IMMUNOCYTOCHEMICAL LOCALIZATION OF NEUROPEPTIDE-F IMMUNOREACTIVITY INTHE CIRCUMOESOPHAGEAL GANGLIA OF THE GASTROPOD MOLLUSK, HELIX-ASPERSAUSING ELECTRON-MICROSCOPY

Neuropeptide F (NPF)-immunoreactivity has been localized by electron m icroscopy in the central nervous system of the gastropod mollusc, Heli x aspersa using a region-specific antiserum in conjunction with post-e mbedding immunogold labelling. The specific antiserum employed, design ated NPF3, was raised to a synthetic N-terminal fragment of H. aspersa NPF. Gold-labelling revealed that NPF-immunoreactivity was found almo st exclusively over the contents of dense-cored secretory vesicles wit hin nerve axons in both cerebral and suboesophageal ganglia. Double-la belling of NPF and FMRFamide demonstrated no apparent co-localization in the paired cerebral ganglia. Instead, immunoreactivities of the two neuropeptides were found to have distinct locations within the gangli a. These findings suggest that NPF may be an important neuroregulator in H. aspersa and that in the cerebral ganglia it may be anatomically- distinct from FMRFamide and related peptides.