Abnormal Muscle Spindle Innervation and Large-Fiber Neuropathy in Diabetic Mice

Karra A MULLER; Janelle M RYALS; Eva L FELDMAN; Douglas E WRIGHT

doi:10.2337/db08-0022

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Abnormal Muscle Spindle Innervation and Large-Fiber Neuropathy in Diabetic Mice

Journal article

Peer reviewed

Abnormal Muscle Spindle Innervation and Large-Fiber Neuropathy in Diabetic Mice

Karra A MULLER, Janelle M RYALS, Eva L FELDMAN and Douglas E WRIGHT

Diabetes (New York, N.Y.), Vol.57(6), pp.1693-1701

2008

DOI: 10.2337/db08-0022

PMID: 18362211

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Abstract

Objective: Large-fiber diabetic polyneuropathy (DPN) leads to balance and gait abnormalities, placing patients at risk for falls. Large sensory axons innervating muscle spindles provide feedback for balance and gait and, when damaged, can cause altered sensorimotor function. This study aimed to determine whether symptoms of large-fiber DPN in type 1 and type 2 diabetic mouse models are related to alterations in muscle spindle innervation. In addition, diabetic mice were treated with insulin to assess whether sensorimotor and spindle deficits were reversible. Research design and methods: Behavioral assessments were performed in untreated and treated streptozotocin (STZ)-injected C57BL/6 mice to quantitate diabetes-induced deficits in balance and gait. Quantification of Ia axon innervation of spindles was carried out using immunohistochemistry and confocal microscopy on STZ-injected C57BL/6 and db/db mice. Results: STZ-injected C57BL/6 mice displayed significant and progressive sensorimotor dysfunction. Analysis of Ia innervation patterns of diabetic C57BL/6 spindles revealed a range of abnormalities suggestive of Ia axon degeneration and/or regeneration. The multiple abnormal Ia fiber morphologies resulted in substantial variability in axonal width and inter-rotational distance (IRD). Likewise, db/db mice displayed significant variability in their IRDs compared with db(+) mice, suggesting that damage to Ia axons occurs in both type 1 and type 2 diabetes models. Insulin treatment improved behavioral deficits and restored Ia fiber innervation in comparison with nondiabetic mice. Conclusions: Similar to small fibers, Ia axons are vulnerable to diabetes, and their damage may contribute to balance and gait deficits. In addition, these studies provide a novel method to assay therapeutic interventions designed for diabetes-induced large-fiber dysfunction.

Fundamental and applied biological sciences. Psychology

Vertebrates: nervous system and sense organs

Diabetes. Impaired glucose tolerance

Biological and medical sciences

Endocrinopathies

Etiopathogenesis. Screening. Investigations. Target tissue resistance

Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors

Medical sciences

Endocrine pancreas. Apud cells (diseases)

Details

Title: Subtitle: Abnormal Muscle Spindle Innervation and Large-Fiber Neuropathy in Diabetic Mice
Creators: Karra A MULLER - Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States
Janelle M RYALS - Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States
Eva L FELDMAN - Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States
Douglas E WRIGHT - Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States
Resource Type: Journal article
Publication Details: Diabetes (New York, N.Y.), Vol.57(6), pp.1693-1701
Publisher: American Diabetes Association; Alexandria, VA
DOI: 10.2337/db08-0022
PMID: 18362211
ISSN: 0012-1797
eISSN: 1939-327X
Language: English
Date published: 2008
Academic Unit: Pathology
Record Identifier: 9984047667702771

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