An optical method to evaluate both mass and functional competence of pancreatic α- and β-cells

Abstract

Imbalanced glucagon and insulin release leads to the onset of type 2 diabetes (T2D). To pinpoint the underlying primary driving force, here we have developed a fast, non-biased optical method to measure ratios of pancreatic α- and β-cell mass and function simultaneously. We firstly label both primary α- and β-cells with a red fluorescent probe ZinRhodaLactam-1 (ZRL1), and then highlight α-cells by selectively quenching the ZRL1 signal from β-cells. Based on the signals before and after quenching, we calculate the α/β cell mass ratios within live islets, which match the results from immunohistochemistry. From the same islets, glucagon/insulin release capability can be concomitantly measured. Thus we have measured ratios of α/β-cells mass and function from wild type and diabetic Leprdb/ Leprdb(db/db) mice at different ages. We find that the initial appeared glucose intolerance in ten-week db/db mice is associated with further expansion of α-cell mass prior to deterioration in functional β-cell mass. Our method is extendable to studies of islet mass and function in other T2D animal models, which shall benefit mechanistic studies of imbalanced hormone secretion during T2D progression.