[Effect and Mechanism of Litchi Semen Effective Constituents on Insulin Resistance in Rats with Type 2 Diabetes Mellitus].

Objective: To observe the effect of Litchi Semen Effective Constituents (LSEC) on insulin resistance (IR) in rats with Type 2 Diabetes Mellitus(T2DM), and to explore its mechanism.
Method: T2DM models in rats with IR were induced by high-fat feeding combined with streptozocin, then the rats were randomly divided into four groups: model group, LSEC high-dose group (1. 87 g/kg), LSEC low-dose group(0. 47 g/kg) and rosiglitazone group(3. 87 x 10(-3) g/kg), blank group was established as control. After medication for four weeks, effects of LSEC on glucose or lipid metabolism and insulin resistance were investigated, histopathology and ultrastructure changes of pancreatic tissues were observed,Stem-loop Real-time fluorescence quantitative RT-PCR was used for evaluation of GRP78 mRNA and CHOP mRNA levels in pancreatic tissue of rats.
Result: LSEC of high-dose group obviously improved fasting blood glucose, serum TG level and glucose tolerance in T2DM rats (P <0. 05 or P <0. 01). ISI was increased, HOMA-IR index was decreased, histopathology change of pancreatic tissue were alleviated, damaged organelle, such as endoplasmic reticulum and mitochondria were repaired in both groups of LSEC. Expression levels of GRP78 mRNA of both groups of LSEC and CHOP mRNA of high-dose group in pancreatic tissue were obviously lower than those of model group (P <0. 01).
Conclusion: LSEC can improve glycolipid metabolism and IR, increase insulin sensitivity to cure T2DM, its effects may be attributed, at least in part, to inhibit the expression of GRP78 mRNA and CHOP mRNA.