Long-term melatonin treatment reduces ovarian mass and enhances tissue antioxidant defenses during ovulation in the rat

Author(s):Show less -

Chuffa, L. G. A. ^{[1, 2]} ; Amorim, J. P. A. ^{[1, 2]} ; Teixeira, G. R. ^[1] ; Mendes, L. O. ^{[1, 2]} ; Fioruci, B. A. ^{[1, 2]} ; Pinheiro, P. F. F. ^[1] ; Seiva, F. R. F. ^[3] ; Novelli, E. L. B. ^[3] ; Mello Junior, W. ^[1] ; Martinez, M. ^[4] ; Martinez, F. E. ^[1]

Affiliation

^[1] Univ Estadual Paulista, Inst Biociencias, Dept Anat, BR-18618000 Botucatu, SP - Brazil

^[2] Univ Estadual Campinas, Inst Biol, Programa Posgrad Biol Celular & Estrutural, Campinas, SP - Brazil

^[3] Univ Estadual Paulista, Inst Biociencias, Dept Quim & Bioquim, BR-18618000 Botucatu, SP - Brazil

^[4] Univ Fed Sao Carlos, Dept Morfol & Patol, BR-13560 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Brazilian Journal of Medical and Biological Research; v. 44, n. 3, p. 217-223, MAR 2011.
• Web of Science Citations: 23

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 mu g.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. (AU)