Melatonin involvement in oxidative processes.
The fact that the pineal gland, by its melatonin (MT) production, responds to environmental light variations (the day-night cycle), being also a modulator of the body adaptation to these conditions, may lead to the assumption of its involvement in the body oxidative processes. The redox capacity of melatonin was followed-up in vitro by the chemiluminescence phenomenon. The system generating chemiluminescence as well as free radicals was made up of luminol and H2O2. Incubation of melatonin in doses of 0.08-0.5 microM/ml with the generating system showed that in doses under 0.25 microM/ml melatonin has a pro-oxidative effect while in doses above this value it has an antioxidative effect. The diagram of the results shows the answer specific to a modulator. The study of the correlation between the dose of melatonin with highest pro-oxidative properties and the various peroxide concentrations in the generating system showed that melatonin gets antioxidative properties with the increase in peroxide concentrations (less than 8 mM/ml). In the presence of a hypothalamic homogenate, which is a stimulant of the chemiluminescence-generating system (PXI = 16), melatonin has a dose-dependent antioxidative effect. Similar results were also obtained by adding tryptophan--a free radicals acceptor (PXI = 0.1) and the substrate in melatonin synthesis to the reaction medium. Melatonin in low concentrations (greater than 0.1 microM/ml) has an antioxidative effect while in higher doses it has a dose-dependent pro-oxidative effect.(ABSTRACT TRUNCATED AT 250 WORDS)
Ianăş
O
O
C. I. Parhon Institute of Endocrinology, Bucharest, Romania.
Olinescu
R
R
Bădescu
I
I
D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004305:Dose-Response Relationship, Drug; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008550:Melatonin / Q000378:metabolism* / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D008550:Melatonin