Aging ; genetics ; metabolism ; Animals ; Diabetes Mellitus ; enzymology ; metabolism ; Humans ; Longevity ; genetics ; physiology ; Neoplasms ; enzymology ; metabolism ; Neurodegenerative Diseases ; enzymology ; metabolism ; Obesity ; enzymology ; metabolism ; Sirtuins ; genetics ; metabolism

OBJECTIVESTo study the changes of sexual gland 5 alpha-reductase type II activity in pubertal and adult rats with diabetes.

METHODSWe selected 40 and 90 days old male Wistar rats as pubertal and adult animal model respectively, 30 rats in each group. The rats were randomly divided into three groups: control group (C), diabetic group (D) and diabetes with insulin replacement group (ID). The activity of 5 alpha-reductase type II was measured with thin layer chromatography in the epididymis, prostate and testis.

RESULTS1. In all sexual glands of pubertal rats, the activity of 5 alpha-reductase type II in D group is significantly lower than that in C and ID groups. 2. In all sexual glands of adult rats. there is no difference in the activity of 5 alpha-reductase type II among these groups.

CONCLUSIONSThe activity of 5 alpha-reductase type II is likely to be influenced by metabolic environment, hormonal levels and local specific factors in pubertal rats, but it is relatively stable in adult rats.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase ; metabolism ; Animals ; Diabetes Mellitus, Experimental ; enzymology ; Epididymis ; enzymology ; Male ; Prostate ; enzymology ; Rats ; Rats, Wistar ; Testis ; enzymology

This project was designed to investigate the role of angiotensin converting enzyme 2 (ACE2) in the diabetic renal injury by observing the expression of ACE2 in the kidney and the level of angiotensin II (AngII) in the circulatory system and kidney tissue of rats with diabetes. SD rats were randomly divided into control group and diabetes group. Diabetic nephropathy model was established by i.p. injection of streptozotocin (STZ). The rats were sacrificed separately on the 15th or 30th day after STZ injection. Biochemical parameters including blood glucose and renal function were examined. The expression of ACE2 in the kidney was detected by real-time PCR and Western blot. The contents of AngII in plasma and kidney were detected by radioimmunoassay. The results are as follows: (1) 48-72 h after STZ injection, the rats showed polyuria, polydipsia and their activity reduced. (2) Blood glucose levels were 4.9-6.5 mmol/L in the control rats, 14.0-17.5 mmol/L in the diabetes group rats on the 15th day, and higher than 24 mmol/L in the diabetes group rats on the 30th day; (3) There was a significant increase of urine glucose level (P < 0.05), and a slight but not significant increase of urine protein level (P > 0.05) in the diabetes group on the 15th day; On the 30th day, the levels of urine glucose and urine protein were significantly higher than those in the control group (P < 0.01); (4) Compared with the control group, the expression of ACE2 mRNA was slightly increased (P > 0.05), and the expression of ACE2 protein was significantly increased (P < 0.05) in the rats of diabetic model group on the 15th day; however, on the 30th day, ACE2 mRNA expression in the rats of diabetic model group was significantly lower than the control group (P < 0.05), and the expression of ACE2 protein was slightly lower than the control group (P = 0.0718). (5) Compared with the control group, the levels of AngII in plasma and kidney of the diabetic rats increased slightly on the 15th day (P > 0.05); while the AngII levels in diabetic model group rats were significantly higher (P < 0.05) than that in control rats on the 30th day. These results suggest that ACE2 plays a positive role in the protection against the pathogenesis of early renal damage. ACE2 expression is reduced gradually with the deepened degree of diabetic kidney damage, leading to the accumulation of AngII in the kidney, thereby increasing the renal injury.
Angiotensin II ; blood ; metabolism ; Animals ; Blood Glucose ; Diabetes Mellitus, Experimental ; enzymology ; physiopathology ; Diabetic Nephropathies ; enzymology ; physiopathology ; Kidney ; enzymology ; physiopathology ; Peptidyl-Dipeptidase A ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo explore the effect of Zhenqing Recipe (ZQR) on renal structure and expressions of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in experimental type 2 diabetic rats.

METHODSThe rat models of type 2 diabetic were set up by intraperitoneally giving small-dose streptozotocin (STZ) after fed with high carbohydrate and high fat diets for one month. The model rats were randomly divided into the model group,the high and low dose ZQR-treated groups,and the enalapril-treated group; a normal control group was also established. The course of treatment continued 8 weeks. The expressions of MMP-9, TIMP-1, and fibronectin (FN) in renal tissues were detected by immunohistochemistry. The morphological changes of glomeruli and renal tubules were checked by microscopy.

RESULTSCompared with the normal control group, the expression of TIMP-1 and FN increased and MMP-9 decreased in the model group; the treated groups could decrease the expressions of TIMP-1 and FN, and increase the expression of MMP-9, especially the high-dose ZQR group had the best effect. The morphological changes of renal tubules and glomerulus in the treated groups were improved better as compared with the model group.

CONCLUSIONThe protective effect of ZQR on renal structure may be achieved by modulating the expressions of MMP-1 and TIMP-1.

Animals ; Diabetes Mellitus, Experimental ; enzymology ; metabolism ; prevention & control ; Diabetes Mellitus, Type 2 ; enzymology ; metabolism ; prevention & control ; Drugs, Chinese Herbal ; pharmacology ; Fibronectins ; metabolism ; Kidney ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Protective Agents ; pharmacology ; Rats ; Tissue Inhibitor of Metalloproteinase-1 ; metabolism

OBJECTIVETo investigate the effects of gastric bypass surgery(GBP) on hepatic phosphoenolpyruvate carboxykinase(PEPCK) mRNA expression in type 2 diabetic Goto-Kakizaki rats.

METHODSMale GK rats were randomized into three groups: gastric bypass surgery(n=10), sham operation with diet restriction(n=10), and sham operation alone(n=10). Liver specimens of GK rats were collected during the intraoperative period for self-control study and 8 weeks after surgery. Fasting blood glucose, food intake, and body weight were recorded before surgery and 1, 2, 4, 8 weeks after surgery. The expression of PEPCK mRNA was measured by real-time PCR.

RESULTSThe fasting plasma glucose level decreased from(17.6±2.1) mmol/L before surgery to(7.5±0.9) mmol/L 8 weeks after surgery in GBP group. The level of PEPCK mRNA decreased from 1.08±0.38 before surgery to 0.41±0.10 8 weeks after surgery, significantly lower than that in sham operation alone group(1.04±0.12)(P<0.01). The level of PEPCK mRNA in diet restriction group increased from 1.15±0.16 before surgery to 2.54±0.82 8 weeks after surgery(P<0.01). The expression of PEPCK mRNA in diet restriction was significantly higher than that in CBP group(P<0.01).

CONCLUSIONSGBP can significantly improve hyperglycemia in type 2 diabetic GK rat models, which may be associated with the decrease of hepatic PEPCK mRNA level.

Animals ; Blood Glucose ; analysis ; Diabetes Mellitus, Experimental ; enzymology ; surgery ; Diabetes Mellitus, Type 2 ; enzymology ; surgery ; Gastric Bypass ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Liver ; enzymology ; Male ; Phosphoenolpyruvate Carboxykinase (GTP) ; genetics ; metabolism ; RNA, Messenger ; genetics ; Rats

OBJECTIVETo observe the change of neuronal nitric oxide synthase (nNOS) expression in the spinal cord of diabetic rats with painful diabetic neuropathy.

METHODSSixty SD rats were randomized equally into painful diabetic neuropathy group (DM group) and control group. Painful diabetic neuropathy was induced by intraperitoneal injection with STZ (60 mg/kg) in DM group, and the rats in the control group received a solvent injection. Blood glucose levels were measured before and at 2, 7, 14, 21, and 28 days after STZ injection (T1-6 respectively). Responses to the mechanical stimulus were measured with von Frey filament, and 50% paw withdraw threshold (PWT) and body weight were recorded at T1 and T3-6. At T1 and T3-6, 6 rats from each group were sacrificed to examine the expression of nNOS in the lumbar segments of the spinal cord using Western blotting.

RESULTSThe level of blood glucose increased while the body weight decreased significantly after STZ injection in DM group (P<0.05). Comparing to those in the control group, PWT decreased while spinal nNOS expression increased significantly in DM group at T4-6 (P<0.05) showing an inverse correlation between them (P<0.01).

CONCLUSIONThe enhanced expression of spinal nNOS might be involved in the pathogenesis of painful diabetic neuropathy in rats.

Animals ; Blood Glucose ; Diabetes Mellitus, Experimental ; enzymology ; Diabetic Neuropathies ; enzymology ; Nitric Oxide Synthase Type I ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; enzymology

OBJECTIVETo explore the effect of irbesartan on angiotensin-converting enzyme 2 (ACE2) mRNA expression in diabetic rat myocardium.

METHODSThirty 8-week-old male Wistar rats were randomly divided into control group (n=7), diabetic model group (n=14) and irbesartan group (n=9). Diabetes was induced by a single intraperitoneal injection of STZ (55 mg/kg), a blood glucose>16.7 mmol/L 72 h after the injection indicated successful establishment of diabetes. Four weeks after the modeling, the rats in irbesartan group were given 50 mg/kg irbesartan. ELISA was used to measure myocardial AngII content in the rats, and myocardial ACE2 mRNA expression was determined by real-time PCR.

RESULTSMyocardial AngII level in the diabetic model group was significantly higher than that in the control group (P<0.001). Irbesartan administration significantly lowered cardiac AngII levels in the diabetic rats (P<0.001). The rats in irbesartan group showed significantly increased myocardial ACE2 mRNA expression compared with those in the control and diabetic rat groups (P<0.05).

CONCLUSIONIrbesartan can increase ACE2 mRNA expression in the myocardium, which might be one of the mechanisms underlying its effect in improving the cardiac function in diabetic rats.

Animals ; Biphenyl Compounds ; pharmacology ; Diabetes Mellitus, Experimental ; enzymology ; Male ; Myocardium ; enzymology ; Peptidyl-Dipeptidase A ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Wistar ; Tetrazoles ; pharmacology

Diabetes mellitus is caused by deficiency of insulin secretion from the pancreatic islet beta cells and/or insulin resistance in liver, muscle and adipocytes, resulting in glucose intolerance and hyperglycemia. Several protein tyrosine phosphatases, such as PTP1B (PTPN1), TCPTP (PTPN2), LYP (PTPN22), PTPIA-2, PTPMEG2 (PTPN9) or OSTPTP are involved in insulin signaling pathway, insulin secretion and autoreactive attack to pancreatic beta cells. Genetic mutation or overexpression of these phosphotases has been found to cause or increase the risk of diabetes mellitus. Some population with high risk for type 2 diabetes has overexpressed PTP1B, a prototypical tyrosine phosphatase which down-regulates insulin and leptin signal transduction. Animal PTP1B knockout model and PTP1B specific inhibitor cellular studies indicate PTP1B may serve as a therapeutic target for type 2 diabetes. TCPTP shares more than 70% sequence identity with PTP1B in their catalytic domain. TCPTP dephosphorylates tyrosine phosphorylated substrates overlapping with PTP1B but also has its own distinct dephosphorylation sites and functions. Recent research indicates TCPTP may have role in type 1 diabetes via dysregultaion of cytokine-mediated immune responses or pancreatic beta cell apoptosis. The tyrosine phosphatase LYP, which down-regulates LCK activity in T cell response, can become mutated as R620W which is highly correlated to type 1 diabetes. LYP R620W may be a gain of function mutation which suppresses TCR signaling. Patients bearing the R620W mutant have impaired T cell responses and increased populations of (CD45RO+CD45RA-) CD4+ T cells. A detailed elucidation of mechanism of R620W in type 1 diabetes and specific LYP inhibitor development will help characterize LYP R620W as a therapeutic target. A receptor tyrosine phosphatase, PTPIA-2/beta is a major autoantigen of type 1 diabetes. A diagnosis kit identifying PTPIA-2/beta autoantibodies is valuable in early detection and prevention of type 1 diabetes. In addition, other phosphatase like OSTPTP and PTPMEG2 are involved in type 2 diabetes via regulation of insulin production, beta cell growth or insulin signaling. Research into understanding the mechanism of these tyrosine phosphatases in diabetes, such as their precise functions in the regulation of insulin secretion, the insulin response and the immune response will strengthen our knowledge of diabetes pathophysiology which may result in new diagnostic and therapeutic strategies for diabetes.
Animals ; Diabetes Mellitus ; enzymology ; Diabetes Mellitus, Type 1 ; enzymology ; Diabetes Mellitus, Type 2 ; enzymology ; Humans ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 2 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; genetics ; metabolism ; Protein Tyrosine Phosphatases, Non-Receptor ; classification ; genetics ; metabolism

OBJECTIVETo investigate the influence and significance of gastric bypass surgery on hepatic gluconeogenesis in type 2 diabetic Goto Kakizaki(GK) rats.

METHODSForty GK rats were randomly divided into Roux-en-Y gastric bypass group(group A) and sham operation group(group B). Differences in glucose tolerance experiment(OGTT) at preoperative and postoperative 1, 2 and 4 weeks were compared and weight was recorded. Glycated hemoglobin levels were measured preoperatively and 4 weeks postoperatively. The animals were sacrificed 4 weeks after surgery and liver tissues were harvested to detect the relative expression of mRNA and protein of glucose 6 phosphatase(G-6-P) and phosphoenol pyruvate kinase(PEPCK) with RT-PCR and Western blot.

RESULTSFasting blood glucose levels were 6.5, 4.9, and 4.7 mmol/L in group A, and were 10.3, 10.4, and 12.5 mmol/L in group B, and the differences between two groups were statistically significant(P<0.05). The blood glucose level at 2 h after stomach lavage were 8.3, 6.4 and 5.5 mmol/L in group A, and were 21.4, 23.8 and 24.7 mmol/L in group B at postoperative 1, 2, 4 weeks, and the differences between two groups were statistically significant(P<0.05). The glycosylated hemoglobin at postoperative 4 weeks was(6.8±1.0)%, significantly lower than that in group B[(7.9±0.8)%, P<0.05]. Hepatic G-6-P and PEPCK mRNA relative expression at postoperative 4 weeks was reduced by 21.0% and 25.9% respectively as compared to group B, and the protein expression reduced as well. Immunohistochemistry showed that hepatic glycogen sedimentary in group A increased significantly.

CONCLUSIONThe relative mRNA and protein level of key enzymes of hepatic gluconeogenesis are significantly decreased after Roux-en-Y gastric bypass surgery and hepatic gluconeogenesis is reduced, which may be a potential mechanism of the decrease of blood glucose.

Animals ; Blood Glucose ; analysis ; Diabetes Mellitus, Experimental ; metabolism ; surgery ; Diabetes Mellitus, Type 2 ; metabolism ; surgery ; Gastric Bypass ; Gluconeogenesis ; Glucose-6-Phosphatase ; metabolism ; Glycated Hemoglobin A ; metabolism ; Intracellular Signaling Peptides and Proteins ; metabolism ; Liver ; enzymology ; Male ; Phosphoenolpyruvate Carboxykinase (GTP) ; metabolism ; Rats

BACKGROUNDBariatric surgery offers a productive resolution of type 2 diabetes mellitus (T2DM). The development of T2DM vasculopathy is due to chronic inflammation, which increases matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) expression. This study sought to examine MMP-9 and TIMP-1 expression in the thoracic aorta after duodenal-jejunal bypass (DJB) surgery on a T2DM rat model induced by a high-fat diet and low dose streptozotocin (STZ).

METHODSTwenty-one T2DM Wistar rats induced by high-fat diet and low dose STZ were randomly divided into DJB and sham duodenal-jejunal bypass (S-DJB) groups. Ten Wistar rats were fed a normal diet as a control. Recovery of gastrointestinal function post-operation and resumption of a normal diet completed the experiment. Body weight, blood glucose, blood lipid levels, and MMP-9 and TIMP-1 expression levels in aortic endothelial cells were measured throughout.

RESULTSDJB rats showed significant weight loss 2 weeks post-operation compared with S-DJB rats. After surgery, DJB rats showed significant improvement and steady glycemic control with improved insulin sensitivity and glucose tolerance. They also exhibited improved lipid metabolism with a decrease in fasting free fatty acids (FFAs) and triglycerides (all P < 0.05). Immunohistochemistry showed decreased MMP-9 and TIMP-1 expression 12 weeks after surgery (P < 0.01).

CONCLUSIONSDJB surgery on an induced T2DM rat model improves blood glucose levels and lipids, following a high-fat diet and low dose STZ treatment. In addition, DJB decreased MMP-9 and TIMP-1 expression in vascular endothelial cells, which may play an important role in delaying the development of T2DM vascular disease.

Animals ; Aorta, Thoracic ; metabolism ; Bariatric Surgery ; Body Weight ; physiology ; Diabetes Mellitus, Type 2 ; enzymology ; Male ; Matrix Metalloproteinase 1 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Rats