EndoPharm 2 Flashcards
Mineralcorticoids function to?
Mineralocorticoids regulate electrolyte and water balance
List three examples of mineralcorticoids.
➢ Aldosterone
➢ Deoxycorticosterone
➢ Fludrocortisone (aldosterone analog)
How do mineralcorticoids act on the kidneys?
▪ Increases Na+ reabsorption into the blood
▪ Promotes excretion of K+ and H+ into the urine
How do mineralcorticoids act on the brain?
Stimulates production of ADH (vasopressin)
How do mineralcorticoids act on the heart?
Renin-angiotensin-aldosterone system
Blood pressure
( ^ ^ ^ Na++ –> Hypertension)
Describe the cellular mechanism of action of mineralcorticoids.
When aldosteorne binds to receptor and transfers into cyotplasm and then the nucleus, MR (mineral cortico receptor responsiv element ) undergoes conformational changes and dissociates with ? proteins and dimerization. Goes down signaling pathway. Regulates transcription of many genes.
MR recpetorsw find in kidney, colon, heart, brain.
MR has affinity for different mineralcoritcoid (see blue box in image)
Aldosterone deficiency results in?
We need agonists in order to boost aldosterone levels.
Both things in green happening at the same time.
Name the Aldosterone agonists used to treat aldosterone deficiency.
❖ Aldosterone
❖ Deoxycorticosterone
❖ Fludrocortisone (aldosterone analog); side effects = rare
Not available as a drug due to its short duration of action when administered orally.
What are the functions of Aldosterone agonists
▪ Increase Na+ reabsorption into the blood
▪ Promote excretion of K+ and H+ into the urine
▪ Regulate blood pressure
Aldosterone agonists are used to treat which medical conditions?
Used to treat hypoadrenocortism (addison’s disease) in dogs and cats.
Excess aldosterone results in?
Name the aldosterone antagonists and describe what medical conditions they treat?
- Spironolactone
- Caneronone
- Epierenone
Treats hypertension and CHF and other conditions where the body remains with excess fluid (edematous states).
Spironolactone functions as?
❖ Spironolactone is a competitive aldosterone antagonist:
▪ Decreases Na+ reabsorption and K+ excretion
▪ Has effects on renin-angiotensin-aldosterone system
Canrenone functions as?
Canrenone is a diuretic metabolite of spironolactone
Eplerenone functions as?
Eplerenone antagonizes the MR (does not bind to PR or AR)
Remember: corticosteroids exhibit effects of both mineral and gluco. In some conditions, the effects of both types is beneficial. Do not need to know numbers.
Flu has both gluco and mineral <– she said to remember this specifically
Thryoid gland secretes two hormones: triiodo (T3) and thyroxine (T4). T3 and T4 control many body functions including heart rate, temp, metabolism, and many other physiological functions.
PG produces thyroid stimulating hormone. Stimulates thyroid gland to produce T3 and T4.
4 thyroid glands in dogs and cats
Parathyroid gland produces its own hormones.
What compound is an essential component of T3 and T4? Explain why.
▪ Iodine (I-) is an essential component of T3 and T4
▪ The correct functioning of thyroid gland depends
on a good supply of iodine from the diet
▪ Deficiency of iodine leads to decrease production of T3 & T4
T4 = inactive form of hormone
T3 = active form of hormone
Diodinase enzymes plays active role in changing inactive T4 into biologically active T3.
What is the difference between T3 and T4?
Explain the binding activities of T3 and T4.
T3 and T4 do not circulate freely. usually found to these three proteins. TBG is secreted in liver and plasma.
Unbound bind to receptors only.
How does protein-binding TH differ among animal species?
Humans = 99% of T4 and 99% of T3 are bound. by plasma proteins.
Dogs = less is bound.
Humans have 4x TBG than dogs.
Cats, birds, etc do not have detectable levels.
See image.
What does T3 function as?
T3 affects almost every physiological process in the body, including growth
and development, metabolism, body temperature, and heart rate
What are the genomic effects? of T3?
Not acting about molecular pathway on left.
Genomic actions: transcription of different genes, mRNA, as well as metabolic rate and neuro development.
What are the non-genomic effects? of T3?
TR metabolites may be coupled to Na++ channels,
Na+, K+- ATPase to affect electrolytes balance
Hypothyroidism is a result of?
Hypothyroidism is caused as a result of insufficient production of thyroxine by the thyroid gland. It is seen in dogs and horses (it is very rarely seen in cats)
Hyperthyroidism is a result of?
Hyperthyroidism: when the thyroid gland produces more thyroxine (T4) resulting
in increased metabolic rate. It is usually seen in older cats. In other species it is likely caused by adenocarcinoma.
Thus, anti-thyroid agents are only recommended for cats.
Which thyroid agent is T4?
Levothyroxine
Which thyroid agent is T3?
Levothyronine
Thyroid agents, such as T3 and T4, are used for what?
Uses: replacement therapy: T4 is preferred to T3 because T4 can maintain higher TH activity in brain than T3
Levothyroxine: Initial dose is 20 μg/kg/day, orally