Elevations in the endogenous levels of the putative morphogen retinoic acid in embryonic mouse limb-buds associated with limb dysmorphogenesis.
Elevations in the endogenous levels of the putative morphogen retinoic acid in embryonic mouse limb-buds associated with limb dysmorphogenesis.
复制标题
与肢体畸形发生相关的胚胎小鼠肢芽中假定的形态发生素视黄酸的内源水平升高。
DOI：
10.1016/0012-1606(89)90055-9
复制
发表时间：
1989
影响因子：
2.7
通讯作者：
Kochhar,DM
中科院分区：
文献类型：
--
作者：
Satre,MA;Kochhar,DM
视黄酸是维生素A（视黄醇）的内源性代谢产物，在脊椎动物肢体发育和再生中具有类似于形态发生素的显著生物活性。妊娠哺乳动物在肢体器官形成期间全身给予维甲酸（RA），必然导致剂量依赖性畸形发生。为了揭示RA在发育中的肢芽中的作用模式，我们通过HPLC方法分析了母体暴露于致畸剂量的RA之前和之后胚胎小鼠组织中RA及其代谢前体视黄醇的水平。在第11天小鼠胚胎（40 ± 2体节）的肢芽中发现了可检测水平的RA及其异构体13-顺式维甲酸。虽然视黄醇是在整个胚胎或肢芽的乙醇提取物中发现的主要类维生素A，但与整个胚胎相比，后者富含RA。这表明在这个发育阶段，与胚胎的其余部分相比，肢芽中的视黄醇代谢或RA的隔离程度更高。一项对处理过的胚胎中类维生素A水平的时间进程的研究表明，变化发生迅速，稳定几个小时，然后开始恢复到处理前的水平。母体给予10 mg/kg RA（导致轻度肢体畸形）后，肢芽中的RA峰值水平比内源性水平增加了50倍;给予100 mg/kg剂量后，发现增加了整整300倍，导致100%的短肢畸形发生率。有趣的是，RA治疗后，在母体血浆以及胚胎中均观察到视黄醇水平的剂量依赖性抑制。研究正在进行中，以追踪视黄醇和RA以及RA在肢芽和其他胚胎组织中的任何进一步活性代谢物的细胞内处置。
Retinoic acid, an endogenous metabolite of vitamin A (retinol), possesses striking biological activity akin to a morphogen in developing and regenerating vertebrate limbs. Systemic administration of retinoic acid (RA) to pregnant mammals during the period of limb organogenesis invariably results in dose-dependent dysmorphogenesis. In an attempt to uncover the mode of action of RA in the developing limb bud we analyzed, by HPLC methods, the levels of RA and its metabolic precursor, retinol, in embryonic mouse tissues prior to and following maternal exposure to a teratogenic dose of RA. Detectable levels of both RA and its isomer 13-cis-retinoic acid were found in the limb buds of Day 11 mouse embryos (40 ± 2 somites). Although retinol was the major retinoid found in ethanolic extracts of either whole embryo or the limb buds, the latter is enriched in RA compared to the whole embryo. This indicated either a higher degree of retinol metabolism or a sequestration of RA in the limb bud compared to the rest of the embryo at this stage of development. A study of the time course of retinoid levels in treated embryos showed that changes occur rapidly, are stable for several hours, and then begin to return to pretreatment levels. After a maternal dose of 10 mg/kg RA, which resulted in a mild degree of limb anomalies, peak RA levels in the limb bud increased 50-fold over the endogenous level; a full 300-fold increase was found after a 100 mg/kg dose which results in 100% incidence of phocomelia. Interestingly, a dose-dependent depression in retinol levels was observed after RA treatment both in maternal plasma as well as the embryo. Studies are in progress to trace the intracellular disposition of both retinol and RA as well as any further active metabolite of RA in the limb buds and other embryonic tissues.