Medical Pharmacology Unit, University Clermont Auvergne, CHU Clermont-Ferrand, UMR INSERM 1107 - NEURO-DOL, Clermont-Ferrand, France. DRCI, University Clermont Auvergne, CHU Clermont-Ferrand, UMR INSERM 1107 - NEURO-DOL, Clermont-Ferrand, France. Analgesia Institute, University Clermont Auvergne, Clermont-Ferrand, France. Gastroenterology Unit, University Clermont Auvergne, CHU Estaing, UMR INSERM 1107 - NEURO-DOL, Clermont-Ferrand, France. University Clermont Auvergne, UMR INSERM 1107 - NEURO-DOL, Clermont-Ferrand, France.