1. Department of Pharmaceutical Science and Biotechnology Center, University of Ferrara, I-441000 Ferrara, Italy, Institute of Pharmacology, University of Ferrara, I-44100 Ferrara, Italy, Peptide Neurochemistry, LCBRA, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, and National Center for Biotechnology Information, National Library of Medicine, Building 38A, 8600 Rockville Pike, Bethesda, Maryland 20894