DESIPRAMINE RESTRICTS ESTROUS-CYCLE OSCILLATIONS IN SWIMMING

1. Desipramine (DMI) is a tricyclic antidepressant which reduces the i mmobility in rats forced to swim; however, it is unknown whether estra l cycle phases impinge on DMI actions on immobility in daily swimming tests during several weeks. 2. In female wistar rats, vaginal smears t aken before testing defined four estral phases. Afterwards, the author s assessed the latency for the first period of immobility in five-min forced swim tests practiced on 21-day DMI (DMI group), 21-day washout saline given after a 21-day DMI treatment (washout-saline group), or n on-treated rats (control group). 3. We observed a longer latency for t he first period of immobility in proestrus-estrus from the control and washout-saline groups. The 21-day treatment with DMI (2.1 mg/kg i.p., once a day) significantly (p < 0.001) increased the latency by about 160% from central regardless of the estral cycle phase. 4. It is concl uded that proestrus-estrus relates to increased struggling behavior. D MI enhances struggling behavior independently of hormonal state.