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.
ABSTRACT
ObjectiveTo explore the mechanism of Dahuang Mudantang in alleviating the intestinal injury in the rat model of acute pancreatitis via the high-mobility group box 1 （HMGB1）/receptor for advanced glycation endproduct （RAGE）/nuclear factor-κB （NF-κB） signaling pathway. MethodOne hundred and twenty SPF-grade Wistar rats received retrograde injection of 5% sodium taurocholate into the biliopancreatic duct for the modeling of intestinal injury in acute pancreatitis. The rats were randomized into blank， model， low-， medium-， and high-dose （3.5， 7， 14 g·kg-1， administrated by gavage） Dahuang Mudantang， and octreotide （1×10-5 g·kg-1， subcutaneous injection） groups （n=20）. The rats in blank and model groups received equal volume of distilled water by gavage. Drugs were administered 1 h before and every 12 h after modeling， and samples were collected 24 h after modeling. The general status of the rats was observed. The biochemical methods were employed to measure the levels of amylase （AMS） and C-reactive protein （CRP） in the serum. The enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of tumor necrosis factor （TNF）-α， interleukin （IL）-1β， and IL-6 in the colon tissue. The morphological changes of pancreatic and colon tissues were observed by hematoxylin-eosin （HE） staining. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot were employed to measure the expression levels of HMGB1， RAGE， inhibitor of NF-κB kinase （IKK）， and NF-κB suppressor protein α（IκBα）in the colon tissue. ResultThe rats in the model group showed poor general survival， writhing response， reduced frequency of defecation， and dry stool. The symptoms of rats in the model group were mitigated in each treatment group， and the high-dose Dahuang Mudantang showed the most significant effect. Compared with the normal group， the model group had elevated AMS and CRP levels （P<0.05）， which were lowered by Dahuang Mudantang （P<0.05）， especially that at the high dose （P<0.05）. Compared with the normal group， the modeling elevated that levels of TNF-α， IL-1β， and IL-6 （P<0.05）. Such elevations were lowered by Dahuang Mudantang （P<0.05）， and the high-dose group and the octreotide group showed better performance （P<0.05）. The modeling caused necrotic， congested， and destructed pancreatic and colonic tissues， which were ameliorated by the drugs， especially high-dose Dahuang Mudantang. Compared with the normal group， the modeling up-regulated the mRNA levels of HMGB1， RAGE， IKK， IκBα， and NF-κB （P<0.05）. Compared with the model group， Dahuang Mudantang and octreotide down-regulated the mRNA levels of HMGB1， RAGE， IKK， IκBα， and NF-κB （P<0.05）， and the high-dose Dahuang Mudantang demonstrated the best performance （P<0.05）. Western blot results showed a trend consistent with the results of Real-time PCR. ConclusionDahuang Mudantang can improved the general status， reduce inflammation， and alleviate histopathological changes in the pancreatic and colon tissues in the rat model of acute pancreatitis by inhibiting the HMGB1/RAGE/NF-κB signaling pathway.