GABA-like immunoreactive neurons in the slug Limax maximus.

Immunohistochemical techniques were used to study the distribution of GABA-like immunoreactive neurons in the nervous system of the slug Limax maximus. Approximately 170 GABA-like immunoreactive cell bodies were found in the central nervous system. These were located in the cerebral, buccal, and pedal ganglia. Most GABA-like immunoreactive neurons had small cell bodies which were aggregated into discrete clusters within the cerebral and pedal ganglia. Three pairs of larger, uniquely identifiable, GABA-like immunoreactive cells were found in the cerebral ganglion. GABA-like immunoreactive nerve fibers were found in all of the central ganglia but were absent from nerves in the periphery. These results suggest that GABA acts as a central neurotransmitter in the slug. The possible roles of GABA-ergic neurotransmission in the slug are discussed.