Despite the well demonstrated role of both pituitary and pineal glands in the regulation of the endocrine system, the knowledge of the functional relation between hypothesis and epiphysis is one of the less established aspect of the human physiology, particularly in the case of pituitary tumors, even though the inhibitory effect of the pineal on tumor cell proliferation has been con????irmed by several experimental conditions. The present study was carried out to study the effects of a chronic administration of the most investigated pineal hormone, melatonin (MLT) in patients with hypophyseal tumors, which did not respond to the conventional therapies. The study included 14 patients (prolactinoma:6; acromegaly:5; ACTH secreting tumor:2; chromophore tumour:1), who were compared with a control group of 50 healthy subjects. The pineal function was evaluated by measuring the daily and nightly urinary excretion of the mail MLT metabolite, the sulfatoxymelatonin (6-MTS). Patients affected by pituitary tumors showed signi????icantly higher mean values of 6-MTS during the light phase of the day than controls, whereas no difference was found in the night mean values. After an oral administration of MLT at a pharmacological dose of 20 mg/day in the late evening for 3 consecutive months, GH and PRL mean values decreased on MLT therapy in acromegaly and prolactinoma patients, respectively, without, however, signi????icant differences. Moreover, a rapid normalization of ACTH levels was achieved in one of the two patients suffering from ACTH secreting tumor. Hypophyseal tumor dimension remained substantially unchanged on study. These preliminary results would suggest an enhanced pineal function with loss of its physiological circadian rhythmicity in patients suffering from pituitary tumors and that the pineal hormone may potentially display an inhibitory effect on pituitary tumor cell proliferation, including patients with pituitary tumors for whom no other effective conventional therapy may be available.
Keywords: Melatonin, Pineal gland, Pituitary tumors
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Copyright: © 2019 Lissoni P, et al. This is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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