title: Quantitative determination and distribution of the myotropic neuropeptide orcokinin in the nervous system of astacidean crustaceans.
abstract: For quantitative determinations of orcokinin, an indirect, noncompetitive sandwich ELISA was developed. This ELISA is highly specific for orcokinin and the detection limit is 1 fmol. In three astacidean species (Orconectes limosus, Homarus americanus, and Astacus astacus) orcokinin immunoreactivity (OK-IR) was measurable in all parts of the nervous system. Upon normalization to the protein content of the tissue (pmol/mg protein), concentrations were shown to be in the same range in all three species. The distribution of OK-IR in the nervous system is also very similar in the three species. In Orconectes limosus the following values were obtained (in pmol/mg protein): cerebral ganglion 215, optic ganglia in the eyestalk 38, subesophageal ganglion 182. The thoracic ganglia have lower concentrations (35-72) and the abdominal ganglia (AG) 1-5 even lower ones (11-17). In the AG 6 of Orconectes, from which the innervation of the hindgut arises, concentrations are approximately five times higher than in the other AG. In hindgut tissue, relatively high concentrations of 22 pmol/mg were measured, which is in agreement with the demonstrated function of orcokinin as a hindgut excitatory substance. Markedly elevated levels of orcokinin were observed in the AG 6 of Astacus, but not in Homarus. Orcokinin could also be measured consistently and reliably in the hemolymph, where its concentration is approximately 1 x 10(-11) M. These results show that orcokinin may be released into the hemolymph and may act as a hormone, in addition to its role as a locally acting neurotransmitter/modulator.
authors.affiliation: Institut für Zoophysiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Bungart
authors.forename: H
authors.initials: H
authors.lastname: Dircksen
authors.forename: R
authors.initials: R
authors.lastname: Keller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003400:Astacoidea / Q000737:chemistry*; D003445:Crustacea / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D008969:Molecular Sequence Data; D009132:Muscles; D008121:Nephropidae / Q000737:chemistry*; D009420:Nervous System / Q000737:chemistry; D009479:Neuropeptides / Q000032:analysis*
chemical_list: D009479:Neuropeptides; C079067:orcokinin