Author:

Keywords:

locustatachykinins, adipokinetic hormone release, cyclic amp, locusta migratoria, central-nervous-system, crustacean cardioactive peptide, vertebrate tachykinin family, calliphora-vomitoria, myotropic peptides, immunoreactive neurons, insect neuropeptides, leucophaea-maderae, corpus cardiacum, migratoria, Science & Technology, Life Sciences & Biomedicine, Endocrinology & Metabolism, Zoology, cyclic AMP, Locusta migratoria, CENTRAL-NERVOUS-SYSTEM, CRUSTACEAN CARDIOACTIVE PEPTIDE, VERTEBRATE TACHYKININ FAMILY, CALLIPHORA-VOMITORIA, MYOTROPIC PEPTIDES, IMMUNOREACTIVE NEURONS, INSECT NEUROPEPTIDES, LEUCOPHAEA-MADERAE, CORPUS CARDIACUM, MIGRATORIA, Animals, Axons, Brain Chemistry, Chromatography, High Pressure Liquid, Cyclic AMP, Grasshoppers, Immunohistochemistry, Insect Hormones, Insect Proteins, Isomerism, Isoquinolines, Neural Pathways, Oligopeptides, Peripheral Nerves, Pyrrolidonecarboxylic Acid, Radioimmunoassay, Tachykinins, 0606 Physiology, 0608 Zoology, 0707 Veterinary Sciences, 3109 Zoology, 3202 Clinical sciences

Abstract:

Four locustatachykinins (LomTK I-IV) were identified in about equal amounts in extracts of corpora cardiaca of locusts, using reverse-phase high-performance liquid chromatography and radioimmunoassay with synthetic LomTK I-IV as standards. Brain extracts also contained the four isoforms in roughly equimolar concentrations. Retrograde tracing of the nervi corporis cardiaci II (NCC II) in vitro with Lucifer yellow in combination with LomTK immunocytochemistry revealed that about half of the secretomotor neurons in the lateral part of the protocerebrum projecting into the glandular lobe of the corpora cardiaca (CCG) contain LomTK-immunoreactive material. Since the four LomTKs are present in the CCG, these four or five neurons in each hemisphere are likely to contain colocalized LomTK I-IV. The role of two of the LomTKs in the regulation of the release of adipokinetic hormones (AKHs) from the adipokinetic cells in the CCG in the locust was investigated. Experiments performed in vitro showed that LomTK I and II induced release of AKH in a dose-dependent manner. These peptides also rapidly and transiently elevated the cyclic AMP-content of the CCG. The peak level of cyclic AMP occurred about 45 seconds after stimulation with LomTK. These results support the proposal that LomTKs are involved in controlling the release of the adipokinetic hormones and suggest that all LomTK isoforms may participate in this cyclic AMP-mediated event. (C) 1999 Academic Press.