Influence of chronic ?-adrenoreceptor blocker treatment on melatonin secretion and sleep quality in patients with essential hypertension

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Abstract
The nocturnal production of melatonin synthesis has been associated with circadian mechanisms of the organization of sleep. It is well known that the synthesis of melatonin is under the control of pineal β1-adrenoreceptors. In this study the effect of ten weeks treatment with the β-adrenoreceptor (β-AR) blockers propranolol and ridazolol on melatonin synthesis and on sleep quality was examined in 42 patients suffering from essential hypertension. Before and after 6 and 10 weeks of β-AR-blocker administration urinary sulfatoxymelatonin excretion rates were measured and sleep factors were evaluated by using a standardized sleep inventory consisting of self-rating sleepiness scales. After 6 and 10 weeks of treatment, a significant about 50 percent reduction of sulfatoxymelatonin was measured. No relationship between these reductions and changes in sleep factors was found. The results indicate that a reduced nightly amplitude of melatonin has minor significance for the organization of physiological sleep. Furthermore, it is suggested that pineal mechanisms beside the β1adrenergic receptor transduction system serve to maintain the melatonin signal to a considerable extent during a chronic βl-AR blockade.