Aminergic neurons in the anterior nervous system of the rat acanthocephalan Moniliformis dubius

The cerebral ganglion and nerve tracts of Moniliformis dubius show intense, specific, green fluorescence that is also associated with the lateral and apical sensory bulbs. Radioenzymatic assays showed that high levels of dopamine were present but only small amounts of the catecholamines norepinephrine and epinephrine were identified. Incubations of the proboscis sac in dilute solutions of dopamine increased fluorescence while incubations in reserpine resulted in loss of fluorescence. Nonfluorogenic amine octopamine was also detected radioenzymatically. Neutral red vitally stained a number of cells in the cerebral ganglion and the nerve tracts extending from the ganglion. Electron microscopy showed that many neurons contained electron-dense vesicles. The close association of the fluorescing, amine-containing nerve tracts with the sensory bulbs suggests that they may play a functional role in sensory reception and transmission in M. dubius. This is the first report on the presence of biogenic amines in the Acanthocephala.