Tehran University Medical Journal

Background: Diabetes mellitus affects numerous intracellular metabolic processes, which are reflected by changes in the concentration of some plasma constituents. Particularly, the disease may indirectly undermine some functions of the nervous system including learning and memory through altering oxidative stress status. On the other hand, probiotics can enhance the antioxidant capacity. This study was designed to evaluate the effects of probiotics on spatial memory, maze learning and indices of oxidative stress in diabetic rats.
Methods: In this experimental study, 40 male Wistar rats were randomly allocated to 4 groups (n=10 for each): Control (CO), Control probiotic (CP), Control diabetic (DC), and Diabetic probiotic (DP). The probiotic supplement, including Lactobacillus acidophilus, Lactobacillus fermentum, Bifidobacterium lactis (334 mg of each with a CFU of ~1010), was administered through drinking water every 12 hours for 8 weeks. Using morris water maze (MWM), spatial learning and memory were evaluated. Serum insulin and oxidative stress indices, including superoxide dismutase (SOD) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), were measured by standard laboratory kits.
Results: Oral administration of probiotics improved impairment of spatial learning (P=0.008) and consolidated memory (P=0.01) in the rats. Moreover, probiotic treatment increased serum insulin (P<0.0001) and serum superoxide dismutase activity (P=0.007) while it decreased their blood glucose (P=0.006) and 8-OHdG (P<0.0001).
Conclusion: Probiotic supplementation reversed the serum concentrations of insulin and glucose along with an increase in antioxidant capacity in diabetic rats. It also improved spatial learning and memory in the animals. Relevancy of the metabolic changes and behavioral functions need to be further studied.