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Irisin-A Pancreatic Islet Hormone.

Daniel Norman1, Carl Johan Drott1, Per-Ola Carlsson1,2

  • 1Department of Medical Cell Biology, Uppsala University, 751 23 Uppsala, Sweden.

Biomedicines
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Summary

Irisin, a hormone primarily from muscle, is found in pancreatic islets. While not affecting insulin secretion, irisin significantly reduces islet blood flow, revealing a novel role in pancreatic physiology.

Keywords:
blood flowirisinpancreatic isletsvascular

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Area of Science:

  • Endocrinology
  • Physiology
  • Molecular Biology

Background:

  • Irisin is a myokine known for its role in glucose homeostasis.
  • It is expressed in skeletal muscle and the pancreas, including pancreatic islets.

Purpose of the Study:

  • To investigate the presence and function of irisin within pancreatic islets.
  • To determine irisin's effects on insulin and glucagon secretion and pancreatic blood flow.

Main Methods:

  • Quantitative PCR (qPCR) and immunohistochemistry to detect FNDC5 (irisin precursor) in rat and human islets.
  • In vitro studies on human and rat islets to assess insulin and glucagon secretion.
  • In vivo study involving intravenous irisin infusion in Sprague Dawley rats to measure islet blood flow.

Main Results:

  • FNDC5, the precursor of irisin, was identified in both rat and human islet cells (alpha and beta cells).
  • Irisin secretion from human islets was glucose-dependent.
  • Irisin did not alter insulin or glucagon secretion or content in vitro.
  • Intravenous irisin infusion in rats led to a nearly 50% reduction in islet blood flow.

Conclusions:

  • Irisin is present and secreted by pancreatic islets.
  • Irisin acts as an islet hormone with a novel function in regulating pancreatic physiology.
  • Irisin exerts local vascular effects by reducing islet blood flow, independent of direct effects on insulin secretion.