Sterilized glucose solution

In each group, four animals were used for the oral glucose tolerance test (OGTT) and the remaining three were employed for the intraperitoneal insulin tolerance test (ipITT). For OGTT, three days prior the end of the animal experiment, 12 h fasting-adapted rats were treated with sterilized glucose solution (2 g/kg, Sigma-Aldrich) by oral gavage. Blood collected from the needle-punched tail vein was used as the sample. The blood glucose levels were measured at 0, 30, 60, 90, and 120 min post-glucose treatment using ACCU-CHEK Active (ACCU-CHECK, Mannheim, Germany). For ipITT, two days before the end of the animal experiment, biosynthetic human insulin (Eli Lilly and Company, Indianapolis, IN, USA) was administered to 12 h fasting-adapted rats by intraperitoneal injection (0.75 U/kg body weight). The glucose levels in the blood samples collected from the needle-punched tail vein at 0, 30, 60, 90, and 120 min post-insulin treatment were determined as mentioned above for the OGTT. The values of OGTT and ipITT were also corrected by baseline and expressed as baseline corrected areas under the curves (AUC) for evaluating the degree of impairment in glucose tolerance and insulin sensitivity, respectively.

The animals were subjected to overnight (12 h) fasting and administered sterilized glucose solution (2 g/kg, Sigma Aldrich, USA) by oral gavage. The glucose levels of the blood samples collected from the tail vein were measured at five different time points (0, 0.5, 1, 1.5, and 2 h) using ACCU-CHEK Active (ACCU-CHEK, Mannheim, Germany). The IPITT was performed 2 days prior to the termination of animal experiment. The animals were subjected to overnight (12 h) fasting, then administrated with biosynthetic human insulin (0.75 U/kg, Eli Lilly and Company, Indianapolis, IN, USA; Um et al., 2004 (link)) by intraperitoneal injection. The glucose levels of the blood samples collected from the tail vein were measured at five different time points (0, 0.5, 1, 1.5, and 2 h) as described above for OGTT.

Oral glucose tolerance test (OGTT) was performed accorded to a previous published paper on day 34. Each animal fasted for 12 h, and was orally administered sterilized glucose solution (2.0 g/kg, Sigma-Aldrich, Louis, MO, USA). Blood samples were collected from the tail vein at five time points (0, 30, 60, 90, and 120 min), and used to measure the glucose concentrations through a glucose-meter (ONETOUCH Ultra, LifeScan, Milpitas, CA, USA).