Cover Story Current Issue
Despite intensive drug development efforts and public health initiatives, obesity is increasing in incidence and predicted to affect over 50% of all adults worldwide by 2035. Being chronically overweight increases the risk of serious disease co-morbidities that, in turn, increase mortality and healthcare costs. Behavioral approaches to combat obesity, such as diet and exercise, rarely produce lasting weight loss commonly due to compensatory hyperphagia and hypometabolism. These limitations have stimulated interest in pharmacotherapies that target gut-derived peptide hormones involved in the regulation of energy homeostasis, such as PYY, GIP, CCK, and GLP-1. These peptides are secreted by different enteroendocrine cells distributed throughout the intestine in response to food intake, subsequently enhancing satiation signaling and ultimately promotes meal termination. However, a major challenge of FDA-approved and experimental weight-loss medications that target GI-derived satiation signals is the frequent occurrence of nausea and vomiting.
Current Issue
Variable glucagon metabolic actions in diverse mouse models of obesity and type 2 diabetes
Variable glucagon metabolic actions in diverse mouse models of obesity and type 2 diabetes
Objective
The study aimed to investigate the effects of glucagon on metabolic pathways in mouse models of obesity, fatty liver disease, and type 2 diabetes (T2D) to determine the extent and variability of hepatic glucagon resistance in these conditions.
Methods
We investigated glucagon's effects in mouse models of fatty liver disease, obesity, and type 2 diabetes (T2D), including male BKS-db/db, high-fat diet-fed, and western diet-fed C57Bl/6 mice. Glucagon tolerance tests were performed using the selective glucagon receptor agonist acyl-glucagon (IUB288). Blood glucose, serum and liver metabolites include lipids and amino acids were measured. Additionally, liver protein expression related to glucagon signalling and a comprehensive liver metabolomics were performed.
Results
Western diet-fed mice displayed impaired glucagon response, with reduced blood glucose and PKA activation. In contrast, high-fat diet-fed and db/db mice maintained normal glucagon sensitivity, showing significant elevations in blood glucose and phospho-PKA motif protein expression. Acyl-glucagon treatment also lowered liver alanine and histidine levels in high-fat diet-fed mice, but not in western diet-fed mice. Additionally, some amino acids, such as methionine, were increased by acyl-glucagon only in chow diet control mice. Despite normal glucagon sensitivity in PKA signalling, db/db mice had a distinct metabolomic response, with acyl-glucagon significantly altering 90 metabolites in db/+ mice but only 42 in db/db mice, and classic glucagon-regulated metabolites, such as cyclic adenosine monophosphate (cAMP), being less responsive in db/db mice.
Conclusions
The study reveals that hepatic glucagon resistance in obesity and T2D is complex and not uniform across metabolic pathways, underscoring the complexity of glucagon action in these conditions.
Articles in Press
Variable glucagon metabolic actions in diverse mouse models of obesity and type 2 diabetes
Variable glucagon metabolic actions in diverse mouse models of obesity and type 2 diabetes
Objective
The study aimed to investigate the effects of glucagon on metabolic pathways in mouse models of obesity, fatty liver disease, and type 2 diabetes (T2D) to determine the extent and variability of hepatic glucagon resistance in these conditions.
Methods
We investigated glucagon's effects in mouse models of fatty liver disease, obesity, and type 2 diabetes (T2D), including male BKS-db/db, high-fat diet-fed, and western diet-fed C57Bl/6 mice. Glucagon tolerance tests were performed using the selective glucagon receptor agonist acyl-glucagon (IUB288). Blood glucose, serum and liver metabolites include lipids and amino acids were measured. Additionally, liver protein expression related to glucagon signalling and a comprehensive liver metabolomics were performed.
Results
Western diet-fed mice displayed impaired glucagon response, with reduced blood glucose and PKA activation. In contrast, high-fat diet-fed and db/db mice maintained normal glucagon sensitivity, showing significant elevations in blood glucose and phospho-PKA motif protein expression. Acyl-glucagon treatment also lowered liver alanine and histidine levels in high-fat diet-fed mice, but not in western diet-fed mice. Additionally, some amino acids, such as methionine, were increased by acyl-glucagon only in chow diet control mice. Despite normal glucagon sensitivity in PKA signalling, db/db mice had a distinct metabolomic response, with acyl-glucagon significantly altering 90 metabolites in db/+ mice but only 42 in db/db mice, and classic glucagon-regulated metabolites, such as cyclic adenosine monophosphate (cAMP), being less responsive in db/db mice.
Conclusions
The study reveals that hepatic glucagon resistance in obesity and T2D is complex and not uniform across metabolic pathways, underscoring the complexity of glucagon action in these conditions.
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13th
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2024 impact factor: 6.6
You are what you eat
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