ABSTRACT
OBJECTIVES: Currently available antidepressant drugs have notable downsides; in addition to their side effects and slow onset of action their moderate efficacy in some individuals may influence compliance. Previous literature has shown that probiotics may have antidepressant effects. Introducing complementary medicine in order to augment the efficacy of therapeutic doses of antidepressant drugs appears to be very important. Therefore, the effect of adding a synbiotic mixture to drinking water was assessed in a mouse model of depression following the administration of three antidepressant drugs belonging to different classes. MATERIALS AND METHODS: The marble burying test (MBT) and forced swimming test (FST) were used as animal models of obsessive behavior and despair. The synbiotic mixture was administered to the mice's drinking water (6.25x106 CFU) for 14 days and the tests were performed 30 min after the injection of the lowest dose of doxepin (1 mg/kg), venlafaxine (15 mg/kg), and fluvoxamine (15 mg/kg) on days 7 and 14. RESULTS: After 7 days of ingestion of the synbiotic mixture, immobility time decreased in the FST for doxepin (92±5.5 s) and venlafaxine (17.3±2.5 s) compared to the control group (drinking water), but fluvoxamine decreased immobility time after 14 days of ingestion of the synbiotic mixture (70±7.5 s). Preadministration of the synbiotic mixture improved the MBT test response for venlafaxine, while it did not change the results for the other two drugs. CONCLUSION: Adding the synbiotic mixture to drinking water improved the efficacy of discrete antidepressant drugs particularly during the FST. Probiotics could be a useful complementary medicine for drug-resistant depressed individuals.