Quintans-Júnior, Lucindo, Laboratory of Neuroscience and Pharmacological Assays (LANEF), Department of Physiology, Federal University of Sergipe-UFS, Av. Marechal Rondom, s/n, São Cristóvão, Sergipe, Brazil. Zip Code: 49.100-000. Tel.: +55-79-21056645; Fax: +55-79-3212-6640. E-mail: lucindo@academico.edu.br; lucindojr@gmail.com, Brazil