Hormonal regulation of platelet-activating factor-acetyltransferase activity in rat tissues.
Hormonal regulation of platelet-activating factor-acetyltransferase activity in rat tissues.
复制标题
大鼠组织中血小板活化因子乙酰转移酶活性的激素调节。
DOI：
10.1006/abbi.1993.1382
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发表时间：
1993
影响因子：
3.9
通讯作者：
Johnston,JM
中科院分区：
文献类型：
--
作者：
Ihara,Y;Frenkel,RA;Johnston,JM
血小板活化因子(PAF)在许多生理或病理条件下起着非常重要的作用。最近，我们和其他人提出，各种组织中的PAF浓度可能受到PAF-AH失活酶(PAF-AH)的调节。此外，还发现PAF-AH的血浆同工酶受多种类固醇激素的调节。Lyso-PAF：乙酰辅酶A乙酰转移酶(PAF-AT)是重塑途径合成PAF的关键酶。本文研究了激素对大鼠不同器官组织PAF-AT活性水平的影响。用地塞米松、17-α-乙炔雌二醇、甲羟孕酮-醋酸酯或赋形剂对雌性大鼠的脾、肺、子宫、肝等脏器进行微体提取，测定其PAF-AT活性。与对照组相比，地塞米松处理组大鼠肝脏(P<；0.00 1)和脾(P<；0.01)的PAF-AT比活性显著降低。地塞米松治疗后PAF-AT比活性呈剂量依赖性降低。注射甲羟孕酮后，肝组织PAF-AT活性显著降低(P<；0.01)。在注射17α-乙炔雌二醇的动物中，没有观察到任何组织中PAF-AT活性的变化。如前所述，地塞米松或甲羟孕酮使血浆PAF-AH活性显著升高，而17α-乙炔雌二醇显著降低血浆PAF-AH活性。地塞米松或甲羟孕酮治疗可降低PAF-AT活性，提高血浆PAF-AH活性，为严密控制PAF在组织中的作用提供了机制。
Platelet-activating factor (PAF) plays a very important role in a number of physiological or pathological conditions. Recently, we and others have suggested that the PAF concentration in various tissues may be regulated by the enzyme that inactivates PAF, PAF acetylhydrolase (PAF-AH). Furthermore, it has been shown that the plasma isozyme of PAF-AH is regulated by various steroid hormones. Lyso-PAF:acetyl-CoA acetyltransferase (PAF-AT) is a key enzyme in PAF biosynthesis by the remodeling pathway. In the present study, the hormonal effects on the tissue levels of PAF-AT activity were investigated in various organs of the rat. The microsomal fraction was prepared from the spleen, lung, uterus, and liver of female rats which had been pretreated with dexamethasone, 17α-ethynylestradiol, medroxyprogesterone-acetate, or vehicle and the PAF-AT activity was assayed. The rats treated with dexamethasone demonstrated significantly lower PAF-AT specific activity in the liver (P< 0.00 1) and spleen (P< 0.01), compared to the control group. A dose-dependent decrease of PAF-AT specific activity was demonstrated following dexamethasone treatment. Medroxyprogesterone injection also caused a significant decrease of PAF-AT activity in the liver (P< 0.01). No change of PAF-AT activity in any tissue was observed in the 17α-ethynylestradiol-injected animals. Plasma PAF-AH activity was increased significantly by the administration of dexamethasone (P< 0.01) or medroxyprogesterone (P< 0.01), and decreased by 17α-ethynylestradiol (P< 0.01), as previously described. The observation that dexamethasone or medroxyprogesterone treatment decreases the activity of PAF-AT and increases the plasma PAF-AH activity provides a mechanism for the tight control of PAF in tissues.