Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury.

Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

Repetitive hypoglycemia increases circulating adrenaline level with resultant worsening of intimal thickening after vascular injury in male Goto-Kakizaki rat carotid artery.

Hypoglycemia associated with diabetes management is a potential risk for cardiovascular diseases. However, the effect of hypoglycemic episodes including a surge of sympathetic activity on the progression of neointima formation after vascular injury remains largely unknown. In this study, insulin was injected intraperitoneally into nonobese diabetic Goto-Kakizaki (GK) rats, once every 3 days for 4 weeks after balloon injury of carotid artery to induce hypoglycemia. Then, we evaluated balloon injury-induced neointima formation. Insulin treatment enhanced neointima formation and increased the number of proliferating cell nuclear antigen (PCNA)-positive cells in the carotid artery. Injection of glucose with insulin prevented hypoglycemia and abrogated intimal thickening. Also, bunazosin, an α1 adrenergic receptor antagonist, prevented intimal thickening and accumulation of PCNA-positive cells induced by insulin treatment despite the presence of concomitant hypoglycemia and high adrenaline levels. Incubation of cultured smooth muscle cells with adrenaline resulted in a significant increase in their proliferation and G0/G1 to S phase progression, which was associated with activation of extracellular signal-regulated kinase, enhanced expression of cell cycle regulatory molecules such as cyclin D1, and cyclin E, and phosphorylation of retinoblastoma protein. These adrenaline-induced effects were abrogated by bunazosin. Our data indicated that increased adrenaline induced by repetitive hypoglycemia promotes intimal thickening and smooth muscle cell proliferation after endothelial denudation in GK rats.

Pulmonary thrombosis associated with antidiuretic hormone replacement therapy due to secondary diabetes insipidus after traumatic brain injury: A case report.

INTRODUCTION: Diabetes insipidus is a well-recognized complication of traumatic brain injury. The majority of patients with post-traumatic diabetes insipidus will require antidiuretic hormone (ADH) replacement therapy and tend to show dehydration. On the other hand, some negative effects of ADH on blood coagulation, such as increased platelet cohesion and the promotion of von Willebrand factor release, have also been reported. However, the incidence of thrombosis during antidiuretic hormone replacement therapy is disputed. PRESENTATION OF CASE: A case of pulmonary thrombosis associated with ADH replacement therapy due to secondary diabetes insipidus after traumatic brain injury is presented here. DISCUSSION: In our case, there were three factors that may have contributed to the observed thrombosis (dehydration, bed rest for a long period and ADH replacement therapy). CONCLUSION: We believe that controlling urinary output and monitoring urinary and serum osmotic pressure are necessary for the management for diabetes insipidus patients after traumatic brain injury. In particular, we must carefully monitor the management of such patients during antidiuretic hormone replacement therapy.

Anagliptin, a DPP-4 inhibitor, suppresses proliferation of vascular smooth muscles and monocyte inflammatory reaction and attenuates atherosclerosis in male apo E-deficient mice.

Dipeptyl peptidase-4 (DPP-4) inhibitors modulate the progression of atherosclerosis. To gain insights into their mechanism of action, 9-wk-old male apolipoprotein E (apoE)-deficient mice were fed a DPP-4 inhibitor, anagliptin-containing diet. The effects of anagliptin were investigated in, a monocyte cell line, human THP-1 cells, and rat smooth muscle cells (SMCs). Treatment with anagliptin for 16 wk significantly reduced accumulation of monocytes and macrophages in the vascular wall, SMC content in plaque areas, and oil red O-stained area around the aortic valve without affecting glucose tolerance or body weight. Serum DPP-4 concentrations were significantly higher in apoE-deficient mice than control mice, and the levels increased with aging, suggesting the involvement of DPP-4 in the progression of atherosclerosis. Indeed, soluble DPP-4 augmented cultured SMC proliferation, and anagliptin suppressed the proliferation by inhibiting ERK phosphorylation. In THP-1 cells, anagliptin reduced lipopolysaccharide-induced TNF-α production with inhibiting ERK phosphorylation and nuclear translocation of nuclear factor-κB. Quantitative analysis also showed that anagliptin reduced the area of atherosclerotic lesion in apoE-deficient mice. These results indicated that the anti-atherosclerotic effect of anagliptin is mediated, at least in part, through its direct inhibition of SMC proliferation and inflammatory reaction of monocytes.

Efficacy of pioglitazone on glycemic control and carotid intima-media thickness in type 2 diabetes patients with inadequate insulin therapy.

UNLABELLED: Aims/Introduction: The present study was designed to determine the effects of pioglitazone on glycemic control and atherosclerosis in patients with poorly controlled type 2 diabetes on insulin therapy. MATERIALS AND METHODS: The study was a prospective, randomized controlled trial involving 48 patients with inadequately controlled type 2 diabetes treated with insulin. We assigned patients to oral pioglitazone titrated from 15-30 mg (n = 22) or no pioglitazone (n = 26), to be taken in addition to their glucose-lowering drugs and other medications. Daily insulin doses and numbers were recorded during the study period. RESULTS: The adjusted mean glycosylated hemoglobin (HbA1c) values decreased significantly by 1.13 ± 1.50% and 0.55 ± 0.76% in the pioglitazone and control groups, respectively. Significant decrease of HbA1c level was observed in the pioglitazone group compared with the control group (P < 0.05). The insulin dose lowered by 0.04 ± 0.10 units/kg/day in the pioglitazone group and increased by 0.03 ± 0.10 units/kg/day in the control group (P < 0.05). The number of insulin injections decreased by 0.1 ± 0.6 times/day in the pioglitazone group and increased by 0.2 ± 0.4 times/day in the control group (P < 0.05). The carotid intima-media thickness estimated by B-mode echography was carried out in both groups and decreased significantly at the end-point only in the pioglitazone group, relative to the baseline. CONCLUSIONS: These findings show that pioglitazone is useful in improving glycemic control and preventing the progression of atherosclerosis in poorly-controlled type 2 diabetics on insulin therapy. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00064.x, 2010).

Efficacy and safety of modified Yale insulin infusion protocol in Japanese diabetic patients after open-heart surgery.

To our knowledge, there is currently no insulin infusion protocol for critically ill patients especially designed for Asian diabetics although many such protocols are used in Western countries. In this study, we modified the Yale insulin infusion protocol taking into consideration the characteristics of Japanese diabetics and hospital environment. We tested the modified protocol in 40 type 2 diabetic patients after elective open-heart surgery (MY group) comparing with 35 type 2 diabetic patients under empirical blood glucose control (EC group). Analyses of 1656 blood glucose measurements during insulin infusion revealed that percentage of samples that showed achievement of target blood glucose level (80-140 mg/dl) was higher under MY (78+/-15%, n=870) than EC (57+/-23%, n=786, p<0.0001). On the other hand, the percentage of samples in which blood glucose was less than 60 mg/dl was comparable in the two groups (MY: 0.5+/-5.9 per thousand, EC: 5.1+/-18.5 per thousand). None of the patients with hypoglycemia showed significant clinical adverse effects. In conclusion, our modified Yale insulin infusion protocol is effective and safe for tight blood glucose control in Japanese diabetic patients after open-heart surgery.