Serotoninergic innervation of the locust mandibular closer muscle modulates contractions through the elevation of cyclic adenosine monophosphate

R. A. Baines, N. M. Tyrer, R. G H Downer

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The mandibular closer muscles of the locust receive innervation that is immunoreactive for the putative transmitter 5-hydroxytryptamine (5-HT). Cobalt-labelling suggests that the origin of this innervation is a group of cells located anteriorly in the suboesophageal ganglion. Bath application of 5-HT while the muscles are active produces marked changes in the contractions, increasing their amplitude, rate of contraction, and rate of relaxation. Incubation of isolated muscles with 5-HT shows that this amine elevates the levels of the cyclic nucleotide cyclic adenosine monophosphate (cAMP). In addition compounds that artificially elevate the levels of cAMP in the muscle - 3-isobutyl-1-methylxanthine (IBMX), forskolin, and the cAMP analogue 8-(4-chlorophenylthio) cAMP - mimic the actions of 5-HT, whereas a potent inhibitor of insect adenylate cyclase, adenosine, considerably delays the onset of the effects produced by 5-HT. The effects observed with 5-HT in the mandibular muscle are similar to those of octopamine in the locust extensor tibiae muscle, and it is possible that this is an analogous modulatory system.
    Original languageEnglish
    Pages (from-to)623-632
    Number of pages9
    JournalJournal of Comparative Neurology
    Volume294
    Issue number4
    Publication statusPublished - 1990

    Keywords

    • 5-Hydroxytryptamine
    • Insect
    • Modulation

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