COEXISTENCE OF CALCITONIN-GENE-RELATED PEPTIDE AND CHOLINE-ACETYLTRANSFERASE IN EEL EFFERENT NEURONS

We applied choline acetyltransferase, (ChAT) and calcitonin gene-relat ed peptide (CGRP) immunocytochemistry to the efferent neurons that inn ervate the lateral line and the ear of the eel. Strong immunoreactivit y to the ChAT antiserum was observed in neurons located within the oct avolateralis efferent nucleus that could be distinguished, on the basi s of their form, location and dendritic organization, from the ChAT-im munopositive motoneurons of the adjacent facial motor nucleus. Both fa cial motoneurons and efferent neurons were found to be immunopositive for CGRP, although the reaction was always stronger in the motoneurons . Double labelling experiments established the presence of both ChAT a nd CGRP in many efferent neurons. The results are evidence that cholin ergic efferent neurons supplying end organs of different modalities ma y also produce calcitonin gene-related peptide.