New insights on strain-specific impacts of probiotics on insulin resistance: evidence from animal study.

Background And Aims: сomparative animal study of effectiveness of intermittent administration of lyophilized single-, three- and alive multistrain probiotic in short courses on insulin resistance (IR) in rats with experimental obesity.

Methods: 70 rats were divided into 7 groups ( = 10 in each). Rats of group I were left intact. Newborn rats in groups II-VII were administered monosodium glutamate (MSG) (4 mg/g) by injection. Rats in group II (MSG-obesity group) were left untreated. The rats in groups III-V received lyophilized mono-probiotics , , respectively. The rats in group VI received all three of these probiotic strains mixed together. Group VII was treated with multi-probiotic "Symbiter", containing 14 different live probiotic strains (, , , genera).

Results: Treatment of newborn rats with MSG lead to the development of obesity in all MSG-obesity rats and up to 20-70% after probiotic administration. Additions to probiotic composition, with preference to alive strains (group VII), led to significantly lower rates of obesity, decrease in HOMA-IR ( < 0.001), proinflammatory cytokines levels - IL-1β ( = 0.003), IL-12Bp40 (p < 0.001) and elevation of adiponectin (p = 0.003), TGF-β ( = 0.010) in comparison with MSG-obesity group. Analysis of results in groups treated with single-strain probiotics (groups III-V) shows significant decrease in HOMA-IR, but changes were less pronounced as compared to mixture groups and did not achieve intact rats level. Other metabolic parameters were not affected significantly by single strains.

Conclusion: Our findings provide major clues for how to design and use probiotics with more efficient compositions in obesity and IR management and may bring new insights into how host-microbe interactions contribute to such protective effects.