Dietary copper‐fructose interactions alter gut microbiome in a sex‐differential manner likely contributes to the sex differences in the metabolic phenotype
Authors: Song Ming , Yuan Fang , Li Xiaohong , Rouchka Eric C. , Zhang Xiang , McClain Craig J. 
Published: April 2020

Objective

Inadequate copper intake and increased fructose consumption represent two important nutritional problems in the US. Dietary copper‐fructose interactions alter gut microbial activity and contribute to the development of metabolic phenotype. The aim of this study is to determine whether dietary copper‐fructose interactions alter gut microbiome in a sex‐differential manner, which may contribute to the sex differences in the metabolic phenotype.

Methods

Male and female weanling Sprague‐Dawley (SD) rats were fed (ad lib) with a modified AIN‐93G purified rodent diet with defined copper content in the form of cupric carbonate for 8 weeks. The copper content is 6mg/kg and 1.6mg/kg in adequate copper diet (CuA) and marginal copper deficient diet (CuM), respectively. Animals had free access to either deionized water or deionized water containing 10% fructose (w/v) as the only drink during the experiment. Body weight gain, plasma ALT, AST and liver histology were evaluated. Fecal and cecal microbiome were analyzed by 16S rDNA sequencing. Fecal and cecal Short chain fatty acids were analyzed by GC‐MS.

Results

Rats fed with CuA or CuM with or without fructose (CuAF or CuMF) did not gain body weight in both male and female. No obvious liver injury was observed in both male and female rats in terms of plasma ALT and AST. A few of female rats developed very mild steatosis, whereas no obvious steatosis was observed in male rats fed with CuAF or CuMF. 16S rDNA sequencing analysis of fecal and cecal DNA showed that Firmicutes was significantly decreased, whereas Bacteroidetes and Proteobacteria were significantly increased in CuAF and CuMF fed female rats compared to controls, suggesting gut microbiota dysbiosis. The significant alterations of gut microbiota composition in phylum level in female rats attribute to the effect of dietary fructose as shown by two‐way ANOVA. However, this effect was not obvious in male rats. In parallel, fecal and cecal short chain fatty acid, butyrate was significantly decreased in female rats fed with CuMF and to a less extent in male rats compared to controls. This effect was due to dietary factors of both copper and fructose in female rats, and copper in male rats.

Conclusion

Female rats exhibit more sensitivity to dietary copper and fructose‐induced metabolic phenotypes and gut microbiota dysbiosis compared to male rats. The metabolic phenotypes are closely associated with the alterations of gut microbiome. These results are different with previous reports, likely due to the factors, such as the dose of copper and fructose as well as species and location.

Support or Funding Information

This study was supported in part by NIH Grants U01AA021901, U01AA022489, R01AA023681, P20GM113226, P50AA024337 and the Jewish Heritage Fund for Excellence Pilot Grant Program at the University of Louisville School of Medicine. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health (C.J.M.); the Veterans Administration (C.J.M.); and the Uof L Clinical and Translational Pilot Program (C.J.M.).