| Co-Investigator(Kenkyū-buntansha) |
APORTADERA Luisa l. Department of Internal Medicine, Davao Medical School Foundation, 助教授
DE la Cruz H ダバオ医科大学, 教授
VICENTE Warlito c. Department of Surgery, Davao Medical School Foundation, 助教授
PAGULAYAN Im フィリピン大学, 理学部, 教授
LASTIMOSA Hi フィリピン大学, 理学部, 教授
SIN Ramon l. Department of Pathology, Faculty of Medicine and Surgery, University of Santo To, 医学部, 教授
TORRALBA Tito p. Department of Internal Medicine, Faculty of Medicine and Surgery, University of, 医学部, 教授
SEVILLA Fortunato Research Center for the Natural Science, University of Santo Tomas, 理学部, 教授
DAYAO Virginia f. Department of Biological Sciences, College of Science, University of Santo Tomas, 理学部, 教授
KANAPI Carmen g. Department of Biological Sciences, College of Science, University of Santo Tomas, 理学部, 教授
MUNEKATA Eisuke Institute of Applied Biochemistry, University of Tsukuba, 応用生物化学系, 教授 (60072766)
MAMO Tadaaki Research Institute of Environmental Medicine, Nagoya University, 環境医学研究所, 教授 (30023659)
DEURA Shigeyuki Department of Anatomy, Fujita Health University School of Medicine, 医学部, 教授 (40021448)
MORI Akitane Department of Neurochemistry, Institute for Neurobiology, Okayama University Med, 医学部, 教授 (20028434)
YAMAMOTO Noriko College of Sciences, Gifu University, 医療技術短期大学部, 教授 (70021409)
ARAKI Yoko Department of Physiology, Gifu University School of Medicine, 医学部, 助手 (20176374)
LEE Ken Department of Physiology, Gifu University School of Medicine, 医学部, 助教授 (00212316)
PAGULAYAN Imelda f. Institute of Biology, College of Science, University of the Philippines
LASTIMOSA Hilda d. Department of Biological Sciences, Cebu College, University of the Phylippines
DE LA CRUZ Honorio e. Department of Pediatrics, Davao Medical School Foundation
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| Research Abstract |
This year, we studied comprehensively effects of biologically-active peptides on the identifiable giant neurones of an African giant snail (Achatina fulica Ferussac) by the electrophysiological methods. The Achatina giant neurones were insensitive to the mammalian neurotransmitter peptides, such as substance P,Met-enkephalin, neurotensin, etc., except for oxytocin. On the other hand, these neurones were sensitive to the neuroactive peptides isolated from invertebrates. These findings were different from those of small molecule putative neurotransmitters, such as dopamine, serotonin and GABA.With these results, it was considered that one peptide neurotransmitter acts on the neurones of the less extent of animal species than the small molecule putative neurotransmitter. Achatina giant neurones were excited by achatin-I (Gly-D-Phe-Ala-Asp), isolated from Achatina ganglia by the collaboration of us, Suntory Institute for Bioorganic Research and University of Santo Tomas. APGW-amide (Ala-Pr
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o-Gly-Trp-NH_2), isolated also from Achatina ganglia by us, were inhibited Achatina giant neurones. These two peptides were proposed to be neurotransmitters for Achatina neurones. Besides, we demonstrated that Achatina cardio-excitatory peptide-1 (ACEP-1) (Ser-Gly-Gln-Ser-Trp-Arg-Pro-Gln-Gly-Arg-Phe-NH_2) isolated from Achatina ganglia by another group showed excitatory effects on Achatina giant neurones, and that fulicin (Phe-D-Asn-Gln-Phe-Val-NH_2) isolated from Achatina ganglia by another group had inhibitory effects on these neurones. We demonstrated also that FMRFFamide (Phe-Met-Arg-Phe-NH_2) isolated from the clam ganglia, AF1 (Lys-Asn-Glu-Phe-Ile-Arg-phe-NH_2), a related compound of FMRFamide isolated from an Ascaris, and [Ser^2]-Mytilus inhibitory peptide ([Ser^2]-MIP) (Gly-Ser-Pro-Met-Phe-Val-NH_2) isolated from Mytilus, had inhibitory effects on these neurones.
The intracellular signal transduction systems for the excitatory effects of achatin-I and the inhibitory effects of fulicin were studied electrophysiologically using the inhibitors for these systems. H-89 (protein kinase (PK) A inhibitor) and W-7 (calmodulin inhibitor) inhibited the achatin-I effects, and IBMX (cyclic AMP phosphodiesterase inhibitor) facilitated the same effects, indicating that achatin-I acted via cyclic AMP-PKA system, and calmodulin participated in this system. On the other hand, KT-5823 (PKG inhibitor), calphostin C (PKC inhibitor) and W-7 suppressed the inhibitory effects of fulicin, indicating that fulicin acted via cyclic GMP-PKG system and/or IP_3 and DG-PKC systems, and calmodulin participated in these systems. IBMX suppressed the inhibitory effects, the mechanism of which cannot be explained at present.
We demonstrated that APGW-amide, as well as achatin-I,acted not only as a neurotransmitter but also as a neuromodulator for Achatina neurones. Less
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