Immunohistochemical localization of phospholipase D1 in the retina of pigs

The expression of phospholipase D1 (PLD1) was examined in the retinas of pigs. Western blot analysis detected the expression of PLD1 in the retinas of 1-day-old piglets and showed that it was enhanced in the retinas of 2 years old adult pigs. Immunohistochemically, PLD1 was mainly immunostained in ganglion cell bodies in the ganglion cell layer, in some radial processes of Muller cells in the retinal layer and in the inner and outer segments of the rod and cone layer in newborn and adult pigs, but not in astrocytic bundles in nerve fiber layers. The immunoreactivity of PLD1 in the radial processes of Muller cells across the retinal layers was enhanced in adult pig retinas compared to those of newborn piglets. This was the first demonstration to show that PLD1 is constitutively expressed in the retina of pigs, implying that retinal PLD1 expression is enhanced in radial fibers of Muller cells with age. This finding suggests that PLD1 plays an important role in signal transduction of glial cells and neuronal cells in the retina.