Exendin-4 affects calcium signalling predominantly during activation and activity of beta cell networks in acute mouse pancreas tissue slices.

Autor: Paradiž Leitgeb E; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia., Kerčmar J; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia., Križančić Bombek L; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia., Pohorec V; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia., Skelin Klemen M; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia., Slak Rupnik M; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.; Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.; Alma Mater Europaea-European Center Maribor, Maribor, Slovenia., Gosak M; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.; Alma Mater Europaea-European Center Maribor, Maribor, Slovenia.; Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia., Dolenšek J; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.; Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia., Stožer A; Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia.
Jazyk: angličtina
Zdroj: Frontiers in endocrinology [Front Endocrinol (Lausanne)] 2024 Jan 16; Vol. 14, pp. 1315520. Date of Electronic Publication: 2024 Jan 16 (Print Publication: 2023).
DOI: 10.3389/fendo.2023.1315520
Abstrakt: Tight control of beta cell stimulus-secretion coupling is crucial for maintaining homeostasis of energy-rich nutrients. While glucose serves as a primary regulator of this process, incretins augment beta cell function, partly by enhancing cytosolic [Ca 2+ ] dynamics. However, the details of how precisely they affect beta cell recruitment during activation, their active time, and functional connectivity during plateau activity, and how they influence beta cell deactivation remain to be described. Performing functional multicellular Ca 2+ imaging in acute mouse pancreas tissue slices enabled us to systematically assess the effects of the GLP-1 receptor agonist exendin-4 (Ex-4) simultaneously in many coupled beta cells with high resolution. In otherwise substimulatory glucose, Ex-4 was able to recruit approximately a quarter of beta cells into an active state. Costimulation with Ex-4 and stimulatory glucose shortened the activation delays and accelerated beta cell activation dynamics. More specifically, active time increased faster, and the time required to reach half-maximal activation was effectively halved in the presence of Ex-4. Moreover, the active time and regularity of [Ca 2+ ] IC oscillations increased, especially during the first part of beta cell response. In contrast, subsequent addition of Ex-4 to already active cells did not significantly enhance beta cell activity. Network analyses further confirmed increased connectivity during activation and activity in the presence of Ex-4, with hub cell roles remaining rather stable in both control experiments and experiments with Ex-4. Interestingly, Ex-4 demonstrated a biphasic effect on deactivation, slightly prolonging beta cell activity at physiological concentrations and shortening deactivation delays at supraphysiological concentrations. In sum, costimulation by Ex-4 and glucose increases [Ca 2+ ] IC during beta cell activation and activity, indicating that the effect of incretins may, to an important extent, be explained by enhanced [Ca 2+ ] IC signals. During deactivation, previous incretin stimulation does not critically prolong cellular activity, which corroborates their low risk of hypoglycemia.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.
(Copyright © 2024 Paradiž Leitgeb, Kerčmar, Križančić Bombek, Pohorec, Skelin Klemen, Slak Rupnik, Gosak, Dolenšek and Stožer.)
Databáze: MEDLINE
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