Omar Hmeadi, Muhmmad
- Department of Animal Biosciences, Swedish University of Agricultural Sciences
- Uppsala University
Abstract
Somatostatin secretion from pancreatic δ-cells inhibits nearby α- and β-cells, and tunes the body’s glycemic setpoint. The role of δ-cells in diabetes remains unclear, in part due to the difficulty separating intrinsic regulation from intra-islet paracrine effects. Here we compared the function of isolated δ-cells of cadaveric non-diabetic and type-2 diabetic donors, by single cell TIRF-microscopy and electrophysiology. Elevated glucose stimulated exocytosis of somatostatin, which was further amplified by glucagon, exendin-4, or forskolin, independent of diabetic status. GABA enhanced exocytosis and electrical activity, while insulin had no effect. Adrenaline and somatostatin strongly inhibited δ-cell activity, leading to autocrine feedback inhibition of somatostatin exocytosis. In type-2 diabetes, δ-cell inhibition by somatostatin and adrenaline was lost, together with a marked reduction in somatostatin receptor (SSTR2) surface expression. We further show that resistance to somatostatin leads to hyperactive δ-cells in type-2 diabetes, and propose that this mechanism contributes to defective blood glucose control.
Keywords
Somatostatin; exocytosis; δ-cells; type-2 diabetes; resistance; insulin; glucagon; human islets; TIRF; patch-clamp
Published in
Publisher: bioRxiv
SLU Authors
UKÄ Subject classification
Endocrinology and Diabetes
Cell and Molecular Biology
Publication identifier
- DOI: https://doi.org/10.64898/2025.12.12.693197
Permanent link to this page (URI)
https://res.slu.se/id/publ/146287