Glycogen Synthase Kinase-3β Inhibition Ameliorates Cardiac Parasympathetic Dysfunction in Type 1 Diabetic Akita Mice

  1. Jonas B. Galper1,3
  1. 1Molecular Cardiology Research Institute, Tufts Medical Center, Boston, MA
  2. 2Departments of Neurology and Physiology, Medical College of Wisconsin, Milwaukee, WI
  3. 3Department of Medicine, Tufts University School of Medicine, Boston, MA
  4. 4Department of Neuroscience, Tufts University School of Medicine, Boston, MA
  5. 5Stanley Center for Psychiatric Research, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA
  6. 6Department of Biochemistry & Molecular Biology, Louisiana State University School of Medicine, New Orleans, LA
  1. Corresponding authors: Jonas B. Galper, jgalper{at}tuftsmedicalcenter.org, and Ho-Jin Park, hpark{at}tuftsmedicalcenter.org.
  1. Y.Z. and C.M.W. contributed equally to this work.

Abstract

Decreased heart rate variability (HRV) is a major risk factor for sudden death and cardiovascular disease. We previously demonstrated that parasympathetic dysfunction in the heart of the Akita type 1 diabetic mouse was due to a decrease in the level of the sterol response element–binding protein (SREBP-1). Here we demonstrate that hyperactivity of glycogen synthase kinase-3β (GSK3β) in the atrium of the Akita mouse results in decreased SREBP-1, attenuation of parasympathetic modulation of heart rate, measured as a decrease in the high-frequency (HF) fraction of HRV in the presence of propranolol, and a decrease in expression of the G-protein coupled inward rectifying K+ (GIRK4) subunit of the acetylcholine (ACh)-activated inward-rectifying K+ channel (IKACh), the ion channel that mediates the heart rate response to parasympathetic stimulation. Treatment of atrial myocytes with the GSK3β inhibitor Kenpaullone increased levels of SREBP-1 and expression of GIRK4 and IKACh, whereas a dominant-active GSK3β mutant decreased SREBP-1 and GIRK4 expression. In Akita mice treated with GSK3β inhibitors Li+ and/or CHIR-99021, Li+ increased IKACh, and Li+ and CHIR-99021 both partially reversed the decrease in HF fraction while increasing GIRK4 and SREBP-1 expression. These data support the conclusion that increased GSK3β activity in the type 1 diabetic heart plays a critical role in parasympathetic dysfunction through an effect on SREBP-1, supporting GSK3β as a new therapeutic target for diabetic autonomic neuropathy.

Footnotes

  • Received October 24, 2012.
  • Accepted January 14, 2014.

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  1. Diabetes vol. 63 no. 6 2097-2113
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