Farnesoid X Receptor Activation Improves Erectile Function in Animal Models of Metabolic Syndrome and Diabetes

Authors

  • Linda Vignozzi MD, PhD,

    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
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  • Annamaria Morelli PhD,

    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
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  • Sandra Filippi PhD,

    1. Interdepartmental Laboratory of Functional and Cellular Pharmacology of Reproduction, Departments of Pharmacology and Clinical Physiopathology, University of Florence, Florence, Italy
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  • Paolo Comeglio PhD,

    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
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  • Aravinda K. Chavalmane PhD,

    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
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  • Matilde Marchetta PhD,

    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
    2. Interdepartmental Laboratory of Functional and Cellular Pharmacology of Reproduction, Departments of Pharmacology and Clinical Physiopathology, University of Florence, Florence, Italy
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  • Mariateresa Toce PhD,

    1. Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
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  • Ravit Yehiely-Cohen MD,

    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
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  • Gabriella B. Vannelli MD,

    1. Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
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  • Luciano Adorini MD,

    1. Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
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  • Mario Maggi MD

    Corresponding author
    1. Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence, Italy
    2. CIRMAR (Centro Interuniversitario di Ricerca sulle basi molecolari della Malattie della Riproduzione), Milan, Italy
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Mario Maggi, MD, Sexual Medicine and Andrology Unit, Department of Clinical Physiopathology, University of Florence, Florence 50139, Italy. Tel: +39 0554271415; Fax: +39 0554271413; E-mail: m.maggi@DFC.UNIFI.IT

ABSTRACT

Introduction.  The farnesoid X receptor (FXR) is critically involved in the regulation of the hepato-biliary system. Recent data suggest a role for FXR in modulating other metabolic pathways and vascular function.

Aim.  To investigate whether long-term administration of the selective FXR agonist INT-747 ameliorates erectile function, we tested it in two animal models of metabolic derangements: a rabbit model of high-fat diet (HFD)-induced metabolic syndrome (MetS) and a rat model of streptozotocin (STZ)-induced type 1 diabetes.

Methods.  HFD rabbit or STZ rats with or without chronic INT-747 dosing (10 mg/kg/day for 12 weeks). INT-747 addition to rabbit penile smooth muscle cells (rpSMCs).

Main Outcome Measure.  Effects of INT-747 on metabolic features and erectile function in animal models and clarification of mechanism of action in isolated cells.

Results.  INT-747 dosing normalized visceral adiposity and glucose intolerance in HFD rabbits. INT-747 increased penile FXR expression and partially restored endothelial nitric oxide synthase and dimethylarginine dimethylaminohydrolase 1 expression as well as impaired nitric oxide (NO)-dependent relaxation (improved responsiveness to acetylcholine and electrical field stimulation). INT-747 was also effective in regulating NO downstream events, as shown by increased sodium nitroprusside-induced relaxation. Because phosphodiesterase type 5 and protein kinase G (PKG) were unaltered by INT-747, we analyzed the calcium-sensitizing RhoA/ROCK pathway. HFD increased, and INT-747 normalized, RhoA membrane translocation/activation. RhoA/ROCK signaling inhibition by INT-747 was confirmed in rpSMCs by confocal microscopy, MYPT1-phosphorylation, cytoskeleton remodeling, cell migration, and smooth muscle-related genes expression. In STZ rats, FXR penile expression was not altered but was significantly upregulated by INT-747 dosing. In this model, INT-747 improved penile erection induced by electrical stimulation of cavernous nerve and hypersensitivity to intracavernous injection of a ROCK-inhibitor, Y-27632, without improving hyperglycemia.

Conclusion.  In HFD rabbits, INT-747 dosing improved glucose sensitivity and MetS-associated erectile dysfunction, via upregulation of NO transmission and inhibition of RhoA/ROCK pathway. In STZ rats, INT-747 restored in vivo penile erection and sensitivity to ROCK inhibition, independently of effects on glycemia. Vignozzi L, Morelli A, Filippi S, Comeglio P, Chavalmane AK, Marchetta M, Toce M, Yehiely-Cohen R, Vannelli GB, Adorini L, and Maggi M. Farnesoid X receptor activation improves erectile function in animal models of metabolic syndrome and diabetes. J Sex Med 2011;8:57–77.

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