An initial screen of a series of neuroactive peptides for activity on identified central neurones of Helix aspersa.
1. Intracellular recordings were made from identified neurones in the suboesophageal ganglia of Helix aspersa. Seven neuropeptides were tested for activity and their actions compared with acetylcholine and FMRFamide. 2. Three peptides isolated from nematodes, AF-1, AF-2 and PAN-1 had mainly inhibitory effects with thresholds of around 1 nM. This inhibition was due to an increase in potassium conductance. 3. The molluscan neuropeptides LSSFVRIamide, CARP and ACEP-1 were all active on certain neurones; the first two showed only inhibitory effects while ACEP-1 was mainly excitatory. The thresholds in each case were 0.1-10 microM. When norleucine replaced methionine in CARP, the potency was reduced by at least 100 times. 4. The echinoderm peptide, SALMF-1, only excited neurones but with a very low threshold, around 1.0 fM. 5. There was no obvious correlation between the action of these peptides and either acetylcholine or FMRFamide.
Pedder
S
S
Department of Physiology, University of Southampton, U.K.
Sharma
R
R
Muneoka
Y
Y
Walker
R J
RJ
D000109:Acetylcholine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D005724:Ganglia / Q000187:drug effects / Q000502:physiology; D006372:Helix, Snails / Q000187:drug effects* / Q000502:physiology; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009479:Neuropeptides / Q000494:pharmacology*
D009479:Neuropeptides; C063480:Achatina cardio-excitatory peptide 1; C063461:AF1 neuropeptide; C073964:AF2 neuropeptide; D000109:Acetylcholine