Stefanelli C, Flamigni F, Carati D, Rossoni C, Caldarera C M
Biochim Biophys Acta. 1987 Aug 19;930(1):79-86. doi: 10.1016/0167-4889(87)90158-3.
Treatment of rats with the glucocorticoid dexamethasone causes an increase in the activity of cytosolic spermidine N1-acetyltransferase both in the spleen and thymus, but not, however, in liver, kidney or lung. The induced spermidine N1-acetyltransferase activity in the spleen catalyses acetylation of spermidine as well as spermine and sym-norspermidine, but not of diamines and histones. The enzyme induction depends on the dose of dexamethasone, and is suppressed by cycloheximide, which suggests that de novo protein synthesis is required for the action of this glucocorticoid. N1-acetylspermidine accumulates in the spleen after dexamethasone treatment, while spermidine progressively decreases and is partly converted into putrescine, the content of which transiently increases. In accordance with previous reports, dexamethasone was found to cause a rapid and large fall in the activity of spleen ornithine decarboxylase which was effected via the appearance of an inhibitor of the enzyme. Glucocorticoids exert large catabolic effects on lymphoid tissues, and further selectively affect the activities of spermidine N1-acetyltransferase and ornithine decarboxylase in the thymus and spleen. These latter selective responses may represent an important early event in lymphoid tissue response to glucocorticoid hormones.
用糖皮质激素地塞米松处理大鼠，会导致脾脏和胸腺中胞质亚精胺N1 - 乙酰转移酶的活性增加，但肝脏、肾脏或肺中则不会。脾脏中诱导产生的亚精胺N1 - 乙酰转移酶活性可催化亚精胺、精胺和对称 - 去甲亚精胺的乙酰化反应，但不催化二胺和组蛋白的乙酰化反应。酶的诱导作用取决于地塞米松的剂量，并被环己酰亚胺抑制，这表明这种糖皮质激素的作用需要从头合成蛋白质。地塞米松处理后，N1 - 乙酰亚精胺在脾脏中积累，而亚精胺逐渐减少并部分转化为腐胺，其含量短暂增加。与之前的报道一致，发现地塞米松会导致脾脏鸟氨酸脱羧酶的活性迅速大幅下降，这是通过该酶抑制剂的出现实现的。糖皮质激素对淋巴组织具有较大的分解代谢作用，并进一步选择性地影响胸腺和脾脏中亚精胺N1 - 乙酰转移酶和鸟氨酸脱羧酶的活性。这些后者的选择性反应可能代表了淋巴组织对糖皮质激素反应中的一个重要早期事件。
