Modulation of neuropeptide effects by achatin-I, an Achatina endogenous tetrapeptide.
Achatin-I (Gly-D-Phe-L-Ala-L-Asp), an endogenous tetrapeptide in the ganglia of Achatina fulica Férussac, at 3 x 10(-6) M suppressed both the inward current (Iin) of an Achatina giant neurone, PON (periodically oscillating neurone), caused by locally ejected oxytocin, and the outward current (Iout) of v-RCDN (ventral-right cerebral distinct neurone) induced by APGW-amide. Dose (pressure duration)-response studies with oxytocin and APGW-amide showed that their ED50 values were not affected by achatin-I, whereas the Emax values were suppressed. The v-RCDN Iout caused by FMRF-amide was enhanced by achatin-I, but the same current induced by [Ser2]Mytilus inhibitory peptide ([Ser2]MIP) was not affected. Achatin-I suppressed the Iout of TAN (tonically autoactive neurone) caused by acetylcholine, but did not affect the Iin of v-RCDN elicited by acetylcholine. The Iout caused by gamma-aminobutyric acid, threo-beta-hydroxy-L-glutamic acid and dopamine was not affected by achatin-I. It is considered that achatin-I acts as a neuromodulator and has both suppressing and enhancing actions on the effects of various neurotransmitters, including peptides, in Achatina giant neurones.
Liu
G J
GJ
Department of Physiology, Gifu University School of Medicine, Japan.
Takeuchi
H
H
D000109:Acetylcholine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia; D004298:Dopamine / Q000494:pharmacology; D019835:FMRFamide; D005971:Glutamates / Q000494:pharmacology; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009842:Oligopeptides / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology; D012908:Snails; D009435:Synaptic Transmission / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D005971:Glutamates; C055988:Mytilus inhibitory peptide; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; C059927:achatin I; C063193:alanyl-prolyl-glycyl-tryptophanamide; D010121:Oxytocin; C011859:hydroxyglutamic acid; D005680:gamma-Aminobutyric Acid; D019835:FMRFamide; D000109:Acetylcholine; D004298:Dopamine