Localization of monoamine fluorescence in the stomatogastric nervous system of lobsters.

Explorations into the crustacean stomatogastric nervous system have focused on the stomatogastric ganglion as a paradigm of neural mechanisms and integrative circuitry. Emerging evidence implicates dopamine as a fundamental modulator of the bursting pacemaker neurons and many of the intraganglionic rhythms. The present paper has employed formaldehyde-induced fluorescence in freeze-dried specimens, a microscopic histochemical technique which demonstrates anatomical structures containing particular putative transmitters, indoleamines and catecholamines. We have localized specific, formaldehyde-induced fluorescence in the lobster stomatogastric nervous system. This fluorescence occurs throughout the stomatogastric ganglion neuropil, in 4-8 cell bodies of the bilaterally paired commissural ganglia and in discrete and continuous neurites interconnecting these 3 ganglia. Variations of the basic fluorescence technique suggest that the specific fluorescence is catecholaminergic. Evidence from related biochemical studies supports this observation and indicates that the catecholaminergic fluorescence is dopaminergic since tests for norepinephrine are negative while concomitant tests for dopamine are positive.