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

Post-cooling semen processing and sperm re-suspension as an alternative method to circumvent poor semen cooling in stallions

BACKGROUND

Artificial insemination with cooled-shipped semen is the primary method used in the equine breeding industry; yet, sperm quality and fertility can be suboptimal for some stallions when standard techniques are used. Therefore, there is a critical need to develop alternative approaches for these stallions.

OBJECTIVE

To assess sperm quality parameters and fertility of cooled-stored stallion semen processed by SpermFilter® or centrifugation and resuspended in three extenders.

STUDY DESIGN

Controlled and field study.

METHODS

In Experiment 1, semen was collected from 21 stallions classified as having good ('Good-coolers', n = 8) or poor ('Bad-coolers', n = 13) semen cooling. The semen was extended at 30 million spermatozoa/mL in a skimmed milk-based (SM) diluent, and refrigerated for 24 h. Then, the cooled-stored semen was processed through SpermFilter® or centrifugation, and the resulting sperm pellets were resuspended in SM, SM containing pentoxifylline (SM-P), or an egg yolk-based (EY) extender. Unprocessed cooled-stored semen served as control. Sperm motility parameters, plasma membrane integrity (PMI), and mitochondrial membrane potential (HMMP) were assessed in cooled-semen pre- and post-processing. Experiment 2, cooled semen from 9 stallions classified as Bad-coolers was used to inseminate 18 embryo donor mares at 66 cycles (Unprocessed, n = 22; SpermFilter®/SM-P, n = 16; or SpermFilter®/EY, n = 28). Data were analysed with a mixed model and Tukey's as posthoc, and logistic regression.

RESULTS

Processed semen resuspended in EY had superior sperm motility compared to unprocessed, SM and SM-P (p < 0.0001). Semen processed by SpermFilter® resuspended in SM-P was similar to EY (p > 0.05). Pellet resuspension with EY and SM-P improved the HMMP of Bad-cooler stallions (p = 0.0010). Semen processed by SpermFilter® had superior PMI to centrifuged semen (p < 0.0001). Mares inseminated with SpermFilter®/SM-P (50%, 8/16) or SpermFilter®/-EY (68%, 9/28) had higher pregnancy rates than mares bred with unprocessed semen (14%, 3/22) (p < 0.001).

MAIN LIMITATIONS

Low number of mares in the fertility trial.

CONCLUSION

Sperm quality and fertility of Bad-cooler stallions can be enhanced by SpermFilter® and pellet resuspension with either EY or SM-P.

Efficacy and Safety of Pentoxifylline for Venous Leg Ulcers: An Updated Meta-Analysis

The venous leg ulcers are debilitating, painful, and often unresponsive to advanced dressing treatments, so drugs used locally and systematically are essential adjuvant therapy-pentoxifylline (PTX) whose anti-inflammatory effects may offer a promising avenue to treat venous leg ulcers. However, the current results are controversial. To further evaluate the efficacy and safety of PTX, we performed an updated meta-analysis of randomized placebo-controlled trials of PTX in the treatment of venous leg ulcers. We systematically searched multiple electronic databases PubMed, Web of Science, Embase, the Cochrane Library, the Cochrane Central Register of Controlled Trials, China Science and Technology Journal Database, WanFang Data, China National Knowledge Infrastructure, and the Chinese Biomedical Literature Database to identify eligible studies. Randomized clinical trials of pentoxifylline versus placebo treatment in patients with venous leg ulcers were considered for inclusion. The primary outcomes included ulcer healing rate and the incidence of adverse events after treatment. The secondary outcomes were the ulcer significant improvement (the ulcer size shrank by more than 60% after treatment) rate, mean duration of complete wound healing and changes in mean ulcer size. A meta-analysis and qualitative analysis were conducted to estimate endpoints. A total of 13 randomized clinical trials, including 921 individuals, were finally included. Compared with placebo, pentoxifylline significantly improved the ulcer healing rate (RR = 1.59, 95%CI 1.22 to 2.07, P < .001) and significant improvement rate (RR = 2.36, 95%CI 1.31 to 4.24, P = .004) while increased the incidence of gastrointestinal disturbances (RR = 2.29, 95%CI 1.04 to 5.03, P = .04) at the same time. Moreover, pentoxifylline also shortened mean duration of complete wound healing (P = .007) and shrank ulcer size (P = .02). Currently available evidence suggests that pentoxifylline could help venous leg ulcers heal more quickly and effectively. However, the evidence is insufficient to prove the results due to moderate-certainty evidence. Large-scale, well-designed randomized clinical trials are warranted.

The effects of caffeine on the motility and viability of stallion spermatozoa at different temperature conditions

The purpose of this study was to evaluate the dose- and time-dependent effect of caffeine treatment on the motility and viability of stallion spermatozoa at different temperatures. Six dose groups (A to F) were established with changing caffeine concentrations (from 0.625 to 10 mg/mL). The control samples were prepared by diluting the ejaculate only with physiological salt solution. The samples were examined after 0, 1, 2 and 3 h of incubation at 5 °C and 37 °C. The motility parameters were evaluated by Computer Assisted Semen Analyzer (CASA) system, and the viability was assessed by the mitochondrial toxicity test at the end of the incubation. A positive effect of the lowest tested caffeine concentration on the motility parameters was observed throughout the incubation period at 5 °C. At the end of the 3h incubation, the viability in every sample in these groups, treated with any caffeine concentration, showed lower values compared to the control. At the higher incubation temperature (37 °C), caffeine positively affected the motility in samples B (P < 0.05) and D, E, F (P < 0.001) after 3 h of incubation; however, the viability showed a slightly decreasing tendency. Our results suggest that caffeine, in an optimal concentration, may be used as a component of stallion semen extenders.