Alterations in fatty acid composition of tissue phospholipids in the developing retinal dystrophic rat

Alterations in lipid composition occur in the retinal pigment epithelium an d photoreceptor cells of the Royal College of Surgeons (RCS) dystrophic rat , a model for inherited retinal degeneration. With respect to lipid composi tion of non-retinal tissues, the developmental timing of lipid alterations and the incidence of dystrophy are unknown. We determined the fatty acid co mposition in choline phosphoglycerides (ChoGpl) and ethanolamine phosphogly cerides (EtnGpl) in the brain, liver, and retina from dystrophic RCS rats a nd from their nondystrophic congenics (controls) at the ages of 3 and 6 wk. At 3 wk, the fatty acid compositions were specific to individual phospholi pid classes without any difference between dystrophic and nondystrophic tis sues. In plasma phospholipids, there was an age-related increase in the rel ative contents of monounsaturated and n-3 polyunsaturated fatty acids, with only minor differences between dystrophic and nondystrophic rats. At 6 wk, the fatty acid compositions in ChoGpl and EtnGpl from dystrophic brain and retina were significantly different from those of nondystrophics. The effe ct of strain on developmental changes in brain fatty acid composition was s ignificant for 18:0 and 22:6n-3 in EtnGpl and for 16:0, 18:0, 18:1n-9, and 20:4n-6 in ChoGpl. The brain ChoGpl fatty acid composition in nondystrophic rats was similar at 6 wk to that of normal rats, and there were almost no postweaning changes in the dystrophics. In retinal phospholipids, the effec t of dystrophy was to increase the 20:4n-6 content in EtnGpl and to decreas e 22:6n-3 in ChoGpl. The 18:2n-6 and 22:6n-3 contents in dystrophic liver C hoGpl were also significantly affected, while no difference was observed in the EtnGpl fraction. The dystrophy affected the phospholipid fatty acid de velopmental changes in a tissue- and class-specific manner. Fatty acid meta bolism could be selectively altered in neural and nonneural tissues of deve loping dystrophic RCS rats.