Nitrosative Stress in the Frontal Cortex From Dogs With Canine Cognitive Dysfunction

Area of Science:

• Neuroscience
• Veterinary Neurology
• Pathology

Background:

• Canine cognitive dysfunction (CCD) is an age-related neurodegenerative disorder in dogs, analogous to human Alzheimer's disease (AD).
• Nitrosative stress is a known factor in AD pathogenesis, but its role in CCD has not been previously investigated.
• Nitric oxide synthases (NOS) and their byproducts are key mediators of nitrosative stress.

Purpose of the Study:

• To investigate the presence and significance of nitrosative stress markers in the brains of dogs with CCD.
• To determine if specific isoforms of NOS and 3-nitrotyrosine (3-NT) are altered in CCD-affected canine brains.

Main Methods:

• Immunohistochemical staining was employed to detect nNOS, eNOS, iNOS, and 3-NT in the frontal cortex of CCD-affected and control dogs.
• Quantitative analysis compared the expression levels of these markers between the two groups.

Main Results:

• All three NOS isoforms and 3-NT were detected in the frontal cortex of both CCD and control dogs.
• nNOS expression was significantly elevated in neurons and astrocytes in the frontal cortex of dogs with CCD.
• Intense 3-NT and iNOS immunoreactivity were observed in upper cortical layers, co-localizing with amyloid-beta deposits in CCD brains.

Conclusions:

• The findings suggest that neuroinflammation and nitrosative stress, indicated by elevated nNOS, iNOS, and 3-NT, may contribute to the neurodegenerative processes in canine cognitive dysfunction.
• These molecular changes likely exacerbate cognitive impairment in aging dogs, highlighting potential therapeutic targets.