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KovachMarina 03-02-2013 01:52 AM

Epinephrine effect on insulin secretion
 
So, FA 2012 Errata says that epinephrine increases insulin secretion. Well, is it true, cause epinephrine should rise blood glucose?

luschka 03-02-2013 04:37 AM

- Catecholamnes (epinephrine & glucagon) increases glyconeogeolysis (breakdown of glycogen).
--- These hormones are the major counter-regulatory hormones for protection against hypoglycemia.
--- These hormones are secreted in response to hypoglycemia, & increase blood glucose predominantly by increasing glycogenolysis.

Doctor Ali 03-02-2013 08:17 AM

If you look on that same page, you will see Glucagon does the same. These two activate Adenylate cyclase.

What about Cortisol? Increase or decrease insulin?

luschka 03-02-2013 09:05 AM

Basic understanding:
- Insulin: decrease serum glucose
- Glucagon: increases serum glucose

---

FA 2012 pg. 315

Yes, it should be that Epinephrine & Glucagon stimulate the enzyme adenylyl cyclase. So, Epinephrine & Glucagon should have a (+) for them.


Refer to FA 2012 pg. 114 for further clarification:

o In fasting state: increase glucagon → stimulate adenylyl cylase → increase cAMP → increase protein kinase A → increasing FBPase-2 (fructose-2-6-bisphophate) and decreasing PFK-2 (phosphofructokinase-2)

o In fasting state: increase glucagon & increase epinephrine → stimulate adenylyl cylase → increase cAMP → increase protein kinase A → stimulate glycogen phosphorylase → break down glycogen for usage bc you're hypoglycemic.

---

Quote:

Originally Posted by Doctor Ali (Post 178006)
If you look on that same page, you will see Glucagon does the same. These two activate Adenylate cyclase.

What about Cortisol? Increase or decrease insulin?

- When the plasma glucose concentration is low, there is an increase in the body secretion of epinephrine, glucagon, and, to a lesser extent cortisol and growth hormone.

- Cortisol increases the transcription of enzymes involved in gluconeogenesis (formation of glucose from fat & protein substrate).

- Insulin action is opposed by a glucagon, epinephrine, cortisol, and growth hormone.

- Thus, cortisol decreases the action of insulin, thus, cortisol increases serum glucose.

KovachMarina 03-02-2013 09:47 AM

I think it's about receptors, and different doses of epinephrine causing different effects. Conrad Fischer physiology lectures made me confused, cause he says that we should think of epinephrine effect on insulin in cases of stress- fright, flight or fight, meaning that epinephrine should increase glucose. And FA says- beta2 receptors agonists increase insulin release. In high doses epi also acts on alpha2 receptors- high doses in stress situations- lift glucose level up???

BritneySpears 03-02-2013 09:56 AM

Adrenaline acts by binding to a variety of adrenergic receptors. Adrenaline is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3. Epinephrine's binding to these receptors triggers a number of metabolic changes. Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis in muscle. β-Adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue. Together, these effects lead to increased blood glucose and fatty acids, providing substrates for energy production within cells throughout the body.

luschka 03-02-2013 10:03 AM

Quote:

Originally Posted by KovachMarina (Post 178016)
I think it's about receptors, and different doses of epinephrine causing different effects. Conrad Fischer physiology lectures made me confused, cause he says that we should think of epinephrine effect on insulin in cases of stress- fright, flight or fight, meaning that epinephrine should increase glucose. And FA says- beta2 receptors agonists increase insulin release. In high doses epi also acts on alpha2 receptors- high doses in stress situations- lift glucose level up???

- Epinephrine (via beta 2) increase insulin release.
- Norepineprhine (via alpha 2) decrease insulin release.

This is a really good website:

http://ahdc.vet.cornell.edu/clinpath...em/glucose.htm

Doctor Ali 03-02-2013 11:36 AM

Quote:

Originally Posted by BritneySpears (Post 178017)
Adrenaline acts by binding to a variety of adrenergic receptors. Adrenaline is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3. Epinephrine's binding to these receptors triggers a number of metabolic changes. Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis in muscle. β-Adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue. Together, these effects lead to increased blood glucose and fatty acids, providing substrates for energy production within cells throughout the body.


Everything seems to be correct except for which I believe, Alpha adrenergic receptor binding triggers Glucagon secretion, inhibition of Insulin. Beta adrenergic receptor binding triggers Insulin secretion, inhibition of Glucagon.

Doctor Ali 03-02-2013 11:42 AM

Quote:

Originally Posted by luschka (Post 178011)
Basic understanding:
- Insulin: decrease serum glucose
- Glucagon: increases serum glucose

---

FA 2012 pg. 315

Yes, it should be that Epinephrine & Glucagon stimulate the enzyme adenylyl cyclase. So, Epinephrine & Glucagon should have a (+) for them.


Refer to FA 2012 pg. 114 for further clarification:

o In fasting state: increase glucagon → stimulate adenylyl cylase → increase cAMP → increase protein kinase A → increasing FBPase-2 (fructose-2-6-bisphophate) and decreasing PFK-2 (phosphofructokinase-2)

o In fasting state: increase glucagon & increase epinephrine → stimulate adenylyl cylase → increase cAMP → increase protein kinase A → stimulate glycogen phosphorylase → break down glycogen for usage bc you're hypoglycemic.

---



- When the plasma glucose concentration is low, there is an increase in the body secretion of epinephrine, glucagon, and, to a lesser extent cortisol and growth hormone.

- Cortisol increases the transcription of enzymes involved in gluconeogenesis (formation of glucose from fat & protein substrate).

- Insulin action is opposed by a glucagon, epinephrine, cortisol, and growth hormone.

- Thus, cortisol decreases the action of insulin, thus, cortisol increases serum glucose.


Yeap!! Just making sure.;)

bigBOSSguy 03-02-2013 12:44 PM

Simple!! In liver,epinephrine and glucagon inhibit glycogen synthase that produce glycogen from glucose.. They also stimulate glycogen phosphorylase to break down glucagon and produces glucose. Epinephrine also work the same way in skeletal muscle glycogen synthase and phosphorylase..Haha...most of u look it in physiology way but this is clearly stated in BIOCHEMISTRY!!!:))

KovachMarina 03-02-2013 10:45 PM

Quote:

Originally Posted by bigBOSSguy (Post 178041)
Simple!! In liver,epinephrine and glucagon inhibit glycogen synthase that produce glycogen from glucose.. They also stimulate glycogen phosphorylase to break down glucagon and produces glucose. Epinephrine also work the same way in skeletal muscle glycogen synthase and phosphorylase..Haha...most of u look it in physiology way but this is clearly stated in BIOCHEMISTRY!!!:))

I agree you're pretty smart, but I don't think that everything is that simple :)

KovachMarina 03-02-2013 10:46 PM

Quote:

Originally Posted by Doctor Ali (Post 178034)
Everything seems to be correct except for which I believe, Alpha adrenergic receptor binding triggers Glucagon secretion, inhibition of Insulin. Beta adrenergic receptor binding triggers Insulin secretion, inhibition of Glucagon.

Glucagon secretion stimulates insulin release

Doctor Ali 03-03-2013 07:29 AM

I was refering to the receptors. Glucagon comes from alpha cells. Insulin comes from beta cells.

dr.ali2011 03-03-2013 08:40 AM

Guys it's like that Norephi dominantly works on Alpha 2 which are Gi coupled so inhibits Insulin secretion, and Epi works on Beta 2 which are Gs coupled so stimulates insulin secretion, but normally there are more Alpha 2 receptors on the Beta cells of pancreas so the dominant effect of adrenergic system is to inhibit insulin secretion

dr shamail 03-03-2013 12:48 PM

Epinephrine increases glucagon secretion so that hyperglycemia occur but as u all know that glucagon have positive response on insulin secretion & insulin have negative response on glucagon secretion i guess by this effect epi causes insulin release


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