Identification of aromatase in the reptilian brain.
Identification of aromatase in the reptilian brain.
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爬行动物大脑中芳香酶的鉴定。
DOI：
10.1210/endo-100-4-1214
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发表时间：
1977
期刊：
影响因子：
4.8
通讯作者：
K. Ryan
中科院分区：
文献类型：
--
作者：
G. Callard;Z. Petro;K. Ryan
目前的研究验证了一种假设，即脑芳香化酶是神经组织的一种“古老”特性，可能在一种非哺乳动物脊椎动物——龟龟的边缘系统的同源物中被发现。组织匀浆（180 mg湿重/2 ml）与[7 α - 3h]雄烯二酮和辅助因子在37℃下孵育60 min，分离雌酮（E1），并通过薄层色谱、甲基化和重结晶进行表征，保持恒定的比活性。未检测到雌二醇-17 β。芳香酶仅在前脑发现，但在整个主要脑区弥漫性分布。没有其他神经或非神经组织，包括中脑和后脑结构，睾丸和卵巢，在我们的系统中合成可检测到的E1。两性的纹状-杏仁核复合体每单位重量比视前-下丘脑区（POA-HTH）或其他前脑结构合成更多的E1。雄激素向雌激素的转化可能在该物种中具有生物学意义，因为该反应发生在自然界活动时所经历的整个生理温度范围内，并且在繁殖季节脑芳香酶活性的性别差异很明显。这些在Chrysemys进行的实验表明，大脑从雄激素合成雌激素的现象并不局限于哺乳动物，也发生在更原始的系统发育水平上。芳香化酶在海龟前脑结构中的限制与哺乳动物边缘系统中酶活性的神经解剖学分布是一致的。成年龟脑的雌激素产出量（3.2-22.6 pmol/g）比成年哺乳动物（0.1-1.9 pmol/g）更接近胎儿（2.7-33 pmol/g）。我们认为，中枢神经系统雌激素的原位合成在脊椎动物进化早期就开始了，可能是调节脊椎动物生理和行为性别的脑类固醇相互作用的原始特征。
The present study tests the hypothesis that brain aromatase is an "ancient" property of nervous tissue and may be identified in homologues of the limbic system in a non-mammalian vertebrate, the turtle Chrysemys picta. Tissue homogenates (180 mg wet weight/2 ml) were incubated with [7 alpha-3H]androstenedione and cofactors for 60 min at 37 C. Estrone (E1) was isolated and characterized by thin layer chromatography, methylation and recrystallization to constant specific activity. No estradiol-17 beta was detected. Aromatase was found only in the forebrain but was diffusely distributed throughout this major brain division. No other neural or non-neural tissues, including mid- and hindbrain structures, testis, and ovary, synthesized detectable quantities of E1 in our system. The strio-amygdaloid complex of both sexes synthesized more E1 per unit weight than the preoptic-hypothalamic area (POA-HTH) or other forebrain structures. It is possible that the conversion of androgen to estrogen has biological significance in this species since the reaction occurred throughout the physiological temperature range experienced during activity in nature and sex differences in brain aromatase activity during the breeding season were apparent. These experiments in Chrysemys demonstrate that the synthesis of estrogen from androgen by the brain is not limited to mammals, but also occurs at a more primitive level of phylogenetic development. Restriction of aromatase to forebrain structures of the turtle is consistent with the neuroanatomic distribution of enzyme activity in the limbic system of mammals. Estrogen yield from adult turtle brain incubates (3.2-22.6 pmol/g) is more like that reported for fetal (2.7-33 pmol/g) than for adult (0.1-1.9 pmol/g) mammals. We suggest that the in situ synthesis of estrogen by the central nervous system has its orgins early in vertebrate evolution and may be a primitive characteristic of brain-steroid interactions that regulate physiological and behavioral sex in vertebrates.