Hyaluronic acid delays boar sperm capacitation after 3 days of storage at 15°C

Effects of Calyculin a on the Motility and Protein Phosphorylation in Frozen-Thawed Bull Spermatozoa

In this study, we examined the effects of calyculin A, a phosphatase inhibitor, on motility, protein phosphorylation, and the distribution of phospho-(Ser/Thr) PKA substrates in frozen-thawed bull spermatozoa that are actually used by most farmers for breeding. The data showed that calyculin A, which has been reported to have a positive effect on the motility of ejaculated fresh spermatozoa, distinctly decreased the motility of frozen-thawed bull spermatozoa even if a cell activator, such as caffeine, was present in the incubation medium and that the suppressive effect of calyculin A was dose-dependent and continued for at least 200 min. Immunoblot analyses revealed that de novo protein phosphorylation was not detected in spermatozoa exposed to caffeine or dbcAMP (a cell-permeable cAMP analog), while the addition of calyculin A to the medium brought about the appearance of several phosphorylated proteins at 50 kDa and 75 kDa, suggesting that 50 kDa and 75 kDa proteins, which were phosphorylated by activation of cAMP-dependent PKA, were not dephosphorylated and were accumulated in spermatozoa due to the suppression of calyculin A-sensitive protein phosphatases. Immunofluorescence microscopy revealed that calyculin A caused, alone or in conjunction with caffeine or dbcAMP, the accumulation of phospho-PKA substrates at the annulus, although caffeine or dbcAMP alone did not. This study suggested that calyculin A decreases the motility of frozen-thawed bull spermatozoa concomitant with the accumulation of phospho-(Ser/Thr) PKA substrates at the annulus of flagella.

Specific phosphodiesterase type-10 inhibitor, papaverine, added after the cooling period improves canine sperm quality

The use of chilled semen has gained increasing interest in canine reproductive services. The addition of phosphodiesterase (PDE) inhibitors that increase the intracellular cyclic adenosine monophosphate levels may improve sperm motility. The purpose of this study was to examine the quality of sperm under the effect of the specific PDE-10 inhibitor (papaverine) added after storage for 1, 2, and 3 days at 5 °C. The ejaculates were obtained from 5 healthy Beagle dogs by digital manipulation. After collection, ejaculates were pooled, extended and cooled at 5 °C during 3 days. Sperm parameters were tested 30 min after the addition of different papaverine (PA) concentrations: 0, 5, 10 and 20 µM. Sperm motility (CASA), viability (PI/FITC-PNA) and capacitation status (chlortetracycline assay) were evaluated. The results showed that the addition of PA has no effect on sperm samples at day 0. However, concentrations of 5 and 10 µM increased (p < .05) sperm motility kinetics and viability significantly compared to the control at day 1, day 2 and day 3 of cooling. The addition of 20 μM PA decreased (p < .05) sperm quality parameters significantly and increased the percentage of capacitated/acrosome-reacted spermatozoa. In conclusion, the addition of 5 and 10 μM PA concentrations after cooled storage improved canine sperm quality.

Effects of Roundup and its main component, glyphosate, upon mammalian sperm function and survival

The wide use of glyphosate-based herbicides (GBHs) has become a matter of concern due to its potential harmful effects on human health, including men fertility. This study sought to investigate, using the pig as a model, the impact of pure glyphosate and its most known commercial formulation, Roundup, on sperm function and survival. With this purpose, fresh commercial semen doses were incubated with different concentrations (0-360 µg/mL) of glyphosate (GLY; exp. 1) or Roundup, at the equivalent GLY concentration (exp. 2), at 38 °C for 3 h. Glyphosate at 360 µg/mL significantly (P < 0.05) decreased sperm motility, viability, mitochondrial activity and acrosome integrity but had no detrimental effect at lower doses. On the other hand, Roundup did significantly (P < 0.05) reduce sperm motility at ≥ 5 µg/mL GLY-equivalent concentration; mitochondrial activity at ≥ 25 µg/mL GLY-equivalent concentration; and sperm viability and acrosome integrity at ≥ 100 µg/mL GLY-equivalent concentration as early as 1 h of incubation. In a similar fashion, GLY and Roundup did not inflict any detrimental effect on sperm DNA integrity. Taken together, these data indicate that, while both glyphosate and Roundup exert a negative impact on male gametes, Roundup is more toxic than its main component, glyphosate.

Addition of chlorogenic acid and caffeine during the processing of cooled boar semen

ABSTRACT A study was conducted to evaluate the effect of chlorogenic acid (ChA) added pre-cooling and its combination with caffeine added during warming on cooled-stored boar semen parameters. Ten ejaculates were diluted in commercial extender with or without 4.5mg/ml ChA and stored at 15°C. After 0, 24 and 72 hours of storage, aliquots of these doses were taken and incubated at 37°C in the presence or absence of 8.0mM caffeine. Semen quality was evaluated after 10 and 120 minutes of incubation. The ChA increased (P <0.01) the sperm motility, viability, acrosomal integrity and the percentage of spermatozoa with high mitochondrial activity (PMHA), however, decreased (P <0.01) the malondialdehyde (MDA) concentration. Caffeine increased (P<0.05) the sperm motility, viability, PMHA and the MDA concentration and reduced (P <0.05) the acrosome integrity. When associated (ChA+caffeine), there was an increase (P <0.05) in sperm motility and viability, PMHA and acrosome integrity. The addition of ChA to the dilution medium improves the quality of the swine inseminating doses. The addition of caffeine during re-warming is only recommended when the semen is stored for prolonged periods (72h), and the inseminating dose should be used immediately after its addition.

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.

Hyaluronan improves neither the long-term storage nor the cryosurvival of liquid-stored CD44-bearing AI boar spermatozoa

Hyaluronan (hyaluronic acid, HA) apparently improves sperm survival in vitro and in vivo (oviduct), maintaining sperm motility and inducing capacitation, but not acrosome exocytosis, either by direct action as a macromolecule or via CD44 membrane receptors. This study explored ejaculated, liquid-extended pig spermatozoa to ascertain (i) the presence (Western blotting) and specific location (immunocytochemistry) of the CD44 receptor, using a specific monoclonal commercial antibody; (ii) whether the CD44 receptor changed location when exposed to bicarbonate, a capacitating trigger, in vitro; and (iii) whether the addition of HA, of molecular size comparable to that produced in the oviduct sperm reservoir (0.0625 to 2.0 mg/ml; 0 HA: control), to semen extenders would improve sperm liquid storage in vitro or cryosurvival post-freezing. Variables tested were sperm velocity and progressive motility (Qualisperm^TM), sperm viability and acrosome status, membrane integrity and early destabilization, mitochondrial activation, and superoxide production (flow cytometry). The CD44 receptor presence in ejaculated, liquid-stored AI boar spermatozoa, as confirmed by a porcine-specific monoclonal antibody, maintained its membrane location under in vitro capacitation-inducing conditions. HA exposure to 24-, 48-, or 72-h liquid-stored (17–20ºC) spermatozoa lowered sperm velocity in membrane-intact spermatozoa, but increased mitochondrial superoxide production. Finally, HA addition during cooling did not improve cryosurvival but did increase mitochondrial activation and membrane destabilization in surviving cells. These results confirm the existence of a CD44 receptor in pig spermatozoa, but the usefulness of adding HA for long-term storage or cryopreservation of liquid-stored, extended boar semen remains in question, thereby warranting further non-empirical analyses of HA-sperm membrane interactions.

The influence of caffeine supplementation and concerted utilization of enzymatic and mechanical semen liquefaction on freezability of dromedary camel spermatozoa

Assisted reproductive technologies have been reported to improve reproductive efficiency and genetic potential in camelids. Two experiments were carried out to determine efficiency of centrifugation in the presence of a mucolytic agent for liquefaction of dromedary semen. In the first experiment, three groups, namely: I. Tris lactose (TL, control), II. Tris lactose supplemented with amylase (TL_A) and III. Tris lactose supplemented with amylase followed by seminal plasma removal via centrifugation (TL_A__Cent.) and re-suspension into enzyme free TL media. After equilibration, control group recorded 62.85 ± 4.28% motility and 1.3 ± 0.13 viscosity score, while TL_A group values were 72.88 ± 3.30% and 0.83 ± 0.07%, respectively. TL_A__Cent. group showed significant viscosity reduction (0.33 ± 0.05) and motility decline 47.85 ± 3.04% with increment in abnormalities and detached acrosome. The second experiment investigated the effect of caffeine addition to tolerate enzymatic and mechanical stress. Using 4 mM caffeine in amylase-treated semen (TL_AC) improved post-thaw motility 50.0 ± 1.29% and recovery rate 77.8 ± 3.83% compared to the control (40.17 ± 2.79% and 62.55 ± 8.39%), respectively. Caffeine supplemented centrifuged samples (TL_AC__Cent.) showed superiority (P < .05) in post-thaw motility and recovery rate (38.33 ± 6.41%, 62.76 ± 8.10%) compared to centrifuged samples TL_A__Cent. without caffeine addition (25.00 ± 2.88% and 40.47 ± 3.48%), respectively. Sperm kinetics showed that TL_A exhibited high (p < .05) values for mostly all sperm kinetics. Caffeine treatments showed superiority in velocity curved line (VCL, µm/s) 94.24 ± 8.44 for TL_AC and 104.25 ± 8.72 for the TL_AC__Cent. group compared to 86.8 ± 5.54 for TL_A, and 85.73 ± 5.99 for the TL_A__Cent. groups. In conclusion, preforming a combined enzymatic-mechanical protocol in the presence of an antioxidant may be crucial for refinement of camel semen cryopreservation.

The use of gelatine in long-term storage (up to 48 hr) at 5°C preserves the pre-freezing and post-thawing quality of brown bear sperm

Sedimentation of spermatozoa occurs during long-term liquid storage and this may produce deleterious changes. Our aim was to apply gelatine supplementation during long-term pre-freezing storage of bear sperm, applying final dilution and 6% glycerol at room temperature and cool in straws. We tested four models of sperm storage using a 1:1 dilution in TTF-ULE-Bear extender (TesT-fructose-egg yolk-glycerol 6%): (i) second 1:1 dilution at room temperature (RT), cooling at 5°C in a tube and final dilution (100 × 10(6)  sperm ml(-1) ) (Standard); (ii) final dilution at RT and cooling in a tube (FD-Tube); (iii) final dilution at RT and cooling in 0.25 ml plastic straw (FD-Straw); and (iv) final dilution at RT in extender supplemented with 1.5% gelatine (Gelatine) and cooling in a 0.25 ml plastic straw. A Standard sample was stored at 5°C for 1 hr (Control); the rest of the samples (Standard, FD-Tube, FD-Straw, Gelatine) were stored for 24 or 48 hrs before freezing (100 × 10(6)  sperm ml(-1) , glycerol 6%). The quality of the samples was assessed for motility by CASA, and viability (SYBR-14/propidium iodide-PI-; VIAB), acrosomal status (PNA-FITC/PI; iACR) and apoptotic status (YO-PRO-1/PI; YOPRO-) by flow cytometry. At pre-freezing, after 48 hr, Gelatine showed significantly higher viability (for VIAB and YOPRO-) and progressiveness (PM, LIN and STR). At 48 hr, Gelatine showed similar YOPRO-, iACR, LIN, STR and ALH respect to Control. At both 24 and 48 h post-thawing, Gelatine sample had similar scores for YOPRO-, iACR, LIN, STR, WOB and VIAB (only 24 hr) when compared with Control, and lower for TM, PM, rapidPM, VAP and ALH. No differences were found among others experimental groups with respect to Control. In conclusion, gelatine could be a suitable alternative to preserve the viability and progressive motility of brown bear ejaculates during long-term pre-freezing storage at 5°C.

Recent Advances in Boar Sperm Cryopreservation: State of the Art and Current Perspectives

While sperm cryopreservation is the best technology to store boar semen for long-term periods, only 1% of all artificial inseminations (AI) conducted worldwide are made using frozen-thawed boar sperm. With the emergence of long-term extenders for liquid storage, the use of cryopreserved sperm in routine AI is less required. However, banks of boar semen contain cryopreserved sperm and planning inseminations in AI centres may benefit from the use of frozen-thawed semen. Therefore, there is an interest in the use of this technology to preserve boar sperm. In this regard, although the first attempts to cryopreserve boar semen date back to the seventies and this technology is still considered as optimal, some relevant improvements have been made in the last decade. After giving a general picture about boar sperm cryodamage, the present review seeks to shed light on these recent cryopreservation advances. These contributions regard to protein markers for predicting ejaculate freezability, sperm selection prior to start cryopreservation procedures, additives to freezing and thawing extenders, relevance of the AI-technique and insemination-to-ovulation interval. In conclusion, most of these progresses have allowed counteracting better boar sperm cryodamage and are thus considered as forward steps for this storage method. It is also worth noting that, despite being lower than fresh/extended semen, reproductive performance outcomes following AI with frozen-thawed boar sperm are currently acceptable.

Specific LED-based red light photo-stimulation procedures improve overall sperm function and reproductive performance of boar ejaculates

The present study evaluated the effects of exposing liquid-stored boar semen to different red light LED regimens on sperm quality and reproductive performance. Of all of the tested photo-stimulation procedures, the best pattern consisted of 10 min light, 10 min rest and 10 min of further light (10-10-10 pattern). This pattern induced an intense and transient increase in the majority of motility parameters, without modifying sperm viability and acrosome integrity. While incubating non-photo-stimulated sperm at 37 °C for 90 min decreased all sperm quality parameters, this reduction was prevented when the previously-described light procedure was applied. This effect was concomitant with an increase in the percentage of sperm with high mitochondrial membrane potential. When sperm were subjected to ‘in vitro’ capacitation, photo-stimulation also increased the percentage of sperm with capacitation-like changes in membrane structure. On the other hand, treating commercial semen doses intended for artificial insemination with the 10-10-10 photo-stimulation pattern significantly increased farrowing rates and the number of both total and live-born piglets for parturition. Therefore, our results indicate that a precise photo-stimulation procedure is able to increase the fertilising ability of boar sperm via a mechanism that could be related to mitochondrial function.

The ubiquitous hyaluronan: Functionally implicated in the oviduct?

Hyaluronan (hyaluronic acid) is a simple, nonantigenic, nonsulfated glycosaminoglycan present everywhere in the extracellular compartments of the body. Noteworthy, it is highly conserved phylogenetically, from sauropsida to mammals; and plays a plethora of roles from embryonic/fetal development to adult physiological and pathological events, including tumor development. In reproduction, hyaluronan has proven related to initial events as sperm survival, buildup of the sperm reservoir in the oviduct, regulation of sperm capacitation, and prefertilization to later participate in embryo, fetal, and placental development. Synthesis, binding (via the CD44 membrane receptor), and degradation of hyaluronan occur in male and female genital organs, the oviduct being no exception. This review discusses our current knowledge on roles of this ubiquitous glycosaminoglycan on the survival of immunologically foreign spermatozoa in the pig oviduct, a relevant event for fertility. During preovulatory storage in the functional tubal sperm reservoir, spermatozoa are entrapped in a mucus-like tubal fluid. This fluid contains fluctuating levels of hyaluronan, which is synthesized by the lining epithelium by hyaluronan synthase 3. Both hyaluronan and its CD44 receptor are particularly evident in the deep mucosal furrows of the sperm reservoir, in which most spermatozoa are embedded in; kept alive, uncapacitated but also undetected by the immune system of the female. Hyaluronan is also present in the seminal plasma, and evidence points toward an involvement of hyaluronan and its receptor in the local (tubal and possibly uterine) production of antiinflammatory cytokines, such as interleukin-10, pertaining maternal immune tolerance of these foreign cells.

Intracellular calcium movements of boar spermatozoa during 'in vitro' capacitation and subsequent acrosome exocytosis follow a multiple-storage place, extracellular calcium-dependent model

This work analysed intracellular calcium stores of boar spermatozoa subjected to 'in vitro' capacitation (IVC) and subsequent progesterone-induced acrosome exocytosis (IVAE). Intracellular calcium was analysed through two calcium markers with different physico-chemical properties, Fluo-3 and Rhod-5N. Indicative parameters of IVC and IVAE were also evaluated. Fluo-3 was located at both the midpiece and the whole head. Rhod-5N was present at the sperm head. This distribution did not change in any of the assayed conditions. Induction of IVC was concomitant with an increase in both head and midpiece Ca(2+) signals. Additionally, while IVC induction was concurrent with a significant (p < 0.05) increase in sperm membrane permeability, no significant changes were observed in O2 consumption and ATP levels. Incubation of boar spermatozoa in the absence of calcium showed a loss of both Ca(2+) labellings concomitantly with the sperm's inability to achieve IVC. The absence of extracellular calcium also induced a severe decrease in the percentage of spermatozoa exhibiting high mitochondrial membrane potential (hMMP). The IVAE was accompanied by a fast increase in both Ca(2+) signalling in control spermatozoa. These peaks were either not detected or much lessened in the absence of calcium. Remarkably, Fluo-3 marking at the midpiece increased after progesterone addition to sperm cells incubated in a medium without Ca(2+) . The simultaneous addition of progesterone with the calcium chelant EGTA inhibited IVAE, and this was accompanied by a significant (p < 0.05) decrease in the intensity of progesterone Ca(2+) -induced peak, O2 consumption and ATP levels. Our results suggest that boar spermatozoa present different calcium deposits with a dynamic equilibrium among them and with the extracellular environment. Additionally, the modulation role of the intracellular calcium in spermatozoa function seems to rely on its precise localization in boar spermatozoa.

Sperm quality and fertility of boar seminal doses after 2 days of storage: does the type of extender really matter?

The present approach was designed to evaluate the extender effects on sperm quality and fertility of short-term refrigerated seminal doses from Landrace boars lodged in husbandry-controlled conditions. For this purpose, we analyzed the sperm quality of seminal doses diluted in short-term (Beltsville Thawing Solution) and extra-long-term (Duragen) extenders from Days 0 to 2 of storage at 17 °C during an 8-month period. Pregnancy rates and litter size were evaluated from double inseminations within an interval of 12 hours (36 and 48 hours of refrigeration) of multiparous females using seminal doses diluted in each extender type. Sperm quality was assessed from the analyses of sperm motility and kinetics, sperm viability, expressed as plasma and acrosome membrane integrity, membrane lipid disorder, intracellular calcium levels, and acrosin activity. Results indicated significant differences between the extenders in the sperm quality of seminal doses. Therefore, the seminal doses diluted in Duragen had higher percentages of progressive motile spermatozoa and membrane-intact spermatozoa than those diluted in Beltsville Thawing Solution throughout all the experimental months. Nevertheless, despite these differences in preserving the sperm quality, pregnancy rates (>90%) and litter sizes (>10 piglets born per litter) were similar between the extenders. Our results had great relevance from a practical point of view because they reported lack of an extender effect on the reproductive performance of seminal doses during short-tem storage.

Cryopreservation of ram semen in extenders containing soybean lecithin as cryoprotectant and hyaluronic acid as antioxidant

A soybean lecithin-based extender supplemented with hyaluronic acid (HA) was assayed for effectiveness to improve the quality of frozen-thawed ram semen. HA has not been tested yet in an extender containing soybean lecithin for freezing ram semen. Thus, the aim of this study was to analyse the effects of soybean lecithin at 1% or 1.5% along with HA at 0, 0.5 and 1 mg ml(-1) in a Tris-based extender on the motion characteristics, membrane integrity (HOST), viability, GSH peroxidase (GSH-PX) activity, lipid peroxidation and acrosomal status after freezing-thawing. Semen was collected from four Mehraban rams during the breeding season and frozen in the six lecithin×HA extenders. The extender containing 1.5% lecithin supplemented with no HA yielded higher total motility (52.5%±1.6), viability (55.8%±1.6) and membrane integrity (44.5%±1.7), but the effects of the lecithin concentration did not reach signification. Linearity-related parameters, ALH, BCF, lipid peroxidation, GSH-PX activity, morphology and acrosomal status were not affected by the extender composition. In general, adding HA significantly decreased sperm velocity (1 mg ml(-1) HA), total motility (only with 1.5% lecithin), viability (1 mg ml(-1) HA for 1% lecithin; both concentrations for 1.5% lecithin) and membrane integrity. In conclusion, adding HA to the freezing extender supplemented with soybean lecithin failed to improve quality-related variables in ram semen. Increasing the lecithin content could have a positive effect, but further studies are needed.

Effects of Enterobacter cloacae on boar sperm quality during liquid storage at 17°C

Contamination of fresh and extended boar sperm often occurs in farms and artificial insemination (AI) centres during semen collection, processing and storage. The presence of bacteria produces detrimental effects on boar sperm quality, which may cause economic losses in reproductive centres. The present study has evaluated for the first time how the presence of Enterobacter cloacae affects the preservation of boar spermatozoa in liquid storage at 15-17 °C for an 11-day period. With this purpose, extended semen samples from seven healthy post-pubertal boars were artificially contaminated with different sperm:bacterium ratios (2:1; 1:1; 1:5 and 1:10) of E. cloacae. The 1:0 ratio (non-inoculated) served as a negative control. The most infective ratios (i.e. 1:5 and 1:10) significantly damaged sperm motility and membrane integrity, increased sperm agglutination, and decreased the osmotic resistance of spermatozoa. In contrast, the negative impact that the lowest bacterial concentration (2:1) had on boar sperm quality was clearly lower. In addition, other parameters such as pH were also more affected at the highest infective ratios (i.e. 1:5 and 1:10), despite no damage being observed on sperm morphology. In conclusion, the present work shows that damage inflicted by the presence of E. cloacae in boar sperm during liquid storage at 15-17 °C compromises the longevity and fertilising ability of seminal doses when bacterial concentration is higher than a 1:1 ratio. Further research is warranted to address by which mechanism E. cloacae impairs boar sperm quality.

Acrosin activity is a suitable indicator of boar semen preservation at 17 °C when increasing environmental temperature and radiation

The effect of increasing environmental temperature and radiation on the sperm quality and the field fertility of refrigerated seminal doses from AI boars (N = 30) was analyzed throughout four experimental months (from March through June). In each experimental month, analyses of sperm quality were performed at days 0, 1, 3, 5, 7, and 9 of refrigeration of seminal doses; pregnancy rate and litter size were evaluated using double monospermic inseminations of multiparous female animals using seminal doses at Days 1 to 2 and Days 3 to 4 of refrigeration. Sperm quality was assessed from the evaluation of conventional parameters of sperm concentration, sperm motility, sperm morphology, and sperm viability, and capacitation parameters of membrane lipid disorder, intracellular calcium content, and acrosin activity. Results showed that sperm quality of boar seminal doses was negatively affected by increasing temperature and radiation, which resulted in significantly decreased sperm motility and viability, acrosin activity, pregnancy rate, and litter size, and significantly increased intracellular calcium levels in the trials performed in June. In any experimental month, aging of refrigerated doses was associated with the progressive increase of intracellular calcium levels and inactivation of acrosin, that began from Day 5 of storage in the trials performed in March and April, from Day 3 in those of May, and from Day 0 in those of June. Among the sperm parameters analyzed, only acrosin activity exhibited a clearly differentiated pattern in association with increasing temperature and radiation, and a significant correlation with pregnancy rate and litter size. These results highlighted the potential role of acrosin activity as an indicator of boar sperm preservation at 17 °C in boars.

Methylxanthines and reproduction

Reproduction is the process by which organisms create descendants. In human reproduction, two kinds of sex cells, or gametes, are involved. Sperm, the male gamete, and egg egg , or ovum ovum Vedi egg , the female gamete, must meet in the female reproductive system to create a new individual and both the female and the male reproductive systems are essential to the occurrence of reproduction. Scientific reports dealing with the effects of methylxanthines on reproduction are mostly centred on the use of these compounds as phosphodiesterase inhibitors that, by maintaining high intracellular levels of cyclic AMP (cAMP) cyclic AMP , will affect the gametes differently. High cAMP levels will sustain sperm sperm maturation while they hold the oocytes in mitotic arrest. Caffeine caffeine , being the methylxanthine most widely consumed by every segment of the population, has been the subject of greatest interest among health professionals and researchers. Conflicting results still seem to characterize the association between male/female caffeine caffeine consumption in adult life and semen quality/fertility fertility , although moderate daily caffeine consumption of levels up to 400-450 mg/day (5.7-6.4 mg/kg/day in a 70-kg adult) do not seem to be associated with adverse effects, i.e. general toxicity, effects on bone status and calcium balance, cardiovascular effects, behavioural changes, increased incidence of cancer, or effects on male fertility. A clear stimulation of egg-laying by the coffee leaf pest Leucoptera coffeella was recently reported, providing support for the hypothesis that caffeine, in a dose-dependent way, in insects stimulates egg-laying, thus leading to the death of coffee trees.