title: Oxidized-LDL and Fe3+/ascorbic acid-induced oxidative modifications and phosphatidylserine exposure in human platelets are reduced by melatonin.
abstract: Low-density lipoprotein (LDL) modifications and platelet activation are major risk factors for cardiovascular diseases. When platelets are exposed to oxidative stress, they become activated. Oxidized LDL (ox-LDL) and metal-catalysed oxidation systems such as Fe3+/ascorbic acid increase free radical production. We wanted to verify whether melatonin has a protective effect against oxidative modifications and phosphatidylserine externalization in platelets induced by ox-LDL and Fe3+/ascorbic acid. For in vitro effects of melatonin on platelets, ADP-activated platelets were incubated with ox-LDL or Fe3+/ascorbic acid for 1 h at 37 degrees C with or without melatonin. Then platelet malondialdehyde, protein carbonyl and glutathione levels were measured. Platelet phosphatidylserine exposure was measured with annexin-V using flow cytometry. Malondialdehyde, protein carbonyl and phosphatidylserine levels of platelets treated with Fe3+/ascorbic acid significantly increased compared to the control group. Glutathione contents of Fe3+/ascorbic acid-treated platelets significantly decreased. Melatonin pre-treatment of Fe3+/ascorbic acid-treated platelets caused a mar ked reduction in malondialdehyde and phosphatidylserine levels and a marked increase in glutathione levels. Melatonin also caused non-significant reduction in protein carbonyl contents of Fe3+/ascorbic acid-treated platelets. Malondialdehyde, protein carbonyl and phosphatidylserine levels of platelets treated with ox-LDL also significantly increased compared to the control group. Platelet glutathione levels non-significantly decreased with ox-LDL. With addition of melatonin, malondialdehyde, protein carbonyl and phosphatidylserine levels of platelets treated with ox-LDL significantly decreased. These data suggest that melatonin may protect platelets from iron overload-induced and ox-LDL-induced oxidative modifications and also from the triggering signals of apoptosis activation, possibly due to its scavenger effect on toxic free radicals.
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Marmara University, Istanbul, Turkey. azizesener@hotmail.com
authors.forename: A
authors.initials: A
authors.lastname: Sener
authors.forename: D
authors.initials: D
authors.lastname: Ozsavci
authors.forename: O
authors.initials: O
authors.lastname: Bingol-Ozakpinar
authors.forename: O
authors.initials: O
authors.lastname: Cevik
authors.forename: G
authors.initials: G
authors.lastname: Yanikkaya-Demirel
authors.forename: T
authors.initials: T
authors.lastname: Yardimci
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism*; D005290:Ferric Compounds / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008315:Malondialdehyde / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects; D010718:Phosphatidylserines / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005290:Ferric Compounds; D008077:Lipoproteins, LDL; D010718:Phosphatidylserines; C099252:oxidized low density lipoprotein; D008315:Malondialdehyde; D005978:Glutathione; D008550:Melatonin; D001205:Ascorbic Acid