The alterations of bile acids in rats with high-fat diet/streptozotocin-induced type 2 diabetes and their negative effects on glucose metabolism.

Purpose: Bile acids (BAs) as a kind of endogenous and signaling molecules altered under the circumstance of T2DM, which could impact on the relevant pathways to further affect the glucose metabolism and insulin secretion and might be associated with the T2DM development and restoration. However, the potential mechanisms still need more various and multifaceted studies. Here, we explored the alterations of BAs features and their mechanisms, and discussed the potential effects of the altered BAs on the glucose metabolic disorder via the relevant signaling pathways.

Main Methods: The high-fat diet (HFD) feeding combining with injection of low-dose streptozotocin (STZ) was employed for inducing the T2DM rat model. Based on that, we investigated the alterations of the concentrations and compositions of BAs and their mechanisms, and explored the effects of the altered BAs on the glucose metabolic disorder via farnesoid X receptor (Fxr) and G protein-coupled bile acid receptor (Tgr5)-mediated pathways.

Key Findings: In rats with T2DM, the BAs in rats with T2DM exhibited characteristic alterations, especially the increased ratio of 12α-OH to non-12α-OH BAs in serum, which could be ascribed to the up-regulated Cyp8b1 mRNA expression ratio in the liver. Moreover, Additionally, the altered BAs had negative effects on glucose metabolic disorder via inhibiting the Trg5/Fxr-mediated pathways in colon, liver and pancreas in rats with T2DM.

Significance: BAs in rats with T2DM exhibited the characteristic alterations, which could provide a cue for searching biomarkers of the T2DM diagnosis, and the altered BAs might aggravate the glucose metabolic disorder.