Retinal cell types are differentially affected in sheep with scrapie

Area of Science:

• Neuroscience
• Ophthalmology
• Veterinary Pathology

Background:

• Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases.
• Prion protein (PrPSc) accumulation occurs in the retina of TSE-affected hosts.
• Retinal pathology in TSEs is not always microscopically evident.

Purpose of the Study:

• To investigate the effect of PrPSc accumulation on retinal neurons in sheep.
• To compare retinal cell type-specific markers in control and scrapie-affected sheep.
• To determine if PrPSc affects retinal cells without causing overt degeneration.

Main Methods:

• Immunohistochemistry was used to detect PrPSc and cell-specific markers in sheep retinas.
• Retinal sections from control and scrapie-affected sheep were analyzed.
• Markers for bipolar cells (PKCalpha, VGLUT1), ganglion cells (MAP2), and Müller glia (GS) were examined.

Main Results:

• PrPSc-immunoreactivity was detected in scrapie-affected sheep retinas.
• Disrupted immunoreactivity patterns were observed for PKCalpha and VGLUT1 (bipolar cells).
• Altered immunoreactivity was also seen for MAP2 (ganglion cells) and GS (Müller glia).

Conclusions:

• PrPSc accumulation in sheep retinas alters the immunoreactivity of specific neuronal and glial markers.
• These changes occur despite the absence of microscopically detectable retinal degeneration.
• Prion protein accumulation may impact retinal cell function before overt pathological changes are visible.