Lecture 7: Hormonal Properties Flashcards
What are the 3 hormone derivatives of isoprene/cholesterol?
- Steroids 2. Vitamin D 3. Retinoids
Are the 3 hormone derivatives of isoprene/cholesterol lipid or water soluble? Do they require carrier proteins?
Lipid Yes!
Where are the receptors of the 3 hormone derivatives of isoprene/cholesterol?
Intracellular
Are thyroid hormones lipid or water soluble?
Partially lipid soluble
Do the thyroid hormones require carrier proteins in the blood? To get through membrane?
Yes
Yes because only partially lipid soluble
Where are the receptors of thyroid hormones?
Nuclear
Do protein and peptide hormones require carrier proteins?
No
Where are the receptors of protein and peptide hormones?
Membrane
Do AA derivative hormones require carrier proteins?
No
Where are the receptors of AA derivative hormones?
Membrane
Are eicosanoid hormones lipid or water soluble?
Lipid
Do eicosanoid hormones require carrier proteins?
Yes
Where are the receptors of eicosanoid hormones?
Membrane (G-protein) and intracellular
How many Cs in androgens (including testosterone)?
19
How many Cs in estrogen?
18
Are estrogens aromatic of aliphatic?
Aromatic
Are androgens aromatic of aliphatic?
Aliphatic
What are the 5 classes of steroid hormones and what does each include?
- Androgens: DHEA and testosterone
- Estrogens: estradiol, estrone, estriol
- Glucocorticoids: cortisol, corticosterone
- Mineralcorticoids: aldosterone, deoxycorticosterone
- Progestins: progesterone
What 3 steroid hormones have 21 Cs?
- Cortisol 2. Aldosterone 3. Progesterone
What is specificity due to in steroid hormones?
The position of the hydrozy group on the ring structure
What is the ring structure of steroid hormones?
- Three 6-membered rings
- One 5-membered ring
What is this?

Progesterone
What is this?

Cortisol
What is this?

Estadiol
What is this?

Testosterone
What is this?

Aldosterone
Is Vitamin D a steroid? Why/Why not?
NOPE, it’s a lysosteroid
Because no longer has a 4-ring structure because the B ring has been disrupted
What is this?

Vitamin D
What is the active form of vitamin D? 3 names
1,25-dihydroxyvitamin D = 1,25-dihydroxycholecalciferol = calcitriol
How is vitamin D synthesized? Draw the pathway
3-step pathway with 3 inactive forms:

What enzyme is the major control point of the 3 step pathway of vitamin D synthesis? Where is it located?
1alpha-hydroxylase (kidney)
What can increase the levels of 1alpha-hydroxylase in the liver?
- Decrease in 1,25-dihydroxyvitamin D3
- Parathyroid hormone
- Low serum phosphate
- Decrease in 24-hydroxylase
How is vitamin D degraded? How is this stimulated?
Through the 24-hydroxylation pathway
Stimulated by 1,25-dihydroxyvitamin D3
What is Rickets caused by? Symptoms?
Vitamin D deficiency causing lack of calcium absorption = soft bones, bone deformation, bow legs, compromised height
What happens when Vitamin D receptors are missing in the body? Why? What disease is this?
Alopecia and oligodontia (lack of teeth) because receptors also interact with other proteins
Also Rickets
Describe the retinoid hormones synthesis pathway.
Beta-carotene → retinaldehyde = Vitamin A → all-trans retinoic acid OR 9-cis retinoic acid
What are the 2 important retinoid hormones? How do they differ?
- All-trans-retinoic acid
- 9-cis-retinoic acid
They only differ at the orientation of the double bond at the 9th position
To what receptor does all-trans-retinoid acid bind? To what end?
Retinoic acid receptor (RAR)
⇒ to help control growth and differentiation
To what receptor does 9-cis-retinoid acid bind? To what end?
Retinoic acid X receptor (RXR)
⇒ to form heterodimers with other receptors
What are 2 examples of protein hormones?
- Insulin
- GH
What are 2 examples of peptide hormones?
SS and glucagon
What are 4 examples of glycoprotein hormones?
- TSH
- LH
- FSH
- hCG
What are 3 examples of AA derivative hormones?
- Histamine
- Epi/Norepi
- Dopamine
= CATECHOLAMINES
Describe the structure of glycoprotein hormones. What will the structure determine? What does the similarity in structure cause?
- Common alpha subunit
- Unique beta subunit: determines what receptor it will bind to
If huge amounts of one of them is produced it will be able to bind to the wrong receptor for another glycoprotein hormone
What is the precursor of epi, histamine, and dopamine?
Tyrosine
What is the order of the epi synthesis pathway? How is the pathway stopped? What enzyme is the rate-limiting one?
Tyrosine → Dopa → Dopamine → Norepi → Epi
Different tissues have different enzymes depending on which of these hormones they need
Rate-limiting enzyme: tyrosine hydroxylase
What enzyme converts norepi to epi?
PNMT = phenylethanolamine N-methyltransferase
What are AA derivative hormones also called?
Catecholamines
What are eicosanoids derived from?
Arachidonic acid
Why does aspirin have an anti-clotting effect? How does it do this? What is the side product?
Archidonic acid |protaglandin synthase=cyclooxygenase + hydroxiperoxide|⇒prostaglandin H2⇒prostacyclin + thromboxane (potent aggregator of platelets)
Aspirin INHIBITS cyclooxygenase by IRREVERSIBLE binding Ser at active site and acetylating it (side product: salicylate)
What are the 2 components of protaglandin synthase?
protaglandin synthase=cyclooxygenase + hydroxiperoxide
What is a lot of the hormones’ specificity due to?
To the way in which hormones are synthesized and modified
Where are steroid hormones sythesized?
ER or mito
Where are thyroid hormones sythesized?
Colloid = follicular space
Where are proteins, peptides, AA derivs hormones synthesized?
RER and Golgi
Where are eicosanoid hormones synthesized?
Membranes
What 2 types of hormones are stored? Where?
- Thyroid hormones: in thyroid
- Proteins/Peptides/AA derivs: in secretory vesicles
What is the half-life of eicosanoid hormones like?
Very short
Are steroid hormones synthesized in their active form?
Yes
Are thyroid hormones synthesized in their active form?
Nope
Are peptide/protein/AA derivs hormones synthesized in their active form?
Nope
Are eicosanoid hormones synthesized in their active form? For what purpose?
Yes
Local action
What regulates the circulating levels of steroid hormones?
The rate of synthesis (no stores)
What regulates the circulating levels of thyroid hormones?
Release of hormones from stores
What regulates the circulating levels of protein/peptide/AA drivs/glycoprotein hormones?
Release of hormones from stores
What modifications can happen to steroid hormones after they are released?
Can be converted into even more active forms in target tissues
What modifications can happen to protein/peptide/AA derivs/glycoproteins hormones after they are released?
Activated in target tissues in specific ways
Do eicosanoid hormones have the potential to be modified in target cells?
YUP
Do lipid soluble hormones require carrier proteins to circulate in the blood?
Yes
Do water soluble hormones require carrier proteins to circulate in the blood?
NOPE
What are the 5 roles of blood carrier proteins of hormones?
- Carry the hormone
- Act as a reservoir for that hormone
- Protect against degradation
- Increase half-life
- Act as buffers to protect against high or low surges of hormone levels (will release hormones when levels are low and will bind hormones when levels are high)
Does the hormone bound to a carrier protein have biological activity?
NOPE
Can a hormone bound to a carrier protein be degraded?
NOPE
Can a hormone bound to a carrier protein bind to a hormone receptor?
NOPE
When is a hormone biologically active?
WHEN IT’S FREE!
What is the purpose of a radioimmunoasay?
Measure amount of hormone present in a solution/serum by using radioactive hormones as a tracer
Explain how radioimmunoassay works.
- Establish standard curve:
- Add antibody to a known concentration of radioactive hormone to obtain 100% antibody-radioactive hormone precipitated complexes
- Add a known amount of non-radioactive hormone (cold hormone) that will compete with the antibody and measure the amount of radioactive hormone that precipitates (this should decrease over time)
- Create standard curve
- Add patient’s serum to 100% antibody-radioactive hormone precipitated complexes
- Measure radioactivity
- Find concentration of hormone per the standard curve
What is the purpose of ELISA?
Measure amount of target hormone in a solution/serum
What is another name for ELISA?
Sandwhich assay
Which one is more commonly used: radioactiveimmuno assay or ELISA?
ELISA
Explain how ELISA works.
- Add patient’s serum to a plate containing a speficif antibody for the hormone
- Add a detecting antibody specific for the hormone
- Add an enzyme-linked secondary antibody that binds to the detecting antibody
- Add a substrate that the linked enzyme will convert to a product with a different color
- Use a spectrometer to measure color change aka hormone amount present
Why do we need such a complicated sandwhich of antibodies in ELISA?
We don’t! But cheaper this way because the last enzyme linked antibody recognizes many other antibodies which is good because it’s expensive to conjugate enzymes to antibodies
What does a beta-adrenergenic agonist do?
Stimulates stress response by activating epi/norepi receptors
Where is Vitamin D made?
- Skin
- Liver
- Kidneys
What is a target tissue of Vitamin D?
Bones
To what carrier protein does cortisol bind in the blood?
Corticosteroid-binding globulin (CBG)
What kind of class of hormones is vasopressin?
Proteins/Glycoproteins/Peptides
What are 2 examples of eicosanoids?
- Prostaglandins
- Thromboxanes
Through what pathway are hormones made from arachidonic acid?
Cyclooxygenase pathway
What kinds of hormone actions do eicosanoids exert?
Autocrine and paracrine
Is estrogen a steroid?
YES
How does the plasma half-life of hydrophilic hormones compare to the half life of hydrophobic hormones? Why?
Shorter half life because not bound to carrier proteins in blood
What are the 4 functions of testosterone?
- Male urogenital development
- Male secondary sexual characteristics
- Male bone maintenance
- Male and female aggression
What are the 5 functions of estadiol?
- Female sex tissue function
- Female bone maintenance
- Female cardiovascular protection before menopause
- Male brain development
- Male fertility
What is DHT?
Testosterone
What is cortisol’s function with regards to the lungs?
Lung development
What is estrogen made from in females? What is the active form of estrogen? With what enzyme?
Testosterone to 17-beta-estradiol (active form)
Aromatase
Describe the vitamin D degradation pathway.
25-hydroxyvitamin D3 + 24-hydroxylase ⇒ 24,25-dihydroxyvitamin D3
Location: bone, cartilage, placenta, intestine
What are the 4 glycoprotein hormones we learned about?
- TSH
- LH
- FSH
- hCG
What second messenger(s) do glycoproteins activate?
G-protein coupled receptors:
cAMP
Phospholipase?
How many polypeptides in GH? Disulfide bonds?
1
2
How many polypep
For which subunit of the glycoprotein are the antibodies in pregnancy tests?
The beta subunit of hCG
How are catecholamines degraded?
By deamination by catechol-O-methyltransferase (COMT)
Describe the structure of arachidonic acid.
Long chain fatty acid
20:4
What is the organic name of aspirin?
Acetylsalicylate
Main 3 functions of prostaglandins?
- Inflammation
- Regulate BP by causing vasodilation
- Soften uterus during labor
How can one accelerate the growth of cells in a lab? Potential side effect?
Provide it with the growing medium previously used by other cells which will contain growth factors
If the previous cell was cancerous, the factors will cause cancer
What are 3 hormone types secreted in their active form?
- Steroids
- Eicosanoids
- Catecholamines
What is the active form of testosterone? Where does activation occur?
Dihydrotestosterone (activation in target tissues)
Which 4 hormones require intracellular processing before secretion?
- POMC to ACTH and other metabolites
- Proinsulin
- Preproparathyroid hormone
- TGB to T3/T4
Describe the characteristics of the hormone carrier proteins.
Low affinity, high capacity
Which is the ONLY hydrophilic hormone that binds to a carrier protein?
IGF-1
What is the carrier protein of aldosterone?
Albumin
What is the carrier protein of estrogen?
TeBG
What are the 2 carrier proteins of testosterone?
- TeBG
- Albumin
What is the carrier protein of retinoic acid?
Albumin
What is the carrier protein of vitamin D?
D-binding protein
Which hormone has the lowest % hormone bound to its carrier protein?
Aldosterone
What is the carrier protein of IGF-1?
IGF-binding proteins (over 6 forms of them)
Can a hormone bound to a receptor go back to being free?
YUP
Can a cell produce a carrier-bound protein?
NOPE
When is the C-peptide removed from insulin?
Before it is secreted!
What is the main role of Vitamin D?
Increase calcium absorption from the intestine
What types of enzymes make modifications to cholesterol to synthesize steroid hormones and vitamin D?
Cytochrome P450 enzymes requiring NADPH carry out modifications to cholesterol
How do the effects of protein/glycoprotein/peptide/AA deriv hormones (excluding THs) compare to those of the effects of other types of hormones?
Immediate effects
Is hydrocortisone active?
YES
Is aldosterone secreted in its active form?
YES
Are catecholamines secreted in their active form?
YES