Molluscan neuropeptide-like and enkephalin-like material coexists in octopus nerves

Antibodies against the opioid peptide enkephalin and the molluscan neuropeptide FMRFamide immunostained identical nerve terminals and neurosecretory granules in a neuropil layer of the octopus vena cava, indicating occurrence of a common enkphalin-Arg-Phe precursor.

Abstract

Antibodies against the opioid peptide enkephalin and the molluscan neuropeptide FMRFamide immunostained identical nerve terminals and neurosecretory granules in a neuropil layer of the octopus vena cava. Enkephalin—like immunoreactivity was significatly enhanced by enzymatic digestion of the sections with trypsin or with carboxypeptidase-B, prior to incubation with antibodies; FMRFamide-like immunoreactivity was prevented by tryptic digestion. Coexistence of the two different immunoreactive substances and the effects of enzymatic cleavages indicate occurrence of a common enkephalin-Arg-Phe precursor. The same population of nerve terminals also contained immunoreactive α-melanotropin-like material.