title: Long-term melatonin treatment reduces ovarian mass and enhances tissue antioxidant defenses during ovulation in the rat.
abstract: Melatonin regulates the reproductive cycle, energy metabolism and may also act as a potential antioxidant indoleamine. The present study was undertaken to investigate whether long-term melatonin treatment can induce reproductive alterations and if it can protect ovarian tissue against lipid peroxidation during ovulation. Twenty-four adult female Wistar rats, 60 days old (± 250-260 g), were randomly divided into two equal groups. The control group received 0.3 mL 0.9% NaCl + 0.04 mL 95% ethanol as vehicle, and the melatonin-treated group received vehicle + melatonin (100 µg·100 g body weight(-1)·day(-1)) both intraperitoneally daily for 60 days. All animals were killed by decapitation during the morning estrus at 4:00 am. Body weight gain and body mass index were reduced by melatonin after 10 days of treatment (P < 0.05). Also, a marked loss of appetite was observed with a fall in food intake, energy intake (melatonin 51.41 ± 1.28 vs control 57.35 ± 1.34 kcal/day) and glucose levels (melatonin 80.3 ± 4.49 vs control 103.5 ± 5.47 mg/dL) towards the end of treatment. Melatonin itself and changes in energy balance promoted reductions in ovarian mass (20.2%) and estrous cycle remained extensive (26.7%), arresting at diestrus. Regarding the oxidative profile, lipid hydroperoxide levels decreased after melatonin treatment (6.9%) and total antioxidant substances were enhanced within the ovaries (23.9%). Additionally, melatonin increased superoxide dismutase (21.3%), catalase (23.6%) and glutathione-reductase (14.8%) activities and the reducing power (10.2% GSH/GSSG ratio). We suggest that melatonin alters ovarian mass and estrous cyclicity and protects the ovaries by increasing superoxide dismutase, catalase and glutathione-reductase activities.
authors.affiliation: Programa de Pós-Graduação em Biologia Celular e Estrutural, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brasil.
authors.forename: L G A
authors.initials: LG
authors.lastname: Chuffa
authors.forename: J P A
authors.initials: JP
authors.lastname: Amorim
authors.forename: G R
authors.initials: GR
authors.lastname: Teixeira
authors.forename: L O
authors.initials: LO
authors.lastname: Mendes
authors.forename: B A
authors.initials: BA
authors.lastname: Fioruci
authors.forename: P F F
authors.initials: PF
authors.lastname: Pinheiro
authors.forename: F R F
authors.initials: FR
authors.lastname: Seiva
authors.forename: E L B
authors.initials: EL
authors.lastname: Novelli
authors.forename: W
authors.initials: W
authors.lastname: Mello Júnior
authors.forename: M
authors.initials: M
authors.lastname: Martinez
authors.forename: F E
authors.initials: FE
authors.lastname: Martinez
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D002374:Catalase / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005979:Glutathione Peroxidase / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D009929:Organ Size / Q000187:drug effects; D010053:Ovary / Q000033:anatomy & histology / Q000187:drug effects* / Q000201:enzymology; D010060:Ovulation / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D000975:Antioxidants; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D008550:Melatonin