SMALL SETS OF PUTATIVE INTERNEURONS ARE OCTOPAMINE-IMMUNOREACTIVE IN THE CENTRAL-NERVOUS-SYSTEM OF THE POND SNAIL, LYMNAEA-STAGNALIS

An antibody raised against conjugated octopamine was applied to map octopamine-containing neurons in the central nervous system of the pond snail Lymnaea stagnalis. A small number of octopamine-like immunoreactive neurones occurs in all ganglia, but the pleural ones. The neurons are located either in small clusters or occur individually. Major concentrations of octopamine-immunoreactive neurons can first of all be found in the buccal, cerebral and pedal ganglia. Varicose arborizations were observed in the neuropiles, but peripheral projections of labelled elements could not be traced. We suggest that a set of octopaminergic interneurons would exist in the Lymnaea brain. Mapping of octopamine-immunoractive neurons given may also facilitate physiological investigations on octopaminergic neurontransmission in the gastropod nervous system.