The Role of Melatonin in Fertility

Abstract

Melatonin is a versatile hormone with functional roles in antioxidant defence and circadian rhythms. Oxidative stress is associated with DNA, lipid and protein damage in the ovarian micro-environment. Sleep disturbances, as a result of circadian rhythm disruption, is correlated with miscarriages, increased time to become pregnant, and irregular menstrual cycles. Thus, the main purpose of this investigation was to examine melatonin, oxidative damage and circadian rhythms in COV434 granulosa cells and fertility patients. Hydrogen peroxide, antimycin A and ferrous sulfate were used to induce oxidative stress in COV434 cells. Cell growth rate and lipid peroxidation were measured using Sybr Green fluorescence readings and the thiobarbituric acid reactive substances assay respectively. An ELISA based method was used to measure follicular melatonin and oxidative DNA damage (8-OHdG), with anti-müllerian hormone levels predicting ovarian reserve. Sleep quality was determined using the Pittsburgh Sleep Quality Index. Fertility outcomes such as stage of oocyte maturation, embryo fragmentation, and fertilisation rates in recruited patients were tracked. COV434 cell growth rate decreased in a dose-dependent manner with hydrogen peroxide and antimycin A treatment. Melatonin pre-treatment, at a range of concentrations, did not protect against the decrease in cell growth rate induced by oxidative stress. COV434 cells were susceptible to lipid peroxidation when treated with ferrous sulfate, as malondialdehyde production increased significantly. Melatonin pre-treatment significantly decreased malondialdehyde levels when compared with cells treated with ferrous sulfate alone. A positive trend was observed between follicular 8-OHdG, and both follicular melatonin levels and ovarian reserve. However, both correlations were not significant. Overall sleep quality was good in all recruited patients, however due to low patient recruitment, it was difficult to draw valid conclusions in respect to melatonin, oxidative stress and fertility outcomes. In conclusion, oxidative stress was found to be detrimental to COV434 granulosa cells, with melatonin ameliorating this effect. Since granulosa cells play a pivotal role in oocyte development, damage or death to these cells can have harmful effects on fertility status. Data collected from the patient study did not produce significant results; however it demonstrated the importance of investigating melatonin, oxidative stress and circadian rhythms in human reproduction.