1 Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Llobregat, Spain.
2 Neuropharmacology and Pain Group, Neuroscience Program, Bellvitge Biomedical Research Institute, Llobregat, Spain.
3 Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States.