Inescapable shocks accentuate fluctuations of forced swimming immobility in different phases of the rat estrous cycle

The forced swimming test is an animal model that is sensitive to the different antidepressant treatments. On the other hand, it is also sensitive to the characteristics changes suffered by animals that have been previously exposed to different depression models. In the present study we xplored the effects on inescapable shock on the forced swimming test, during different phases of the rat estrous cycle. There was an increase of the immobility during diestrus as compared to estrus. Furthermore, inescapable shock increased the immobility, byt only during diestrus. Thus the differences found between both phases of the estrous cycle were accentuated. Due to the fact that diring diestrus there is an absence of progesterone, and that depressed women exacerbate their symptoms during the premenstrual phase, the authors suggest that the immobility registered during the forced swimming test may be useful in the study of premenstrual depression

Clomipramine modifies fluctuations of forced swimming immobility in different phase of the rat estrous cycle

Many symptoms that define the premenstrual syndrome (PMS) are present in depressive states. The fact that there are not adequate animal models to study the OMS may explain the lack of knowledge about its etiology. An alternative might be the use of animal models which are useful to study depression, such as the forced swimming test. Eighteen female rats were subjected to the forced swimming test once a week for six consecutive weeks. An increase of immobility was observed during diestrus as compared to estrus. On the other hand, some premestrual symptoms have been suggested to be caused by the influence of gonadal hormones on the activity of cental serotonergic systems. Thus, the effects of clomipramine were further studied. The drug reduced rat immobility during diestrus, so that the differences between the two estrous cycle phases disappeared. We conclude that the use of the forced swimming test might be a helpful model in the study of OMS