Melatonin prevents hypochlorous acid‐induced alterations in microtubule and chromosomal structure in metaphase‐II mouse oocytes

Abstract

Hypochlorous acid (HOCl) is generated by myeloperoxidase, using chloride and hydrogen peroxide as substrates. Here we demonstrate that HOCl alters metaphase-II mouse oocyte microtubules and chromosomal (CH) alignment which can be prevented by melatonin. Metaphase-II mouse oocytes, obtained commercially, were grouped as: control, melatonin (150, 200nmol/mL), HOCl (10, 20, 50, and 100nmol/mL), and HOCl (50nmol/mL) pretreated with 150 and 200 nmol/mL of melatonin. Microtubule and CH alignment was studied utilizing an indirect immunofluorescence technique and scored by two observers. Pearson chi-square test and Fisher's exact test were used to compare outcomes between controls and treated groups and also among each group. Poor scores for the spindle and chromosomes increased significantly at 50nmol/mL of HOCl (P<0.001). Oocytes treated with melatonin only at 150 and 200 nmol/mL showed no changes; significant differences (P<0.001) were observed when oocytes exposed to 50nmol/mL of HOCl were compared to oocytes pretreated with 200 nmol/mL melatonin. Fifty percent of the oocytes demonstrated good scores, both in microtubule and CH alterations, when pretreated with melatonin at 150 nmol/mL compared to 0% in the HOCl-only group. HOCl alters the metaphase-II mouse oocyte spindle and CH alignment in a dose-dependant manner, which might be a potential cause of poor oocyte quality (e.g., in patients with endometriosis). Melatonin prevented the HOCl-mediated spindle and CH damage, and therefore, may be an attractive therapeutic option to prevent oocyte damage in endometriosis or inflammatory diseases where HOCl levels are known to be elevated.

Oxidative stress and ageing of the post-ovulatory oocyte

“…These effects are presumably a direct result of relief from oxidative stress, as melatonin-treated aged oocytes exhibited significantly reduced levels of ROS (Lord et al 2013). Further to this, previous studies have highlighted the ability of melatonin to reverse the deleterious effects of H 2 O 2 treatment on MII oocytes (Tamura et al 2008) and prevent hypochlorous acid-induced abnormalities in chromosomes and microtubules (Banerjee et al 2012). Importantly, melatonin has a lack of demonstrable toxicity (Jahnke et al 1999), making it a primary candidate for utilization in an assisted reproduction setting.…”

Melatonin Prevents Myeloperoxidase Heme Destruction and the Generation of Free Iron Mediated by Self-Generated Hypochlorous Acid

“…iron (III), copper and zinc), and subsequently reduce their cytoplasmic availability [61][62][63]. In addition, several in vivo studies have shown that administration of MLT directly or indirectly neutralizes a variety of ROS, resulting in the reduction of lipid peroxidation, protein oxidation, and DNA damage, thus helping the immune system [11,[62][63][64][65]. One other factor that distinguishes MLT from other HOCl scavengers (e.g.…”

“…In humans, as in most vertebrates, MLT operates as a modulator of circadian rhythms, and displays an oscillatory pattern through its unique ability to function as a signal, which organisms use to synchronize their circadian systems [3,5,6]. Multiple studies have shown that when MLT is administered either exogenously in vivo or when added to cultured cells via regulation of cellular pathways [3,[7][8][9][10][11] MLT has the ability to scavenge a wide range of reactive oxygen species (ROS) through its distinct antioxidant and anti-inflammatory effects [3,[7][8][9][10][11].The effects and action mechanisms of MLT belong to or take part in many different cell types including inflammatory cells such as monocytes-macrophages, neutrophils, eosinophils, basophils, mast cells, and natural killer cells [10,12]. Therefore, various doses of synthetic MLT supplements have been used to treat a variety of medical scenarios in which inflammation plays a role such as a weakened immune system due to stress, oxidative hemolysis of red blood cells, and cancer progression [13][14][15].…”

Melatonin Scavenger Properties against Oxidative and Nitrosative Stress: Impact on <em>In Vitro</em> Embryo Production in Mammals

“…In mammalian oocytes, melatonin can prevents the damage generated by hypochlorous acid (HOCl) on spindle microtubule and chromosome alteration in metaphase-II mouse oocytes [114], it can upregulates MnSOD [77,115] and Cu-ZnSOD transcripts in cumulus cells [77], it decreases ROS levels in oocytes [77], it can suppress Bax protein expression and decreases Bax/Bcl-2 ratio in ovaries [115], prevents DNA damage [116] and decreases nuclear fragmentation in cumulus cells [77]. In human, long term treatments with melatonin reduce ovarian aging, increasing litter size, pool of follicles and telomere length [115].…”