CARBON MONOXIDE MODULATES MELATONIN SYNTHESIS IN PORCINE PINEAL CELLS IN VITRO: A PRELIMINARY STUDY

Two main isoforms of heme oxygenase (HO-1 and HO-2), the main enzyme of heme metabolism, were identified in the pineal gland. This suggests possible interactions between the melatonin synthesis pathway and the HO system. The aim of this study was to investigate the participation of carbon monoxide (CO), an HO by-product, on the melatonin synthesis pathway. Tests were carried using primary cell cultures of porcine pineal glands. The tricarbonyldichlororuthenium (II) dimer (CORM-2) compound was used as a CO donor at concentrations of 1 and 3 mu M, as low concentrations of CORM-2 affect the regulation of the melatonin synthesis pathway in pineal cells in vitro. In addition, the presence of Sn-protoporphyrin-IX, an HO inhibitor, changed the melatonin response of pineal cells. These results suggest the existence of an intermediate mechanism in the pineal gland, which is associated with HO activity, that is involved in the modulation of melatonin synthesis.