ANTIDEPRESSANT-LIKE ACTIVITIES OF ROSIGLITAZONE IN THE RAT FORCED SWIM AND THE MOUSE TAIL SUSPENSION TESTS

The current study aimed to investigate the possible antidepressant-like activity of rosiglitazone using the rat forced swimming test (FST) and the mouse tail suspension test (TST), two models predictive of antidepressant activities. In FST, 5 days administration of rosiglitazone (6 or 12 mg/kg, p.o.) significantly decreased the time of immobility without affecting the swimming time. Moreover, rosiglitazone significantly increased climbing, head shaking, and rubbing water away behaviors. These effects were not accompanied by any alteration in the locomotor activity of rats when tested in the open field test (OFT). Additionally. treatment of rats with rosiglitazone significantly reduced plasma corticosterone levels. Administration of fluoxetine (10 mg/kg, p.o.) to the rats for 5 consecutive days. as a positive control, significantly reduced floating and increased swimming time without affecting climbing duration. Moreover, fluoxetine significantly increased head shaking behavior and reduced fecal boli count. However, fluoxetine produced no effect on plasma corticosterone levels. In TST, 5 days administration of rosiglitazone (8.5 or 17 mg/kg, p.o.) significantly reduced the immobility time, this effect was comparable to that observed with fluoxetine. Furthermore, rosiglitazone (17 mg/kg, p.o.) significantly antagonized dexamethazon induced prolongation of immobility time in mice TST. In conclusion, the present investigation suggests that rosiglitazone possesses a antidepressant-like activity in rodents behavioral models and that this effect may be mediated through reduction ofplasma corticosterone level.