Effect of heparin, caffeine and calcium ionophore A23187 on in vitro induction of the acrosome reaction of fresh ram spermatozoa

Supplementation of caffeine to extender improves post-thaw seminal attributes of Poitou donkey semen

The current study was conducted with an objective of elucidating the effect of addition of various levels of caffeine to jack semen on seminal attributes at pre- and post-thaw stage. Six ejaculates from each three adult jack stallions were collected via artificial vagina using estrus jenny as dummy. Caffeine was added to semen extender at 0.1, 0.5 and 2 mM at pre-freeze stage and the semen was cryopreserved according to standard protocol. Sperm motility, viability and other functional attributes were assessed at pre-freeze and post-thaw stages. The present study revealed that, adding caffeine to jack semen extender at 0.1 mM, 0.5 mM or 2 mM levels had positive impact on seminal parameters compared to the control semen. Sperm kinetics (VAP, VSL and STR) and motility increased in the caffeine treated groups in comparison to the control group. The caffeine at 2.0 mM concentration resulted in better post-thaw sperm motility, viability, and acrosome integrity as compared to 1 or 0.5 mM of caffeine and control. Caffeine supplementation also enhanced post-thaw sperm kinematic parameters, which implies its potential as an alternative antioxidant supplement. It was concluded that, 2 mM caffeine supplementation to donkey semen significantly improved post-thaw sperm motility and other functional attributes as compared to the control. However, the potential benefits of caffeine on the fertility rates needs to be investigated.

Artemisia vulgaris extract causes precocious acrosome reaction and viability loss but low rate of membrane damage in mouse spermatozoa

Several herbs including Artemisia are known to possess conceptive property. In the present study, mouse spermatozoa were incubated with ethanol extract of Artemisia vulgaris leaves. The effect of extract on acrosome exocytosis was studied by labeling spermatozoa with fluorescein isothiocyanate (FITC) peanut agglutinin and by staining with Coomassie blue. Viability and membrane integrity were studied by Trypan-blue staining and hypo-osmotic swelling test. Artemisia extract at very low concentration caused precocious acrosome reaction and loss of sperm viability. Acrosome reaction increased remarkably from 22.63% to 88.42% with increasing extract concentration from 0 to 2,000 µg/mL. However, the viability loss of spermatozoa was increased from 11.71% in control to 63.73% in samples treated, evaluated by Trypan-blue staining method. Membrane damage caused by the extract, evaluated by hypo-osmotic swelling test was even low, ranging from 2.27% to only 24.23%. These results indicate that Artemisia extract might block fertilization by causing precocious acrosome exocytosis in spermatozoa. A direct contraceptive effect was tested by injecting the plant extract into the vagina of female mice and then allowing them to mate with normal males. The treated female mice delivered significantly fewer litters in comparison to the control.

Enhancing liquid-chilled storage and cryopreservation capacities of ram spermatozoa by supplementing the diluent with different additives

Objective

In the present study, we determined efficiency of incorporating caffeine, melatonin or omega-3 polyunsaturated fatty acid in the diluent on mitigating consequences of (a) liquid chilled- and (b) cryo-storage of ram spermatozoa.

Methods

In the first experiment, ejaculates (n = 30) were collected from 5 adult rams and were pooled, diluted (1:10) with Tris-citric acid (base diluent) and were split into 4 aliquots assigned for: control (untreated), caffeine (0.1 mM), melatonin (0.3 mM) or omega-3 fatty acids (0.3 mM) (T₀). The diluted specimens were stored at 4°C for 48 h, during which sperm physical and cytological properties were evaluated along with oxidative stress indices (T₂₄, T₄₈). In the second experiment, 15 ejaculates (3 per male) were pooled, diluted with glycerolized base diluent (4% glycerol, v/v) and were split corresponding to the same previous treatment groups before being processed for cryopreservation. Post-thaw physical and kinematic sperm properties were assessed by a computer-assisted sperm analysis system.

Results

The results clarified superiority of both melatonin and omega-3 supplementation on maintaining (p<0.05) sperm properties, while reducing (p<0.05) lipid peroxidase reaction and enzymatic activities of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase in preservation medium, compared to caffeine either during liquid-chilled storage or cryopreservation of spermatozoa.

Conclusion

Melatonin and omega-3 are regarded efficient alternatives to caffeine when processing ram spermatozoa for application of artificial insemination or in vitro fertilization.

Effect of adding different levels of caffeine in the extender on some biochemical constituents, enzymatic activities and physical characteristics of chilled and frozen ram semen

Two experiments were carried out to determine the efficiency of supplementation of ram semen extender with caffeine on chilled storage and frozen capacity of spermatozoa. In the first experiment, eighty ejaculates were collected by an artificial vagina from five adult Barki rams, aged 2-3 years and weighted 45.0 ± 2.0 kg throughout the experimental period (January to February 2017). The ejaculates were pooled and diluted (1:10) with tris-citric egg yolk extender and were split into five groups. Group 1 served as control, whereas groups 2-5 were supplemented with 0.1, 0.2, 0.3 and 0.4 mM caffeine. All diluted semen specimens were evaluated for physical characteristics immediately after dilution (T₀ ) and throughout preservation period of 48 hr at 4°C. Simultaneously, oxidative stress and indices such as total antioxidant capacity (TAC), malondialdehyde concentrations (MDA) and alkaline transaminase (AKP) concentrations and value of resazurin reduction test (RRT) were determined. In the second experiment, the raw pooled ejaculates were diluted (1:10) with glycerolated tris-citric egg yolk extender, receiving the previously mentioned caffeine levels. The post-thaw assessment of cryopreserved spermatozoa, in all groups, was conducted by a computer-assisted sperm analysis (CASA) system. The results revealed that adding caffeine to ram semen extender at low (0.1 mM) or medium (0.2 mM) levels had positive impact on both physical characteristics of ram sperm and the enzymatic activities compared to the other semen groups. Caffeine supplementation also enhanced post-thaw sperm dynamics, which implies its potential as an exogenous antioxidant supplement.