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Differential expression of orexin receptors 1 and 2 in the rat brain

Authors

  • Jacob N. Marcus,

    1. Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02215
    2. Department of Medicine and Division of Endocrinology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
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  • Carl J. Aschkenasi,

    1. Department of Neurology, Beth Israel Deaconess Medical Center, and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02215
    2. Department of Medicine and Division of Endocrinology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
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  • Charlotte E. Lee,

    1. Department of Neurology, Beth Israel Deaconess Medical Center, and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02215
    2. Department of Medicine and Division of Endocrinology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
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  • Richard M. Chemelli,

    1. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9050
    2. Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9050
    3. Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9050
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  • Clifford B. Saper,

    1. Department of Neurology, Beth Israel Deaconess Medical Center, and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02215
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  • Masashi Yanagisawa,

    1. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9050
    2. Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9050
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  • Joel K. Elmquist

    Corresponding author
    1. Department of Neurology, Beth Israel Deaconess Medical Center, and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02215
    2. Department of Medicine and Division of Endocrinology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215
    • 99 Brookline Avenue, Room 347, Department of Medicine and Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, 02215
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Abstract

Orexins (hypocretins) are neuropeptides synthesized in the central nervous system exclusively by neurons of the lateral hypothalamus. Orexin-containing neurons have widespread projections and have been implicated in complex physiological functions including feeding behavior, sleep states, neuroendocrine function, and autonomic control. Two orexin receptors (OX1R and OX2R) have been identified, with distinct expression patterns throughout the brain, but a systematic examination of orexin receptor expression in the brain has not appeared. We used in situ hybridization histochemistry to examine the patterns of expression of mRNA for both orexin receptors throughout the brain. OX1R mRNA was observed in many brain regions including the prefrontal and infralimbic cortex, hippocampus, paraventricular thalamic nucleus, ventromedial hypothalamic nucleus, dorsal raphe nucleus, and locus coeruleus. OX2R mRNA was prominent in a complementary distribution including the cerebral cortex, septal nuclei, hippocampus, medial thalamic groups, raphe nuclei, and many hypothalamic nuclei including the tuberomammillary nucleus, dorsomedial nucleus, paraventricular nucleus, and ventral premammillary nucleus. The differential distribution of orexin receptors is consistent with the proposed multifaceted roles of orexin in regulating homeostasis and may explain the unique role of the OX2R receptor in regulating sleep state stability. J. Comp. Neurol. 435:6–25, 2001. © 2001 Wiley-Liss, Inc.

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