1990 Fiscal Year Final Research Report Summary
Development of the Control of Autonomic Visceral Functions in Amphibians
| Project/Area Number |
01044093
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | Shimane University |
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Principal Investigator |
NAITOH Tomio Shimane University, Associate Professor, 理学部, 助教授 (40069042)
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| Co-Investigator(Kenkyū-buntansha) |
GWYN David Graham Dalhousie University, Professor, 医学部, 教授
WASSERSUG Ri ダルハウジー大学, 医学部, 教授
WASSERSUG Richard Joel Dalhousie University, Professor
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| Project Period (FY) |
1989 – 1990
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| Keywords | Amphibians / Tadpole / Frog / Visceral Functions / Vomiting / HRP / Gut Motility / Vagal Nucleus |
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| Research Abstract |
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.
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