Okumura K, Matsui H, Kikuchi M, Mukawa H, Toki Y, Ito T
Second Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Can J Cardiol. 1995 Jul-Aug;11(7):565-72.
1,2-Diacylglycerol (DAG) is an intracellular signal mediator that may initiate protein synthesis and cardiac hypertrophy via activation of protein kinase C. The amounts of 1,2-DAG and its fatty acid components in the myocardium was assessed and compared with the concentrations of RNA and DNA in cardiac hypertrophy induced by administering triiodothyronine (T3) with and without cycloheximide, an inhibitor of protein synthesis. After the first injection of T3 no cardiac hypertrophy was observed, and there were no differences in myocardial 1,2-DAG content or in RNA and DNA concentrations. Cardiac hypertrophy was present on days 3 and 7 after a daily injection of T3. Myocardial RNA concentration was increased by 26% on day 3 and by 34% on day 7, whereas the myocardial 1,2-DAG content was decreased by 8% on day 3 and by 24% on day 7. Pretreatment with cycloheximide of T3-treated rats prevented the development of cardiac hypertrophy, but elevated the RNA concentration and lowered the 1,2-DAG content compared with the findings in T3-treated rats. Analysis of the fatty acid components of 1,2-DAG revealed that the amounts of 16:0, 18:1 and 18:2 were decreased, accompanied by an elevation of RNA concentration and a decrease in 1,2-DAG content. It seems that RNA synthesis preceded the alteration in 1,2-DAG. These findings suggest that 1,2-DAG is not involved in the initiation of cardiac hypertrophy induced by T3, but is affected by the enhanced concentration of RNA resulting from the introduction of thyroid hormones into the myocardium.
1,2 - 二酰甘油（DAG）是一种细胞内信号介质，可通过激活蛋白激酶C启动蛋白质合成和心脏肥大。评估了心肌中1,2 - DAG及其脂肪酸成分的含量，并将其与在给予和不给予蛋白质合成抑制剂环己酰亚胺的情况下，由注射三碘甲状腺原氨酸（T3）诱导的心脏肥大中RNA和DNA的浓度进行比较。首次注射T3后未观察到心脏肥大，心肌1,2 - DAG含量以及RNA和DNA浓度均无差异。每日注射T3后第3天和第7天出现心脏肥大。第3天心肌RNA浓度增加26%，第7天增加34%，而心肌1,2 - DAG含量在第3天降低8%，第7天降低24%。用环己酰亚胺预处理T3处理的大鼠可防止心脏肥大的发展，但与T3处理的大鼠相比，RNA浓度升高而1,2 - DAG含量降低。对1,2 - DAG的脂肪酸成分分析表明，16:0、18:1和18:2的含量降低，同时伴随着RNA浓度升高和1,2 - DAG含量降低。似乎RNA合成先于1,2 - DAG的改变。这些发现表明，1,2 - DAG不参与T3诱导的心脏肥大的起始，但受心肌中引入甲状腺激素后RNA浓度升高的影响。
