TGR5 contributes to glucoregulatory improvements after vertical sleeve gastrectomy in mice.
Vertical sleeve gastrectomy (VSG) produces high rates of type 2 diabetes remission; however, the mechanisms responsible remain incompletely defined. VSG increases circulating bile acid concentrations and bile acid signalling through TGR5 improves glucose homeostasis. Therefore, we investigated the role of TGR5 signalling in mediating the glucoregulatory benefits of VSG.



VSG or sham surgery was performed in high-fat-fed male Tgr5+/+(wild type) and Tgr5-/-(knockout) littermates. Sham-operated mice were fed ad libitum or food restricted to match their body weight to VSG-operated mice. Body weight, food intake, energy expenditure, insulin signalling and circulating bile acid profiles were measured and oral glucose tolerance testing, islet immunohistochemistry and gut microbial profiling were performed.



VSG decreased food intake and body weight, increased energy expenditure and circulating bile acid concentrations, improved fasting glycaemia, glucose tolerance and glucose-stimulated insulin secretion, enhanced nutrient-stimulated glucagon-like peptide 1 secretion and produced favourable shifts in gut microbial populations in both genotypes. However, the body weight-independent improvements in fasting glycaemia, glucose tolerance, hepatic insulin signalling, hepatic inflammation and islet morphology after VSG were attenuated in Tgr5-/-relative to Tgr5+/+mice. Furthermore, VSG produced metabolically favourable alterations in circulating bile acid profiles that were blunted in Tgr5-/-relative to Tgr5+/+mice. TGR5-dependent regulation of hepatic Cyp8b1 expression may have contributed to TGR5-mediated shifts in the circulating bile acid pool after VSG.



These results suggest that TGR5 contributes to the glucoregulatory benefits of VSG surgery by promoting metabolically favourable shifts in the circulating bile acid pool.
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Anne K
AK
McGavigan
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Darline
D
Garibay
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA.|Department of Microbiology, Cornell University, Ithaca, New York, USA.
Zachariah M
ZM
Henseler
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Jack
J
Chen
Department of Nutrition, University of California, Davis, Davis, California, USA.
Ahmed
A
Bettaieb
Department of Nutrition, University of California, Davis, Davis, California, USA.
Fawaz G
FG
Haj
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA.|Department of Microbiology, Cornell University, Ithaca, New York, USA.
Ruth E
RE
Ley
Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA.
Michael L
ML
Chouinard
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, USA.
Bethany P
BP
Cummings
D000818:Animals; D001647:Bile Acids and Salts / Q000097:blood*; D001786:Blood Glucose / Q000378:metabolism*; D001835:Body Weight; D004435:Eating; D004734:Energy Metabolism; D005215:Fasting; D005743:Gastrectomy / Q000379:methods; D000069196:Gastrointestinal Microbiome; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000737:chemistry / Q000473:pathology; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013253:Steroid 12-alpha-Hydroxylase / Q000378:metabolism
D001647:Bile Acids and Salts; D001786:Blood Glucose; C513561:Gpbar1 protein, mouse; D007328:Insulin; D043562:Receptors, G-Protein-Coupled; D052216:Glucagon-Like Peptide 1; D013253:Steroid 12-alpha-Hydroxylase
BILE ACID; COLONIC MICROFLORA; DIABETES MELLITUS; GASTRECTOMY; GASTROINTESTINAL HORMONES