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Nicotine and estrogen may influence depressive behavior in women. In this study, we sought to determine whether nicotine (NIC), alone and in combination with 17β-estradiol (E₂), might influence depressive characteristics of female rats in the forced swim test (FST). Ovariectomized adult female Sprague–Dawley rats (n=8/group) received subcutaneous (s.c.) injections of nicotine, E₂ or the combination (NIC: 0.2mg/kg, bw and E₂: 10μg) before the FST. Controls received saline and/or corn oil. Locomotor activity was also assessed. Acute administration of nicotine significantly reduced immobility in the FST. Acute administration of E₂ also decreased immobility. The combination of nicotine (0.2mg/kg) and E₂ (10μg) significantly reduced immobility; however, this reduction was not greater than either agent administered alone. No differences in locomotor activity were detected among the treatment groups. Acute …