Gut microbiota contribute to the glucoregulatory and body compositional changes that accompany 10,12 CLA-mediated weight loss in mice.
Obesity continues to be a major problem, despite known treatment strategies such as lifestyle modifications, pharmaceuticals, and surgical options, necessitating the development of novel weight loss approaches. The naturally occurring fatty acid, 10,12 conjugated linoleic acid (10,12 CLA), promotes weight loss by increasing fat oxidation and browning of white adipose tissue, leading to increased energy expenditure in obese mice. Coincident with weight loss, 10,12 CLA also alters the gut microbiota of mice by enriching for microbes that produce short chain fatty acids (SCFAs), with concurrent elevations in fecal butyrate and plasma acetate. To determine if the observed microbiota changes are required for 10,12 CLA-mediated weight loss, adult male mice with diet-induced obesity were given broad-spectrum antibiotics (ABX) to perturb the microbiota prior to and during 10,12 CLA-mediated weight loss. Conversely, to determine whether gut microbes were sufficient to induce weight loss, conventionally-raised and germ-free mice were transplanted with cecal contents from mice that had undergone weight loss by 10,12 CLA supplementation. While body weight was minimally modulated by ABX-mediated perturbation of gut bacteria, the adult male mice given ABX were more resistant to the increased energy expenditure and fat loss that are induced by 10,12 CLA supplementation. Conversely, transplanting cecal contents from donor mice losing weight due to oral 10,12 CLA consumption into germ-free mice led to improved glucose metabolism. These data suggest a critical role for the microbiota in dietary-modulated changes in energy balance and glucose metabolism and distinguish the metabolic effects of oral delivery of 10,12 CLA from fecal/cecal transplantation of the resulting microbiota.