Alberghina M, Viola M, Insirello L, Giuffrida Stella A M
Institute of Biochemistry, Faculty of Medicine, University of Catania, Italy.
Neurochem Pathol. 1988 Apr;8(2):131-48. doi: 10.1007/BF03160141.
We examined the effects of age on RNA and lipid formation by whole retina and optic nerve in vitro. Male Wistar rats, aged 4, 12, and 24 mo, were used. From the results obtained the following conclusions may be drawn: 1. In assaying the lipid biosynthesis during aging, a striking difference between the retina and optic nerve clearly emerged; 2. In isolated retina, [3H]uridine incorporation into RNA was relatively constant at the three ages, whereas both [14C]palmitate and [3H]choline incorporation into lipids showed a substantial increase in rats at 24 mo of age compared with those at 4 mo; 3. In contrast, in the optic nerve of the oldest rats, compared with the youngest, a significant decrease of [14C]acetate and [14C]palmitate incorporation into acylglycerols, cerebrosides, and phospholipids was found. Each fatty acid precursor label was incorporated to a proportion that reflected the typical acyl group composition of individual lipids; 4. Following labeling of the optic nerve with [3H]choline, the specific radioactivity of choline-containing phospholipids was drastically decreased with increasing rat age; and 5. The incorporation of [2-3H]glycerol into optic nerve diacylglycerols, PtdEtn, and PtdIns declined with age, whereas no significant change took place in the incorporation into PtdCho. The results strongly support the concept that RNA metabolism of rat retina (most likely photoreceptor cell layer) is not altered during aging; on the contrary, phospholipid synthesis is stimulated in comparison with that of the optic nerve, for which a serious impairment was concomitantly observed. The physiological significance of these responses, and the mechanism by which retinal tissue is spared from the general age derangement of the nervous system, remain to be defined.
我们研究了年龄对体外培养的整个视网膜和视神经中RNA及脂质形成的影响。选用了4月龄、12月龄和24月龄的雄性Wistar大鼠。从所得结果可得出以下结论：1. 在测定衰老过程中的脂质生物合成时，视网膜和视神经之间出现了明显差异；2. 在分离的视网膜中，[3H]尿苷掺入RNA在三个年龄组中相对恒定，而[14C]棕榈酸酯和[3H]胆碱掺入脂质的量在24月龄大鼠中比4月龄大鼠有显著增加；3. 相反，在最老龄大鼠的视神经中，与最年轻的大鼠相比，[14C]乙酸盐和[14C]棕榈酸酯掺入酰基甘油、脑苷脂和磷脂的量显著减少。每种脂肪酸前体标记物的掺入比例反映了各个脂质的典型酰基组成；4. 用[3H]胆碱标记视神经后，含胆碱磷脂的比放射性随着大鼠年龄的增加而急剧下降；5. [2-3H]甘油掺入视神经二酰甘油、磷脂酰乙醇胺和磷脂酰肌醇的量随年龄下降，而掺入磷脂酰胆碱的量没有显著变化。结果有力地支持了这样一种观点，即大鼠视网膜（很可能是光感受器细胞层）的RNA代谢在衰老过程中没有改变；相反，与视神经相比，磷脂合成受到刺激，而视神经同时出现了严重损伤。这些反应的生理意义以及视网膜组织免受神经系统普遍衰老紊乱影响的机制仍有待确定。
