Diurnal expressions of four subtypes of melatonin receptor genes in the optic tectum and retina of goldfish

Taro Ikegami, Kyoichi Azuma, Masahisa Nakamura, Nobuo Suzuki, Atsuhiko Hattori, Hironori Ando*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    31 Citations (Scopus)


    Four subtypes of melatonin receptor genes (Mel1a 1.4, Mel1a 1.7, Mel1b, and Mel1c) are considered to be expressed to mediate various physiological functions of melatonin in goldfish (Carassius auratus). To examine their tissue distribution and diurnal changes in expression levels, we cloned partial gene fragments for these melatonin receptor subtypes, and established specific RT-PCR and quantitative real-time PCR systems. Mel1a 1.4 and Mel1b were predominantly expressed in various neuronal and peripheral tissues, while Mel1a 1.7 and Mel1c were expressed in the restricted tissues. All subtype genes were expressed in the optic tectum, diencephalon, mesencephalon, vagal lobe, retina and spleen. The real-time PCR analyses showed that significant differences among time were observed for Mel1a 1.4 in the optic tectum and for Mel1a 1.7 and Mel1b in the retina. In the retina, the levels of Mel1a 1.7 and Mel1b mRNAs showed diurnal changes with one peak at ZT24. The present results show differential distribution of four subtypes of melatonin receptor mRNAs in the neuronal and peripheral tissues. However, the expressions of all subtype genes in the retinorecipient brain regions and retina reinforce the role of the melatonin receptor in processing visual information. Furthermore, the present study demonstrates diurnal expressions of the major subtype genes, i.e. Mel1a 1.4 in the optic tectum and Mel1a 1.7 in the retina.

    Original languageEnglish
    Pages (from-to)219-224
    Number of pages6
    JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
    Issue number2
    Publication statusPublished - 2009 Feb


    • Brain
    • Diurnal rhythm
    • Goldfish
    • Melatonin receptor
    • Optic tectum
    • Retina

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Biology
    • Physiology


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