Cortisol and prolactin modulation of caudal neurosecretory system activity in the euryhaline flounder Platichthys flesus

Richard Marley, Weiqun Lu, Richard J. Balment, Catherine R. McCrohan

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Previous studies have shown roles for cortisol and prolactin in osmoregulatory adaptation to seawater and freshwater, respectively, in euryhaline fish. This study of the European flounder investigated the potential for these hormones to modulate activity of the caudal neurosecretory system (CNSS), which is thought to be involved in physiological adaptation to changing external salinity. Superfusion of isolated CNSS with either cortisol or prolactin (10 μM; 15 min) led to changes in firing activity in neuroendocrine Dahlgren cells, recorded extracellularly. Cortisol evoked a modest increase in overall firing activity, with the response delayed by 4 h after treatment. The response to prolactin was short latency, continued to build up over the subsequent 4-h wash period, and comprised increased firing activity together with recruitment of previously silent Dahlgren cells. Immunoreactivity for glucocorticoid and prolactin receptors was localised to Dahlgren cells. The CNSS expression level for glucocorticoid-2 receptor mRNA, measured by Q-PCR, was significantly lower in fish fully acclimated to freshwater, compared to seawater. No differences were seen between these two states for prolactin receptor mRNA expression. These results provide evidence for a modulatory action of both hormones on the neurosecretory function of the CNSS. © 2008 Elsevier Inc. All rights reserved.
    Original languageEnglish
    Pages (from-to)71-77
    Number of pages6
    JournalComparative Biochemistry and Physiology. Part A: Molecular & Integrative Physiology
    Volume151
    Issue number1
    DOIs
    Publication statusPublished - Sept 2008

    Keywords

    • Caudal neurosecretory system
    • Cortisol
    • Fish
    • Flounder
    • Neuromodulation
    • Osmoregulation
    • Prolactin
    • Teleost

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