Parentini Ilaria, Bergamini Ettore, Cecchi Lauretta, Cavallini Gabriella, Donati Alessio, Maccheroni Marco, Tamburini Ilaria, Gorii Zina
Centro di Ricerca Interdipartimentale di Biologia e Patologia dell'Invecchiamento, University di Pisa, Pisa, Italy.
Biogerontology. 2003;4(6):365-70. doi: 10.1023/B:BGEN.0000006556.76899.29.
Dolichol (D) is a long-chain polyprenoid broadly distributed in the cell membranes, possibly endowed with a free-radical scavenging activity, whose concentration in tissues increases with increasing age. No enzyme pathway for D degradation has been discovered. In order to test the hypothesis that D might undergo a non-enzymatic free-radical mediated decomposition the effects of a xenobiotic agent (carbon tetrachloride, CCl(4)) and ultraviolet-B (UV-B) radiation on D levels were studied in liver cells isolated from male ad libitum fed Sprague-Dawley rats aged 3 or 24 months. Liver cells (90 mg/ml) were incubated in sealed flasks (6 ml cell suspension each) for 0, 5, 10 and 20 min after the addition of 25, 50 or 200 microl CCl(4) in the central well. 50 ml of a 6 mg/ml liver cell suspension were poured in a 120 cm(2) Petri dish and the sediment liver cell monolayer was exposed to UVB radiation for 0, 5, 10, 20 and 40 min. At the given time, cells were taken and D was extracted and assayed by the HPLC procedure. D levels were remarkably higher in older than in younger cells as expected ( P < 0.001). Treatment with CCl(4) and UVB caused a highly significant decrease in D ( P < 0.001) whose percentage was larger in younger than in older cells. The conclusions are that free-radicals generated either by chemical or by physical agents cause a very rapid depletion of D in liver cells, and that the effect of the free radical attack on D decomposition may be lower percentage wise in older than in younger cells, which might account at least in part for the accumulation of D in older tissues.
多萜醇（D）是一种广泛分布于细胞膜中的长链多萜类化合物，可能具有自由基清除活性，其在组织中的浓度随年龄增长而增加。尚未发现D降解的酶促途径。为了验证D可能会发生非酶促自由基介导的分解这一假设，研究了异源生物剂（四氯化碳，CCl₄）和紫外线B（UV-B）辐射对从自由采食的3月龄或24月龄雄性Sprague-Dawley大鼠分离的肝细胞中D水平的影响。将肝细胞（90 mg/ml）在密封烧瓶（每个烧瓶6 ml细胞悬液）中培养，在中央孔中加入25、50或200 μl CCl₄后分别培养0、5、10和20分钟。将50 ml 6 mg/ml的肝细胞悬液倒入120 cm²的培养皿中，将沉淀的肝细胞单层暴露于UVB辐射0、5、10、20和40分钟。在给定时间，取出细胞，通过HPLC程序提取并测定D。正如预期的那样，老年细胞中的D水平明显高于年轻细胞（P < 0.001）。用CCl₄和UVB处理导致D显著降低（P < 0.001），其降低百分比在年轻细胞中比老年细胞中更大。结论是，化学或物理因素产生的自由基会导致肝细胞中D迅速耗竭，并且自由基攻击对D分解的影响在老年细胞中按百分比计算可能低于年轻细胞，这可能至少部分解释了D在老年组织中的积累。
