engleski

Changes in neurofilament 200 and tyrosine hydroxylase expression in the cardiac innervation of diabetic rats during ageing

Changes in sensory and sympathetic innervation during diabetes mellitus (DM) can be predictor of arrhythmias, silent myocardial ischemia and chronic heart failure, but knowledge about these changes is still unsatisfactorily. We analysed whether prolonged DM induces changes in density of sensory and sympathetic nerve terminals of rat’s heart and whether it contributes to cardiomyopathy during ageing. DM was induced by i/p injecting 55 mg/kg streptozotocin (STZ) to male Sprague-Dawley rats, and was validated by measuring blood glucose level. Control group received citrate buffer. Animals were sacrificed after 2 weeks, 2 months, 6 months and 12 months. Five areas of cardiac sections were analyzed. Antibodies raised against Tyrosine Hydroxylase (TH) and Neurofilament 200 kDa (NF 200) were used to detect sympathetic and sensory fibers. TH immunoreactive fibers density increased in DM groups 2 weeks after induction, reaching peek after 2 months, while in later stages of DM (6 and 12 months) there was no significant difference compared to control. NF 200 immunoreactive fibers density increased 2 weeks after induction compared to control. There were no consistent pattern of changes during given period both in DM or control groups. In DM group, we found thickening of the left ventricle wall (LV) (P<0.05) as the sign of cardiomyopathy. Our findings suggest that hyperglycaemia as hallmark of DM in early stages can lead to proliferation of sympathetic and sensory nerve terminals. This finding can contribute to better understanding of occurrence of arrhythmias and silent myocardial ischemia in DM.

diabetes mellitus ; innervation ; neurofilament 200kDa ; tyrosine hydroxylase ; neuropathy

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