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Intestinal Methanobrevibacter smithii but not total bacteria is related to diet‐induced weight gain in rats
Author(s) -
Mathur Ruchi,
Kim Gene,
Morales Walter,
Sung Jaekyu,
Rooks Emily,
Pokkunuri Venkata,
Weitsman Stacy,
Barlow Gillian M.,
Chang Christopher,
Pimentel Mark
Publication year - 2013
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1002/oby.20277
Subject(s) - cecum , biology , ileum , feces , colonization , weight gain , duodenum , jejunum , small intestine , medicine , inoculation , zoology , body weight , endocrinology , microbiology and biotechnology , immunology , ecology
It is increasingly understood that gastrointestinal (GI) methanogens, including Methanobrevibacter smithii, influence host metabolism. Objective: Therefore, we compared M. smithii colonization and weight gain in a rat model under different dietary conditions. Design and Methods: Sprague‐Dawley rats were inoculated with M. smithii or vehicle ( N = 10/group), fed normal chow until day 112 postinoculation, high‐fat chow until day 182, then normal chow until day 253. Thereafter, five rats from each group were fed high‐fat and normal chow until euthanasia. Results: Both groups exhibited M. smithii colonization, which increased following inoculation only for the first 9 days. Change to high‐fat chow correlated with significant increases in weight ( P < 0.00001) and stool M. smithii ( P < 0.01) in all rats, with stool M. smithi decreasing on return to normal chow. Rats switched back to high‐fat on day 253 further increased weight ( P < 0.001) and stool M. smithii ( P = 0.039). Euthanasia revealed all animals had higher M. smithii, but not total bacteria, in the small intestine than in the colon. Rats switched back to high‐fat chow had higher M. smithii levels in the duodenum, ileum, and cecum than those fed normal chow; total bacteria did not differ in any bowel segment. Rats which gained more weight had more bowel segments colonized, and the lowest weight recorded was in a rat on high‐fat chow which had minimal M. smithii colonization. Conclusions: We conclude that M. smithii colonization occurs in the small bowel as well as in the colon, and that the level and extent of M. smithii colonization is predictive of degree of weight gain in this animal model.