Effects of reduced glutathione on acrosin activity in frozen–thawed boar spermatozoa

Abstract

In pigs, acrosin activity in extended semen is correlated with reproductive performance and has recently been identified as a freezability marker. Reduced glutathione (GSH) is known to decrease sperm cryodamage and increase the reproductive performance of frozen-thawed boar spermatozoa. However, the effects of GSH on the acrosin activity of good and poor freezability ejaculates (GFE and PFE, respectively) is yet to be examined. The present study investigated how supplementing cryopreservation media with GSH affected acrosin activity in GFE and PFE, as well as the relationship between acrosin activity and reproductive performance in frozen-thawed boar spermatozoa. In addition, we examined whether the increase in fertility rates and litter sizes observed after the addition of 2mM GSH to cryopreservation extenders was related to acrosin activity. Supplementing freezing media with 2mM GSH partially counteracted the cryopreservation-related decrease in acrosin activity in GFE but not PFE. Acrosin activity was found to be significantly correlated with in vivo reproductive performance of frozen-thawed boar semen. In conclusion, the effects of adding GSH to freezing extenders on the acrosin activity of frozen-thawed boar spermatozoa rely on the intrinsic freezability of the ejaculate. Furthermore, the maintenance of proper acrosin activity could contribute to the increase in reproductive performance mediated by GSH.

Preservation of boar semen: An update

“…Similarly, the use of 1.0 mM of butylated hydroxytoluene (BHT) improves its fertilization capacity (Trzcińska, Bryła, Gajda, & Gogol, ). The addition of 2 mM of GSH maintained the acrosin activity in well‐frozen ejaculates, this enzyme positively correlating with reproductive output (Estrada et al, ). With respect to plant‐based antioxidants, rosemary (Malo, Gil, Cano, Martínez, & Galé, ), salvia and fennel (Monton et al, ) extracts have been used in boars, reporting significant improvements in the quality of the thawed frozen epididymal sperm; however, supplementation with tea plants (Gale et al, ) reduces lipoxidation, but does not improve the sperm parameters of boar ejaculates.…”

“…(Trzcińska, Bryła, Gajda, & Gogol, 2015). The addition of 2 mM of GSH maintained the acrosin activity in well-frozen ejaculates, this enzyme positively correlating with reproductive output (Estrada et al, 2017). With respect to plant-based antioxidants, rosemary (Malo, Gil, Cano, Martínez, & Galé, 2011), salvia and fennel (Monton et al, 2015) extracts have been used in boars, reporting significant improvements in the quality of the thawed frozen epididymal sperm;…”

“…For this reason, frozen-thawed boar semen has not been widely accepted by the pork industry due to the greater costs of the semen and reduced fertility (Grossfeld et al, 2008). Hence, efforts are focused on achieving more satisfactory results, or modifying the existing protocols, by adding cholesterol (Tomás, Gómez-Fernández, Gómez-Izquierdo, Mocé, & de Mercado, 2014), seminal plasma (Torres et al, 2016), antioxidants (Estrada, Rodríguez-Gil, Rivera Del Álamo, Peña, & Yeste, 2017;Qian et al, 2016), identifying freezability markers in reproductive males (Casas et al, 2009;Guimarães et al, 2017) and so forth. The aim of this article is to provide the reader with background on boar semen preservation methods (storage in liquid, slow and fast freezing), the effects of cryopreservation on boar sperm, and updated information about the advances and the impact of these on fertilization rates, which is the best predictor of the quality of a frozen-thawed semen sample.…”

The achievement of boar spermin vitrocapacitation is related to an increase of disrupted disulphide bonds and intracellular reactive oxygen species levels

“…These modifications involve the activation of several signalling pathways, which are related to an increase in intracellular secondary messengers, such as cAMP and Ca² + , changes in motility patterns and reorganization of plasma membrane. Interestingly, the presence of antioxidants in cryopreservation media appears to stabilize better the sperm membrane (Yeste et al, 2013;Giaretta et al, 2015), and, particularly, reduced glutathione (GSH) improves the fertilizing ability of boar spermatozoa both in vitro and in vivo (Gadea et al, 2004(Gadea et al, , 2005Estrada et al, 2014Estrada et al, , 2017a. Antioxidant agents have been used to improve storage strategies for mammalian spermatozoa (Yeste, 2016).…”

“…On this respect, it is worth mentioning that cryopreservation detrimentally affects sperm function and survival, decreasing their motility and increasing lipid packaging of plasma membrane (Cormier et al, 1997;Bailey et al, 2000;Yeste, 2015;Yeste et al, 2017). Interestingly, the presence of antioxidants in cryopreservation media appears to stabilize better the sperm membrane (Yeste et al, 2013;Giaretta et al, 2015), and, particularly, reduced glutathione (GSH) improves the fertilizing ability of boar spermatozoa both in vitro and in vivo (Gadea et al, 2004(Gadea et al, , 2005Estrada et al, 2014Estrada et al, , 2017a. Notably, some of the positive effects of GSH on sperm function and survival (Yeste et al, 2013;Estrada et al, 2014Estrada et al, , 2017b appear to be related to a better maintenance of the intracellular redox balance (Jacob et al, 2003).…”