Dihydromyricetin improves Parkinson's disease-like lesions in T2DM rats by activating AMPK/ULK1 pathway / 生理学报

The purpose of this study was to explore the effect and mechanism of dihydromyricetin (DHM) on Parkinson's disease (PD)-like lesions in type 2 diabetes mellitus (T2DM) rats. The T2DM model was established by feeding Sprague Dawley (SD) rats with high-fat diet and intraperitoneal injection of streptozocin (STZ). The rats were intragastrically administered with DHM (125 or 250 mg/kg per day) for 24 weeks. The motor ability of the rats was measured by balance beam experiment, the changes of dopaminergic (DA) neurons and the expression of autophagy initiation related protein ULK1 in the midbrains of the rats were detected by immunohistochemistry, and the protein expression levels of α-synuclein (α-syn), tyrosine hydroxylase (TH), as well as AMPK activation level, in the midbrains of the rats were detected by Western blot. The results showed that, compared with normal control, the rats with long-term T2DM exhibited motor dysfunction, increased α-syn aggregation, down-regulated TH protein expression, decreased number of DA neurons, declined activation level of AMPK, and significantly down-regulated ULK1 expression in the midbrain. DHM (250 mg/kg per day) treatment for 24 weeks significantly improved the above PD-like lesions, increased AMPK activity, and up-regulated ULK1 protein expression in T2DM rats. These results suggest that DHM may improve PD-like lesions in T2DM rats by activating AMPK/ULK1 pathway.

Dihydromyricin inhibited hepatic lipid deposition induced by high-fat diet in obese mice by activating SIRT1-AMPK pathway / 中国药理学通报

Aim To investigate the effect of dihydromyricetin (DHM) on lipid accumulation in liver of obese mice induced by high fat diet and its mechanism. Methods Sixty C57BL/6J mices were randomly divided into six groups (n = 10); (1)ND group; normal diet, (2)ND + L-DHM group; normal diet and treatment with low-dose DHM (125 mg • kg

Overexpression of wild-type p21Ras plays a prominent role in colorectal cancer.

Colorectal cancer (CRC) is the most common gastrointestinal type of cancer. The overexpression of Ras proteins, particularly p21Ras, are involved in the development of CRC. However, the subtypes of the p21Ras proteins that are overexpressed and the mutation status remain unknown restricting the development of therapeutic antibodies targeting p21Ras proteins. The present study aimed to investigate the mutation status of ras genes associated with Ras proteins that are overexpressed in CRC and explore whether or not wild-type p21Ras could be a target for CRC therapy. p21Ras expression was examined immunohistochemically in normal colorectal epithelium, benign lesions and malignant colorectal tumor tissues by monoclonal antibody (Mab) KGH-R1 which is able to react with three types of p21Ras proteins: H-p21Ras, N-p21Ras and K-p21Ras. Then, the expression levels of p21Ras subtypes were determined in CRC by a specific Mab for each p21Ras subtype. Mutation status of ras genes in p21Ras-overexpressing CRC was detected by DNA sequencing. There was rare p21Ras expression in normal colorectal epithelium but a high level of p21Ras expression in CRC, with a significant increase from normal colorectal epithelium to inflammatory polyps, low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia and invasive colorectal adenocarcinoma, respectively. Overexpression of K-p21Ras was found in all CRC tissues tested, overexpression of N-p21Ras was found in 85.7% of the CRC tissues, while H-p21Ras expression was not found in any CRC tissue. DNA sequencing showed that there were no K-ras mutations in 60% of the K-p21Ras-overexpressing CRC, while 40% of the CRC tissues harbored K-ras mutations. N-ras mutations were not found in any N-p21Ras-overexpressing CRC. Our findings indicate that overexpression of wild-type p21Ras may play a prominent role in the development of CRC in addition to ras mutations and could be a promising target for CRC therapy.

The role of arecoline on hepatic insulin resistance in type 2 diabetes rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the effects of arecoline on hepatic insulin resistance in type 2 diabetes rats and to elucidate its possible mechanism.</p><p><b>METHODS</b>Forty five Wistar rats were fed with high fructose diet for 12 weeks to induce type 2 diabetic rat model. rats were randomly divided into 5 groups (n = 8): control group, model group and model group were treated with different dose (0, 0.5, 1, 5 mg/kg) of arecoline. After 4 weeks, the fasting blood glucose, blood lipid and insulin level measured , mRNA expression of liver constitutive androstane receptor (CAR), pregnane X receptor (PXR), glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were detected by reverse transcription polymerase chain reaction (RT-PCR), the protein expression of p-AKT and glucose transporter4 (GLUT4) were detected by Western blot.</p><p><b>RESULTS</b>1.5 mg/kg arecoline could significantly decrease the level of fasting blood glucose, blood lipid, blood insulin level and liver G6Pase, PEPCK, IL-6, TNF-alpha mRNA level in type 2 diabetes rats. 1.5 mg/kg arecoline also could significantly increase CAR, PXR mRNA level and p-AKT and GLUT4 protein expression.</p><p><b>CONCLUSION</b>Arecoline improved hepatic insulin resistance in type 2 diabetes rats by increasing the mRNA levels of CAR and PXR leading to the creased glucose metabolism and inflammation related genes expression.</p>

miRNA expression change of differentiation of mice marrow mesenchymal stem cells into adipocytes / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore miRNA expression change of differentiation of mice marrow mesenchymal stem cells (MSCs) into adipocytes, which lay the foundation for further studies on molecular mechanism of miRNA regulating the differentiation of MSCs into adipocytes.</p><p><b>METHODS</b>C57BL/6 mice MSCs were isolated, cultured through the whole bone marrow method, amplified by the differential adherent method. Cell growth was observed by morphology and the expression of superficial antigen CD29, CD44, CD34 were detected through immunohistochemistry. MSCs was induced to differentiation into adipocytes with adipocyte differentiation medium, and adipogenic differentiation of MSCs was analyzed by oil Red O staining. MicroRNA microarray was used to investigate the differentially expressed miRNAs in MSCs and adipocytes.</p><p><b>RESULTS</b>(1) The fifth passage of MSCs had high purity under an inverted m icroscope. Immunohistochemistry staining showed that CD29, CD44 were positive and CD34 was negative in more than 90% MSCs. There were a large number of lipid droplets in cytoplasm after MSCs were induced with adipocyte differentiation medium, Oil O staining was positive. (2) The microarray experiment showed that 75 differentially expressed miRNAs were obtained in adipocytes compared with MSCs, 20 up-regulated and 55 down-regulated miRNAs were observed among them.</p><p><b>CONCLUSION</b>There was a expression change of miRNA of differentiation of MSCs into adipocytes, some miRNAs might play important roles in MSCs adipogenic differentiation.</p>

Effects of rosiglitazone on aortic function in rats with insulin resistant-hypertension / 生理学报

Rosiglitazone (ROSI), thiazolidione peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activator, reduces insulin resistance in patients with type 2 diabetes (T2DM). It also improves vascular reactivity in T2DM patients and some animal models by unclear mechanisms. In order to investigate the effect of ROSI on aortic systolic and diastolic function of insulin resistant-hypertensive rats (IRHR) and the underlying mechanism, male Sprague-Dawley (SD) rats were fed with high fructose (HF) for 8 weeks to induce IRHR model. To verify IRHR model, systolic blood pressure (SBP), fasting blood sugar (FBS), fasting serum insulin (FSI) were measured respectively in each group, and insulin sensitive index (ISI) was also calculated. Subsequently, the vascular function test was performed. The thoracic aortic ring of SD rats was mounted on a bath system. The effect of rosiglitazone on the contraction elicited by L-phenylephrine (PE) and potassium chloride (KCl) and the relaxation induced by acetylcholine (ACh) and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) was used and serum nitric oxide (NO) was measured. The results obtained were as follows: (1) Rosiglitazone reduced the level of SBP, serum insulin and improved insulin resistance in IRHRs. (2) The contractive responses of thoracic aortic rings to PE and KCl were enhanced and the relaxation response to ACh was depressed significantly in the HF group, and the effect was reversed by ROSI. (3) After pretreatment with L-NAME, the relaxation response to ACh was further impaired in the HF group, this effect was partly reversed by ROSI. (4) Sodium nitroprusside (SNP)-induced vasodilator responses did not differ significantly among the groups. (5) Aortic systolic and diastolic function of the control group was not affected markedly by ROSI. (6) Compared with the control group, serum nitric oxide was significantly reduced in the HF group, but after rosiglitazone treatment it was remarkably increased. These findings suggest that ROSI can improve aortic diastolic function of insulin resistant-hypertensive rats, the mechanism of this effect might be associated with an increase in nitric oxide mediated partly by NOS pathway, a decrease in the level of blood pressure, serum insulin and the improvement of insulin resistance.

17β-estradiol protects against injury of aortic relaxation and contraction in ovariectomized rats with insulin resistance induced by fructose / 生理学报

The purpose of the present study was to investigate the effect of 17beta-estradiol (17beta-E(2)) on the structure and relaxation and contraction activity of thoracic aortas in ovariectomized rats with insulin resistance induced by fructose. Ovariectomized mature female Sprague-Dawley rats were fed with high fructose diet for 8 weeks to induce insulin resistance. Physiological dose of 17beta-E(2) (30 mug/kg) was injected subcutaneously every day for 8 weeks. Systolic blood pressure (SBP) was measured by use of tail-cuff. Serum nitric oxide (NO), estradiol (E(2)), fasting blood sugar (FBS) and fasting serum insulin (FSI) were measured respectively in each group. The insulin sensitive index (ISI) was calculated. The thoracic aortas were fixed in formalin, sliced and HE dyed. The structure of thoracic aortas, lumen breadth, media thickness, media thickness/lumen breadth ratio and media cross-section area were measured. The contraction response of thoracic aorta rings induced by L-phenylephrine (PE) and the relaxation response of thoracic aorta rings induced by ACh and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME) was used. The results obtained are as follows: (1) 17beta-E(2) protected against the effect of high fructose diet, which caused an increase in SBP, hyperinsulinemia and a decrease in ISI in ovariectomized rats. (2) The structure of thoracic aortas had no significant difference among the groups. (3) Compared with the ovariectomized group (OVX) or fructose fed group (F), serum nitric oxide was significantly reduced, the contraction response of thoracic aorta rings to PE was enhanced and the relaxation response to ACh was depressed significantly in ovariectomized+fructose fed group (OVX+F). The effect of high fructose was reversed by 17beta-E(2). After pretreatment with L-NAME, the effect of 17beta-E(2), which enhanced the relaxation response of thoracic aorta rings to ACh in ovariectomized+fructose+17beta-E(2) group (OVX+F+E(2)), was partly blocked. (4) The relaxation response of thoracic aorta rings to SNP had no significant difference among the groups. (5) The contraction response of thoracic aorta rings without endothelium to PE had no significant difference among the groups. These findings suggest that 17beta-E(2) may provide protection against the effect of high fructose diet, which causes hypertension, dysfunction of endothelial cells and insulin resistance. The mechanism of this effect of 17beta-E(2) could be partly associated with the increase of NO by NOS pathway, or associated with the decrease in the level of systolic blood pressure and serum insulin, and the improvement of insulin resistance.