ABSTRACT
ObjectiveTo validate the alleviating effect of Gegen Qinliantang （GGQLT） on insulin resistance in db/db diabetic mice by regulating the silent information regulator 1 （SIRT1）/forkhead transcription factor O1 （FoxO1） autophagy pathway. MethodSeventy-five SPF-grade spontaneous type 2 diabetic db/db mice and 15 control db/m mice were selected and maintained on regular feed for one week before measuring blood glucose. They were randomly divided into six groups， with 15 mice in each group. The groups included a normal group （physiological saline， 0.2 g·kg-1）， a metformin group （0.2 g·kg-1）， high-， medium-， and low-dose GGQLT groups （31.9， 19.1， 6.9 g·kg-1）， and a model group （physiological saline， 0.2 g·kg-1）. They were orally treated with corresponding drugs for eight weeks， once daily. Fasting blood glucose （FBG） was measured using a Roche glucometer. Serum levels of high-density lipoprotein cholesterol （HDL-C）， low-density lipoprotein cholesterol （LDL-C）， triglyceride （TG）， and total cholesterol （TC） were measured using an automated biochemical analyzer. Fasting serum insulin （INS） levels were determined using enzyme-linked immunosorbent assay （ELISA）， and the homeostasis model assessment of insulin resistance （HOMA-IR） was calculated. Western blot was used to detect the expression of Beclin-1， microtubule-associated protein 1 light chain 3 （LC3）， and SIRT1/FoxO1 autophagy pathway-related proteins in liver tissues. Immunohistochemistry was performed to assess the expression of SIRT1， FoxO1， Beclin-1， and LC3B proteins in liver tissues. Transmission electron microscopy was used to observe the formation of autophagosomes in the liver. ResultCompared with the normal group， the model group showed significant increases in FBG， FINS， HOMA-IR， TC， TG， LDL-C， and HDL-C levels （P<0.01）， and significant increases in the expression of SIRT1， Beclin-1， LC3， and FoxO1 proteins in liver tissues （P<0.01）. Transmission electron microscopy revealed the highest number of autophagosomes in the model group. Compared with the model group， the metformin group and the low-， medium-， and high-dose GGQLT groups showed significant decreases in serum FBG， FINS， HOMA-IR， TC， TG， LDL-C， and HDL-C levels （P<0.05， P<0.01）， significant decreases in the expression of SIRT1， Beclin-1， LC3 （P<0.05， P<0.01）， and up-regulated FoxO1 protein （P<0.01）. Transmission electron microscopy showed a reduction in the degree of autophagy in the treatment groups. Compared with the metformin group， the medium- and high-dose GGQLT groups showed significant decreases in FBG， FINS， and TG levels （P<0.01）， significant decreases in the expression of SIRT1， Beclin-1， and LC3 in liver tissues （P<0.05， P<0.01）， and reduced FoxO1 protein （P<0.01）. The high-dose GGQLT group showed reduced HOMA-IR， TC， LDL-C， and HDL-C levels （P<0.05， P<0.01）. Transmission electron microscopy revealed a significant reduction in autophagosomes in the medium- and high-dose GGQLT groups. ConclusionGGQLT can significantly improve glucose and lipid metabolism disorders， alleviate insulin resistance in db/db mice， and prevent and treat type 2 diabetes by activating the SIRT1/FoxO1 autophagy pathway.
ABSTRACT
Objective:To observe the effects of different doses of Gegen Qinlian Decoction on nucleotide oligomeric domain-like receptor protein 3 (NLRP3)/Caspase-1/IL1β inflammatory signaling pathway in liver of db/db mice with type 2 diabetes mellitus (T2DM).Methods:Totally 75 SPF male db/db mice were randomly divided into model group, metformin group (0.2 g/kg), Gegen Qinlian Decoction high-, medium-, and low-dosage groups (61.80, 30.90, 15.45 g/kg), with 15 mice in each group. Another 15 db/m male mice were selected as blank control group. Each administration group was given relevant medicine for gavage, while the blank group and model group were given 0.9% sodium chloride solution for gavage, once a day, for 12 weeks. The body weight, fasting blood glucose (FBG) and glycosylated hemoglobin (HbA1c) contents of each group were measured after treatment. The mRNA expression levels of NLRP3, Caspase-1 and interleukin-1β (IL-1β) in liver were detected by real-time quantitative PCR. The expression levels of NLRP3, Caspase-1, IL-1β and IL-18 in liver tissues were detected by Western Blot. HE staining was used to observe the morphology of liver tissues.Results:Compared with model group, body weight, fasting blood glucose and HbA1c contents of mice in Gegen Qinlian Decoction high- and medium-dosage groups and metformin groups decreased ( P<0.05), the body weight and fasting blood glucose levels of mice in Gegen Qinlian Decoction low-dosage group decreased ( P<0.05); the mRNA levels of NLRP3 and IL-1β in liver tissues of all treatment groups decreased ( P<0.05), the mRNA level of Caspase-1 in liver tissue decreased in Gegen Qinlian Decoction high- and medium-dosage groups ( P<0.05); the expression of NLRP3, Caspase-1, and IL-18 in liver tissue of each treatment group decreased ( P<0.05), while the expression of IL-1β in Gegen Qinlian Decoction high- and medium-dosage groups and the metformin group decreased ( P<0.05); compared with the metformin group, the body weight and fasting blood glucose of mice in the Gegen Qinlian Decoction high-dosage decreased ( P<0.05), while the HbA1c levels in the Qinlian Decoction high- and medium-dosage decreased ( P<0.05); the expressions of NLRP3, Caspase-1 and IL-18 in liver tissues of Gegen Qinlian Decoction high-dosage group decreased ( P<0.05), the expression of IL-1β, NLRP3, Caspase-1, IL-1β, and IL-18 decreased ( P<0.05); HE staining showed that the pathological changes of liver tissue were reduced in all treatment groups. Conclusion:Gegen Qinlian Decoction may reduce blood sugar by inhibiting the activation of NLRP3/Caspase-1/IL-1β inflammatory signaling pathway in liver of db/db mice, thereby improving the inflammatory damage of T2DM.