Thein vitroeffects of melatonin on human sperm function and its scavenging activities on NO and ROS

Abstract

Various systems of antioxidants exist endogenously in the body to help protect it against free radical damage by scavenging excessive ROS and RNS. Melatonin, a hormone secreted by the pineal gland, and responsible for controlling the circadian rhythm, is one such endogenous antioxidant. Melatonin has been reported to be present in human seminal fluid, but its antioxidant activities in semen are rather contradictory. This study aimed at establishing the effects of melatonin treatment on human spermatozoa. Spermatozoa were incubated with 2 mm melatonin (120 min, 37 degrees C, 5% CO(2)) after which motility parameters were measured by computer aided motility analysis, while cell viability (PI), intracellular NO (DAF-2/DA) and ROS (DCFH-DA) were assessed using flow cytometry. In vitro melatonin treated samples (n = 12) showed a significantly higher percentage of motile, progressive motile and rapid cells, while simultaneously reducing the number of nonviable spermatozoa when compared with the control. Endogenous NO was significantly decreased, but no effect was observed on ROS levels. From these results, it can be concluded that melatonin was able to directly or indirectly scavenge NO, as indicated by the reduction in 4,5-diaminofluorescein-2/diacetate fluorescence. Future studies will indicate whether melatonin treatment during sperm preparation techniques could protect spermatozoa from excessive NO production.

Evidences for the Role of Melatonin as a Protective Additive During Buffalo Semen Freezing

“…Addition of 0.1 mM melatonin to the semen diluent is sufficiently effective to improve buffalo spermatozoa fertilizing ability and in vitro fertilizing potentials. These results came in agreement with (Fujinoki, 2008;Du Plessis et al, 2010;Succu et al, 2011) who reported that in vitro melatonin addition to hamster, human and ram spermatozoa, respectively had beneficial effects on their total progress motility. Moreover, Succu et al (2011) reported that those effects of melatonin might be built on its role in enhancing the total ATP level in the sperm cells after treatment.…”

“…Additionally, melatonin at 0.1 mM enhanced the acrosomal integrity and viability index of buffalo sperm cells. This melatonin improving effect might be due to a potent scavenging effect of melatonin on NO and Reactive Oxygen Species (ROS) that directly and indirectly affect the sperm viability by triggering the sperm apoptosis (Du Plessis et al, 2010;Espino et al, 2011). Therefore, the beneficial effect of melatonin on the freezability and in vitro fertilizing potentials may be attributed to its positive effect on antioxidant enzymes.…”

Melatonin: A pleiotropic molecule regulating inflammation

“…Melatonin is a powerful anti-oxidant [75] as it has been shown to scavenge different types of free radicals in vitro [76], in body fluids [77] and in cells [78]. Furthermore, melatonin plays an important role in activating anti-oxidant defenses such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSH-Rd) and glucose-6-phosphate dehydrogenase (G6PD) [79,80].…”

Efeito de diferentes concentrações de melatonina em espermatozoides de carneiros sobre estresse oxidativo após criopreservação

“…Vários autores têm relatado que a melatonina apresenta efeito benéfico sobre a preservação de espermatozoides de mamíferos, melhorando seus parâmetros funcionais (Rao & Gangadharan 2008, Casao et al 2010, Du Plessis et al 2010, Ashrafi et al 2013. Deste modo, a análise dos diferentes parâmetros seminais, como: motilidade espermática, integridade da membrana plasmática e acrossomal, atividade mitocondrial e a produção de MDA, são importantes para predizer a qualidade espermática para posterior utilização do sêmen congelado/descongelado em inseminação artificial.…”