1. Several pharmacological maneuvers in very young rats produce later changes resembling human depression. 2. Rats were submitted to a wide lesion in lateral septal region at 8th day after birth and forced to swim at maturity. 3. Male lesioned group showed the highest amount of immobility; whereas, female sham lesion group showed a greater response to treatments. 4. A gender-dependent sensitivity to early lateral septal nucleus lesions and to antidepressants are concluded.