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Old 03-02-2013
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Question 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?
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- 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.
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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?
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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 View Post
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.
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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???
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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.
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Quote:
Originally Posted by KovachMarina View Post
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
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Quote:
Originally Posted by BritneySpears View Post
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.
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Quote:
Originally Posted by luschka View Post
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.
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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!!!
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Quote:
Originally Posted by bigBOSSguy View Post
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
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Quote:
Originally Posted by Doctor Ali View Post
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
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I was refering to the receptors. Glucagon comes from alpha cells. Insulin comes from beta cells.
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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
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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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