Glucagon
Ben Greenstein in Rapid Revision in Endocrinology, 2017
This chapter presents a brief outline of the nature and biosynthesis of glucagon. It aims to compare and contrast glucagon and insulin in terms of synthesis control and physiological actions. The chapter discusses the given symptoms of hypersecretion of glucagon. Glucagon is released between meals when plasma fatty acids and glucose levels fall. Secretion is inhibited when energy substrates, notably plasma glucose, ketone bodies and fatty acid levels rise in plasma. The autonomic system regulates glucagon release through both sympathetic and parasympathetic stimulation. Several gastrointestinal tract hormones stimulate glucagon release, for example, cholecystokinin and vasoactive intestinal peptide. Some physiological actions of glucagon are: promotes hepatic breakdown of glycogen to glucose, promotes hepatic glucose formation from amino acids, inhibits hepatic glycogenesis, and stimulates free fatty acid conversion to ketone bodies.
Gene Control and Cellular Signaling Pathways
David S. Latchman in Gene Control, 2020
The altered levels of the proteins encoded by the target genes will then produce the appropriate change in cellular characteristics in response to the signal, so as to allow the signal to have a biological effect. In the case of signaling molecules that can enter the cell, direct binding of the ligand to the transcription factor is a frequently used mechanism for transcription factor activation. In the case of a signaling molecule which enters the cell, it can potentially bind to a transcription factor and directly regulate its activity, for example, by inducing a conformational change in the transcription factor. The cyclic AMP/CREB pathway is initiated by the binding of extracellular signaling molecules, such as glucagon, serotonin or epinephrine, to specific receptors on the cell surface. In the cases described so far, cellular signaling processes result in the direct phosphorylation of a target transcription factor by specific kinases.
Specific Combinations of Nutrients
Luke Bucci in Nutrients as Ergogenic Aids for Sports and Exercise, 2020
An almost limitless number of possible combinations of ergogenic aids is imaginable. The availability of specific nutrient combinations has grown to the point where over a hundred brands have between one and several dozen products marketed specifically for exercise and sports applications. Product sophistication continues to outpace any possibility of definitive testing, much less of preliminary studies. The demand for new products is fueled by the willingness of the public to try products that are usually untested and based on hypothetical mechanisms. Another category of combinations of nutritional ergogenic aids is dietary manipulation of macronutrient compositions to accentuate certain hormone levels, which, in turn, will affect exercise metabolism. A comprehensive and simple diet program incorporating everyday foods is based on the relationship between insulin and glucagon, levels of which can be influenced by food intake. Glucagon is a mobilization hormone that produces glucose from glycogen and fatty acids from stored body fat. Exercise inhibits insulin secretion and stimulates glucagon secretion.
Insulin modulation of glucagon secretion: The role of insulin and other factors in the regulation of glucagon secretion
Published in Islets, 2009
Dan Kawamori, Rohit N. Kulkarni
Glucagon plays a critical counter-regulatory role to insulin to maintain optimal glucose homeostasis. Glucagon secretion from pancreatic α-cells is regulated by glycemia, neural input, and secretion from neighboring β-cells. Recently, we provided direct genetic evidence of a critical role for insulin signaling in the regulation of glucagon secretion in vivo. Pancreatic α-cell targeted disruption of insulin receptor expression in mice resulted in glucose intolerance, hyperglycemia and hyperglucagonemia coupled with an abnormal glucagon response to hypoglycemia. Furthermore, streptozotocin treated mice exhibited paradoxically increased plasma glucagon suggesting a dominant role for insulin in the regulation of glucagon secretion compared with glucose. In fact, normalization of hyperglycemia by phrolidzin treatment decreased plasma glucagon levels suggesting a stimulatory effect of glucose on glucagon secretion and also revealed the significance of insulin in hyperglycemic states. Together these studies provide novel insights into intra-islet regulatory pathways in the modulation of glucagon secretion and provide potential opportunities to develop therapeutic approaches for the correction of α-cell dysfunction in diabetes.
Human factors studies of a prefilled syringe with stable liquid glucagon in a simulated severe hypoglycemia rescue situation
Published in Expert Opinion on Drug Delivery, 2019
Brett Newswanger, Steven Prestrelski, Anthony D. Andre
Background: Two human factors studies evaluated whether a stable liquid formulation of glucagon in a prefilled syringe (G-PFS) could be safely and effectively administered and evaluated the effectiveness of the product label guide and instructions-for-use (IFU). Research design and methods: In a formative study, 11 participants received orientation with the G-PFS instructional materials and performed a single unaided rescue attempt. In the validation study, 75 adult and adolescent participants received training or familiarized themselves with the G-PFS IFU, Label Guide, and device. All participants returned 1 week later to perform a single unaided rescue attempt of a simulated person with diabetes suffering from an emergency severe hypoglycemic event. Results: The formative study resulted in a 100% success rate across all rescue dose attempts. The validation study resulted in 74/75 (99%) of participants successfully using the G-PFS to administer the full glucagon rescue dose, and validated that intended users could learn from, comprehend, and recall the G-PFS instructions to successfully use the product. Conclusion: The G-PFS provides a familiar, easy-to-use alternative to currently marketed lyophilized glucagon kits for treating severe hypoglycemia. The G-PFS IFU and Label Guide enable even untrained users to successfully administer a full rescue dose of stable liquid glucagon.
Successful Administration of Intranasal Glucagon in the Out-of-Hospital Environment
Published in Prehospital Emergency Care, 2013
Ted Sibley, Ryan Jacobsen, Joseph Salomone
We present a case of successful prehospital treatment of hypoglycemia with intranasal (IN) glucagon. Episodes of hypoglycemia can be of varying severity and often requires quick reversal to prevent alteration in mental status or hypoglycemic coma. Glucagon has been shown to be as effective as glucose for the treatment of hypoglycemia. The inability to obtain intravenous (IV) access often impairs delivery of this peptide and is therefore frequently given via the intramuscular (IM) route. Intranasal administration of glucagon has been shown to be as effective as the IV route and may be used for rapid correction of hypoglycemic episodes where IV access is difficult or unavailable and IM administration is undesirable. We describe the first documentation in the peer-reviewed literature of the successful treatment and reversal of an insulin-induced hypoglycemic episode with IN glucagon in the prehospital setting. We also present a review of the literature regarding this novel medication administration route.
Related Knowledge Centers
- Blood Glucose
- Central Nervous System
- Intestines
- Pancreas
- Proglucagon
- Like Peptides
- Hormone