The effect and mechanism of metformin on peripheral neuropathy in type 1 diabetic rats / 药学学报

Diabetic peripheral neuropathy (DPN) is one of the most common microvascular complications occurring in both type 1 and type 2 diabetes mellitus patients, which often results in patients suffering from severe hyperalgesia and allodynia. Up to now, the clinical therapeutic effect of DPN is still unsatisfactory. Metformin is an anti-diabetic drug that has been safely and widely used for the treatment of type 2 diabetes for decades. Studies have shown that metformin can improve pain caused by DPN, but its effects on the nerve conduction velocity and morphology of the sciatic nerve of DPN, and the mechanism for improving DPN are not clear. Therefore, the STZ-induced model of type 1 DPN in SD rats was used to study the effects of metformin on DPN, and to preliminarily explore its mechanism in this study. All animal experiments were carried out with approval of the Experimental Animal Welfare Ethics Committee of the Institute of Materia Medica (Chinese Academy of Medical Sciences and Peking Union Medical College). After the model was established successfully, STZ diabetic rats were randomly divided into a model group and a metformin treatment group, and 10 normal SD rats were selected as the normal control group, and the rats were intragastrically administered for 12 weeks. The results showed that metformin significantly reduced blood glucose, glycosylated hemoglobin, food consumption and water consumption in STZ rats. Metformin markedly increased the motor nerve conduction velocity and mechanical stabbing pain threshold, prolonged the hot plate latency threshold, and improved the pathological morphological abnormalities of the sciatic nerve in STZ rats. In addition, metformin increased the content of glutathione (GSH), enhanced the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), and reduced the content of malondialdehyde (MDA) in serum and sciatic nerve of STZ diabetic rats, as well as regulating the expression of genes related to oxidative stress in the sciatic nerve. Metformin obviously reduced the levels of pro-inflammatory factors such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 in the serum in STZ rats, and inhibited the gene expression of these inflammatory factors in the sciatic nerve. In summary, metformin significantly increased nerve conduction velocity, improved sciatic nerve morphological abnormalities and pain in DPN rats, which may be related to its effect in improving oxidative stress and reducing inflammation.

Effects and mechanism of Morus alba L. (Sangzhi) alkaloids combined with metformin on glucose metabolism in diabetic KKAy mice / 药学学报

To investigate the effects and mechanism of the combination of Morus alba L. (Sangzhi) alkaloids(SZ-A) and metformin (Met) on glucose metabolism in type 2 diabetic mice, KKAy mice were divided into four groups according to the glucose and lipid indexes: control group (control), Morus alba L. (Sangzhi) alkaloids group (SZ-A, 100 mg·kg-1), metformin group (Met, 100 mg·kg-1) and combined administration group (combination, Comb, 100 mg·kg-1 SZ-A + 100 mg·kg-1 Met). All groups were administered by gavage once daily for 7 weeks accompanied with monitoring food intake, water intake, body weight as well as glycemia. Additionally, oral glucose tolerance test (OGTT), insulin tolerance test (ITT) and oral sodium pyruvate tolerance test (OPTT) were performed at week 2, week 5, week 6, respectively. The experiments were approved by the Institutional Animal Care and Use Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College (00004332). We determined the weight and lipid content of liver, and then performed the histopathological analysis after sacrificed. Furthermore, Western blot assay was used to detect the protein levels of key molecules of PI3K/PDK1/Akt/GLUT signaling pathway in liver, muscle and adipose tissue. Compared to the SZ-A or Met monotherapy group, SZ-A + Met significantly improved the glucose metabolism disorder, which was showed in reduced food intake, water intake, the level of fasting blood glucose, postprandial blood glucose and glycosylated hemoglobin A1c (HbA1c) of KKAy mice, as well as improved glucose tolerance, enhanced insulin sensitivity and inhibited gluconeogenesis. In addition, SZ-A + Met obviously up-regulated the protein expression levels in PI3K/PDK1/Akt/GLUT signaling pathway in liver, muscle and adipose tissue of KKAy mice. Moreover, the liver lipid accumulation and blood aminotransferase level of KKAy mice in the combined administration group were significantly reduced. Therefore, we concluded that the combination of SZ-A and Met improved glucose metabolism and inhibited the occurrence and development of T2DM via promoting glucose uptake and utilization, suggesting that the combination of SZ-A and Met is a more useful treatment for T2DM.

The Chinese patent medicine, Jin-tang-ning, ameliorates hyperglycemia through improving β cell function in pre-diabetic KKAy mice / 中国天然药物

Jin-tang-ning (JTN), a Chinese patent medicine, mainly comprised of Bombyx moriL., has been proved to show α-glucosidase inhibitory efficacy and clinically effective for the treatment of type 2 diabetes (T2DM). Recently, we have reported that JTN could ameliorate postprandial hyperglycemia and improved β cell function in monosodium glutamate (MSG)-induced obese mice, suggesting that JTN might play a potential role in preventing the conversion of impaired glucose tolerance (IGT) to T2DM. In this study, we evaluated the effect of JTN on the progression of T2DM in the pre-diabetic KKAy mice. During the 10 weeks of treatment, blood biochemical analysis and oral glucose tolerance tests were performed to evaluate glucose and lipid profiles. The β cell function was quantified using hyperglycemic clamp at the end of the study. JTN-treated groups exhibited slowly raised fasting and postprandial blood glucose levels, and also ameliorated lipid profile. JTN improved glucose intolerance after 8 weeks of treatment. Meanwhile, JTN restored glucose-stimulated first-phase of insulin secretion and induced higher maximum insulin levels in the hyperglycemic clamp. Thus, to investigate the underlying mechanisms of JTN in protecting β cell function, the morphologic changes of the pancreatic islets were observed by optical microscope and immunofluorescence of hormones (insulin and glucagon). Pancreatic protein expression levels of key factors involving in insulin secretion-related pathway and ER stress were also detected by Western blot. Pre-diabetic KKAy mice exhibited a compensatory augment in β cell mass and abnormal α cell distribution. Long-term treatment of JTN recovered islet morphology accompanied by reducing α cell area in KKAy mice. JTN upregulated expression levels of glucokinase (GCK), pyruvate carboxylase (PCB) and pancreas duodenum homeobox-1 (PDX-1), while down-regulating C/EBP homologous protein (Chop) expression in pancreas of the hyperglycemic clamp, which indicated the improvement of mitochondrial metabolism and relief of endoplasmic reticulum (ER) stress of β cells after JTN treatment. These results will provide a new insight into exploring a novel strategy of JTN for protecting β cell function and preventing the onset of pre-diabetes to T2DM.

Anti-diabetic effects of the fraction of alkaloids from Ramulus Mori, an innovative Sangzhi alkaloids as an α-glucosidase inhibitor / 药学学报

Sangzhi alkaloids (SZ-A) are derived from traditional Chinese medicine Ramulus Mori, serving well as an innovative antidiabetic drug, due to α-glucosidase inhibition. To evaluate the potency of glucosidase inhibitory effect of SZ-A, the enzyme-based screening platforms, including sucrase, maltase and amylase were established, and IC50 was calculated. The effects of SZ-A on postprandial blood glucose at a single dose, oral sucrose, starch and glucose loading were determined in normal ICR mice and alloxan-induced hyperglycemic mice. To confirm the anti-diabetic effects of SZ-A on glucose and lipid metabolism after long-term administration, the postprandial and fasting blood glucose, serum insulin, urinary glucose levels, glycosylated serum proteins and blood lipid levels were determined in high-fat fed C57 obese mice (pre-diabetic HFC57 mice) and diabetic rats induced by streptozotocin (STZ). The Experimental Animal Welfare Ethics Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College approved all of the protocols for this research. We found that SZ-A exhibited a significant inhibitory effect on the sucrase and maltase. SZ-A showed no effect on amylase. In normal ICR mice and alloxan-induced hyperglycemic mice, SZ-A at a single dose significantly delayed and reduced the peak of blood glucose after sucrose or starch loading, but showed no effect on the increase of blood glucose after glucose loading. In STZ diabetic rats, SZ-A significantly reduced the postprandial or fasting blood glucose levels, glycosylated serum proteins and urinary glucose. SZ-A also reduced serum triglyceride (TG) and cholesterol (TC) levels after 3 weeks of treatment. SZ-A ameliorated the postprandial blood glucose or the fasting blood glucose elevation, and reduced the incidence of hyperglycemia in HFC57 mice. SZ-A decreased the basal insulin level, improved insulin sensitivity, and ameliorated glucose intolerance in pre-diabetic HFC57 mice. Our results indicated that SZ-A had a novel inhibitory activity on α-glucosidase, especially on disaccharidases. SZ-A at a single dose significantly reduced the peak of blood glucose elevation and delayed the increase of blood glucose in normal and diabetic mice after disaccharide and polysaccharide loading. Long-term SZ-A treatment improved glucose and lipid metabolic profiles by delaying carbohydrate absorption from the intestine and reduced the postprandial blood glucose levels in both pre-diabetic and diabetic animal models. Therefore, SZ-A application may display a beneficial role in preventing the development and complications of diabetes.

Determination of serum acetaminophen based on the diazo reaction and its application in the evaluation of gastric emptying / 药学学报

This study aims to establish a method to determine the serum acetaminophen concentration based on diazo reaction, and apply it in the gastric emptying evaluation. Theoretically, acetaminophen could take hydrolysis reaction in hydrochloric acid solution to produce p-aminophenol, which could then take diazo reaction resulting in a product with special absorption peak at 312 nm. Then the serum acetaminophen concentration and recovery rate were calculated according to the standard curve drawn with absorbance at 312 nm. ICR mice were given a dose of acetaminophen (500 mg x kg(-1)) by gavage and the serum acetaminophen was dynamically measured through the diazo reaction. Besides, ICR mice were subcutaneously injected with the long-acting GLP-1 analog GW002 before the gavage of acetaminophen, and serum acetaminophen concentration was measured as above to study how GW002 could influence the gastric emptying. The data showed acetaminophen ranging from 0 to 160 μg x mL(-1) could take diazo reaction with excellent linear relationship, and the regression equation was y = 0.0181 x +0.0104, R2 = 0.9997. The serum acetaminophen was also measured with good linear relationship (y = 0.0045 x + 0.0462, R = 0.9982) and the recovery rate was 97.4%-116.7%. The serum concentration of acetaminophen reached peak at about 0.5 h after gavage, and then gradually decreased. GW002 could significantly lower the serum acetaminophen concentration and make the area under the concentration-time curve (AUC) decrease by 28.4%. In conclusion, a method for the determination of serum acetaminophen based on the diazo reaction was established with good accuracy and could be used in the evaluation of gastric emptying.

Primary culture and growth characteristics of four different species of lens epithelial cells / 国际眼科杂志(Guoji Yanke Zazhi)

AlM:To explore the primary culture conditions for four kinds of lens epithelial cells ( LECs) of rat, rabbit, dog, and human, and measure their growth characteristics.METHODS:The lens capsule or anterior capsular tissue of rat, rabbit, dog and patient were removed by different methods, and they were cut into tiny pieces for primary culture by modified tissue adherent method. The morphological features of four kinds of LECs were observed under an inverted microscope.RESULTS: Four kinds of LECs of rat, rabbit, dog and human could be cultured primarily by tissue adherent method. With the evolution of tissue source, the adherent capacity of LECs gradually strengthened, cells form were changed from irregular polygon to oval, nucleus rounded and cytoplasm enriched gradually. Four kinds of LECs had fibrotic changes after several passages.CONCLUSlON: LECs of rat, rabbit, dog and human can be primarily cultured. This method lays the foundation for the mechanism research of caratact and related fields on the cellular and molecular levels.

Advances of the mechanism study on berberine in the control of blood glucose and lipid as well as metabolism disorders / 药学学报

Berberine, an isoquinoline alkaloid isolated from some Chinese medicinal herbs such as Coptidis rhizoma, has been used for the treatment of diarrhea and other gastrointestinal infections as an antibacterial drug in Chinese medicine. In recent years, it was reported to have beneficial effects on the metabolism disorders states of diabetes. The mechanisms involve many aspects of the diabetes, including regulating the blood cholesterol and triglyceride, lowering blood glucose, ameliorating the insulin resistant state and influencing the function of the pancreatic beta cell.

Inhibition effect of epalrestat on rat lens osmotic expansion / 药学学报

Epalrestat is the unique aldose reductase inhibitor on the market, which was mainly used for the diabetic neuropathy. Lenses osmotic expansion could be induced by galactose to mimic the pathological process of diabetic cataract in vitro. In present study, we mainly investigated whether epalrestat possesses inhibitory effect on the lens osmotic expansion. The results indicated that epalrestat could not only markedly inhibit rat lens osmotic expansion in vitro, but also significantly reduced the high expression of the osmotic expansion-related genes such as AR and AQP1 in mRNA and protein levels. The findings may provide an important reference to epalrestat in the clinical application for the treatment of diabetic cataract.