Can psychobiotics administration influence behavioral responses and physiological stress in healthy rats?

Background: There is a well-documented cross-talk between the gut and brain. Evidence is accumulating to suggest beneficial effects of psychobiotics [prebiotics, probiotics or synbiotics] on psychological distress in disease states. However, their role in healthy status remains relatively unclear. The present study was aimed to clarify if psychobiotics could influence behavioral responses and physiological stress in healthy rats.

Methods: In the present experiment, 28 male Wistar rats were divided into four groups (healthy rats treated by Lactobacillus plantarum (L. plantarum), inulin, and their combination (synbiotic), as well as control group). Then, psychobiotics were administered to the intervention groups for 8 weeks. Behavioral tests (Morris water maze, Elevated plus maze, and Forced swimming test) were performed at endpoint. Then, serum and brain levels of superoxide dismutase, malondialdehyde, glutathione peroxidase, total antioxidant capacity, brain-derived neurotrophic factor (BDNF), and serotonin were measured.

Results: Our findings indicated that unlike inulin, the administration of L. plantarum and synbiotic could ameliorate depression and anxiety-like behavior and cognitive performance (P<0.05). Serum and brain oxidative stress markers were significantly improved by synbiotic consumption. The intake of L. plantarum led to decreased oxidative stress in the hippocampus and amygdala (P<0.05). A significant increase in the hippocampal serotonin and BDNF concentration was also observed after both synbiotic and L. plantarum intake (P<0.05). In addition, there was a strong correlation of serum and brain markers with behavioral performance (P< 0.05).

Conclusion: The present study suggests that psychobiotics therapy may have favorable effects on the amelioration of some psychological disorders.