Further study on the effects of achatin-I, an Achatina endogenous neuroexcitatory tetrapeptide having a D-phenylalanine residue, on Achatina neurones.
Achatin-I (Gly-D-Phe-Ala-Asp), a tetrapeptide having a D-phenylalanine residue and isolated from Achatina ganglia, has been proposed as an excitatory neurotransmitter of Achatina neurones. In the present study, it was demonstrated using Achatina giant neurones that achetin-I, perfused at alow concentration, enhanced an inward current (Iin) caused by 5-hydroxytryptamine (fast component) and an outward current (Iout) caused by FMRFamide (Phe-Met-Arg-Phe-NH2), and that this peptide suppressed an Iin caused by oxytocin, and Iout caused by acetylcholine and APGW-amide (Ala-Pro-Gly-Trp-NH2). These findings indicate that achatin-I acts not only as a neurotransmitter but also as a neuromodulator for these neurones. In the preliminary experiments, it was shown that an Iin caused by achatin-I on an Achatina giant neurone type, PON (periodically oscillating neurone), was suppressed by H-89 (a PKA inhibitor) and W-7 (calmodulin inhibitor), and that an Iin caused by achatin-I on v-RCON (ventral-right cerebral distinct neurone) was suppressed by KT5823 (PKG inhibitor), suggesting that achatin-I acts on PON via the cyclic AMP-PKA system and on v-RCON via the cyclic GMP-PKG system. Moreover, calmodulin would play a role to produce the Iin for achatin-I on PON via the system mentioned.
Takeuchi
H
H
Department of Physiology, Gifu University School of Medicine, Japan.
Emaduddin
M
M
Araki
Y
Y
Zhang
W
W
Han
X Y
XY
Salunga
T L
TL
Wong
S M
SM
D000595:Amino Acid Sequence; D000818:Animals; D002147:Calmodulin / Q000502:physiology; D004594:Electrophysiology; D019835:FMRFamide; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D009479:Neuropeptides / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D018377:Neurotransmitter Agents / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D009712:Nucleotides, Cyclic / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D012908:Snails / Q000187:drug effects / Q000502:physiology*
D002147:Calmodulin; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009712:Nucleotides, Cyclic; C059927:achatin I; D012701:Serotonin; D019835:FMRFamide