Metabolic changes in hepatic cholesterol metabolism by dietary amino acid

为了阐明高胆固醇血症的机制，我们测定了肝脏HMG-CoA还原酶、肝脏HMG-CoA还原酶mRNA、LDL受体mRNA和注射入血的I-LDL的消失率。发现如下：1。血清胆固醇在饲喂富胱氨酸日粮后3 ~ 5 d内升高。肝脏HMG-CoA还原酶活性在饲喂富胱氨酸日粮后3 d内升高。饲喂富胱氨酸饲粮2 d后，肝脏HMG-CoA还原酶mRNA升高1.6 ~ 1.8倍。饲喂富胱氨酸饲粮3 d后，肝脏LDL受体mRNA升高。富胱氨酸饮食使注入血液的I-LDL（<125>）从血液中消失的比率增加。从上述结果可以推测，饲喂富含胱氨酸的饮食引起的高胆固醇血症可能是由于肝脏中胆固醇合成的增强。

In order to clarify the mechanism for the hypercholesterolemia induced by feeding the cystine rich diet, liver HMG-CoA reductase, liver HMG-CoA reductase mRNA,LDL receptor mRNA and, the disappearance rate of ^<125>I-LDL injected into blood were estimated. The following were found.1.Serum cholesterol was increased within 3-5 days after feeding the cystine rich diet.2.Hepatic HMG-CoA reductase activity was increased within 3 days after feeding the cystine rich diet diet.3.Hepatic HMG-CoA reductase mRNA was increased 1.6-1.8 folds after feeding the cystine rich diet for 2 days.4.LDL receptor mRNA in the liver was increased after feeding the cystine rich diet for 3 days.5.The disappearance rate from the blood of ^<125>I-LDL injected into blood was increased in the rats fed the cystine rich diet.From these results described above, it is surmised that the hypercholesterolemia induced by feeding teh cystin rich diet might be due to the enhanced synthesis of cholesterol in the liver.