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Tvrdá E., Greifová H., Mackovich A., Hashim F., Lukáč N. (2018): Curcumin offers antioxidant protection to cryopreserved bovine semen. Czech J. Anim. Sci., 63,[247][248][249][250][251][252][253][254][255] Evidence shows that oxidative stress associated with sperm cryopreservation may lead to a significant decrease of the structural integrity and functional activity of male gametes. Curcumin (CUR) has become a substance of scientific interest for its free radical-quenching abilities, which could enhance the post-thaw quality of male gametes. This study assessed the effects of CUR on the post-thaw vitality and selected oxidative stress markers of bovine spermatozoa. Thirty ejaculates collected from 10 breeding bulls were divided into two aliquots and cryopreserved in the absence (control) or presence of CUR (50 μmol/l). Immediately before use, the control or experimental straws were thawed at 37°C for 20 s. CUR administration led to a significantly higher preservation of spermatozoa motion (P < 0.001) as well as membrane (P < 0.05) and acrosomal (P < 0.01) integrity in comparison with the control. Moreover, spermatozoa exposed to CUR exhibited a significantly higher mitochondrial activity (P < 0.001). Significantly decreased amounts of reactive oxygen species (P < 0.01) and superoxide (P < 0.001) were detected following CUR supplementation. Finally, a significant decrease of oxidative damage to proteins (P < 0.01), lipids (P < 0.001), and DNA (P < 0.05) was recorded in samples to which CUR was administered in comparison to the control. In this study, CUR proved to act as an efficient antioxidant molecule offering protection to male gametes against oxidative damage during cryopreservation.

Natural processes along with increased industrial production and the irresponsible behavior of mankind have resulted in environmental pollution. Environmental pollutants can be categorized based on their characteristics and appearance into the following groups: physical, biological, and chemical. Every single one of them represents a serious threat to the male reproductive tract despite the different modes of action. Male gonads and gametes are especially vulnerable to the effect of exogenous factors; therefore, they are considered a reliable indicator of environmental pollution. The impact of xenobiotics or radiation leads to an irreversible impairment of fertility displayed by histological changes, modulated androgen production, or compromised spermatozoa (or germ cells) quality. The present article reviews the exogenous threats, male reproductive system, the mode of action, and overall impact on the reproductive health of humans and animals.

Reactive oxygen species overgeneration as a side effect of semen cryopreservation may lead to lipid peroxidation, protein degradation, DNA fragmentation and cell death, resulting in a decrease of sperm survival and fertilisation ability. Lycopene has been proposed as a potential supplement to semen extenders because of its antioxidant properties. The aim of this study was to evaluate the effects of lycopene on the structural integrity, functional activity and selected oxidative stress parameters of cryopreserved bovine sperm. Thirty bovine ejaculates were split into two aliquots and diluted with a commercial semen extender supplemented with 1.5 mmol/l lycopene or containing no supplement (control), cooled down to 4 °C, frozen and kept in liquid nitrogen. Prior to experiments, frozen straws were thawed at 37 °C for 20 s. Lycopene addition resulted in a higher sperm motility (P &lt; 0.001), progressive motility (P &lt; 0.001) and all secondary motion characteristics (P &lt; 0.001 with respect to the average path velocity, linear velocity, velocity of curvilinear motion, beat cross frequency, path straightness and linearity; P &lt; 0.01 in the case of the amplitude of lateral head displacement). Furthermore, lycopene exhibited protective effects on the sperm membrane (P &lt; 0.05) and acrosomal (P &lt; 0.01) integrity in comparison to control. An assay for metabolic function revealed that lycopene supplementation to the cryopreservation medium resulted in a higher preservation of the sperm mitochondrial activity (P &lt; 0.001). Reactive oxygen species production as well as intracellular superoxide generation were decreased following lycopene addition (P &lt; 0.01 in the case of reactive oxygen species; P &lt; 0.001 with respect to superoxide production). Finally, the presence of lycopene led to a decrease in protein carbonyl production (P &lt; 0.01), lipid peroxidation (P &lt; 0.001) as well as oxidative DNA damage (P &lt; 0.05) when compared to control. In conclusion, lycopene exhibited significant reactive oxygen species-trapping and antioxidant properties which may prevent oxidative damage to frozen-thawed sperm, and, thus, enhance the post-thaw vitality of male reproductive cells in cattle breeding.

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