Positive effect of butylated hydroxytoluene (BHT) on the quality of cryopreserved cat spermatozoa

Ascorbic acid 2-glucoside improves survival, quality, and fertility of frozen-thawed C57Bl/6J and C57Bl/6N mouse spermatozoa

BACKGROUND

Ascorbic acid 2-glucoside (AA2G) is a stabilized form of ascorbic acid and a potent antioxidant. Ascorbic acid is present in the testes and epididymis and helps maintain the physiological integrity of reproductive organs. Its properties have been utilized to protect spermatozoa of different species from oxidative stress.

MATERIALS AND METHODS

Spermatozoa of C57Bl/6J and C57Bl/6N strains were frozen and analyzed, after thawing, by supplementing the capacitation medium with AA2G, both in the presence and absence of methyl-β-cyclodextrin (MBCD). The effect of treatment was evaluated by SCA System (Microptic) analyzing the velocity, vitality, morphology, and the DNA fragmentation. We also examined sperm capacitation (CTC), acrosome reaction (Coomassie Brillant Blue), and fertility (in vitro fertilization) of treated spermatozoa.

RESULTS

AA2G improved sperm quality and fertility particularly in association with MBCD. We observed a significant increase of sperm motility, velocity, and vitality associated with an enhanced capacitation and acrosome reaction. These improvements resulted in a marked increase in in vitro fertilization success. Embryos obtained were cultured and reached normally the blastocyst stage.

DISCUSSION

This study aimed to determine if AA2G could safeguard mouse spermatozoa during cryopreservation. We found a protective effect of AA2G that increased sperm survivability resulting in higher fertilization rate.

CONCLUSION

This newly improved protocol shows potential for reanimating cryopreserved GEMMs stored in mouse biobanks and international repositories, such as the European Mouse Mutant Archive (EMMA). This can serve as a pivotal tool in fulfilling the 3Rs mission (replacement, reduction, and refinement), promoting ethical and humane research practices.

The antioxidant effects of butylated hydroxytoluene on cryopreserved goat sperm from a proteomic perspective

At present, there are few reports about the proteomics changes provoked by butylated hydroxytoluene (BHT) supplementation on cryopreserved semen in mammals. Thus, we aimed to evaluate the effects of different concentrations of BHT on goat sperm and to investigate the proteomics changes of adding BHT to cryopreserved goat (Capra hircus) sperm. Firstly, semen samples were collected from four goats, and frozen in the basic extenders containing different concentrations of BHT (0.5 mM, 1.0 mM, 2.0 mM) and a control without BHT, respectively. After thawing, the protective effects of dose-dependent replenished BHT to the freezing medium on post-thaw sperm motility, integrities of plasma membrane and acrosome, reactive oxygen species levels were confirmed, with 0.5 mM BHT being the best (B group) as compared to the control (without BHT, C group). Afterwards, TMT-based quantitative proteomic technique was performed to profile proteome of the goat sperm between C group and B group. Parallel reaction monitoring was used to confirm reliability of the data. Overall, 2,476 proteins were identified and quantified via this approach. Comparing the C and B groups directly (C vs. B), there were 17 differentially abundant proteins (DAPs) po-tentially associated with sperm characteristics and functions were identified, wherein three were upregulated and 14 were downregulated, respectively. GO annotation analysis demonstrated the potential involvement of the identified DAPs in metabolic process, multi-organism process, reproduction, reproductive process, and cellular process. KEGG enrichment analysis further indicated their potential roles in renin-angiotensin system and glutathione metabolism pathways. Together, this novel study clearly shows that BHT can effectively improve quality parameters and fertility potential of post-thawed goat sperm at the optimal concentration, and its cryoprotection may be realized through regulation of sperm metabolism and antioxidative capability from the perspective of sperm proteomic modification.

Oxidative and nitrosative stress in frozen-thawed pig spermatozoa. I: Protective effect of melatonin and butylhydroxytoluene on sperm function

The addition of antioxidants to the cryopreservation medium has been shown to exert a positive effect on the quality of frozen-thawed sperm in different species. The objective of the present study was to evaluate the effects of supplementing the freezing medium with butylhydroxytoluene (BHT) and melatonin (MEL) in frozen-thawed pig spermatozoa. With this purpose, six ejaculates coming from six separate boars were cryopreserved in traditional freezing medium (i.e. lactose/egg-yolk/glycerol; Control) supplemented with 1.0 mM BHT (BHT-1), 2.0 mM BHT (BHT-2), 0.01 μM MEL (MEL-1) and 1.0 μM MEL (MEL-2). We evaluated sperm viability, membrane lipid disorder, acrosome integrity, mitochondrial membrane potential, lipid peroxidation, oxidation of thiol groups, and levels of total reactive oxygen species (ROS), peroxynitrite and superoxide anion (·O₂^-). We also analysed total (TM) and progressive sperm motilities (PM), and kinetic parameters at post-thaw (T0, T30 and T60). The BHT-2 and MEL-2 groups presented higher viability and acrosome integrity, and lower levels of peroxynitrite, ·O₂^- and lipid peroxidation than the control (P < 0.05), whereas MEL-2 diminished the levels of total ROS (P < 0.05). TM and PM were not affected by the treatment, while, LIN and STR shows differences between experimental groups. In conclusion, the addition of BHT and MEL to cryopreservation medium diminishes oxidative and nitrosative stress markers, which has repercussions for the integrity of plasma and acrosomal membranes of frozen-thawed spermatozoa.

Addition of butylated hydroxytoluene (BHT) in tris-based extender improves post-thaw quality and motion dynamics of dog spermatozoa

The aim of this study was to evaluate the interaction of different concentrations of butylated hydroxytoluene (BHT) in a tris-based extender on semen quality parameters in post-thawed dog semen. Twenty-four ejaculates were collected from eight male Beagle dogs using an artificial vagina. Pooled semen was diluted with a tris-based extender supplemented with 0 (control), 0.5, 1.0, 1.5, and 2.0 mM BHT, at a final concentration of 200 × 10⁶ spermatozoa/mL. After thawing, sperm samples were assessed for motility parameters (CASA), membrane integrity (SYBR-14/PI), acrosome integrity (FITC-PNA), mitochondrial activity (JC-1/PI), malondialdehyde (MDA) concentration, and glutathione peroxidase (GPx) activity. The total motility, progressive motility, and average path velocity of the frozen-thawed sperm were significantly higher in the BHT1.5 group than in the control and the other sample groups (P < 0.05). Higher values of straight-line velocity, curvilinear velocity, amplitude of the lateral head displacement, and linearity were observed in the BHT1.0, BHT1.5, and BHT2.0 groups than in the control (P < 0.05). The BHT1.0 and BHT1.5 groups had higher percentages of straightness and acrosome integrity than the other groups (P < 0.05). Beat cross frequency, plasma membrane integrity, and GPx activity of the BHT1.5 and BHT2.0 groups were higher than those of the control (P < 0.05). A lower concentration of MDA was observed in the BHT1.0, BHT1.5, and BHT2.0 groups than in the control (BHT0) (P < 0.05). Our results indicate that 1.5 mM BHT is the optimal concentration for improving the post-thaw quality of canine spermatozoa.

Can amides be alternative cryoprotectors for the preservation of feline semen?

Sperm cryopreservation is a tool for the conservation of the genetic material of animals of genetic importance or for species preservation. In the case of domestic cats, this can be used to generate information about seminal harvest, evaluation and preservation, which is especially important due to its applicability to wild felids. This study evaluated seminal samples harvested by urethral catheterisation from 13 adult domestic cats. Samples were cryopreserved with experimental groups of extenders were defined by the penetrating cryoprotectant: 6% glycerol (GLY6%), 3% dimethylacetamide (DMA3%) and 3% dimethylformamide (DMF3%). The samples were thawed and evaluated by conventional microscopy and by computer-assisted sperm analysis (CASA). The structural and functional membrane integrity was assessed by supravital tests (EOS), hypoosmotic swelling tests (HOST) and flow cytometry (FC). There was a correlation (P < 0.05) between total motility and EOS (r = 0.54), HOST and FC (r = -0.62) and total motility and flow cytometry (r = 0.63), indicating that these are complementary parameters that increase the accuracy of the feline sperm quality evaluation post-thaw. The results regarding the structural and functional integrity of the sperm plasma membrane did not differ (P > 0.05) among groups. However, the DMA3% group had a lower (P < 0.05) percentage of morphological changes in the sperm tail compared to samples cryopreserved with GLY6% and DMF3%. Additionally, DMA3% provided lower values of immobile sperm post-thaw when compared to DMF3%. DMA is an interesting alternative to GLY and superior to DMF for the cryopreservation of feline semen at the studied concentrations.

Short-term storage sperm of coho salmon (Oncorhynchus kisutch) at 4 °C: Effect of sperm: Extender dilution ratios and antioxidant butyl-hydroxytoluene (BHT) on sperm function

Short-term storage of semen is a necessary key procedure in fish; it allows maximizing the use of gametes. Nevertheless, sperm quality decreases during storage has been associated with oxidative stress damage due to an increase in reactive oxygen species (ROS) during storage. This study was designed to optimize a short-term storage protocol for Coho salmon (Oncorhynchus kisutch) spermatozoa, evaluating the effect of extender dilution and the addition of butyl-hydroxytoluene (BHT) antioxidant on sperm function parameters. In the first experiment, fresh semen was diluted in Storfish®: extender dilution (1:2 and 1:3) and a control sample undiluted and stored at 4 °C for 7-days. In both experiments motility (MO), viability and integrity of plasma membrane, mitochondrial membrane potential (MMP) and superoxide anion level (O₂^-) were evaluated at 0, 3 and 7 days. Result shows that, 1:3 dilution maintained a higher sperm function for a longer period time. In the second experiment, spermatozoa were suspended in Storfish® (1:3) supplemented with two different concentrations of BHT (1.0 mM and 2.0 mM) and a control sample without antioxidant and stored at 4 °C for 7 days. The results demonstrated that, antioxidant-supplemented samples greater MO than control samples (P < 0.05). The viability remained >75% during storage in all groups. MMP was higher in 2.0 mM BHT compared to 1.0 mM and control (P < 0.05), in addition, this concentration reduced O₂^- level (P < 0.05). In conclusion, sperm: extender dilution 1:3 and adding of 2.0 mM BHT in sperm storage extender may enhance protection sperm function in Oncorhynchus kisutch against effects harmful of the oxidative stress during the in vitro storage.

The Importance of Oxidative Stress in Determining the Functionality of Mammalian Spermatozoa: A Two-Edged Sword

This article addresses the importance of oxidative processes in both the generation of functional gametes and the aetiology of defective sperm function. Functionally, sperm capacitation is recognized as a redox-regulated process, wherein a low level of reactive oxygen species (ROS) generation is intimately involved in driving such events as the stimulation of tyrosine phosphorylation, the facilitation of cholesterol efflux and the promotion of cAMP generation. However, the continuous generation of ROS ultimately creates problems for spermatozoa because their unique physical architecture and unusual biochemical composition means that they are vulnerable to oxidative stress. As a consequence, they are heavily dependent on the antioxidant protection afforded by the fluids in the male and female reproductive tracts and, during the precarious process of insemination, seminal plasma. If this antioxidant protection should be compromised for any reason, then the spermatozoa experience pathological oxidative damage. In addition, situations may prevail that cause the spermatozoa to become exposed to high levels of ROS emanating either from other cells in the immediate vicinity (particularly neutrophils) or from the spermatozoa themselves. The environmental and lifestyle factors that promote ROS generation by the spermatozoa are reviewed in this article, as are the techniques that might be used in a diagnostic context to identify patients whose reproductive capacity is under oxidative threat. Understanding the strengths and weaknesses of ROS-monitoring methodologies is critical if we are to effectively identify those patients for whom treatment with antioxidants might be considered a rational management strategy.