PHYLOGENY OF ENTERIC SEROTONERGIC NEURONS
PHYLOGENY OF ENTERIC SEROTONERGIC NEURONS
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DOI：
10.1002/cne.901900103
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发表时间：
1980-01-01
影响因子：
2.5
通讯作者：
GERSHON, MD
中科院分区：
文献类型：
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作者：
GOODRICH, JT;BERND, P;GERSHON, MD
5-羟色胺能神经元此前已在人类、亚人灵长类动物、啮齿动物和兔子的肠道神经系统中被发现。研究了肠道5-羟色胺能神经元在低等脊椎动物中的分布，以确定这些神经元是否仅限于哺乳动物，以及如果它们在脊椎动物中更普遍地被发现，它们何时首次出现在脊椎动物的系统发育中。由于哺乳动物肠道5-羟色胺能神经元摄取~3H-5-羟色胺是一种高度特异的机制，因此用放射自显影显示轴突摄取~3H-5-羟色胺是寻找这些神经元的主要工具。已知的干扰哺乳动物肠道神经元摄取~3H-5-羟色胺的条件也被研究了。这些对照包括与10微米氟西汀(一种特定的拮抗剂)孵育，在无Na+的介质中孵育，以及在100倍的非放射性5-羟色胺存在的情况下孵育。放射自显影标记必须在所有三种对照条件下都不存在或大大减少，才能认为~3H-5-羟色胺标记是特异的。在环口动物(八目鳗)、硬骨鱼(金鱼)和两栖动物(牛蛙)中发现了标记的肠轴突，而在被囊动物(海鞘、海瓶)和棘皮动物(海参)中未发现标记的肠轴突。测量了两种脊椎动物肠道中的5-羟色胺浓度，这两种脊椎动物分别是无含5-羟色胺的肠嗜铬细胞的八头鳗和金鱼。两者都含有5-羟色胺；在八头鳗中，含有肌间神经丛的外肌制剂中的胺浓度最高。肠道5-羟色胺能神经元显然出现在脊椎动物进化的早期，可能存在于类似文昌鱼的祖先脊索中，尽管可能不存在于更原始的前脊椎动物中，它们是脊椎动物肠道的一般特征。
Serotonergic neurons have previously been identified in the enteric nervous systems of humans, subhuman primates, rodents and rabbits. The distribution of enteric serotonergic neurons in lower vertebrates was examined to determine if these neurons are restricted to mammals and, if they are found more generally among vertebrates, when they first appear in vertebrate phylogeny. Since mammalian enteric serotonergic neurons take up 3H-serotonin by a highly specific mechanism, the radioautographic demonstration of axonal uptake of 3H-serotonin was used as the primary tool in looking for these neurons. Conditions known to interfere with 3H-serotonin uptake by mammalian enteric neurons were also examined. These controls included incubation with 10 .mu.M fluoxetine, a specific antagonist, incubation in Na+-free medium, and incubation in the presence of a 100-fold excess of nonradioactive serotonin. Radioautographic labeling had to be absent or greatly reduced under all three control conditions for labeling by 3H-serotonin to be considered specific. Labeled enteric axons were found in cyclostomes (hagfish), teleosts (goldfish) and amphibia (bullfrog) but not in tunicates (sea squirt; sea vase) or echinoderms (sea cucumber). The serotonin concentration was measured in the intestine of 2 vertebrates, hagfish and goldfish, that do not have serotonin-containing enterochromaffin cells. Serotonin was found in both; in hagfish, the amine concentration was highest in preparations of muscularis externa containing the myenteric plexus. Enteric serotonergic neurons apparently arose early in vertebrate evolution, possibly in an ancestral chordate resembling amphioxus, although probably not in more primitive prevertebrates, and they are a general feature of the vertebrate bowel.