Studies on the Inactivation of Thyrotropin-Releasing Hormone (TRH)∗
Studies on the Inactivation of Thyrotropin-Releasing Hormone (TRH)∗
复制标题
促甲状腺激素释放激素（TRH）失活的研究*
DOI：
--
复制
发表时间：
1969
期刊：
影响因子：
--
通讯作者：
A. Schally
中科院分区：
文献类型：
--
作者：
T. Redding;A. Schally
使用维持低碘饮食并用5 μCi 125 I和0.085 μg三碘甲腺原氨酸预处理的小鼠，测定血浆组分对猪促甲状腺素释放激素（TRH）的体外灭活作用。TRH与猪、牛或人血清孵育30 min后可完全失活，失活的最适pH为7，最适温度为30 ~ 40 ℃。TRH的失活率与酶浓度和时间成正比。将大鼠血浆预热至56 ℃ 30 min可大大降低这种失活。当猪、牛和人来源的血浆组分与TRH在Krebs-Ringer碳酸氢盐（pH 7.4）中于37 ℃孵育30 min时，α、β和γ球蛋白组分使添加的TRH失活80-90%。白蛋白和纤维蛋白原导致TRH活性降低40-50%，而β-脂蛋白组分仅诱导TRH轻微失活。TRH与大鼠肝、肾、脑皮质和骨骼肌组织切片一起孵育也可消除TRF活性。这些组织在煮沸之前减少了TRH的失活。这些结果最好解释为血浆和各种组织中存在一种能够使TRH失活的酶。
Summary Inactivation of porcine thyrotropin-releasing hormone (TRH) by plasma fractions in vitro was determined using mice maintained on a low iodine diet and pre-treated with 5 μCi of 125I and 0.085 μg of triiodothyronine. Incubation of TRH with porcine, bovine, or human serum caused a complete inactivation in 30 min. The optimum pH for the inactivation was about 7 and the optimal temperature was between 30 and 40°. The rate of inactivation of TRH was proportional to the enzyme concentration and time. Preheating rat plasma to 56° for 30 min greatly reduced this inactivation. When plasma fractions of porcine, bovine, and human origin were incubated with TRH in Krebs-Ringer bicarbonate, pH 7.4, at 37° for 30 min, alpha, beta, and gamma globulin fractions caused an 80-90% inactivation of added TRH. Albumin and fibrinogen caused a 40-50% reduction in TRH activity while the beta-lipoprotein fraction only induced a slight inactivation of TRH. Incubation of TRH with slices of rat liver, kidney, brain cortex, and skeletal muscle tissue also abolished TRF activity. Prior boiling of these tissues reduced the inactivation of TRH. These results are best explained by the presence of an enzyme in the plasma and various tissues which is capable of inactivating TRH.