How Does Glucagon Help Restore Blood Glucose Level?

Share on facebook

Quantifying The Contribution Of The Liver To Glucose Homeostasis: A Detailed Kinetic Model Of Human Hepatic Glucose Metabolism

Abstract Despite the crucial role of the liver in glucose homeostasis, a detailed mathematical model of human hepatic glucose metabolism is lacking so far. Here we present a detailed kinetic model of glycolysis, gluconeogenesis and glycogen metabolism in human hepatocytes integrated with the hormonal control of these pathways by insulin, glucagon and epinephrine. Model simulations are in good agreement with experimental data on (i) the quantitative contributions of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization under varying physiological states. (ii) the time courses of postprandial glycogen storage as well as glycogen depletion in overnight fasting and short term fasting (iii) the switch from net hepatic glucose production under hypoglycemia to net hepatic glucose utilization under hyperglycemia essential for glucose homeostasis (iv) hormone perturbations of hepatic glucose metabolism. Response analysis reveals an extra high capacity of the liver to counteract changes of plasma glucose level below 5 mM (hypoglycemia) and above 7.5 mM (hyperglycemia). Our model may serve as an important module of a whole-body mode Continue reading >>

Share on facebook

Popular Questions

  1. 21joanna12

    As I understand, both cortisol and glucagon cause an increase in blood sugar concentrations. However I don't understand how they work differently or why they work separately. I would be very grateful if someone could explain the seperate roles and functions of these two hormones and also the different effects that they have (I believe cortisol also has something to do with promoting lypogenesis in adipose tissue at the trunk of the body and lypolysis at the extremities).

  2. Vance L Albaugh

    Glucagon and cortisol are VERY different types of hormones, though each of them can affect glucose metabolism and effectively can increase glucose concentrations in the blood (albeit through different mechanisms).
    Glucagon, pictured above, is a 31 amino acid peptide hormone (i.e. PROTEIN) that is released from the alpha-cells within the pancreatic islets. Glucagon travels through the blood and acts predominately in the liver on glucagon receptors. The glucagon peptide binds to the glucagon receptor on the OUTSIDE of the cell and transmits a signal to the INSIDE of the cell. This occurs when the glucagon binds to the receptor, changing its conformation or "shape" on the inside of the cell, which then causes binding and activation of a G-protein inside the cell (

    GS). This

    GS protein activates an enzyme within the cell (adenylyl cyclase) to increase the concentration of a substance called cyclic AMP (aka cAMP) that activates a number of enzymes that ultimately increase the amount of glucose released by the liver. These effects are IMMEDIATE effects, which is why we sometimes give glucagon injections to treat patients with hypoglycemia (i.e. dangerously low blood sugar concentration). However, sustained glucagon signaling likely has effects on the expression of the enzymes that cause the glucose to be released from the liver as well (though that is a discussion for another question).
    Cortisol, pictured above, is a steroid hormone (i.e. LIPID) that is released from the adrenal glands, specifically the zona fasciulata, which is the middle of the three 'layers' of the adrenal gland. Cortisol is referred to as a glucocorticoid and exerts its major effects through changing gene transcription in a variety of cell types. The way that cortisol does this is by binding its cortisol receptor, which is generally thought to be in the cytoplasm inside the cell. Upon binding of cortisol to the cortisol receptor, that complex is then transported into the nucleus of the cell where it binds DNA and can increase or decrease the transcription or expression of target genes. In the case of cortisol, these genes are for the enzymes that increase glucose production of the liver, and thus increase the body's capacity to maintain or elevate blood glucose. There is also some evidence that cortisol has additional effects independent of gene transcription, but that is outside the scope of this question. Regardless, the effects of cortisol on glucose metabolism are not immediate, but rather they take >30 minutes to several hours to begin to take effect.
    As mentioned in the question, both glucagon and cortisol affect glucose metabolism. Cortisol also affects the transcription of a number of genes involved in adipose tissue and lipid metabolism, as well as genes that are involved in protein metabolism and inflammation. Cortisol can be injected into a patient with an autoimmune "flare-up" in order to quell the inflammation, but those are different mechanisms of cortisol than its effects on glucose metabolism. A description of those effects is also outside the scope of this question, but could easily be read about in recent reviews on cortisol available on PubMed, e.g. Recent Cortisol and Fatty Liver Review.

  3. sunboyharry

    Glucagon increase the blood sugar level in normal physiological pathway. It just mediate the blood sugar level when the level is too low.
    On the other hand, cortisol is used when body under stress. It is used for "fight or flight" response in body, and it increases the energy production temporarily. When body is faced with stressor, the cortisol is secreted by a complex hormonal cascade, and the cortisol helps body to produce energy immediately to muscle and narrows the arteries to increase the heart rate, which force blood to pump harder and faster, and it also inhibits the activity of insulin. When body solves the problem, the hormone level return to normal.
    Cortisol also can reduce the inflammation in the body, which can suppress the immune system.
    Here is the paper maybe you will be interested. Cortisol — Its Role in Stress, Inflammation, and Indications for Diet Therapy

  4. -> Continue reading
read more close

Related Articles

  • How Does Glucagon Help Restore Blood Glucose Level?

    Liver Pathology Functions of the liver: Manufacture - blood proteins - albumen, clotting proteins urea - nitrogenous waste from amino acid metabolism bile - excretory for the bile pigments, emulsification of fats by bile salts Storage - glycogen - carbohydrate fuel iron - as hemosiderin and ferritin fat soluble vitamins A, D, E, K Detoxification - alcohol drugs and medicines environmental toxins Protein metabolism - (See Figure 25.15) transaminat ...

    diabetes Jan 11, 2018
  • How Does Insulin And Glucagon Control Blood Glucose Levels?

    The storage and metabolism of glucose is controlled at the organ level by hormones. The hormones glucagon and insulin are secreted by the pancreas during periods of low or high blood sugar, respectively. Glucagon causes the liver to produce glucose from the storage polysaccharide glycogen or to synthesize glucose from pyruvate using the pathway gluconeogenesis. The released glucose enters into the blood and travels to muscle for oxidation by glyc ...

    insulin Jan 14, 2018
  • How Does Glucagon Increase Blood Glucose Levels?

    Changes in your blood sugar levels can affect how you feel. To help you keep the level steady and healthy, your body makes a hormone called glucagon while you sleep and after you eat. It's made in your pancreas, a small organ above your liver, and it can raise levels of glucose, or sugar, in your blood. That's the fuel your muscles and organs use to work and stay healthy. Glucagon helps your liver break down the food you eat to make glucose. If y ...

    insulin Jan 13, 2018
  • Does Glucagon Raise Blood Sugar

    The food insulin index data indicates that there is both a blood sugar and an insulin response to the glucogenic component of protein. [1] A higher protein intake tends to lead to better blood sugar control, increased satiety and reduced caloric intake. Digested amino acids from protein circulate in the bloodstream until they are required for protein synthesis, gluconeogenesis or the production of ketones. The release of glucose from protein via ...

    insulin Jan 12, 2018
  • How Does Glucagon Raise Blood Sugar Levels?

    In a person without diabetes, a rise in blood amino acid concentration (the result of protein metabolism) stimulates the secretion of both glucagon and insulin, so their blood sugar remains stable. But in people with diabetes, the release of glucagon without insulin or with impaired insulin response can cause our blood sugar to rise precipitously several hours after a meal high in protein. The insulin is secreted to stimulate protein synthesis--t ...

    diabetes Jan 16, 2018
  • How Does Glucagon Get Your Blood Sugar Back To Normal?

    If you take insulin or diabetes medication, you may be at risk of hypoglycemia, or low blood sugar. Without quick attention, hypoglycemia can lead to serious complications, so it’s important to know what to do if it happens to you. “In very severe cases, it can lead to seizures or loss of consciousness,” says Marilyn Tan, MD, an assistant professor of medicine, endocrinology, gerontology, and metabolism at Stanford Health Care. It's possibl ...

    diabetes Jan 16, 2018

Popular Articles

More in diabetes