Sirtuin 1 as the mechanism of action of agents used in the diabetes mellitus pharmacotherapy.

SIRT1 (sirtuin 1, a member of histone deacetylase III family) is responsible for deacetylation of lysine in histones and the conservation of DNA in the state of transcriptionally inactive heterochromatin. SIRT1 is also capable of deacetylation of transcription factors, as well as other regulatory proteins. The SIRT1 activity plays a unique role in the prevention of metabolic memory, reducing many pathways leading to chronic diabetic complications or diseases concomitant with diabetes. Factors modifying expression and/or activity of SIRT1 may be especially helpful for patients with diabetes. This article attempts to sum up the current state of knowledge about agents commonly used in the treatment of type 2 diabetes which might have an impact on the SIRT1 expression and activity. It is the review of several studies regarding drug-induced pleiotropic activity and the way in which their interference with cellular pathways gives us better understanding of this activity, as well as the influence of therapy on the course of the disease.

The impact of dapagliflozin on glucose excursions related to early proatherogenic derangement in the aortic wall.

INTRODUCTION: Cardiovascular risk in the course of diabetes depends greatly on glycemic variability which is even more significant than chronic hyperglycemia. Optimal management of diabetes involves a multidisciplinary approach focused in particular on decreasing the risk of atherosclerosis. Therefore, our purpose was to evaluate the impact of dapagliflozin on glucose excursions and related proatherogenic changes in the aortic wall. METHODS AND MATERIALS: Animal model of type 2 diabetes rich-fat/STZ rats was used. Wistar rats were randomized into 3 groups: dapagliflozin-treated with glucose excursions, placebo-treated with glucose excursions and placebo-treated with stable diabetes. Dapagliflozin was administered once a day, 1 mg/kg, for 8 consecutive weeks. Glucose levels were measured twice a week at fasting and postprandially. The samples of aortas were taken for histopathological and immunochemistry examinations at the end of the experiment. The derangement in the aortic wall and the distribution of CD68+ cells in the aorta were considered early signs of atherosclerosis. RESULTS: Dapagliflozin reduced glucose excursion to the level characteristic for stable, well-controlled diabetes. It was related to a significant decrease in histopathological changes which were observed in the placebo-treated rats with glucose variability. Dapagliflozin significantly reduced also the accumulation of CD68+ macrophages in the aortic adventitia. CONCLUSION: Dapagliflozin provides not only mere beneficial regulation of metabolic status with the depletion of glucose variability, but is also helpful in the prevention of early atherosclerosis related to the course of diabetes type 2.

Simvastatin attenuates the aberrant expression of angiogenic factors induced by glucose variability.

AIM: Over the last few years, studies have indicated that fluctuant hyperglycemia is very likely to increase the risk of cardiovascular complications of diabetes. Statins are widely used in diabetes for the prevention of cardiovascular complications, but it is still not clear whether simvastatin could also prevent glycaemic variability - induced aberrant angiogenesis which plays a significant role in the development of atherosclerosis. METHODS: Wistar rats were divided into four groups: (1) simvastatin-treated (20 mg/kg for 8 consecutive weeks) type 2 diabetes rat model with daily glucose excursions, (2) placebo-treated type 2 diabetes rat model with daily glucose excursions, (3) placebo-treated stable well-controlled type 2 diabetes rat model and (4) placebo-treated non-diabetic rats. Daily glucose fluctuations and several angiogenic factors: cVEGF, mRNA VEGF, VEGF-R1, VEGF-R2, TGF-beta expression, circulating endothelial and progenitor endothelial cells were measured in all groups. RESULTS: Simvastatin decreased several factors enhanced by glucose excursions: circulating VEGF, mRNA TGF-beta expression in the myocardium and mRNA VEGFR-2 expression in the aorta. Simvastatin increased some factors attenuated by glucose fluctuations: mRNA VEGF expression and mRNA VEGFR-1 expression in the myocardium and in the aorta. In the simvastatin-treated group with glycaemic variability, the percentage of circulating endothelial cells was lower and the percentage of progenitor endothelial cells in peripheral blood was higher than in the placebo-treated rats with glucose-fluctuations. CONCLUSIONS: Simvastatin used in the rat model of type 2 diabetes with glucose variability reduces glucose variability and limits glucose fluctuations-induced changes in the expression of angiogenic factors in the cardiovascular system.