Reductions in taurine secondary to photoreceptor loss in Irish setters with rod-cone dysplasia.
These studies show that onset of photoreceptor cell degeneration preceded the loss of taurine in retinas of Irish setters with rod-cone dysplasia. The numbers of photoreceptor cell nuclei were within the normal adult range in affected setters at 10 through 26 days of age but declined rapidly between 26 and 45 days and more gradually thereafter; their numbers became reduced to 50% of normal at 45 days and then to 12-20% and 3-10% of normal at 192 and 346 days, respectively. Taurine concentrations increased within the photoreceptor cell layer during normal development to peak values (50 mM) at a time (45 days of age) corresponding to the development of adult photoreceptor function. In the affected setters, taurine levels increased as in the normal until 26 days of age and then remained at that value until 40-50% of the photoreceptor cells had degenerated. Thereafter, taurine levels declined gradually throughout the period of photoreceptor cell degeneration and were reduced to 30-40% of the normal adult level at the time (346 days) when the thickness of the outer nuclear layer was reduced to less than one complete row of nuclei. These observations agree with findings in retinal degeneration (rd) mice and RCS rats and indicate that in all three of these animal models of hereditary retinal degenerations, reductions in retinal taurine levels occur secondary to the loss of photoreceptor cells.
D000818:Animals; D004285:Dogs; D010786:Photoreceptor Cells / Q000032:analysis*; D012162:Retinal Degeneration / Q000378:metabolism; D012164:Retinal Diseases / Q000378:metabolism*; D013654:Taurine / Q000032:analysis*
D013654:Taurine