Study for the effects of neuroactive peptides newly isolated

今年，我们用电生理学方法全面研究了生物活性多肽对非洲巨型蜗牛(Achat Ina Fulica Ferussac)可识别的巨型神经元的影响。除催产素外，Achat ina巨细胞对P物质、甲硫氨酸脑啡肽、神经降压素等哺乳动物神经递质不敏感。另一方面，这些神经元对从无脊椎动物中分离的神经活性多肽敏感。这些发现不同于小分子神经递质，如多巴胺、5-羟色胺和GABA。因此，我们认为一种多肽神经递质作用于动物种类的神经元的程度比小分子神经递质的作用范围要小。我们与三得利生物有机研究所和圣托马斯大学合作，从龙舌兰神经节中分离出Aachatin-I(Gly-D-Phe-Ala-Asp)，它能兴奋Achat ina巨型神经元。APGW-酰胺(ALA-PR…更多的o-Gly-Trp-NH_2)，也是我们从龙舌兰神经节中分离到的，被抑制的龙舌兰巨神经元。这两种多肽被认为是Achat ina神经元的神经递质。此外，我们还证实了另一组从Achat ina神经节分离的ACEP-1(Ser-Gly-Gln-Ser-Trp-Arg-Pro-Gln-Gly-Arg-Phe-NH_2)对Achat ina巨型神经元有兴奋作用，而另一组从Achat ina神经节分离的黄曲素(Phe-D-Asn-Gln-Phe-Val-NH_2)对这些神经元有抑制作用。我们还证实了从文蛤神经节分离的FMRFFamide(Phe-Met-Arg-Phe-Nh_2)、从蛔虫中分离的FMRFamide的相关化合物AF1(Lys-Asn-Glu-Phe-Ile-Arg-Phe-Nh_2)和从Mytilus中分离的[Ser^2]-Mytilus抑制肽([Ser^2]-MIP)(Gly-Ser-Pro-Met-Phe-Val-Nh_2)对这些神经元具有抑制作用。H-89(蛋白激酶(PK)A抑制剂)和W-7(钙调蛋白抑制剂)可抑制Achatin-I的作用，而环状AMP磷酸二酯酶抑制剂(IBMX)则有促进作用，提示Achatin-I是通过环状AMP-PKA系统发挥作用的，钙调蛋白参与了该系统。另一方面，KT-5823(PKG抑制剂)、Calphostin C(PKC抑制剂)和W-7可抑制黄褐素的抑制作用，表明黄褐素通过环化GMP-PKG系统和/或IP_3和DG-PKC系统发挥作用，钙调蛋白参与了这些系统。IBMX抑制了这种抑制作用，其机制目前尚不清楚。我们证明了APGW-酰胺和Aachatin-I不仅是一种神经递质，而且还是一种神经调节剂。较少

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 … More 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