1-methylnicotinamide (MNA) is a primary metabolite of nicotinamide. In recent years several activities of MNA have been described, such as anti-inflammatory activity in skin diseases, induction of prostacyclin synthesis via COX-2, aortal endothelium protection in diabetes and hypertriglyceridaemia and increasing survival rate of diabetic rats. The aim of the present study was to verify whether the increased survival rate of diabetic animals could be explained by anti-hyperglycaemic activity of MNA and/or by its protective effects on vascular endothelium. We used Sprague-Dawley male rats with an experimental streptozotocin diabetes. The animals received either MNA or pure drinking water. At the particular time intervals groups of rats were sacrificed and the blood was collected. We have shown that MNA increases levels of PGI2 in diabetic rats, but the effect is limited only to the early stage of diabetes. We were unable to prove anti-inflammatory effects of MNA, as it did not affect increased TNF-alpha in diabetic animals. We have confirmed our previous observations that MNA improved survival of diabetic animals, but contrary to our previous study, this effect was not accompanied by improvement in the parameters of long-term glycaemic control. Overall, we conclude that anti-diabetic activity of MNA manifested in the improved lifespan of diabetic animals is rather due to MNA pro-prostacyclin activity, and it may not be substantially related to glycaemic control in diabetes. Still other potential mechanism(s) await further elucidation.
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