OBJECTIVE:To establish a method for the concentration determination of indigo in rats'plasma,and study the pharmacokinetic characteristics in rats in vivo. METHODS:18 rats were randomly divided into low-dose,medium-dose,high-dose groups,6 in each group,which were intragastrically administrated 10,20,40 mg/kg of indigo solution. The sample blood 0.3 mL was taken from eye socket before administration and 0.083,0.25,0.5,0.75,1,2,4,6,8,10,12,16,24,48,72 h after ad-ministration,separating the plasma,then LC-MS/MS was used to determine the plasma concentration of indigo after methanol pre-cipitation. The column was Agilent Poroshell EC-C18 with mobile phase consisting of methanol-5 mmol/L ammonium acetate solu-tion(95:5,V/V)at a flow rate of 0.4 mL/min;multiple reaction monitoring was conducted for the quantitative analysis,with ion pair of 263.1-218.8 (indigo) and 237.2-194.1 (carbamazepine,internal standard). Pharmacokinetic parameters were calculated by DAS 3.0 software. RESULTS:The linear range of indigo was 0.5-100 ng/mL(r=0.9999),intra-day and inter-day RSDs were low-er than 9%(n=5);matrix effects of low,medium and high does quality control samples were (98.25 ± 3.71)%,(102.23 ± 2.64)%,(102.29±3.79)%(n=5). The pharmacokinetic parameters of indigo in low-dose,medium-dose,high-dose groups were tmax of(8.6±1.1),(9.2±0.8)and(9.5±0.8)h;cmax of(30.9±8.6),(44.9±10.1),(96.1±17.4)ng/mL;t1/2 of(14.9±2.1), (16.3±2.9),(15.3±3.7)h;AUC0-72 h of(366.6±83.4),(694.9±105.8),(1223.42±108.7)ng·h/mL,respectively. CONCLU-SIONS:The method shows high sensitivity,good specificity,and can be used for the content determination of indigo in plasma samples of rats. The pharmacokinetics of indigo in rats in vivo fits non-compartment model.

Aim: To observe the influence of high fat-high sucrose diet and chronic stress on insulin resistance. Methods: Male rats were divided into four groups: control, high fat-high sucrose diet( HFSD), chronic stress( CS), high fat-high sucrose diet plus chronic stress( HFSD + CS). After feeding the animals for 10 weeks, fat, glucose and insulin concentrations in blood and PPAR-α mRNA expression in liver were examined, and glu-cose infusion rate was detected by a hyperinsulinemic euglycemic clamp experiment. Results: Insulin resistance was observed in all three treated groups, showing the highest in the HFSD + CS group. Dyslipidemia, hypergly-cosemia, hyperinsulinism and the decrease of PPAR-α mRNA expression in liver were also shown in all treated groups. There was an obvious interaction of insulin resistance, hyperglycosemia and high FFA between high fat-high sucrose diet and chronic stress. Conclusion: Combination of high fat-high sucrose diet and chronic stress could promote the development of insulin resistance, which is likely due to the high level of serum FFA.