTH

Back 62

Adrenocorticotropic hormone (ACTH), also known as corticotropin, is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. ACTH is made from another molecule called pre-pro-opiomelanocortin (pre-POMC) which is a large protein precursor that has ACTH in it but it also has a lot of other hormones. Hormones you get depends on which peptides you cleave.

Front 63

Compare binding proteins and receptors

Back 63

1. Carrier proteins are NOT receptors; they are merely binding proteins

2. In endocrinology, receptors are defined as proteins that bind specifically to a hormone and transduce a response

3. That hormone binding initiates a signal cascade within the cell

4. Receptors thus have at least two activities/domains; a hormone binding domain and a transduction domain

5. Hormone binding can give rise to the formation of second messengers such as cAMP or they can bind to DNA and modulate transcription

Front 64

Characteristics of hormone receptors

Back 64

-all receptors transduce a signal, therefore they have at least two functional domains

1. Hormone binding domain
-specific high affinity, reversible binding, can be determined by binding assays (Scatchard plots)
-agonists bind and bring about a response
-antagonists bind and inhibit agonist responses
-antagonists are often weak agonists

2. Transducing domain
-induction of second messengers, activation of transcription

Front 65

Characteristics of hormone transport

Back 65

-carrier proteins act as a reservoir for hormone; they protect against degradation, and thus increase the half-life of the hormone
-carrier proteins act as a buffer to prevent large surges in hormone levels
-only isoprenoid derived hormones and insulin like growth factors (IGFs) bind to carrier proteins
-there are at least 6 IGF-binding proteins. These are unusual in that they bind hormone with high affinity and that they play a role in the control of IGF activity.

Front 66

Which have a longer half life hydrophobic or hydrophilic hormones?

Back 66

Hydrophobic have longer half life than hydrophilic hormones (they dont bind carrier proteins)

Front 67

How do binding proteins affect hormone homeostasis?

Back 67

Cells making carrier proteins, lets free hormone into circulation, can bind to receptors, be degraded, may go through kidneythis is active form, binds to hormone receptor.
Once it does that, has a biological effect.

One such effect of all endocrine systems is FEEDBACK MECHANISM: either direct or indirect. Normally is direct

1. Hormone binds to endocrine system making hormone and shuts down production (Direct)
-Have active equilibrium here where you produce hormone, levels go up, and you come back and turn it off again
2. Carrier bound .. Mops up a lot of hormone, reversible low affinity binding.. Can think of this as a reservoir of hormone.Forget endocrine cell, just think about free hormone. When free hormone goes down, immediately release hormone from the carrier bound state, to the free state. There is an EQUILIBRIUM. This is one of main ways we keep hormone levels constant. This is why halflife can be quite long. If you decrease hormone immediately release more from carrier bound form – automatic not enzymatic. Lower hormone stop binding to receptor, biological effect is release of negative feedback, then get hormone released.

Front 68

Methods used to measure hormone levels

Back 68

Methods used to measure hormone levels.
RADIOIMMUNOASSAY and ELISA (elisa no radioactivity.. Enzyme linked, produce color) 

Radioimmunoassay: 
-uses antiobody and radioactivity
-antibody used to precipitate a complex of radioactive hormone and nonradioactive hormone.
Measure amount of radioactivity that comes down and use that as a way of quantitating hormone levels. 
Take radioactive hormone and have ab, and precipitate get an ab-hormone complex.
Can measure amount of radioactivity.Then toss in non-radioactive hormone that we’ve purified, but know exactly how much you’re adding
Can dilute radioactivity with cold/nonradioactive hormone, do the experiment again and can compete away the radioactive hormone and when you do the assay get less radioactivity being pulled down.
We can do a standard curve, maximum get 100%, as we add cold hormone decreases linearly/curve.
*Can repeat experiment, but instead of adding what we know is hormone, add human serum. Take patient, add aliquot of their serum, hormone present in serum is going to compete with the radioactivity, and going to get some reading so you can come across and read the concentration of hormone in the blood stream. NOW more common way of doing this is ELISA.