Development of the Control of Autonomic Visceral Functions in Amphibians

本项目侧重于两栖动物内脏功能的三个方面。呕吐：我们从它们的呕吐反应中证实，有10种无尾两栖动物具有呕吐的能力。我们的数据表明，无尾两栖动物的呕吐行为类似于哺乳动物(Naitoh等人，Physiol。因此，我们提出无尾两栖动物是研究呕吐机制基本问题的有用动物模型(Naitoh等人，Comp.生物化学。PhysIOL，1991，印刷中)。我们现在已经证明，尾龙也会呕吐。因为脊椎动物的呕吐可能与摄食活动有关，所以我们研究了CCK对呕吐的影响，CCK导致饱腹感。但是，尚不清楚CCK是否参与了呕吐机制。肠道运动的发展及其神经控制：在无尾两栖动物的发育过程中，大肠是消化道中首先获得成人型收缩行为的部分(Naitoh等人，comp.生物化学。PhysIOL，97c：201-207,1990)。纵向收缩和环形收缩似乎独立地发生在蝌蚪和青蛙的大肠中。我们认为，高等脊椎动物肠道中纵向和环状肌层收缩的协调是与肠道神经丛的发育协调进化的。胃和小肠的运动发育较晚，直到变态才出现完整的成体模式。支配内脏中枢的发育：专门研究迷走神经核团的发育变化。令人惊讶的是，DAB对细胞核的HRP染色表明，蝌蚪中的神经元比青蛙的更多。核嘴区的一些神经元在变态后消失。然而，核团中的神经元与肠道各部分之间的关系尚未建立。

The present project focused on the three aspects of the visceral functions in amphibians.1. Vomiting : We have confirmed from their emetic responses that anurans in 10 species possess the ability to vomit. Our data indicate that the vomiting act of anurans is similar to that of mammals (Naitoh et al., Physiol. Zool., 62 : 819-813, 1989), we thus propose that the anurans are useful animal models for studying basic issues of emetic mechanisms (Naitoh et al., Comp. Biochem. Physiol., 1991, in press). We have now shown that urodeles can also vomit. Because emesis in vertebrates can be related to feeding activity, we studied the effect of CCK, which causes satiety, on emesis. But, it was not clear if CCK took part in the vomiting mechanism or not.2. Development of the gut motility and its neural control : In the development of anurans, the large intestine is the portion of the alimentary tract that first attains the adult-type of contractile behavior (Naitoh et al., Comp. biochem. Physiol., 97C : 201-207, 1990). Longitudinal contractions and circular ones seem to occur independently in both the tadpole and frog large intestines. We propose that the coordination of the contractions of the longitudinal and circular muscle layers shown in the gut of higher vertebrates is phylogenetically evolved in harmony with the development of the enteric nervous plexus. Movements of the stomach and small intestine develop later, with the full adult-pattern not appearing until metamorphosis.3. Development of the center controlling viscera : Developmental change of vagal nucleus was exclusively studied. Surprisingly HRP staining of the nucleus with DAB indicates that neurons in the tadpoles are more numerous than in the frog. Some neurons in the rostral region of the nucleus disappear after metamorphosis. However, relationship between the neurons in the nucleus and each part of the gut is not yet established.