title: Comparison of potential protective effects of melatonin and propylthiouracil against lipid peroxidation caused by nitrobenzene in the thyroid gland.
abstract: BACKGROUND
  Nitrobenzene is a carcinogen, which induces-among others-thyroid tumors. Melatonin is an effective antioxidant, whereas some antioxidative effects of propylthiouracil (PTU; an antithyroid medication used for the treatment of thyrotoxicosis) were also found. The aim of the study was to compare protective effects of melatonin and PTU against lipid peroxidation in homogenates of porcine thyroids, incubated in the presence of nitrobenzene.
  
  
  METHODS
  Homogenates of porcine thyroids were incubated for 30 min in the presence of nitrobenzene (0.001, 0.01, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 7.5, and 10.0 mM). The level of lipid peroxidation products (malondialdehyde + 4-hydroxyalkenals) was measured spectrophotometrically. Nitrobenzene (7.5 and 10.0 mM) increased lipid peroxidation in the homogenates of porcine thyroids. Subsequently, homogenates of porcine thyroids were incubated for 30 min in the presence of nitrobenzene (7.5 mM) plus one of the antioxidants: melatonin (0.000001, 0.00001, 0.0001, 0.001, 0.01, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, and 7.5 mM) or PTU (0.01, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, and 7.5 mM).
  
  
  RESULTS
  Lipid peroxidation caused by nitrobenzene was effectively prevented by melatonin, with the lowest effective concentration of 0.0001 mM, being only two orders of magnitude higher than physiological blood concentration in humans. At the same time, PTU revealed protective effects only in the highest used concentration (7.5 mM), which is practically never reached during pharmacological treatment in patients with thyrotoxicosis.
  
  
  CONCLUSIONS
  Melatonin can serve as an effective agent in protection against nitrobenzene-induced lipid peroxidation in porcine thyroid.
authors.affiliation: Department of Oncological Endocrinology, Medical University of Lodz, Lodz, Poland Polish Mother's Memorial Hospital, Research Institute, Lodz, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Zasada
authors.affiliation: Department of Oncological Endocrinology, Medical University of Lodz, Lodz, Poland Polish Mother's Memorial Hospital, Research Institute, Lodz, Poland MKarbownik@hotmail.com.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Karbownik-Lewinska
mesh_terms: D000003:Abattoirs; D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology; D013956:Antithyroid Agents / Q000494:pharmacology; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D002273:Carcinogens / Q000037:antagonists & inhibitors* / Q000633:toxicity; D002474:Cell-Free System / Q000187:drug effects / Q000378:metabolism; D002863:Chromogenic Compounds / Q000737:chemistry; D007211:Indoles / Q000737:chemistry; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008315:Malondialdehyde / Q000737:chemistry / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D009578:Nitrobenzenes / Q000037:antagonists & inhibitors* / Q000633:toxicity; D009994:Osmolar Concentration; D011441:Propylthiouracil / Q000494:pharmacology*; D034421:Sus scrofa; D013961:Thyroid Gland / Q000187:drug effects* / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; D000975:Antioxidants; D013956:Antithyroid Agents; D015415:Biomarkers; D002273:Carcinogens; D002863:Chromogenic Compounds; D007211:Indoles; D009578:Nitrobenzenes; D008315:Malondialdehyde; D011441:Propylthiouracil; C036077:nitrobenzene; C520322:1-methyl-2-phenylindole; D008550:Melatonin
keywords: Lipid peroxidation; melatonin; nitrobenzene; propylthiouracil; thyroid