Characterization of responses to enkephalins and FMRFamide on B neurons of the cerebral ganglion of Aplysia

1. Cerebral B neurons of Aplysia vary in reponse to leu- and met-enkephalin. Some neurons show inward currents to the enkephalins, while others show outward or biphasic currents. 2. The FMRFamide and acetylcholine responses also vary among the B neurons. 3. While acetylcholine and FMRFamide responses were usually accompanied by clear conductance changes and voltage dependency, those to the enkephalins often showed no conductance change and minimal voltage dependency. 4. The inward currents elicited by both the enkephalins and FMRFamide were increased by forskolin, an activator of adenylate cyclase, and by phosphodiesterase inhibitors.