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

Braz J Med Biol Res. 2011 Mar;44(3):217-23. doi: 10.1590/s0100-879x2011007500018. Epub 2011 Feb 11.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants / administration & dosage
  • Antioxidants / pharmacology*
  • Catalase / drug effects
  • Catalase / metabolism
  • Female
  • Glutathione Peroxidase / drug effects
  • Glutathione Peroxidase / metabolism
  • Lipid Peroxidation / drug effects*
  • Melatonin / administration & dosage
  • Melatonin / pharmacology*
  • Organ Size / drug effects
  • Ovary / anatomy & histology
  • Ovary / drug effects*
  • Ovary / enzymology
  • Ovulation / drug effects*
  • Random Allocation
  • Rats
  • Rats, Wistar
  • Superoxide Dismutase / drug effects
  • Superoxide Dismutase / metabolism
  • Time Factors

Substances

  • Antioxidants
  • Catalase
  • Glutathione Peroxidase
  • Superoxide Dismutase
  • Melatonin