Tacrolimus Induces Insulin Resistance and Increases the Glucose Absorption in the Jejunum: A Potential Mechanism of the Diabetogenic Effects

The use of the immunosuppressive drug tacrolimus (TAC) is related to new onset diabetes after transplantation. Herein, we examined the effect of intraperitoneal administered TAC on intestinal glucose absorption in mice. Animals received low, medium, or high dose TAC (0.5, 1, or 5 mg/kg/d, respectively), or 0.9% saline solution (control) for 14 days. Oral glucose tolerance test (OGTT), insulin concentration test, and serum TAC concentration measurements was performed after 14 days of TAC exposure. Plasma insulin was assessed and electrogenic glucose absorption were measured by the sodium-dependent increase of the short-circuit current. Expression levels of the glucose transporters sodium glucose co-transporter (SGLT) 1, glucose transporter (GLUT) 2, and GLUT5 were also determined. Oral glucose absorption assessed by OGTT was significantly enhanced in the low, medium, and high groups. Serum insulin was elevated in the medium and high group compared with the control. Moreover, glucose-induced Isc was significantly higher in TAC administrated groups, which indicates that SGLT1 activity increased. Transcription levels and protein abundance of SGLT1 in the experimental groups also increased compared with the control. TAC induced insulin resistance and strengthened intestinal glucose absorption by increasing the activity and expression of the glucose transporter, SGLT1.