Decreased melatonin synthesis in patients with coronary artery disease

Aims Decreased night-time plasma levels of melatonin were recently reported in patients with coronary artery disease, and it was postulated that melat onin production may be impaired, due to a lack of synthesizing enzymes. How ever, since artefacts possibly influencing the release pattern were not tak en into account, this interpretation was strongly criticized. We therefore carefully investigated night-time melatonin production in patients with cor onary artery disease using an appropriate experimental approach. Furthermor e, we examined the effect of beta-blockers, a frequently used drug in coron ary artery disease therapy. Methods and Results Forty-eight male patients with angiographically documen ted severe coronary artery disease, 24 of them taking beta-blockers daily i n therapeutic dosages, were included. Eighteen age-matched men, with no evi dence of coronary sclerosis, served as controls. To determine melatonin pro duction, 6-sulfatoxymelatonin (aMT6s) was measured radioimmunologically fro m overnight urine. Urinary aMT6s concentration was significantly decreased in patients, and beta-blocker treatment did not further suppress melatonin production. Conclusions The data obtained using this investigative approach provide cle arcut evidence that melatonin production in patients with corollary artery disease is decreased. Whether a decreased melatonin level may be a predispo sing factor for coronary artery disease, or whether the occurrence of coron ary artery disease decreases melatonin synthesis remains to be determined.