Abstract
Purpose:
The generation of reactive oxygen species by oxidative stress is implicated in various pathological conditions of the retina and optic nerve. Peroxiredoxins (Prdxs) are a recently characterized family of antioxidant enzymes. To date, little information exists relating to the distribution of the various peroxiredoxins in the eye. Herein, we employed a combination of qPCR, immunohistochemistry and Western blotting to determine the level of expression and distribution of each of the six members of the peroxiredoxin family in the retina and optic nerve of the rat. In addition, we performed some parallel analyses on retina and optic nerve from the common marmoset (Callithrix Jacchus).
Methods:
Eyes with optic nerves attached were dissected from adult Sprague-Dawley rats and from three adult marmosets that were being euthanised. For immunohistochemistry, specimens were fixed, embedded in paraffin and 4μm thick sections taken. Sections were then processed for immunohistochemistry using standard methodologies.For qPCR and Western blotting studies, retina, optic nerve and brain samples were carefully dissected and subsequently analysed using standard methodologies.
Results:
In the rat, all of the Prdx transcripts were expressed in relatively high amounts in both retina and optic nerve, with abundances ranging from approximately 3% to 50% of the level of the housekeeping gene cyclophilin. Nevertheless, a marked variation was evident between the Prdx isoforms. With regard to protein expression, each of the isoforms was detected in the retina and optic nerve by either Western blotting and/or immunohistochemistry. With the exception of Prdx4, there was a good correspondence between the rodent and primate results. In the retina, Prdx1 and Prdx2 were principally localised to neurons in the inner nuclear layer as well as cone photoreceptors, Prdx3 and Prdx5 displayed characteristic mitochondrial patterns of immunolabelling, while Prdx6 was associated with astrocytes and Müller cells. In the optic nerve, Prdx1 was robustly expressed by oligodendrocytes, Prdx3 and Prdx5 were observed in axons, and Prdx6 was restricted to astrocytes.
Conclusions:
The present findings greatly augment our understanding of the distribution and expression of the Prdxs in the retina and optic nerve of rodents and primates and lay the foundation for subsequent analysis of their involvement in diseases such as glaucoma and age-related macular degeneration.