Effects of Short-Term Metformin Treatment on Gut Microbiota Profile Using Female Obese Zucker Rat Model

Abstract Objectives The correlation of short-term metformin treatment and specific alterations to the gut microbiota in obese models is less known. So, the objectives of this experiment was to investigate the effects of short-term metformin treatment on population of gut microbiota profile in obese rat model. Methods Five week old obese (n = 16) female Zucker rats after one week of acclimation, received AIN-93 G diet for 8 weeks and then rats were randomly assigned 8 rats/group): to 1) obese without metformin (ObC), or 2) obese with metformin (ObMet). Metformin were mixed with AIN-93G diet at 1000 mg/kg of diet. Rats were weighed twice per week. All rats were sacrificed 10 weeks post-metformin treatment and fecal samples were collected and kept at − 80c. Total microbial DNA were collected directly from the fecal samples using a PowerSoil® DNA isolation kit. Isolated DNA were used for shotgun-metagenomics data collection using Illumina NextSeq500 and analyzed using MetaPlAn and HUMAnN. DEICODE and Songbird used calculate log-ratios and differential ranks of taxa and functional pathways associated with metformin treatment respectively. The were then visualized using Qurro. Results There was no significant difference between ObC vs. ObMet group body weight (P = 0.20). Overall microbial beta-diversity (DEICODE), showed significant separation between the obese control and metformin samples (P = 0.0007). Differential ranking (Songbird) of Bacteroides dorei and B. massiliensis vs. all other Bacteroides spp., revealed that B. dorei and B. massiliensis were enriched in the obese metformin group, while the remaining Bacteroides spp. where enriched in the obese control group (P = 0.002). The differential ranking of pathway diversity contributed by the Bacteroides were also associated with treatment group (P = 0.008). Conclusions In summary, in the obese zucker rat model, short-term metformin treatment changes the gut microbiota profile. Funding Sources Arkansas Biosciences Institute.