title: The distribution of histamine-immunoreactive neurons in the ventral nerve cord of the cricket, Gryllus bimaculatus.
abstract: The present study demonstrates the immunocytochemical localisation of the biogenic amine, histamine (HA), in interneurons within the ventral nerve cord of the cricket, Gryllus bimaculatus. Analysis of whole-mount preparations combined with histology of serial sections reveals a constant number of HA-immunoreactive (HA-ir) neurons in the suboesophageal (n=8), thoracic (n=4) and abdominal ganglia (females/males n=24/20). Except for the suboesophageal and prothoracic ganglion, each thoracic and abdominal neuromere contains one pair of bilateral-symmetric HA-ir somata in a medio-ventral position. Axons from HA-ir cells in the thorax extend anteriorly and share common projection areas in thoracic associative neuropils; they terminate in the brain. HA-ir cells also display efferent descending axons. Extending posteriorly, these axons give rise to varicose HA-ir fibre plexuses on the surface of nerve 1 of the abdominal ganglia. In the suboesophageal ganglion, processes from a bilateral symmetric group of clustered HA-ir cells ascend into the tritocerebrum of the brain and further project into the frontal ganglion and the recurrent nerve. Ultrastructural analysis reveals dense-core vesicles, indicative of non-synaptic secretion, in HA-ir elements within the stomatogastric nervous system. Arborisations of HA-ir neurons are present in all major neuropil regions of the ventral nerve cord and display characteristic varicose structures also detected in other types of amine-containing cells. Central HA-ir varicose projections in dorsal and ventral neuropils are located in close apposition to the ganglionic surface. The wide-spread innervation of all neuromeres by HA-ir interneurons and the identification of possible neurohemal release sites suggest a general role of HA as a neuroactive substance, including neuromodulatory and neurohormonal functions.
authors.affiliation: I. Zoologisches Institut, Abteilung für Zellbiologie, Universität Göttingen, Berlinerstrasse 28, D-37073 Göttingen, Germany. mhoerne@gwdg.de
authors.forename: M
authors.initials: M
authors.lastname: Hörner
authors.forename: J
authors.initials: J
authors.lastname: Helle
authors.forename: F W
authors.initials: FW
authors.lastname: Schürmann
mesh_terms: D000005:Abdomen / Q000294:innervation; D000818:Animals; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism; D005260:Female; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000378:metabolism*; D006135:Gryllidae / Q000378:metabolism*; D006257:Head / Q000294:innervation; D006632:Histamine / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D013909:Thorax / Q000294:innervation
chemical_list: D006632:Histamine