Effect of Dietary Protein on the Changes of Lipoprotein Fractions in Carbon Tetrachloride-Treated Rats

식이성 단백질 함량에 따른 흰쥐에 사염화탄소 투여시 Lipoprotein 분획비의 변동

To evaluate an effect of dietary protein on lipoprotein profile serum of carbon tetrachloride-treated rats, carbon tetrachloride (50% in olive oil) was twice given at 0.1ml/100g body weight at intervals of 24hours to the male rats and then the degree of liver damage in carbon tetrachloride-treated animals fed a low protein diet was compared with that fed a high protein diet. The increasing rate of liver weight/body weight and the serum levels of alanine aminotransferase in carbon tetrachloride-treated rats to the control group were higher in rats fed high protein diet than those fed low protein diet. In the serum levels of lipid (total lipid, total cholesterol and triglyceride) remarkable differences were not found between low protein diet group and high protein diet group. But these serum lipids in carbon tetrachloride-treated rats were decreased and the decreasing rate of serum lipids to control group were higher in carbon tetrachloride-treated rats fed high protein diet than those fed low protein diet. Under the animal model as identified by the present data herein, serum pre $\beta$-lipoprotein and $\alpha$-lipoprotein fractions were decreased in carbon tetrachloride-treated rats, but the serum levels of $\beta$-lipoprotein were rather increased in the both group by the injection of carbon tetrachloride. Especially, the decreasing rate of $\alpha$-lipoprotein fraction was higher in $CCl_4$-treated rats fed a high protein diet than those fed a low protein diet to its control group and the increasing rate of serum $\beta$-lipoprotein fraction was also higher in $CCl_4$-treated rats fed high protein diet than those fed low protein diet.

단백식이조건을 달리하여 성장시킨 동물에 $CCl_4$를 투여하였을 때 혈청중 lipoprotein 분획비의 변동 및 이의 원인을 검토할 목적으로 흰쥐를 저단백식이(7% casein : LP) 및 고단백식이 (20% casein : HP)로 성장시킨 후, 50% $CCl_4$(v/v in olive oil)를 복강내 주사한 다음 간 중량 및 혈청 ALT 활성도 측정으로 간손상을 확인함과 동시에, 혈청지질과 혈청 lipoprotein 분획비를 측정하였다. $CCl_4$투여시 체중 당 간무게 및 혈청중 ALT의 활성도는 대조군에 비해 증가하였으며 그 증가율은 HP군이 LP군보다 더 높게 나타났다. 혈청중 총지질, 총 cholesterol 및 triglyceride의 함량은 대조군간에 별다른 차이를 관찰할 수 없었으나, $CCl_4$투여로 인해 이들 지질은 대조군에 비해 감소하였으며, 그 감소율은 HP군이 LP군보다 높게 나타났다. $CCl_4$투여로 인한 lipoprotein분획비의 변동은 대조군에 비하여 양군 공히 pre $\beta$-lipoprotein비율 및 $\alpha$-lipoprotein 비율은 감소되었고, 그 감소율은 HP군이 LP군에 비해 더 크게 나타났다. 한편 $\beta$-lipoprotein비율은 $CCl_4$투여로 인하여 두군 공히 증가하였으며 그 증가율은 HP군에서 높게 나타났다. 이상의 실험결과와 문헌상의 지견을 종합해 볼때 $CCl_4$투여시 LP군에 비하여 HP군에서 간손상이 보다 더 심하게 나타나며, 이로 인하여 apoprotein의 합성억제현상이 초래됨으로써 혈청중 lipoprotein분획비의 변동이 높게 나타날 것으로 생각된다.