Red LED Light Acts on the Mitochondrial Electron Chain of Mammalian Sperm via Light-Time Exposure-Dependent Mechanisms.

Olga Blanco-Prieto,Marc Yeste,Maria Montserrat Rivera Del Álamo,Sergi Bonet,Lina Trujillo-Rojas,Marc Llavanera,Jaime Catalán,Alejandro Peña,Joan E Rodríguez-Gil,Josep Maria Fernández-Novell

doi:10.3390/cells9122546

Olga Blanco-Prieto, Marc Yeste + Show 8 more

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https://doi.org/10.3390/cells9122546

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Abstract

This work analyzes the effects of red LED light on mammalian sperm mitochondrial function, using the pig as an animal model. Liquid-stored pig semen was stimulated with red-light for 1, 5 and 10 min in the presence or absence of oligomycin A, a specific inhibitor of mitochondrial ATP synthase, or carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), a specific disruptor of mitochondrial electron chain. Whereas exposure for 1 and 5 min significantly (p < 0.05) decreased total motility and intracellular ATP levels, irradiation for 10 min induced the opposite effect. Oligomycin A abolished the light-effects on intracellular ATP levels, O2 consumption and mitochondrial membrane potential, whereas compared to non-irradiated samples, FCCP significantly (p < 0.05) increased O2 consumption when sperm were irradiated for 1 min. Both oligomycin A and FCCP significantly (p < 0.05) decreased total motility. Red-light increased cytochrome c oxidase activity with a maximal effect after 5 min of irradiation, which was abolished by both oligomycin A and FCCP. In conclusion, red-light modulates sperm mitochondrial function via electron chain activity in an exposition, time-dependent manner.

Highlights

Since about 95% of swine farms in Western countries use Artificial Insemination (AI) with liquid-stored pig semen, its optimization in that sector is crucial [1,2,3]
Results are shown as percentages of spermatozoa with high membrane potential (MMP) and intermediate/medium MMP, and as the ratios between the geometric mean of fluorescence intensities (GMFI) of JC1agg (FL2; orange) and JC1 monomers (JC1mon) (FL1; green) for the sperm populations with high and intermediate/medium MMP (JC1agg /JC1mon ratio—i.e., orange/green ratio)
Do the observed percentages of spermatozoa with high and intermediate MMP and their JC1agg /JC1mon ratios support that the time of exposure to red-light has a different impact on mitochondrial membrane potential and that not all spermatozoa exhibit the same response

Summary

Introduction

Since about 95% of swine farms in Western countries use Artificial Insemination (AI) with liquid-stored pig semen (resulting in an estimated mean fertility of 90%), its optimization in that sector is crucial [1,2,3]. As any technique aimed at increasing reproductive performance needs to be contemplated, several approaches have been undertaken over recent years Among these approaches is red-light irradiation, which increases both farrowing rates and litter sizes showing, significant. The literature remains inconsistent on how light-irradiation affects sperm function and its ability to modulate in vitro capacitation [4,6,7]. In this context, additional research about the mechanism/s underlying the mammalian sperm response to red-light is warranted. The first one hypothesizes that light interacts with plasma membrane receptors, such as those belonging to the Transient Receptor Potential (TRP)

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