Spontaneous demyelinating myelopathy in aging laboratory mice

Area of Science:

• Veterinary Pathology
• Neuroscience
• Toxicology

Background:

• Spontaneous demyelination is a rare occurrence in aging laboratory mice.
• These lesions are typically observed in the thoracic spinal cord.
• Their presence can impact the interpretation of toxicological studies.

Purpose of the Study:

• To identify the cause of spontaneous demyelination in aging mice.
• To determine the relevance of these lesions in chemical safety studies.

Main Methods:

• Histopathological examination of spinal cord tissues.
• Immunohistochemical staining for viral proteins, specifically VP-1 (virus protein).

Main Results:

• Spontaneous demyelination was observed in the thoracic spinal cord of aging mice.
• Immunohistochemistry confirmed the presence of VP-1, indicating infection with Theiler's murine encephalomyelitis virus.
• The observed lesions were sporadic and did not affect the overall quality of chemical safety studies.

Conclusions:

• Theiler's murine encephalomyelitis virus is associated with spontaneous demyelination in aging mice.
• Understanding this viral association is crucial for accurate interpretation of long-term chemical safety study data.
• This knowledge aids in distinguishing naturally occurring lesions from chemically induced effects.