Melatonin affects gene expression of noradrenaline transporter and enzymes in the hearts of stressed rats.

The role of stress is important in the etiology of depression which subsequently affects cardiovascular regulation. There has been a lot of evidence of the beneficial effects of melatonin in various cardiovascular pathologies. We examined the effect of chronic melatonin treatment on noradrenaline content, synthesis, transport and degradation in the left atria and ventricle of rats exposed to chronic mild unpredictable stress (CUMS). Our results show that CUMS decreased expression of mRNA TH and NET in the left atria and COMT in the left ventricles, whereas increased MAO-A enzymes in the left ventricles. Melatonin treatment induced a significant increase in gene expression of NET in the atria and a decrease in MAO-A in the ventricle. The observed beneficial effects of enhanced uptake and reduced degradation during melatonin treatment were most probably a compensatory mechanism which protects cardiomyocytes from the deleterious effects of noradrenaline overstimulation. [ABSTRACT FROM AUTHOR]