Effect of pituitary hormones on alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase in rat.
Effect of pituitary hormones on alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase in rat.
复制标题
垂体激素对大鼠α-氨基-β-羧基粘康酸-ε-半醛脱羧酶的影响。
DOI：
10.3177/jnsv.26.607
复制
发表时间：
1980
影响因子：
1.6
通讯作者：
M. Miyazaki
中科院分区：
文献类型：
--
作者：
H. Sanada;M. Miyazaki
为了阐明色氨酸烟酸在不同生理状态下代谢的变化，研究了α-氨基β-羧酸-e-半醛脱羧酶的激素调节。每12小时给去垂体大鼠注射琥珀酸倍多宁和各种垂体激素，连续2~4d。然后测定其肝脏吡啶甲酸羧基酶的活性。单独注射强的宁可提高去垂体大鼠的酶活性。另一方面，大鼠或牛的脑下垂体提取物被发现抑制这种酶的诱导，当它在注射强的宁之前给药时。加热或添加蛋白水解酶，如胰酶和胰凝乳酶，可使脑下垂体提取物失去抑制酶的活性。这些结果表明，提取液中的有效物质可能是多肽。通过对牛脑垂体提取液的凝胶过滤，得到两个有效部位，它们能抑制依赖于前多宁的肝脏吡啶甲酸羧化酶的诱导。这些物质的分子量估计分别约为23,000和2,000-4,000。这两种有效物质均定位于脑垂体前叶。在所测试的多种垂体激素中，牛生长激素和哺乳类催乳素被发现能有效地抑制去垂体大鼠对前多宁依赖的肝脏吡啶甲酸羧化酶的诱导。为了了解糖尿病大鼠肝脏吡啶甲酸羧基酶活性升高的机制，对糖尿病大鼠每隔12小时给予牛生长激素或大鼠脑垂体提取物4或7天。此激素治疗未见对糖尿病大鼠的酶活性有抑制作用。这些结果被认为提示，垂体激素的变化不是糖尿病大鼠酶活性升高的原因。
The hormonal regulation of α-amino β-carboxymuconate-e-semialdehyde decarboxylase (picolinic carboxylase) was studied to clarify the change of tryptophan-niacin metabolism in the different physiological states. Hypophysectomized rats were administered with predonine hemisuccinate and various kinds of pituitary hormones for 2 or 4 days every 12 hr. The activity of their liver picolinic carboxylase was then assayed. The injection of predonine alone elevated the enzyme activity in hypophysectomized rats. On the other hand, rat or bovine pituitary extract was found to suppress such enzyme induction when it was administered prior to predonine injection. The enzyme-suppressing activity of the pituitary extract was lost by heat treatment or addition of proteolytic enzyme such as trypsin and chymotrypsin. These results indicate that the effective substances in the extract may be polypeptides. By gel filtration of bovine pituitary extract, two effective fractions were obtained, which were able to suppress the predonine-dependent induction of liver picolinic carboxylase. The molecular weights of these substances were estimated to be about 23, 000 and 2, 000-4, 000, respectively. Both of these effective substances were shown to be localized in the anterior lobe of hypophysis. In the many kinds of pituitary hormones tested, bovine somatotropin and mammalian prolactin were found to be effective in suppressing the predonine-dependent induction of liver picolinic carbo xylase in hypophysectomized rats. To obtain some information on the mechanism by which liver picolinic carboxylase activity is elevated in diabetic rats, bovine somatotropin or rat pituitary extract was administered to diabetic rats for 4 or 7 days every 12 hr. This hormone treatment was not observed to depress the enzyme activity in the diabetic rats. These results are considred to suggest that changes in pituitary hormone are not responsible for the elevation of the enzyme activity in the diabetic rat.