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Serotonin 5-HT2A and 5-HT5A receptors are expressed by different motoneuron populations in rat Onuf's nucleus

Authors

  • Chen Xu,

    1. Groupe de Recherche en Urologie, UPRESS EA 1602, Faculté de Médecine Paris-Sud, 94270 Le Kremlin-Bicêtre, France
    2. Laboratory of Electron Microscopy, Chongqing University of Medical Sciences, 400016, Chongqing, P.R. China
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  • François Giuliano,

    1. Groupe de Recherche en Urologie, UPRESS EA 1602, Faculté de Médecine Paris-Sud, 94270 Le Kremlin-Bicêtre, France
    2. AP-HP, Neuro-Urology Unit, Department of Physical Medicine and Rehabilitation, Raymond Poincaré Hospital, 92380 Garches, France
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  • X.Q. Sun,

    1. Groupe de Recherche en Urologie, UPRESS EA 1602, Faculté de Médecine Paris-Sud, 94270 Le Kremlin-Bicêtre, France
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  • Marie-Jeanne Brisorgueil,

    1. Neurobiologie des Signaux Intercellulaires, CNRS UMR 7101, IFR 83, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France
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  • Patrick Leclerc,

    1. IFR 93-Inserm, 94276 Le Kremlin-Bicêtre, France
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  • Daniel Vergé,

    1. Neurobiologie des Signaux Intercellulaires, CNRS UMR 7101, IFR 83, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France
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  • Marie Conrath

    Corresponding author
    1. Neurobiologie des Signaux Intercellulaires, CNRS UMR 7101, IFR 83, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France
    • Neurobiologie des Signaux Intercellulaires, CNRS UMR 7101, Université Pierre et Marie Curie, 7 Quai Saint-Bernard, 75252 Paris Cedex 05, France
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Abstract

Motoneurons of Onuf's nucleus innervate the pelvic striated muscles, which play a crucial role in erection, ejaculation, and urinary continence. Serotonergic descending projections from the brain are involved in the modulation of Onuf's motoneuron activity. However, conflicting results regarding the effects of spinal serotonin (5-HT) on pelvi-perineal functions have been reported. They may be partly accounted for by the multiplicity of neuronal targets and receptor subtypes on which 5-HT is acting. In order to provide comparative data regarding 5-HT receptor expression in various groups of Onuf's motoneurons, we used retrograde tracing techniques from different pelvic muscles combined with immunocytochemistry of 5-HT2A and 5-HT5A receptors in male and female rats. In males, 5-HT2A receptor immunolabeling was very dense in motoneurons innervating the ischiocavernosus muscle. By contrast, in female rats, 5-HT2A receptor expression in Onuf's nucleus was very weak. In both genders, 5-HT5A receptor immunoreactivity was found in motoneurons innervating the external urethral sphincter. In males, a moderate or low 5-HT5A immunolabeling was observed in motoneurons innervating the bulbospongiosus and ischiocavernosus muscles, respectively. These data show a preferential localization of 5-HT2A and 5-HT5A receptors to motoneurons controlling the striated muscles located at the penile crus and sphincter muscles, respectively, suggesting a specific serotoninergic control on different pelvic functions. In addition, the subcellular distribution of receptors suggests a different mode of action of 5-HT, paracrine at 5-HT2A receptors and synaptic at 5-HT5A receptors. This might have implications for pharmacological research targeting different pelvic functions e.g., micturition and ejaculation. J. Comp. Neurol. 502:620–634, 2007. © 2007 Wiley-Liss, Inc.

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