Melatonin reduces nitric oxide synthase activity in rat hypothalamus

Authors

  • Ilham Bettahi,

    1. Department of Medical Biochemistry and Molecular Biology, The University of Seville School of Medicine and Virgen Macarena Hospital, Seville, Spain
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  • David Pozo,

    1. Department of Medical Biochemistry and Molecular Biology, The University of Seville School of Medicine and Virgen Macarena Hospital, Seville, Spain
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  • Carmen Osuna,

    1. Department of Medical Biochemistry and Molecular Biology, The University of Seville School of Medicine and Virgen Macarena Hospital, Seville, Spain
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  • Russel J. Reiter,

    1. Department of Cellular and Structural Biology; The University of Texas, Health Science Center at San Antonio, San Antonio, TX, USA
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  • Dario Acuña-Castroviejo,

    1. Department of Physiology, The University of Granada School of Medicine, Granada, Spain
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  • Juan M. Guerrero

    Corresponding author
    1. Department of Medical Biochemistry and Molecular Biology, The University of Seville School of Medicine and Virgen Macarena Hospital, Seville, Spain
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Address reprint requests to Juan M. Guerrero, Department of Medical Biochemistry and Molecular Biology, The University of Seville School of Medicine, Avda Sanchez Pizjuan 4, 41009-Seville, Spain.

Abstract

Abstract: In this report, rat hypothalamic nitric oxide synthase (NOS) activity is shown to be partially inhibited by physiological concentrations of the pineal hormone melatonin. In vitro studies demonstrate that 1 nM melatonin, which approximates the physiological concentration of the hormone at night, significantly inhibited NOS activity. In vivo studies show that administering melatonin or collecting the hypothalamus from animals at night, when endogenous melatonin levels are elevated, results in a significant decrease of NOS activity. Results also show that calmodulin may be involved in this process since its presence in the incubation medium prevents the inhibitory effect of melatonin on NOS activity.

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