Distinct cellular localization of α- synuclein and β-synuclein in the chick retina.

α-Synuclein and β-synuclein are critical regulators of synaptic function and play significant roles in physiology and disease. While their retinal expression patterns are well-characterized in mammals, limited studies exist for the chicken retina, a model valuable for studying human retinal degenerative diseases due to its cone-dominant photoreceptor structure. Notably, research on β-synuclein in chickens remains scarce, leaving synucleinopathy models underdeveloped. Using immunofluorescence, we analyzed α- and β-synuclein expression in the chicken retina. Our results show that β-synuclein has a broader distribution than α-synuclein, similar to mouse retinas. Unique to chickens, α- and β-synuclein were highly expressed in horizontal cells, a feature absent in mice. Additionally, most dopaminergic and cholinergic amacrine cells co-expressed both α- and β-synucleins, unlike the mouse retina. These findings highlight species-specific differences in synuclein expression, providing insights into their roles in retinal function and pathology. This research may advance understanding of synucleinopathies and aid in the development of diagnostic and therapeutic strategies for neurodegenerative diseases.