Small and big mouse islets were compared with special reference to their content of glucagon-producing α-cells and somatostatin-producing δ-cells. Areas stained for glucagon and somatostatin were measured in the largest cross section of small (diameter < 60 μm) and big (diameter > 100 μm) islets. Comparison of the areas indicated proportionally more δ- than α-cells in the small islets. After isolation with collagenase these islets were practically devoid of α-cells. We evaluated the functional importance of the islet size by measuring the Ca(2+) signal for insulin release. A majority of the small islets responded to the hyperpolarization action of somatostatin with periodic decrease of cytoplasmic Ca(2+) when glucose was elevated after tolbutamide blockade of the KATP channels.
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http://dx.doi.org/10.1155/2016/4930741 | DOI Listing |
Life Metab
February 2025
New Cornerstone Science Laboratory, State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, National Biomedical Imaging Center, The Beijing Laboratory of Biomedical Imaging, Peking-Tsinghua Center for Life Sciences, School of Future Technology, Peking University, Beijing 100871, China.
Glucose-stimulated insulin release from pancreatic β-cells is critical for maintaining blood glucose homeostasis. An abrupt increase in blood glucose concentration evokes a rapid and transient rise in insulin secretion followed by a prolonged, slower phase. A diminished first phase is one of the earliest indicators of β-cell dysfunction in individuals predisposed to develop type 2 diabetes.
View Article and Find Full Text PDFObesity-associated inflammation is characterized by macrophage infiltration into peripheral tissues, contributing to the progression of prediabetes and type 2 diabetes (T2D). The enzyme 12-lipoxygenase (12-LOX) catalyzes the formation of pro-inflammatory eicosanoids and is known to promote the migration of macrophages, yet its role in obesity-associated inflammation remains incompletely understood. Furthermore, differences between mouse and human orthologs of 12-LOX have limited efforts to study existing pharmacologic inhibitors of 12-LOX.
View Article and Find Full Text PDFInt J Mol Sci
January 2025
Unidad de Investigación en Enfermedades Metabólicas, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City 06720, Mexico.
Diabetes Mellitus Type 1 (DM1) is an autoimmune disease characterized by the destruction of beta cells in the pancreas. Although amyloid formation has been well-studied in Diabetes Mellitus Type 2 (DM2), its role in DM1 remains unclear. Understanding how islet amyloid polypeptide (IAPP) contributes to beta cell dysfunction and death in DM1 could provide critical insights into disease mechanisms and pave the way for novel diagnostic and therapeutic strategies.
View Article and Find Full Text PDFBiochem Biophys Res Commun
January 2025
Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8560, Japan.
People in Eastern Asia, including Japan, traditionally consume higher amounts of sodium chloride than in the United States and Western Europe, and it is common knowledge that impaired insulin secretion-rather than insulin resistance-is highly prevalent in Asian people who have diabetes mellitus. We previously reported that mice fed a high-fat and high-sodium chloride (HFHS) diet had a relatively lower degree of obesity than mice fed a high-fat diet, but had a comparatively impaired insulin secretion. Sodium-glucose cotransporter-2 (SGLT2) inhibitors have been shown to dampen down the sympathetic nervous system, which reportedly is activated by a high-sodium chloride diet.
View Article and Find Full Text PDFPLoS One
January 2025
Department of Clinical Science, SUS, Division of Islet Cell Physiology, University of Lund, Malmö, Sweden.
The impact of islet neuronal nitric oxide synthase (nNOS) on glucose-stimulated insulin secretion (GSIS) is less understood. We investigated this issue by performing simultaneous measurements of the activity of nNOS versus inducible NOS (iNOS) in GSIS using isolated murine islets. Additionally, the significance of extracellular NO on GSIS was studied.
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