Supported l/y the Western Australian Retinitis Pigmentosa Foundation (Perth), the Australian Retinitis Pigmentosa Association (Spence), and the Lions Save-Sight Foundation (original) (raw)

2020

Abstract

,"\ and IanJ. Constable* Purpose. The aim of this study was to identify whether abnormalities in the synthesis of basic fibroblast growth factor (bFGF) or its receptor (bFGF-R) were responsible for the photoreceptor dystrophy in Royal College of Surgeons (RCS) rats. Methods. The polymerase chain reaction was used to detect the expression of bFGF and bFGF-R messenger RNA in the retinal pigment epithelial (RPE) cells and the neural retina of RCS dystrophic rats and in PVG/C and RCS-rrf)> + control animals. Results. In the RPE, it was found that there was no significant difference in the expression of bFGF and bFGF-R between RCS rats and the controls at the ages of 21 days and 3 mo. In the neural retina, the level of bFGF expression was lower in the 21-day-old RCS rats compared with the control group, but bFGF-R expression was as strong as in the PVG/C and RCS-rd)> + animals. However, in 3-mo-old RCS rat neural retina, the bFGF and bFGF-R expression was found to be significantly lower than in the control animals. Conclusions. Although the mutant gene in RCS rats is expressed in the RPE cells, these results suggest that there is no significant defect in bFGF or bFGF-R expression in the RPE cells of RCS rats, which would be an initiating factor in the development of photoreceptor degeneration in these animals. The lowered bFGF levels in the neural retina at early stages (postnatal day 21) may explain the prolongation of photoreceptor survival when exogenous bFGF is injected. Invest Ophthalmol Vis Sci. 1993; 34:1845-1852 JLJegeneration of photoreceptors leads to permanent blindness because, in common with other central nervous system neuronal cells, they cannot be replaced by cell division in adults. The Royal College of Surgeons (RCS) mutant strain of rats with inherited retinal dys- trophy has been used widely as a model to study photoreceptor degeneration. 1 Although this particular type of defect is not common in humans, the procedures that prolong photoreceptor survival in this condition may be more widely applicable. The cellular nature of the genetic abnormality in RCS rats is known, but the underlying molecular defect has not yet been identified. In the RCS rat, the retinal pigment epithelium (RPE) does not phagocytose shed outer segments, 2 thus resulting in accumulation of membranous debris in the subretinal space and subsequent death of the rod photoreceptors. Transplantation of RPE cells from normal rats results in long-term (5 mo after treatment) rescue of photore-

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