Mechanism of Rhei Radix et Rhizoma-Coptidis Rhizoma Improving Liver Insulin Resistance in db/db Mice by Regulating AMPK/ULK1/Beclin1 Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveThis study aims to examine the effect of Rhei Radix et Rhizoma-Coptidis Rhizoma on reducing insulin resistance in db/db mice by regulating the adenylate activated protein kinase （AMPK）/UNC-51-like kinase 1 （ULK1）/key molecule of autophagy， benzyl chloride 1 （Beclin1） pathway and elucidate the underlying mechanism. MethodSixty 6-week-old male db/db mice were studied. They were randomly divided into the model group， metformin group （0.26 g·kg-1）， and low-， middle-， and high-dose groups （2.25， 4.5， 9 g·kg-1） of Rhei Radix et Rhizoma-Coptidis Rhizoma. A blank group of db/m mice of the same age was set， with 12 mice in each group. After eight weeks of continuous intragastric administration， the blank group and model group received distilled water intragastrically once a day. The survival status of the mice was observed， and fasting blood glucose （FBG） was measured using a Roche blood glucose device. Fasting serum insulin （FINS） was measured using an enzyme-linked immunosorbent assay， and the insulin resistance index （HOMA-IR） was calculated. Hematoxylin-eosin （HE） staining was performed to observe the pathological changes in the liver of the mice. The protein expression levels of AMPK， Beclin1， autophagy associated protein 5 （Atg5）， and p62 in liver tissue were determined by using Western blot. The protein expression levels of autophagy associated protein 1 light chain 3B （LC3B） and ULK1 in liver tissue were determined using immunofluorescence. Real-time fluorescence quantitative PCR （Real-time PCR） was used to measure mRNA expression levels of AMPK， Beclin1， Atg5， ULK1， and p62. ResultCompared with the blank group， the model group exhibited a significant increase in body mass （P<0.01）. Additionally， the levels of FBG， FINS， and HOMA-IR significantly changed （P<0.01）. The structure of liver cells was disordered. The protein expression levels of AMPK， Beclin1， and Atg5 in liver tissue were significantly decreased （P<0.01）， while the expression level of p62 protein was significantly increased （P<0.01）. The expression levels of mRNA and proteins were consistent. Compared with the model group， the body mass of the metformin group and high and medium-dose groups of Rhei Radix et Rhizoma-Coptidis Rhizoma was significantly decreased （P<0.05）. FBG， FINS， and HOMA-IR were significantly decreased （P<0.05，P<0.01）. After treatment， the liver structure damage in each group was alleviated to varying degrees. The protein expressions of AMPK， Beclin1， Atg5， LC3B， and ULK1 were increased （P<0.05，P<0.01）， while the protein expression of p62 was decreased （P<0.01）. The expression levels of mRNA and proteins were generally consistent. ConclusionThe combination of Rhei Radix et Rhizoma-Coptidis Rhizoma can effectively improve liver insulin resistance， regulate the AMPK autophagy signaling pathway， alleviate insulin resistance in db/db mice， and effectively prevent the occurrence and development of type 2 diabetes.