Short-Term Metformin Treatment Enriches Bacteroides dorei in an Obese Liver Steatosis Zucker Rat Model

Michael S Robeson 2nd; Kanishka Manna; Christopher Randolph; Stephanie Byrum; Reza Hakkak

doi:10.3389/fmicb.2022.834776

Short-Term Metformin Treatment Enriches Bacteroides dorei in an Obese Liver Steatosis Zucker Rat Model

Front Microbiol. 2022 Mar 30:13:834776. doi: 10.3389/fmicb.2022.834776. eCollection 2022.

Authors

Michael S Robeson 2nd¹, Kanishka Manna², Christopher Randolph³, Stephanie Byrum², Reza Hakkak^{3

4

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Affiliations

¹ Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
² Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
³ Arkansas Children's Research Institute, Little Rock, AR, United States.
⁴ Department of Dietetics and Nutrition, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
⁵ Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States.

Abstract

Obesity is the leading cause of health-related diseases in the United States and World. Previously, we reported that obesity can change gut microbiota using the Zucker rat model. Metformin is an oral anti-hyperglycemic agent approved by the FDA to treat type 2 diabetes (T2D) in adults and children older than 10 years of age. The correlation of short-term metformin treatment and specific alterations to the gut microbiota in obese models is less known. Short-term metformin has been shown to reduce liver steatosis. Here we investigate the effects of short-term metformin treatment on population of gut microbiota profile in an obese rat model. Five week old obese (n = 12) female Zucker rats after 1 week of acclimation, received AIN-93 G diet for 8 weeks and then rats were randomly assigned into two groups (6 rats/group): (1) obese without metformin (ObC), or (2) obese with metformin (ObMet). Metformin was mixed with AIN-93G diet at 1,000 mg/kg of diet. Rats were weighed twice per week. All rats were sacrificed at the end of metformin treatment at 10 weeks and fecal samples were collected and kept at -80°C. Total microbial DNA was collected directly from the fecal samples used for shotgun-metagenomics sequencing and subsequently analyzed using MetaPlAn and HUMAnN. After stringent data filtering and quality control we found significant differences (p = 0.0007) in beta diversity (Aitchison distances) between the ObC vs. ObMet groups. Supervised and unsupervised analysis of the log-ratios Bacteroides dorei and B. massiliensis vs. all other Bacteroides spp., revealed that B. dorei and B. massiliensis were enriched in the ObMet group, while the remaining Bacteroides spp. where enriched in the ObC group (p = 0.002). The contributional diversity of pathways is also significantly associated by treatment group (p = 0.008). In summary, in the obese Zucker rat model, short-term metformin treatment changes the gut microbiota profile, particularly altering the composition Bacteroides spp. between ObC and ObMet.

Keywords: Bacteroides dorei; Zucker rat; gut microbiota; metformin; obesity.