Dynamic changes of taurine-conjugated bile acid levels during the development and progression of type 2 diabetes in OLETF rats

Objective To observe the changes of serum and fecal taurine-conjugated bile acid levels and its association with glucose metabolism during the spontaneous development of type 2 diabetes in OLETO rats. Methods Twenty male OLETF rats(4 weeks old)were included and 10 male LETO rats of the same age were used as the normal control group. OLETF rats were fed with high fat diet whereas LETO rats were fed with normal diet. Serum and fecal taurine-conjugated bile acid levels of OLETF rats were tested at different stage of diabetes including baseline, normal glucose tolerance, impaired glucose tolerance and diabetes periods, and the association of taurine-conjugated bile acid level with body weight, blood glucose, and glucose-regulating hormones were also investigated. Results Compared with LETO rats, the baseline serum levels of taurine-conjugated bile acid in OLETF rats did not change, but the levels of fecal taurine-conjugated bile acid including taurine-conjugated chenodeoxycholic acid(TCDCA), taurocholic acid(TCA)and taurine-conjugated deoxycholic acid(TDCA)were significantly decreased [(14.25±7.18 vs 0.90±0.31)mg/kg, (7.12±4.14 vs 1.30±0.35)mg/kg, (4.30±1.78 vs 1.02±0.14)mg/kg, all P<0.01]. During the development of diabetes, the fecal levels of TCDCA, TCA and TDCA were still lower than those in the control rats. TDCA was negatively associated with the level of fasting blood glucose(r=-0.470, P=0.032), but positively associated with the serum level of glucagon-like peptide(GLP)-l(r=0.406, P=0.044). Conclusion The decrease of intestinal taurine-conjugated bile acid level is involved in the development of diabetes in OLETF rats. Intestinal TDCA may regulate the secretion of GLP-1 by paracrine pathway. (Chin J Endocrinol Metab, 2017, 33: 590-595) Key words: Taurine-conjugated bile acid; Diabetes mellitus, type 2; Glucagon-like peptide-1; Taurine deoxycholic acid