monly used for the assessment of the antidepressant-like properties of drugs (Cesana, Ciprandi and Borsini, 1995; Cohen, Perrault and Sanger, 1997; Hemby et al., 1997). In the original Porsolt test (Porsolt, Le Pichon and Jalfre, 1977b), rats are immersed during a fifteen minute pre-test in a cylindrical tank with water. Twenty four hours later, the rats are replaced in the cylinder for five mi...