title: Tyramine injections reduce locust viability.
abstract: In the locust nervous system, tyramine is the direct precursor for octopamine synthesis and, as an octopamine analogue, it can activate octopamine receptors. Furthermore, the identification of specific tyramine receptors in Locusta migratoria and Drosophila melanogaster suggests that it is an important transmitter or modulator candidate. In this paper, we report that repeated tyramine injections reduced the viability of last instar larvae of Locusta and Schistocerca. In addition, a retardation of the last ecdysis was observed as a sublethal effect of the repeated tyramine treatment. Moreover, egg deposition by adult females was also retarded and/or drastically reduced. These effects show similarity to sublethal effects described for certain "insecticidal" octopamine receptor agonists, such as formamidines and phenyliminoimidazolidines. Since certain formamidine compounds were also shown to be agonists for the cloned tyramine receptors, it cannot be excluded that some lethal or sublethal consequences of tyramine administration are the result of an interaction with specific tyramine receptors.
authors.affiliation: Department of Biology, Laboratory for Developmental Physiology and Molecular Biology, K.U. Leuven, Zoological Institute, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Torfs
authors.forename: W
authors.initials: W
authors.lastname: Van Poyer
authors.forename: J
authors.initials: J
authors.lastname: Poels
authors.forename: E
authors.initials: E
authors.lastname: Swinnen
authors.forename: A
authors.initials: A
authors.lastname: De Loof
authors.forename: J
authors.initials: J
authors.lastname: Vanden Broeck
mesh_terms: D000818:Animals; D005260:Female; D006110:Grasshoppers / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D007814:Larva / Q000187:drug effects; D018377:Neurotransmitter Agents / Q000494:pharmacology / Q000502:physiology; D009655:Octopamine / Q000502:physiology; D010058:Oviposition / Q000187:drug effects; D017982:Receptors, Biogenic Amine / Q000187:drug effects / Q000502:physiology; D014439:Tyramine / Q000494:pharmacology* / Q000502:physiology
chemical_list: D018377:Neurotransmitter Agents; D017982:Receptors, Biogenic Amine; C066175:tyramine receptor; D009655:Octopamine; D014439:Tyramine