The use of pentoxifylline to improve motility of cryopreserved equine spermatozoa

Effect of pentoxifylline on the testicular hemodynamic, volume, testosterone, nitric oxide levels and semen quality in Ossimi rams during non breeding-season

During the non-breeding season, Ossimi rams have testicular regression, including reductions in blood flow, size and spermatogenesis. The objective was to determine the effect of pentoxifylline (PTX) on Ossimi rams during the non-breeding season. Fifteen sexually mature Ossimi rams were allotted to three groups: (1) G0 (n = 5) control group (basic diet, no PTX); (2) G1 (n = 5) 10 mg/kg BW PTX; and (3) G2 (n = 5) 20 mg/kg BW PTX. The PTX was given orally once daily for 7 weeks (wk1 to wk7), whereas ultrasonographic assessment of testes, and collection of semen and blood started 1 week before PTX and were done weekly for 8 weeks (wk0 to wk7). In G2, there was a decrease(P < 0.05) in both Doppler indices (resistive index, pulsatility index) in G2 from wk2 to wk4 and an increase(P < 0.05) in ultrasonographic testicular coloration from wk2 to wk7. Moreover, G2 had the highest (P < 0.05) testicular volume (wk5 to wk7), individual motility, sperm viability and acrosome integrity (wk4 to wk7) and sperm cell concentration (wk6 and wk7). Blood concentrations of testosterone and nitric oxide were increased (P < 0.05) concurrent with decreased Doppler indices. In conclusion, PTX enhanced testicular blood flow and volume, semen quality, and concentrations of testosterone and nitric oxide potential in Ossimi rams during the non-breeding season, with potential to ameliorate deleterious effects of heat stress and perhaps enhance ram fertility.

Comparison of the performance of targeted mitochondrial antioxidant mitoquinone and non-targeted antioxidant pentoxifylline in improving rooster sperm parameters during freezing and thawing

Oxidative stress is associated with impaired sperm quality after thawing. Since mitochondria are the main source of reactive oxygen species (ROS) in sperm, the aim of this study was to investigate the effects of targeted mitochondrial antioxidant mitoquinone (MitoQ) and non-targeted mitochondrial antioxidant pentoxifylline (PTX) during cooling and cryopreservation of rooster sperm. Sperm samples were collected from 15 roosters aged 28 wk and diluted with Beltsville extender. After dilution and addition of treatments (50, 100, and 200 pMol MitoQ and 0.5, 0.75, and 1 μM PTX), samples were cooled for 2 h to 4°C and they were first analyzed at this stage and were frozen and re-evaluated after thawing. After the freezing and thawing, level of 100 pMol MitoQ significantly increased total motility (TM), progressive motility (PGM), curvilinear velocity (VCL), membrane integrity, viability, total antioxidant capacity (TAC) and the glutathione peroxidase (GPx), as well as the level of 50 pMol significantly increased TM, PGM, average path velocity (VAP), straight-line velocity (VSL), membrane integrity, viability, and mitochondrial activity. Moreover, these 2 levels (50 and 100 PMol) decreased malondialdehyde and sperm with abnormal morphology. Addition of 0.75 μM PTX also increased total motility compared to the control group and levels of 0.5 and 0.75 μM decreased sperm with abnormal morphology. It could be concluded the addition of MitoQ and PTX can be useful for sperm cryopreservation industry and reduce the harmful effects of freeze-thawing.

Influence of pentoxifylline and caffeine on stallion epididymal sperm motility after thawing

Two substances at two concentrations each were added to frozen-thawed stallion epididymal spermatozoa to improve motility indicators, which were assessed 30, 60, 120, 180 and 240 min after thawing. Pentoxifylline was added at concentrations of 3.6 mM (1 mg/ml) and 7.18 mM (2 mg/ml). Both concentrations had a positive effect on total and progressive motility of spermatozoa throughout the study. The other substance, caffeine, was added at concentrations of 2 mM (0.4 mg/ml) and 5.5 mM (1 mg/ml). Both concentrations had a positive effect on total and progressive motility of spermatozoa only 30 and 60 min after thawing. Subsequently, 180 min after thawing, improvement was found only in total sperm motility.

Evaluation of pentoxifylline and Basal Medium Eagle supplemented to diluent on cryopreserved goat spermatozoa

This study investigated the effect of pentoxifylline (PTX) and Basal Medium Eagle (BME) on frozen-thawed goat spermatozoa. Immediately after initial examination of ejaculated semen, samples were pooled and reexamined for quality. Then, samples were divided into eight equal aliquots and diluted with a basic tris-extender containing PTX (3, 6, 9 mM) and BME (5 mM) to reach a final concentration of 25 × 10⁹ and frozen. After 24 hr, the samples were individually thawed at 37°C for 30 s and evaluated for different characteristics. Obtained post-thaw results from Computer-Assisted Sperm Analysis indicate using of 3 and 6 mM PTX led significantly to an improvement in total motility, progressive motility and velocity characteristics of spermatozoa, except the beat/cross frequency (BCF) which indicated statistically no differences (p > .05) among control and treatments. Diluents prepared with BME (5 mM) and PTX alone (3 and 6 mM) improved significantly the membrane integrity-functionality, acrosome integrity and also hyaluronidase activity. Regarding recovery rate, the results showed significantly (p < .05) higher values for diluents containing 3 and 6 mM PTX compared to other groups. Malondialdehyde concentration exhibited also a significant difference (p < .05) in diluents supplemented with 5 mM BME, 3, 6 and 9 mM PTX, and mixture of 3 mM PTX and 5 mM BME which illustrate a similarity for active mitochondria, apoptotic-like and dead spermatozoa. Finally, the ratio of sperm chromatin dispersion stained spermatozoa presented significant differences (p < .05) among treatments in which the diluents added PTX alone demonstrated significantly lower values than control and extenders containing the mixtures of BME and PTX. In conclusion, the observation in this study indicates using of 3 and 6 mM PTX and BME alone may improve significantly (p < .05) the quality of cryopreserved goat spermatozoa.

Effect of Caffeine and Pentoxifylline Added Before or After Cooling on Sperm Characteristics of Stallion Sperm

Different additives have been tested in cooled stallion sperm, in order to maintain sperm quality and to ameliorate the decrease in sperm fertility potential. In several species, caffeine and pentoxifylline promote sperm motility by increasing energy production. We evaluate the effects of caffeine and pentoxifylline when added to stallion sperm before or after cooling. Three ejaculates from five stallions each were processed and resuspended in skim milk extender. Caffeine (5 mM), pentoxifylline (3.5 mM), or both additives combined were included to sperm before or after cooling (4°C for 24 hours). Cooled sperm were incubated at 37°C and evaluated at 0, 30, 60, and 120 minutes for motility, morphology, viability (flow cytometry), and membrane functionality (hypo-osmotic swelling test). Results were analyzed by two-factor mixed model for repeated measures and Tukey comparisons. As main effects, the caffeine and pentoxifylline affected significantly motility and kinematic parameters, without interaction between treatment and incubation after cooling. No differences were observed whether the additives were added prior or after cooling. Pentoxifylline added after cooling reduced significantly motility during incubation, but with higher values at 30 minutes. We detected a decrease in morphologically normal sperm (P < .0001), caused by an increase of tail defects (P < .003) in the presence of both additives. Viability and membrane functionality were also significantly impaired by additives. Pentoxifylline when added after cooling improved sperm motility and kinematic parameters for a short period of time. However, sperm characteristic related to fertility potential was compromised after a prolonged exposure to caffeine or pentoxifylline.

The Effect of Different Concentrations of Caffeine, Pentoxifylline and 2’-Deoxyadenosine on the Biological Properties of Frozen-Thawed Canine Semen

Artificial insemination (AI) and semen cryopreservation are the most accessible and commonly used techniques for breeding domestic animals. Among many parameters, such as plasma membrane integrity and acrosome structure, one of the key factors that determine the quality of frozen-thawed samples for artificial insemination is sperm motility. Sperm motility is one of the key parameters that determine the quality of frozen-thawed samples for AI. The total number of progressively motile spermatozoa in thawed canine semen is correlated with fertility. A variety of substances were used to compare sperm motility with the control. The aim of this study was to determine the effect of semen extender supplementation with motility stimulants, pentoxifylline (PTX), caffeine (CAF) and 2’-deoxyadenosine (DX), after different post-thaw incubation times (30, 60, 120 min) on the motility, selected kinematic parameters, plasma membrane integrity and mitochondrial membrane potential of cryopreserved canine spermatozoa. During attempts to improve the quality of cryopreserved semen, the applied substances exerted beneficial effects at a concentration of 10 mM. We demonstrated that both phosphodiesterase inhibitors, caffeine and pentoxifylline, as well as 2’-deoxyadenosine increased the motility and selected kinematic parameters of thawed canine spermatozoa.

Effects of pentoxifylline supplementation to semen extender on post-breeding inflammation response assessed by endometrial cytology and vascular perfusion in mares

The aim was to evaluate effects of addition of pentoxifylline to skimmed milk semen extender on uterine inflammatory response. Thirty-six estrous cycles of 15 mares were randomly divided into five groups for artificial insemination (AI): Control: mimicking the AI procedure (n = 7); Extender: deposition of skimmed milk based extender (n = 7); Extender + PTX: skimmed milk based extender plus pentoxifylline (7.18 mM; n = 8); Semen: semen diluted with extender without pentoxifylline (n = 7), and Semen + PTX: semen diluted with extender containing pentoxifylline (n = 7). Mares in estrus were examined by trans-rectal palpation and using ultrasonography, and ovulation was induced. Uterine hemodynamics were assessed immediately before ovulation induction (T-30), immediately before AI (T0), 2 (T2), 6 (T6), 12 (T12), 24 (T24) and 48 (T48) h after AI. Endometrial samples were collected 6 h after AI, and slides were stained and examined to determine percentage of PMN. Pentoxifylline had no additional effect on vascular perfusion. There was a major inflammatory response with pentoxifylline treatment that was greater than that of the control group. In the group treated with Extender + PTX, there were more PMN (57.98 ± 9.42%) than in the group treated with Extender (20.20 ± 6.63%) and in the Semen + PTX group more PMN (82.84 ± 5.71%) than in the Semen-treated group (47.83 ± 10.61%). These findings indicate the addition of pentoxifylline does not stimulate blood flow; however, it induces a greater immune defense response because more neutrophils migrate to the uterine lumen.

Effect of selenium and pentoxifylline on expression of CATSPER1 and 2 genes and FSH/LH levels in treated mice by dexamethasone

Dexamethasone has deleterious effects on male fertility and sperm parameters. In this study, the effect of dexamethasone on expression of CATSPER1 and 2 genes was investigated. These two genes play an important role in sperm motility. Selenium and pentoxifylline were subsequently used to protect testis tissue against the destructive effects of dexamethasone. Each group received one of the following treatments for 7 days: dexamethasone (7 mg/kg), pentoxifylline (200 mg/kg), selenium (0.3 mg/kg), dexamethasone + pentoxifylline or selenium + dexamethasone. Animals in the control group received a normal saline injection. The expression of CATSPER1 and 2 genes was analysed by real-time PCR and serum levels of FSH and LH were determined with the enzyme-linked immunosorbent assay method. Based on the results, dexamethasone decreases not only CATSPER1 and 2 gene expression but also serum levels of LH (p ≤ 0.05); however, it has no effect on FSH (p > 0.05). Treating with selenium significantly increased the gene expression of both CATSPER1 and 2 (p ≤ 0.05), while pentoxifylline enhanced only CATSPER2 gene expression (p ≤ 0.05). These two antioxidants were shown to increase serum levels of LH (p ≤ 0.05). Our data suggest that selenium is more effective than pentoxifylline in overcoming adverse effects of dexamethasone on male fertility.

Post-thaw Addition of Caffeine and/or Pentoxifylline Affect Differently Motility of Horse and Donkey-Cryopreserved Spermatozoa

To increase sperm motility, several molecules have been tested in mammals. Methylxanthines have shown effects on sperm motility, capacitation, and on in vitro fertilization processes. The aim of the study was to evaluate if the post-thaw addition of caffeine and/or pentoxifylline changes motility parameters of cryopreserved stallion and donkey spermatozoa. Straws derived from 14 horses and 7 donkeys were thawed and diluted in a milk-based extender to obtain the following final concentrations: CTR (control, no additives), CAF 5 (5 mM caffeine), CAF 10 (10 mM caffeine), PTX 5 (5 mM pentoxifylline), PTX 10 (10 mM pentoxifylline), CAF-PTX (5 mM caffeine and 5 mM pentoxifylline). Samples were evaluated immediately post-thaw and after 60 and 120 minutes of incubation at 37°C. In horses, overall total motility was significantly lower in CTR than in to CAF5, CAF-PTX, PTX5, PTX10, whereas progressive motility increased only in CAF5 and PTX5 (P < .05). No differences between control and treatments were seen for donkey semen. In CTR, during the first hour of incubation horses' sperm cells showed a larger decrease than donkeys' ones in all parameters (P < .05), except for lateral sperm head displacement. Thus, post-thaw motility and velocity decreased more sharply in horses than in donkeys. Caffeine and pentoxifylline-added post-thaw were able to increase the proportion of motile spermatozoa only for stallions and not for donkeys. Whether the improvement in post-thaw motility of equine spermatozoa may have an effect on in vivo or in vitro pregnancy rates remains to be determined.

Pentoxifylline effects on capacitation and fertility of stallion epididymal sperm

The aims of this study were to determinate whether pentoxifylline (PTX) increases the motion parameters of fresh and frozen-thawed equine epididymal spermatozoa, to evaluate the tyrosine phosphorylation of frozen-thawed epididymal sperm in the presence of PTX and to determine whether the PTX-treatment of stallion epididymal sperm prior to freezing improves the fertility response of mares to a reduced number of spermatozoa per insemination dose. Fifty epididymis were flushed with a skim milk based extender with or without PTX. The pre-treatment with PTX enhanced the sperm motility after being harvested (P<0.05); however the freeze-thaw process did not alter the sperm kinematics between control and treated samples (P>0.05). Plasma membrane integrity did not differ between control and PTX group after recovery and after thawing (P>0.05), as observed in tyrosine phosphorylation, which the PTX treatment did not alter the percentage of tail-associated immunofluorescence of cryopreserved epididymal sperm (P>0.05). For the fertility trial, different insemination groups were tested: 800×10⁶ epididymal sperm (C800); 100×10⁶ epididymal sperm (C100); 100×10⁶ epididymal sperm recovered in an extender containing PTX (PTX100). The conception rates for C800; C100 and PTX100 were 68.7% (11/16); 31.5% (5/16) and 50% (8/16), respectively. The conception rate did not differ among groups (P>0.05), however, a low number of animals was used in this study. A trend toward significance (P=0.07) was observed between C800 and C100 groups. In conclusion, PTX has no deleterious effect on sperm motility, viability and capacitation of cryopreserved stallion epididymal sperm. The conventional artificial insemination with 100×10⁶ sperm recovered with PTX ensures acceptable conception rates and maximize the limited number of doses of cryopreserved stallion epididymal sperm.

Localization and functional modification of L-type voltage-gated calcium channels in equine spermatozoa from fresh and frozen semen

It is well known that insemination of cryopreserved semen always results in lower fertility when compared with fresh semen, but there is an increased interest and demand for frozen equine semen by the major breeder associations because of the utility arising from semen already "on hand" at breeding time. In this article, we report that equine sperm cells express L-type voltage-gated calcium channels; their localization is restricted to sperm neck and to the principal piece of the tail in both fresh and frozen-thawed spermatozoa. We also studied the causes of cryoinjury at the membrane level focusing on the function of L-type calcium channels. We report that in cryopreserved spermatozoa the mean basal value of [Ca(2+)]i is higher than that of spermatozoa from fresh semen (447.130 vs. 288.3 nM; P < 0.001) and L-type channels function differently in response to their agonist and antagonist in relation to semen condition (fresh or frozen-thawed). We found that on addition of agonist to the culture medium, the increase in intracellular calcium concentrations ([Ca(2+)]i) was greater in frozen semen than in fresh semen (Δ[Ca(2+)]i = 124.59 vs. 16.04 nM; P < 0.001), whereas after the addition of antagonist the decrease in [Ca(2+)]i was lower in frozen semen than in fresh semen (Δ[Ca(2+)]i = 32.5 vs. 82.5 nM; P < 0.001). In this article, we also discuss the impact of cryopreservation on sperm physiology.

GPX5 orthologs of the mouse epididymis-restricted and sperm-bound selenium-independent glutathione peroxidase are not expressed with the same quantitative and spatial characteristics in large domestic animals

We report here on the cloning of cDNAs coding bovine and equine orthologs of mouse epididymis-restricted and sperm-bound glutathione peroxidase 5 (GPX5), a selenium-independent member of the multigenic GPX family in mammals. The complete sequence of bovine GPX5 as well as a partial sequence of the equine GPX5 were characterized, conceptually translated and aligned with other known mammalian GPX5 proteins. Using Northern blotting assays, we show that the level of expression of GPX5 is high in bovine but low in equine and that in both species the regionalization of GPX5 expression in epididymis is not totally identical to what was reported for rodent mouse GPX5. An antibody was produced against GPX5 and used in Western blot assays as well as in immunohistochemistry assays on bovine epididymis sections. It shows that the protein is essentially present in the cytoplasmic compartment of the caput segment 2 epithelium of the bovine epididymis. Unlike in the mouse model, bovine GPX5 seems to be poorly secreted and does not seem to be present on cauda epididymal spermatozoa.

Cryopreservation of sperm ofXenopus laevis andXenopus tropicalis

Now that transgenic strains of Xenopus laevis and X. tropicalis can be generated efficiently and with genomic sequence resources available for X. tropicalis, early amphibian development can be studied using integrated biochemical and genetic approaches. However, housing large numbers of animals generated during genetic screens or produced as novel transgenic lines presents a considerable challenge. We describe a method for cryopreserving Xenopus sperm that should facilitate low maintenance, long-term storage of male gametes. By optimising the cryoprotectant, the rates of cooling and thawing, and conditions for fertilisation, sperm from the equivalent of one-eighth of a X. laevis testis or of two X. tropicalis testes have been cryopreserved and used to fertilise eggs of both species after thawing. Sperm undergo a substantial loss of viability during a freeze-thaw cycle, but sufficient survive to fertilise eggs. Gametes of mutagenised frogs are being stored in connection with a screen for developmental mutations.

Sperm preparation for ART

The onset of clinical assisted reproduction, a quarter of a century ago, required the isolation of motile spermatozoa. As the indication of assisted reproduction shifted from mere gynaecological indications to andrological indications during the years, this urged andrological research to understand the physiology of male germ cell better and develop more sophisticated techniques to separate functional spermatozoa from those that are immotile, have poor morphology or are not capable to fertilize oocytes. Initially, starting from simple washing of spermatozoa, separation techniques, based on different principles like migration, filtration or density gradient centrifugation evolved. The most simple and cheapest is the conventional swim-up procedure. A more sophisticated and most gentle migration method is migration-sedimentation. However, its yield is relatively small and the technique is therefore normally only limited to ejaculates with a high number of motile spermatozoa. Recently, however, the method was also successfully used to isolate spermatozoa for intracytoplasmic sperm injection (ICSI). Sperm separation methods that yield a higher number of motile spermatozoa are glass wool filtration or density gradient centrifugation with different media. Since Percoll as a density medium was removed from the market in 1996 for clinical use in the human because of its risk of contamination with endotoxins, other media like IxaPrep, Nycodenz, SilSelect, PureSperm or Isolate were developed in order to replace Percoll. Today, an array of different methods is available and the selection depends on the quality of the ejaculates, which also includes production of reactive oxygen species (ROS) by spermatozoa and leukocytes. Ejaculates with ROS production should not be separated by means of conventional swim-up, as this can severely damage the spermatozoa. In order to protect the male germ cells from the influence of ROS and to stimulate their motility to increase the yield, a number of substances can be added to the ejaculate or the separation medium. Caffeine, pentoxifylline and 2-deoxyadenosine are substances that were used to stimulate motility. Recent approaches to stimulate spermatozoa include bicarbonate, metal chelators or platelet-activating factor (PAF). While the use of PAF already resulted in pregnancies in intrauterine insemination, the suitability of the other substances for the clinical use still needs to be tested. Finally, the isolation of functional spermatozoa from highly viscous ejaculates is a special challenge and can be performed enzymatically to liquefy the ejaculate. The older method, by which the ejaculate is forcefully aspirated through a narrow-gauge needle, should be abandoned as it can severely damage spermatozoa, thus resulting in immotile sperm.