Melatonin restores the basal level of lipid peroxidation in rat tissues exposed to potassium bromate in vitro.
OBJECTIVE
Potassium bromate (KBrO3) is a prooxidant and carcinogen. Melatonin is a highly effective antioxidant. Indole-3-propionic acid (IPA; indole substance) and propylothiouracil (PTU; antithyroid drug) reveal some antioxidative effects. The aim of the study was to evaluate KBrO3-induced lipid peroxidation (LPO) in vitro in tissues collected from control or melatonin-treated rats, and to compare potential preventive effects of melatonin, IPA and PTU.


METHODS
Kidney, liver and lung homogenates from either control or melatonin-pretreated rats (0.0645 mmol/kg b.w., i.p., twice daily, 10 days) were incubated in the presence of KBrO3 (0.1, 0.5, 1.0, 2.5, 5.0, 10.0 mM). Then, control lung homogenates were incubated with KBrO3 (10.0 mM) together with melatonin (0.01, 0.1, 0.5, 1.0, 5.0, 7.5 mM), or with IPA or with PTU. LPO products (malondialdehyde+4-hydroxyalkenals) were measured spectrophotometrically.


RESULTS
Melatonin injections prevented KBrO3-induced LPO in lung homogenates. Melatonin, IPA and PTU, used in vitro, reduced KBrO3-induced LPO in control lungs. Unexpectedly, KBrO3 caused a concentration-dependent decrease in LPO in liver and kidney homogenates from control but not from melatonin-treated rats.


CONCLUSIONS
Potassium bromate-induced LPO in the rat lung homogenates suggests that the lung may be the target for this carcinogen. An exposure of organisms to melatonin decreases tissue sensitivity to KBrO3-induced damage, possibly by restoring the oxidative balance.
Stasiak
Magdalena
M
Department of Endocrinology and Metabolic Diseases, Polish Mother's Memorial Hospital - Research Institute of Lodz, Lodz, Poland. MKarbownik@hotmail.com
Zasada
Krzysztof
K
Lewinski
Andrzej
A
Karbownik-Lewinska
Małgorzata
M
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001959:Bromates / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats
D000975:Antioxidants; D001959:Bromates; D007211:Indoles; C019536:potassium bromate; D011441:Propylthiouracil; C015292:indolepropionic acid; D008550:Melatonin