Attenuating effects of testosterone on depressive-like behavior in the forced swim test in healthy male rats

The androgenic steroid testosterone is well known for its function in reproduction, sexual differentiation and sexual behavior. A growing number of human and animal studies suggest a modulatory role of testosterone in the regulation of emotionality and associated psychiatric disorders, including depressive-like disorders. However, most of the studies have been carried out in subjects deficient in androgenic steroid levels. Here, we tested potential beneficial effects of subcutaneously applied testosterone on emotionality and depressive-like behavior in healthy male rats. For this purpose, male Wistar rats (3-4 months) received either vehicle or testosterone (1.0, 2.0, 4.0 mg/kg) subcutaneously and were tested for potential effects on motor activity and anxiety-like behavior in a novel open field and elevated plus-maze. The forced swim test was used for assessing potential beneficial effects of testosterone on depressive-like behavior. The results show, that, while subcutaneous application of testosterone failed to influence spontaneous motor activity as well as anxiety-like behavior in the open field, a trend for an increase in the time spent on the open arms in the elevated plus-maze with the highest dose was found. Furthermore, in the forced swim test, testosterone application induced a dose-dependent reduction of immobility behavior, indicating antidepressant-like action of testosterone in healthy animals.