Alford F P, Milea M, Reaven G M
Horm Metab Res. 1976 Mar;8(2):118-22. doi: 10.1055/s-0028-1093665.
The protein synthetic activities of membrane-bound and free hepatic ribosomes isolated from intact rats fed ad libitum, and normal rats subjected to food restriction to match that of hypophysectomised (Hx) rats were compared to the in vitro protein synthetic capacity of hepatic ribosomes isolated from Hx rats. Hypophysectomy resulted in decreased protein synthetic ability of bound ribosomes, whether protein synthesis was directed by endogenous messenger RNA (mRNA) (p less than 0.05) or by polyuridylic acid (polyU) (p less than 0.01). In contrast, the protein synthetic activity of free hepatic ribosomes from Hx rats was reduced when protein synthesis was directed by endogenous mRNA (p less than 0.05) but, when polyU was substituted as the messenger, the protein synthetic activity of these free ribosomes was equal to that of control rats. On the other hand the effects of food restriction on hepatic ribosomal function could be clearly differentiated from the effects observed following hypophysectomy. Thus, the reduced protein synthetic activity of hepatic bound ribosomes isolated from food restricted normal rats was not demonstrable, when polyU was used to direct protein synthesis. Further, food restriction had no effect on the protein synthetic activity of free hepatic ribosomes, and this was true when protein synthesis was directed by either endogenous or artificial messenger. It is concluded that hypophysectomy reduces the protein synthetic ability of both bound and free hepatic ribosomes, and this change of ribosomal function of Hx rats cannot be attributed to their decreased food intake.
将从随意进食的完整大鼠以及食物受限以使其进食量与垂体切除（Hx）大鼠相匹配的正常大鼠中分离出的膜结合型和游离型肝脏核糖体的蛋白质合成活性，与从Hx大鼠中分离出的肝脏核糖体的体外蛋白质合成能力进行了比较。垂体切除导致结合核糖体的蛋白质合成能力下降，无论蛋白质合成是由内源性信使核糖核酸（mRNA）（p<0.05）还是由聚尿苷酸（polyU）（p<0.01）指导。相比之下，当蛋白质合成由内源性mRNA指导时，Hx大鼠游离肝脏核糖体的蛋白质合成活性降低（p<0.05），但是，当用polyU替代信使时，这些游离核糖体的蛋白质合成活性与对照大鼠的相等。另一方面，食物限制对肝脏核糖体功能的影响可以与垂体切除后观察到的影响明显区分开来。因此，当用polyU指导蛋白质合成时，从食物受限的正常大鼠中分离出的肝脏结合核糖体降低的蛋白质合成活性并未得到证实。此外，食物限制对游离肝脏核糖体的蛋白质合成活性没有影响，当蛋白质合成由内源性或人工信使指导时都是如此。结论是，垂体切除降低了肝脏结合型和游离型核糖体的蛋白质合成能力，并且Hx大鼠核糖体功能的这种变化不能归因于它们食物摄入量的减少。
