Detection of "apoptosis-like" changes during the cryopreservation process in equine sperm

The kinematics of the appearance of apoptotic markers was studied by flow cytometry and immunoblot assays in equine spermatozoa subjected to freezing and thawing. Caspase activity, low mitochondrial membrane potential, and increases in sperm membrane permeability were observed in all of the phases of the cryopreservation procedure. Freezing and thawing caused an increase in membrane permeability and changes in the pattern of caspase activity; decreases in mitochondrial membrane potential were observed after centrifugation and cooling to 4 degrees C and after freezing and thawing. It is proposed that sperm mitochondria may be directly involved in the subtle damage that is present in most spermatozoa surviving freezing and thawing.     

Effect of pentoxifylline on motility and membrane integrity of cryopreserved human spermatozoa

The purpose of this study was to examine the effects of pentoxifylline used before and after semen cryopreservation-thawing on sperm motility and membrane integrity. Twenty-four semen samples were split into four equal aliquots. Aliquots were incubated at 37 degrees C for 30 min, followed by cryopreservation with TEST-yolk freezing medium using slow programmable freezing protocol. After 2 weeks the sperm samples were thawed, washed twice in Quinn's Sperm Washing Medium (modified HTF with 5.0 mg/mL Human Albumin) and incubated at 37 degrees C for 30 min. Aliquots were treated by adding 3 mmol/L pentoxifylline to: (1) fresh sperm samples during incubation period prior to cryopreservation, (2) sperm samples as a supplement to the cryoprotectant prior to cryopreservation, and (3) thawed sperm samples during incubation period. One aliquot received no treatment (control group). The addition of 3 mmol/L pentoxifylline to fresh semen during incubation period prior to cryopreservation significantly decreased progressive and total motility compared with controls. However, the addition of 3 mmol/L pentoxifylline to cryopreserved semen after thawing significantly increased progressive and total motility compared with controls. After post-thaw, no differences in motion characteristics between sperm samples treated by adding 3 mmol/L pentoxifylline as a supplement to the cryoprotectant and control groups were observed. Post-thaw hypoosmotic swelling (HOS) test scores did not improve with the addition of pentoxifylline compared with the control group. It is concluded that pentoxifylline enhanced post-thaw motility of cryopreserved human spermatozoa when added after thawing. No improvement was found by freezing sperm with pentoxifylline.     

Concentration of glutathione and expression of glutathione peroxidases 1 and 4 in fresh sperm provide a forecast of the outcome of cryopreservation of human spermatozoa

Oxidative stress imbalance potentially leads to damage of the structure of the cell and macromolecules such as plasma membrane components, proteins, and DNA. The plasma membrane of the sperm cell, which has high levels of polyunsaturated fatty acids, renders it particularly sensitive to free radical-mediated attacks. The freezing and subsequent thawing of sperm is a physically stressful process carried out during routine procedures in assisted reproduction techniques, which results in a highly variable and unpredictable reduction in the number of motile sperm cells. Subsequently, oxidative status can positively or negatively affect the motility, viability, and fertilizing capacity of thawed sperm. These effects are counteracted by various oxidative defense enzymes and anti-oxidants such as glutathione peroxidase isoforms GPx1 and GPx4, glutathione reductase (GR), and cellular glutathione (reduced) (GSH). In this way, oxidative status could represent a predictive marker of sperm quality following the freeze-thaw process. This study was based on 56 human sperm samples. We observed direct positive and negative relationships between the postthaw motile sperm recovery rate and GPx1 and GPx4 expression and activity, on the one hand, and GSH concentrations, on the other. No correlation was found between this recovery rate and GR or basic semen parameters. Predictive values clearly demonstrate that, among the molecules analyzed, the most accurate diagnoses result when analyses are conducted for GPx1 and GPx1 messenger RNA expression, GPx1 and GPx4 enzymatic activity, and GSH concentration. In conclusion, a reserve of glutathione, together with GPx expression, is necessary to eliminate free radicals using GSH or a like structural protein and seems to be essential for a good postthaw recovery. These molecules can be employed as indicators of postthaw sperm quality.     

Antioxidant effect of lemon balm (Melissa officinalis) and mate tea (Ilex paraguensys) on quality,lipid peroxidation and DNA oxidation of cryopreserved boar epididymal spermatozoa

In this study, we investigated the protective ability of the addition of two antioxidant herb extracts, mate tea and lemon balm, on boar epididymal frozen–thawed spermatozoa quality. Testes from mature boars were collected at local slaughterhouse, and sperm samples from epididymis were recovered by flushing. Spermatozoa were cryopreserved in lactose–egg yolk buffer supplemented with various concentrations of lemon balm and mate tea (0, 2.5, 5 and 10 g l^?1) using the straw‐freezing procedure. Motion parameters, acrosome and plasma membrane integrity, lipoperoxidation levels and DNA oxidative damage (8‐hydroxy‐2′‐deoxyguanosine base lesion) were evaluated. There were no differences among experimental groups with regard to motility characteristics, viability, acrosome and plasma membrane integrity; however, the highest concentration of lemon balm produced significant (P < 0.05) improvement in curvilinear trajectory, straightness and amplitude of lateral head displacement after thawing. The supplementation of freezing extender with mate tea and lemon balm reduced sperm lipid membrane peroxidation, and only mate tea protected DNA against oxidative damage during cryopreservation at 120 min post‐thawing (P < 0.05). Mate tea experimental extender at concentration of 10 g l^?1 showed the lowest percentage of sperm oxidised DNA and malondialdehyde generation; thus, mate tea is a potential candidate such as antioxidant compound on boar sperm cryopreservation medium.     

Effects of cryopreservation on penetration ability of human spermatozoa into bovine cervical mucus

Cryopreserved sperm exhibit lower fertilizing capacity in comparison to fresh sperm, partly due to effects of glycerol as the common cryoprotectant medium. Since standard semen analysis is not a good predictive method to assess sperm fertilizing capacity, functional tests like cervical mucus penetration may provide more useful information. A total of 24 semen samples were examined before and after cryopreservation for sperm parameters as well as number and motility of penetrated sperm into bovine cervical mucus (BCM) as an alternative for human cervical mucus. Freezing and thawing procedures have negative effects on sperm penetration into cervical mucus. No significant relation was noticed between sperm motility percentage or its penetration into BCM before and after cryopreservation, which denotes the variability in resistance of sperm to damaging effects of freezing.     

Ultrastructural changes in membranes and acrosome of human sperm during cryopreservation

Functional ultrastructural changes in human sperm heads were evaluated following semen dilution in cryoprotective medium (with and without seminal plasma) as well as freezing/thawing. Plasma membranes were as much altered by dilution as by freezing/thawing when compared with fresh samples. The most striking effect on acrosome noted during freezing/thawing was a dramatic decline in percentage of intact spermatozoa. Acrosomal changes seemed to be less important in the fractions without seminal plasma. These deleterious effects were very demonstrable using transmission electron microscopy (TEM), rather than conventional staining. TEM is useful in obtaining more detailed information on membrane and acrosome integrity until a specific procedure to evaluate functional/physical integrity can be found. Cryopreservation in the absence of seminal plasma can be used for intrauterine insemination in AIH, AID programs with frozen semen.     

Sperm maturation in dogs: sperm profile and enzymatic antioxidant status in ejaculated and epididymal spermatozoa

Spermatozoa become more susceptible to the attack of reactive oxygen species during maturation. To avoid oxidative damage, the epididymis must provide the necessary antioxidant protection. The aim of this study was to compare the canine sperm profile and the enzymatic antioxidant status of the ejaculated fractions and samples collected from the different segments of the epididymis (caput, corpus and cauda). Five adult dogs were used, and after 1–3 weeks, subsequently to bilateral orchiectomy and epididymal storage, sperm samples were collected from the different segments of the epididymis. Samples were evaluated for conventional microscopy and computer‐assisted motility analysis: sperm plasma membrane permeability and the activity of the antioxidant enzymes catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). Samples collected from the caput and corpus showed lower values for most of the motility variables evaluated, indicating different levels of immaturity. Catalase activity was observed only in ejaculated samples. Conversely, GPx activity was higher in the cauda epididymidis. Correlations were found between SOD and GPx and SOD and sperm motility in the epididymal cauda and corpus, highlighting the importance of the enzymes for the protection of spermatozoa during the transit along the epididymis.     

低温冷冻对人精子染色体的影响

目的 :评价低温冷冻对人精子染色体的影响。　方法 :用人精子与去透明带金黄地鼠卵异种体外授精技术制备精子染色体 ,通过比较冷冻前后及不同冷冻方法间精子染色体畸变率和性染色体比例来评价低温冷冻对人精子染色体的影响。　结果 :精子染色体畸变率在冷冻前为 9.4 0 % (11/ 117) ,经速冻法冷冻后为 7.4 8% (8/ 10 7) ,经缓冻法冷冻后为 8.74 % (9/ 10 3) ,3者差异无显著性 (P >0 .75 )。X精子与Y精子比例在 3者间也差异无显著性 (P >0 .90 )。　结论 :低温冷冻对人精子染色体没有产生影响     

A comparative study of two cooling protocols on stallion sperm cryosurvival

There are many protocols for horse sperm cryopreservation, but results are inconsistent; sperm survival after freeze‐thawing is usually poor; in consequence, fertility is low. The objective of this work was to see whether slow cooling before freezing to minus 3 °C instead of +5 °C, the traditional target temperature, could improve horse sperm cryosurvival, capability to carry out capacitation and the acrosome reaction induced by progesterone. Spermatozoa from five stallions were packaged in straws and slowly cooled to +5 °C. Half of the straws were frozen directly and the other half was further cooled to ?3 °C before freezing. Progressive motility, viability, plasma membrane integrity, acrosome integrity and capacitation status were assessed. After thawing, there were no differences between cooling treatments on motility, viability, acrosome integrity and capacitation status; however, there was difference (P < 0.05) regarding plasma membrane integrity. Acrosome integrity decreased as incubation, without or with progesterone (2 μg ml^?1), progressed, but there were no differences between cooling treatments regardless of progesterone. Both capacitated and acrosome‐reacted spermatozoa increased as incubation progressed, but there were no differences between cooling treatments regardless of progesterone. Slow cooling to ?3 °C before freezing did not improve horse sperm cryosurvival or capability to undergo the acrosome reaction.     

Functional aspects of human sperm binding to the zona pellucida using the hemizona assay

The hemizona assay (HZA) has facilitated investigations of sperm function in relation to zona pellucida binding. In this study, the authors examined: 1) the association between hyperactivated sperm motility and HZA binding; 2) the binding kinetics and efficiency of sperm from subfertile men; and 3) the influence of sperm freezing and thawing on binding capacity. For each HZA, a nonviable human oocyte was cut into equal zona hemispheres. The mean number of bound sperm and the incidence of hyperactivation were significantly greater for samples of sperm from fertile men compared with sperm from subfertile men (P less than 0.05). Subfertile sperm had a binding curve that paralleled the curve for fertile sperm, although the magnitude of binding was markedly reduced. Freezing and thawing of sperm from fertile samples impaired their capacity to bind to the zona pellucida. The HZA binding efficiency was reduced by 30%, although the binding curves for fresh versus frozen samples remained parallel.     

冷冻精子受精能力的综合评价

目的：观察不同冷冻期冷冻精子的受精能力。方法：应用精液常规分析（ＳＦＡ）、精子尾部低渗肿胀试验（ＨＯＳ）、去透明带地鼠卵穿透试验（ＨＯＰ）及冷冻精液人工授精（ＡＩＤ）对冷冻前后及不同冻存期的精液标本进行综合性检测。结果：１０份正常精液标本的冷冻精子活动率、ＨＯＳ值、ＨＯＰ值均明显低于冷冻前（Ｐ＜０．００１），而不同冻存期的精液行ＡＩＤ术后的总妊娠率与新鲜精液ＡＩＤ术的总妊娠率比较，则基本相同。结论：精子细胞膜虽在冷冻复温过程中受到一定的损伤，使精子活动率和受精能力下降。但是，精液的长期冻存及精子细胞膜部分改变并不完全影响精子的受精能力。     

Cryopreservation of composite tissue flaps: experimental studies in the rat

Cryopreservation has the potential to improve availability of donor parts for composite tissue allotransplantation and may reduce their antigenicity. This study investigates whether the component tissues of composite flaps remain viable after cryopreservation. Forty-one epigastric flaps were harvested from Lewis rats. Twenty-one flaps were perfused with DMSO/trehalose, frozen by controlled cooling to -140 degrees C, and stored in liquid nitrogen for 2 weeks. Ten fresh and 10 cryopreserved/thawed flaps were examined histologically with hematoxylin & eosin and factor VIII staining. An epithelial viability index was calculated for 10 fresh and 11 cryopreserved flaps using the MTT assay. In all cryopreserved samples, hematoxylin & eosin, and factor VIII staining revealed a well-preserved cellular architecture, which was indistinguishable from fresh specimens. The viability index for the cryopreserved samples was 10.90 +/- 2.09 compared with 12.15 +/- 1.32 for fresh flaps (P = 0.123). Results suggest that the skin, adipose, and vascular endothelial cells of composite tissue flaps retain their viability after cryopreservation and thawing.     

Male genital tract antioxidant enzymes: their source,function in the female,and ability to preserve sperm DNA integrity in the golden hamster

Recently, we reported that male accessory sex gland (ASG) secretions protect sperm genomic integrity by demonstrating that DNA damage was more extensive in sperm not exposed to the secretions. The present study was conducted to find out if ASGs secrete the main antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx or GSH-Px), and catalase (CAT) and if the most abundant one, SOD, can protect those sperm that were not exposed to ASG secretions against NADPH-induced oxidative stress. Four experimental groups of male golden hamsters were used: intact animals with proven fertility, animals with all major ASGs removed (TX), animals that were bilaterally vasectomized, and sham-operated controls. SOD, CAT, and GPx activities were measured in secretions from all 5 ASGs and sperm-free uterine flushing from virgin females and those mated with the experimental males. The alkaline comet assay was used to analyze DNA integrity of the TX group sperm after incubation in a medium containing 50 U/mL of SOD along with 0 to 20 mmol/L NADPH. The main antioxidant enzyme in ASGs was SOD from coagulating glands (P <.05) and GPx together with CAT from ampullary glands (P <.05). Uterine flushing of ejaculates that contained ASG secretions had more SOD and CAT activities than those with epididymal secretions alone (P <.05 and P <.001, respectively), whereas activity of GPx was the same (P >.05). Addition of SOD in vitro dose dependently decreased the incidence of single-strand DNA damage in sperm not exposed to ASG secretions incubated in the presence of 0 to 20 mmol/L NADPH (P <.001). These results indicated that, in terms of abundance, SOD was the main antioxidant enzyme secreted by male ASGs, whereas CAT was the second one. The GPx activity came from both epididymis and ASGs. We conclude that ASG secretions play a significant role in protecting sperm against oxidative stress.     

Cryopreservation of rhesus monkey (Macaca mulatta) epididymal spermatozoa before and after refrigerated storage

Recently, there has been an increased interest in preservation of epididymal sperm as a potential source of material for genetic resource banking; however, cryopreservation of epididymal sperm from the rhesus monkey has not been explored. This study evaluated the effect of prolonged refrigerated storage of the intact cauda epididymides at various conditions on the postthaw motility of rhesus monkey epididymal spermatozoa, and also tested whether altering cryoprotectants and cooling methods could improve post-thaw motility for epididymal sperm after refrigerated storage. Motility before freezing decreased significantly after refrigerated storage (0 degrees C) for a period of 24 or 48 hours. Although postthaw motility was not significantly different after 24 hours of refrigerated storage, epididymides stored at a higher temperature (4 degrees C-10 degrees C) yielded better results, but postthaw motility still decreased significantly after 48 hours of refrigerated storage at 4 degrees C. Comparisons of glycerol and ethylene glycol at 3% and 6% revealed similar postthaw motility. However, consistently high postthaw motility was obtained with 3% glycerol throughout all freezing trials regardless of whether samples were collected fresh or after refrigerated storage for 24 or 48 hours. Cooling at a higher rate of 220 degrees C/min was found to yield better postthaw motility than the slower rate of 29 degrees C/min. Thawing time duration was evaluated, and a minimum of 30 seconds was required for thawing 0.25-mL straws containing 50-microL semen samples. An overall average of 42% postthaw motility was obtained for rhesus monkey epididymal sperm packed in 3% glycerol and cooled after 24 or 48 hours refrigerated storage. These postthaw motility results for epididymal sperm indicate that this method should be practical for use in preserving epididymal sperm, even if tissue must be shipped from sites remote from the cryopreservation laboratory.     

冷冻及复温后人精子超微结构变化的研究

本文研究了冷冻及复温过程中人精子超微结构的变化.用甘油-卵黄-三羟甲基氨基甲烷-葡萄糖-柠檬酸混合液或纯甘油作精子冷冻保护剂,采用阶段降温法。标本在-196℃液氮中贮存一周后.37℃水浴中复温5～10分钟.透射电镜(TEM)下观察.精子超微结构变化主要在头部,可见顶体前段及质膜肿胀,顶体外膜破裂,顶体物质流失;甚至顶体内膜及核膜破损,丧失成为裸核精子。与新鲜精液相比.有完整质膜.顶体的精子百分比明显下降(P<0.01)。线粒体基质局部透亮,呈空泡状改变,并可见细小颗粒物质沉积.尾部轴丝“9 2”结构存在;质膜和核之间可见尾结构。精子头部结构完整率与精子存活率呈正相关(r=0.88 P<0.01).结果表明同一供者的冻精作人工授精,其成功率必然低于鲜精的成功率;它也可能是一般冻精人工授精成功率低于鲜精的原因.     

Evaluation of chromatin integrity in human sperm using acridine orange staining with different fixatives and after cryopreservation

Staining of cells with acridine orange (AO) has been widely accepted as a predictor of DNA damage in many cell types. Because of variability of protocols used in previous studies, the AO staining technique has not been widely accepted as a screening test to predict DNA damage in human sperm. In order to further validate the use of AO staining, sperm were evaluated using numerous variations in the staining protocol. This study also elucidated the effects of cryopreservation on sperm DNA. Sperm fixation in Carnoy's solution showed significantly (P < 0.05) more DNA damage (29.9 +/- 4.5%) than 2% glutaraldehyde (14.4 +/- 2.1%), 4% paraformaldehyde (5.5 +/- 1.7%), no fixation (15.8 +/- 4.3%) but did not differ from Diff Quik solution (19.2 +/- 5.8%). No difference was observed for sperm DNA damage assessment using a 0.2 m (15.5 +/- 3.2%) or 0.3 m (14.9 +/- 3.3%) concentration of Na(2)HPO(4).7H(2)O in the AO staining solution. Frozen-thawed semen samples showed increased damage to sperm DNA under both Carnoy's (fresh: 10.9 +/- 1.3%; frozen: 30.8 +/- 2.9%; P < 0.05) and Diff Quik fixation (fresh: 6.2 +/- 0.8; frozen: 17.1 +/- 2.5%P < 0.05). Present data also showed that spermatozoa from some individuals are more prone to DNA damage after freezing and thawing procedures than others. In conclusion, Carnoy's fixative provides a better predictive value for DNA damage to sperm using AO staining. Additionally, cryopreservation increased damage to the sperm DNA.     

Changes in motion characteristics, plasma membrane integrity, and acrosome morphology during cryopreservation of buffalo spermatozoa

Motion characteristics, plasma membrane integrity, and acrosome morphology of buffalo spermatozoa after different stages of cryopreservation (ie, dilution, cooling to 4 degrees C, equilibration at 4 degrees C, and freezing and thawing) were examined. Semen ejaculates from 4 buffalo bulls were pooled (n = 5), diluted in tris-citric acid extender, cooled to 4 degrees C over 2 hours, equilibrated at 4 degrees C for 4 hours, dispensed into 0.5-mL straws, and frozen in a programmable cell freezer before plunging into liquid nitrogen. Frozen semen was thawed at 37 degrees C for 15 seconds. After completion of each stage, sperm motion characteristics, plasma membrane integrity, and acrosomal morphology were determined using computer-assisted semen analysis, hypo-osmotic swelling assay, and phase-contrast microscopy, respectively. Data were presented as mean +/- standard error of the mean. Visual and computerized motility did not differ due to dilution, cooling, or equilibration (77.3% +/- 2.3% and 90.5% +/- 1.2%, respectively), but was reduced (P < .05) after freezing and thawing (53.0% +/- 4.6% and 48.6% +/- 6.5%, respectively). Linear motility of spermatozoa was lower (P < .05) after dilution or equilibration (56.2% +/- 2.4%) than after cooling or freezing and thawing (79.6% +/- 1.4%). Sperm curvilinear velocity was reduced (P < .05) from 112.4 +/- 5.3 microm/sec after dilution to 96.0 +/- 5.8 microm/s after cooling, and from 87.6 +/- 4.1 microm/s after equilibration to 69.4 +/- 2.0 microm/s after freezing and thawing. Sperm lateral head displacement differed (P < .05) after each stage (ie, dilution, 3.9 +/- 0.2 microm; cooling, 2.3 +/- 0.2 microm; equilibration, 3.1 +/- 0.3 microm; and freezing and thawing, 1.7 +/- 0.2 microm). Spermatozoa with intact plasma membranes were 80.2% +/- 3.9% after dilution, reduced (P < .05) to 60.4% +/- 5.6% after equilibration, and then to 32.6% +/- 3.8% after freezing and thawing. The percentage of spermatozoa with normal acrosomes remained higher after dilution, cooling, or equilibration (73.2% +/- 2.4%) than after freezing and thawing (61.8% +/- 2.4%; P < .05). In conclusion, the maximal damage to the motility apparatus, plasma membrane, and acrosomal cap of buffalo spermatozoa occurs during freezing and thawing followed by equilibration.     

Pulmonary effects of short term selenium deficiency.

BACKGROUND: Selenium dependent glutathione peroxidase (GPx) reduces hydrogen peroxide (H2O2) and organic hydrogen peroxides in both normal and pathological states. Chronic dietary deficiency of selenium results in a gradual decrease in GPx and altered response to environmental stress. However, glutathione-S-transferase (GST) isozymes may increase and compensate for chronic GPx deficiency. The pattern of antioxidant enzyme activity and immunolocalisation of various enzymes in rat lung has not been described in short term (< 3 weeks) acute selenium deficiency. METHODS: The time course of GPx depletion from rat lung (measured every five days in subgroups of rats) during acute dietary selenium deficiency was evaluated. After 20 days of depletion, enzyme activity of lung GPx, catalase, superoxide dismutase (SOD), glutathione reductase (GR), glucose-6-phosphodiesterase (G-6-PD), and GST were determined. Immunohistochemical localisation of GPx and SOD was also performed. The response to lethal hyperoxia (> 95%) in control and selenium deficient rats was then established. RESULTS: At 20 days, lung GPx activity in the rats fed a selenium deficient diet was one third less than in control animals who received a normal diet, while changes in blood enzymes between control and deficient animals were similar. Other lung enzyme activities remained normal with the exception of cyanide inhibited SOD activity measured in selenium deficient rat lungs which declined to approximately 50% of normal. Immunohistochemical localisation of GPx showed a generalised loss of the enzyme throughout the lung parenchyma with some possible sparing of activity in epithelial cells of the bronchioles. When exposed to lethal hyperoxia, selenium deficient animals were more susceptible than control rats. CONCLUSIONS: This is the earliest time at which dietary selenium deficiency has been shown to produce moderate loss of GPx activity. This change in activity was associated with increased susceptibility to pulmonary oxidant stress. However, the role of decreased SOD activity (presumed to represent copper, zinc SOD), although unexpected, may have been a major contributor to increased damage from hyperoxia. These results emphasise the complex potential interaction of elemental deficiency with the natural antioxidant response to lethal hyperoxia.     

精子冻存技术及上游法精子处理技术对精子DNA完整性的影响

目的通过对冷冻前后及精子处理前后精子DNA完整性的比较,探讨冷冻技术、冷冻时间及上游法精子处理技术对精子DNA完整性的影响。方法（1）精液常规检测正常的患者30例,手淫法取精,精液液化混匀后分4份,分别用于精子染色质扩散（SCD）实验检测精子DNA完整性、上游法处理精液、以及两组冻存实验（不加保护剂直接冻存的为冻存1组;添加蛋黄葡萄糖保护剂冻存的为冻存2组）;（2）上游法处理后的精液一部分用于检测精子动力和形态,一部分用于精子DNA完整性检测;（3）冻存1组分别于冻存第7天和第90天解冻,SCD实验检测精子DNA完整性;（4）冻存2组分别于第7天和第90天解冻,0．1ml用于精子DNA完整性检测,剩余精液应用上游法处理,检测上游处理前后精子DNA的完整性。结果（1）冻存1组中,冻存90d后解冻的精子DNA损伤率[（25．6土7．3）％]显著高于冻存7d者[（22．4±7．4）％]（P〈0．05）,且均显著高于新鲜精液的精子DNA损伤率[（20．6±7．3）％]（P〈O．05）;冻存2组中,冻存90d后精子DNA损伤率显著高于冻存7d者[（25．9±7．2）％VS．（23．6土7．8）％]（P〈O．05）,且均显著高于新鲜精液（P〈0．05）;而冻存7d和90d后,两个冻存组间比较,精子DNA损伤率均无显著差异（P〉0．05）。（2）新鲜精液经上游法处理后,精子DNA损伤率由处理前的（20．6±7．3）％降为（6．4±2．5）％（P〈O．05）;冻存2组中精液冻存7d和90d后复苏上游法处理后,精子DNA损伤率较未经上游法处理者均显著降低[分别为（9．38±2．8）％VS．（23．6±7．8）％和（9．7±2．6）％VS．（25．9±7．2）％]（P％0．05）。结论冻存对精子DNA有损伤,冻存时间对于精子DNA完整性有影响。不添加保护剂直接冻存和添加保护剂对精子DNA完整性的影响无显著差异。不论是新鲜精液还是冻存复苏精液,上游法处理并不会增加精子DNA的损伤,且有利于筛选出具有更好DNA完整性的精子。     

Sperm characteristics and DNA integrity of Iberian red deer (Cervus elaphus hispanicus) epididymal spermatozoa frozen in the presence of enzymatic and nonenzymatic antioxidants

The main goal of this study was to investigate the potential protective effects of enzymatic and nonenzymatic antioxidants on cryopreservation injuries to red deer epididymal spermatozoa. In Experiment 1, the effects on sperm freezability of the enzymatic antioxidants catalase, superoxide dismutase, and a combination thereof were studied. In Experiment 2, sperm cryoresistance was evaluated when different nonenzymatic antioxidants, such as vitamin E, vitamin C, and butylated hydroxytoluene (BHT), were added to the freezing extender. Sperm quality was judged in vitro by microscopic assessments of individual sperm motility (SMI), viability, and acrosome (ie, spermatozoa with normal apical ridges; % NAR) and membrane (by means of the HOS test) integrity. To address fully these topics, we incorporated a new set of functional sperm tests for mitochondrial function, membrane phospholipid disorder, and sperm chromatin stability. Samples were evaluated after freezing and thawing, and after a 2-hour period of incubation at 37 degrees C. The present study demonstrates that the addition of enzymatic antioxidants to freezing extenders improves sperm viability after cooling, and improves sperm motility, acrosome integrity, and mitochondrial status (P<.05) after thawing. After a 2-hour incubation period at 37 degrees C in the presence of enzymatic antioxidants, an improvement in membrane integrity (P<.05) was observed. However, when nonenzymatic antioxidants were present in the freezing diluents, no positive effects on thawed sperm parameters were noted. The chromatin stability test did not show significant differences between the treatments. We conclude that enzymatic antioxidants should be present in the early steps of cryopreservation of epididymal spermatozoa from red deer, so as to improve motility and acrosome integrity.