Vitamin A and reproduction in rats
Vitamin A and reproduction in rats
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维生素 A 与大鼠生殖
DOI：
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发表时间：
1964
期刊：
影响因子：
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通讯作者：
G. Pitt
中科院分区：
文献类型：
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作者：
J. Thompson;J. Howell;G. Pitt
维甲酸(维生素A酸)是一种羧酸，相当于初级酒精视黄醇(维生素A)，以前被认为满足维生素A的所有功能，但在视觉方面除外，因为喂食缺乏视黄醇但补充了维甲酸的饮食的大鼠生长良好，表面上看起来很健康，但却失明了。本文报道了这种饮食的雌性大鼠有正常的发情周期并在交配时怀孕，但总是吸收胎儿，没有产下小鼠。第一次发现的异常是妊娠第16天左右胎盘周围的坏死和轻微的多形性浸润性病变。直到第十天才补充视黄醇，结果产下了一窝健康的幼崽。因此，维甲酸维持了妊娠的早期，但不是后期。当怀孕期间给予极少量的视黄醇时，死亡或虚弱的幼崽就会出生；如果补充较高的维生素，幼崽就会成功断奶。通过这种方法，幼鼠的视黄醇储存可以忽略不计。喂食维甲酸但不喂视黄醇的雄性大鼠的睾丸较小，而且常常是水肿性的。生发上皮脱落，部分管腔消失，另一些管腔保留，部分精母细胞和精原细胞顽强地固定在管腔内。与服用视黄醇的对照组相比，精囊较小。在出生时维甲酸含量微乎其微的大鼠中，睾丸仍处于幼稚状态；精子细胞从未形成。饲喂视黄醇可恢复退化睾丸的生精功能，促进仍处于幼年期的睾丸的正常发育，并保证精囊的生长。因此，尽管维甲酸在维持生命、生长和一般健康方面取代了真正的维生素，但它并不起到生殖作用。除了后者所谓的系统功能外，维生素A在生殖过程中必须具有离散和特定的作用，即。这是由视黄醇完成的，而不是由维甲酸完成的。从之前报道的维生素A缺乏动物生殖障碍的许多特征中，可以区分哪些是由于这一特定的“生殖”作用的失败，哪些是由于“系统性”缺陷。维甲酸在生殖过程中的不活跃表明，在大鼠体内，维生素A不是像以前认为的那样有两种，而是三种可分离的作用模式：(1)全身作用；(2)视觉作用；(3)生殖作用。
Retinoic acid (vitamin A acid), the carboxylic acid corresponding to the primary alcohol retinol (vitamin A), has previously been thought to fulfil all the functions of vitamin A except in vision, since rats fed a diet deficient in retinol but supplemented with retinoic acid grow well, outwardly appearing healthy, yet become blind. This paper reports that female rats on such a diet had normal oestrous cycles and became pregnant when mated, but always resorbed the foetuses and no litters were born. The first abnormalities detected were necrosis and slight polymorph infiltration around the periphery of the placental disk about the sixteenth day of pregnancy. Supplementation with retinol as late as the tenth day resulted in the birth of a healthy litter. Retinoic acid therefore maintained the early but not the later stages of gestation. When very small amounts of retinol were given during pregnancy, dead or weak young were born; on higher supplements of the vitamin, litters were weaned successfully. By this means young rats were produced with negligible stores of retinol. Male rats fed retinoic acid but not retinol had small and often oedematous testes. The germinal epithelium sloughed off and in some tubules the lumen was obliterated, but in others the lumen remained, and in these some spermatocytes and spermatogonia were held tenaciously. The seminal vesicles were smaller than in controls given retinol. In rats born with negligible stores of retinol—see above—and maintained on retinoic acid, the testes remained infantile; spermatids were never formed. Feeding retinol restored spermatogenesis in degenerate testes and promoted the normal development of testes that had remained infantile; it also ensured the growth of the seminal vesicles. Retinoic acid did not therefore serve in reproduction, although it replaced the true vitamin in maintaining life, growth and general health. Besides the latter so-called systemic function, vitamin A must have a discrete and specific role in reproduction, viz. that performed by retinol but not by retinoic acid. From among the many previously reported features of disordered reproduction in vitamin A-deficient animals, it was possible to distinguish which had arisen from a failure of this specifically ‘reproductive’ role and which from a ‘systemic’ deficiency. The inactivity of retinoic acid in reproduction demonstrates that in rats vitamin A has not two, as previously thought, but three dissociable modes of action: (1) systemic; (2) in vision; and (3) in reproduction.