title: Toward locating the source of serotonergic axons in the tail nerve of Aplysia.
abstract: Stimulation of the tail nerve (pedal nerve 9, p9) of the mollusk, Aplysia                         californica, causes release of serotonin (5-HT), which mediates sensitization of withdrawal responses. There are about 35 serotonin-immunoreactive (5-HT-ir) axons in p9, yet the cell bodies of these axons have not been located. Backfills of p9 were combined with 5-HT immunohistochemistry to locate the cell bodies of 5-HT-ir neurons with axons in p9. About 100 neurons had axons in p9. Only about ten neurons, however, were both backfilled and 5-HT-ir. These double-labeled neurons were all located in the pedal ganglion associated with p9, which had a total of approximately 42 5-HT-ir somata. The discrepancy between the number of 5-HT-ir axons and double-labeled cell bodies is not likely due to neurons having multiple axons in the nerve; intracellular fills suggest that these neurons do not branch before entering p9. Additionally, no evidence was found for peripheral 5-HT-ir cell bodies that project axons centrally through p9. Thus, approximately 70% of the neurons that give rise to the 5-HT-ir axons in tail nerve are unaccounted for, but likely to reside in the pedal ganglion.
authors.affiliation: Neuroscience Institute, Georgia State University, P.O. Box 5030, Atlanta, GA 30302, USA.
authors.forename: Sagar
authors.initials: S
authors.lastname: Jhala
authors.forename: Arianna N
authors.initials: AN
authors.lastname: Tamvacakis
authors.forename: Paul S
authors.initials: PS
authors.lastname: Katz
mesh_terms: D000818:Animals; D001048:Aplysia; D001369:Axons / Q000737:chemistry; D017952:Ganglia, Invertebrate / Q000166:cytology*; D007150:Immunohistochemistry; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009475:Neurons, Afferent; D009928:Organ Specificity; D010812:Physical Stimulation; D012701:Serotonin / Q000032:analysis / Q000378:metabolism; D013623:Tail / Q000294:innervation*; D014110:Touch / Q000502:physiology
chemical_list: D012701:Serotonin