Neural Control of Opaline Release: A Model System to Study the Electrophysiological and Biochemical Mechanisms Underlying Glandular Secretion

摘要

When exposed to a noxious stimulus Aplysia californica secreres opaline, a viscous substance that presumably discourages predators. A series of electrophysiological and pharmacologic studies were done to characterize the motor neurons that control the release of opaline from the opaline gland. Three cells were found in the right pleural ganglion in which action potentials in the neurons were associated with contraction of the opaline gland. Electrophysiological studies further showed that the neurons send axons in the nerve trunk innervating the gland. The neurons also can produce gland contraction when synaptic activity in the central nervous system is blocked and make excitatory synpatic connections with contractile cells on the surface of the opaline gland. The excitatory connections have several features similar to excitatory junctional potentials described in other motor systems in Aplysia. Based on these properties the three neurons were identified as opaline motor neurons. The identified neurons were shown to make up a large portion of the motor input to the opaline gland via the nerve pathway studied in vitro. The opaline motor neurons also demonstrate a firing pattern and type of synoptic input which are similar to the features previously described for the motor neurons controlling ink release that is another presumably defensive secretory response in Aplysia.