Abstract
OBJECTIVES: Disruption of the hypothalamic-pituitary-adrenal axis by stress and glucocorticoid drugs is a major cause of depression. The benefits of probiotics may extend to systems beyond the gastrointestinal tract, i.e., the central nervous system. Therefore, the effect of a synbiotic (probiotic + prebiotic) mixture on dexamethasone (Dex) and stress-induced depression was investigated. MATERIALS AND METHODS: Male albino mice were used, the forced swimming test (FST) measured despair, and the sucrose preference test measured anhedonia. The synbiotic regimen (12.5x106 CFU) was supplemented in drinking water for 7 days. Dex was administered subcutaneously either in a single dose on the test day or for 7 days. Water avoidance stress (WAS) was induced for 1 hour each day for 4 days. RESULTS: Drinking the synbiotic reduced immobility time during the FST (54±7 sec vs. 111±6 sec in the control water group, p<0.001). Dex injection significantly increased the immobility time (single dose: 166±6 sec and 7 days: 174±9 sec) compared with the control groups, while adding the synbiotic to their drinking water reduced it (single dose: 81±6.6 sec, and 7 days: 84±14 sec), indicating that the synbiotic reversed Dex-induced depression. WAS increased the immobility time (148±11 sec vs. sham 99±6 sec, p<0.001) in the FST test. When the synbiotic treatment was added following WAS, the immobility time decreased (81±6.5 sec). The synbiotic groups also had a higher sucrose preference percentage. CONCLUSION: The synbiotic mixture prevented the effects of WAS, acute or sub-acute Dex-induced depression in mice. Therefore, probiotics might be useful and safe supplements to prevent depression related to stress or glucocorticoid therapies, a phenomenon that deserves further evaluation.