Abnormalities in rod photoreceptors, amacrine cells, and horizontal cells in human retinas with retinitis pigmentosa

PURPOSE: To evaluate changes in the rods and amacrine cells and horizontal cells in human retinas with retinitis pigmentosa, METHODS: Seven retinas from patient donors with retinitis pigmentosa and 14 age- and postmortem-matched normal human retinas were processed for immuno cytochemistry and confocal microscopy. The following cell-specific antibodi es were used: anti-rhodopsin (rods), anti-gamma-aminobutyric acid (amacrine cells), anticalbindin (cones and horizontal cells), anti-glial fibrillary acidic protein (astrocytes and reactive Muller cells), and anti-synaptophys in and anti-SV2 (synaptic vesicles). RESULTS: In retinal regions with significant photoreceptor loss, the rods, gamma-aminobutyric acid-positive amacrine cells, and calbindin-positive hor izontal cells had undergone neurite sprouting, The rod, amacrine and horizo ntal cell neurites were associated with the surfaces of glial fibrillary ac idic protein-immunoreactive Muller cells. Most rod neurites that projected into the inner retina contacted the somata of gamma-aminobutyric acid-posit ive amacrine cells. CONCLUSIONS: Rods, amacrine and horizontal cells undergo neurite sprouting in human retinas with retinitis pigmentosa. These changes in the retinal ne urons may contribute to the electroretinographic abnormalities and progress ive decline in vision noted by patients with retinitis pigmentosa, These al terations may also complicate strategies for treatment of retinitis pigment osa, (Am J Ophthalmol 2000;129:215-223, (C) 2000 by Elsevier Science Inc. A ll rights reserved.)