Dietary effects on the retina of hamsters

The retina is a sensory tissue in the back of the eye, which captures visual information and relays it to the brain. The retinal pigment epithelium separates the neural retina from the choroidal (systemic) circulation and is thereby exposed to circulating lipoprotein particles. Herein, we used hamsters and conducted various retinal evaluations of animals fed either a normal diet or a Western-type diet (WTD). Prior to evaluations, hamsters were injected with indocyanine green (ICG), a fluorescent dye that binds to various proteins and lipids in the systemic circulation. The WTD increased plasma levels of total and HDL cholesterol 1.8- and 2.1-fold, respectively, and led to additional HDL₂ and HDL₃ subpopulations. The diet also increased the ICG fluorescence in the retinal pigment epithelium and the underlying choroidal circulation on histological tracking and altered retinal protein abundance as assessed by proteomics. Functional enrichments were found in the retinal gene expression, energy production, intracellular transport, cytoskeleton- and synapse-related processes, and protein ubiquitination. The biochemical basis linking the WTD, retinal energy production, and retinal neurotransmission was suggested as well. The data obtained were then compared with those from our previous investigations of hamsters and different mouse genotypes. We identified common retinal processes that can be affected by circulating lipoprotein particles regardless of the mechanism by which their levels and subpopulations were altered (through diet or genetic modification). Thus, we obtained novel mechanistic insights into how lipids in the systemic circulation can affect the retina.