In vitro effect of gossypol acetate on yellow perch (Perca flavescens) spermatozoa

Effects of captan, mancozeb and azoxystrobin fungicides on motility, oxidative stress and fatty acid profiles in rainbow trout (Oncorhynchus mykiss) spermatozoa

An in vitro study using rainbow trout spermatozoa was designed to evaluate the toxic effects of different concentrations of captan (CPT), mancozeb (MCZ), and azoxystrobin (AZX) fungicides on motility parameters, lipid peroxidation, SOD activity, total antioxidant capacity (TAC), and DPPH inhibition. Moreover, changes in fatty acids profiles caused by the fungicides were determined for the first time. The results revealed that motility parameters, SOD activities, TAC values, and DPPH inhibitions decreased significantly while lipid peroxidation increased after ≥2 µg/L of CPT, ≥1 µg/L of MCZ, and ≥5 µg/L of AZX incubations for 2 h at 4 °C. Additionally, 10 µg/L CPT, 5 µg/L MCZ, and 200 µg/L AZX reduced motility to the 50 % level. Our results clearly demonstrated significant changes in the fatty acids profiles of spermatozoa exposed to these concentrations of the fungicides. The highest lipid peroxidation and the lowest monounsaturated and polyunsaturated saturated fatty acids (MUFA and PUFA, respectively) were detected in AZX. Even though the susceptibility of spermatozoa to oxidative damage is generally attributed to PUFA contents, the results of this study have represented that MUFA content could play a part in this tendency. Moreover, the lower concentration of MCZ reduced motility to the % 50 level while it deteriorated the fatty acids profile less than did AZX. Overall, the present study demonstrated that the detrimental effects of the fungicides on mitochondrial respiration and related enzymes have more priority than oxidative stress in terms of their toxicities on spermatozoa. It has also been suggested that fish spermatozoa are a good model for determining changes in the fatty acid profiles by fungicides, probably, by other pesticides and environmental contaminants as well.

Optimalisation of the Activation Medium and Effect of Inhibiting Activities of Acid Phosphatase, Lactate Dehydrogenase and β-N-Acetylglucosaminidase on the Fertilisation Success of Eurasian Perch (Perca fluviatilis L.)

Simple Summary

The purpose of this study is to determine the composition of the optimal activating solution for activating sperm motility and perch eggs, because scientific studies and reproductive procedures should be conducted in stable and repeatable conditions. We found that the best activating solution was composed of 80 mM NaCl, 20 mM KCl, 10 mM Tris, with pH 8.0 and 206 mOsm/kg. In spite of this, we also checked the influence of adding the enzyme inhibitors, such as ammonium molybdate–acid phosphatase inhibitor, gossypol – lactate dehydrogenase inhibitor and acetamide–β-N-acetylglucosaminidase inhibitor on perch sperm motility and successful perch fertilisation. We showed that the addition of acid phosphatase inhibitor in perch semen did not affect the process of fertilisation; in contrast, the addition of lactate dehydrogenase and β-N-acetylglucosaminidase inhibitors significantly decreased the percentage of perch fertilised eggs.

Abstract

Although methods for the artificial reproduction of perch have been developed, a lack of information remains regarding the enzymes present in its semen, as well as their role in the fertilisation process. In this study, we first select the optimal activating solution for perch fertilisation and then determine the inhibition effect of enzymes that have already been reported as present in the sperm of teleosts—acid phosphatase (AcP), lactic dehydrogenase (LDH) and β-N-acetylglucosaminidase (β-NAGase)—on the percentage of motile spermatozoa and fertilised eggs. Of the 8 studied activation media, a solution composed of 80 mM NaCl, 20 mM KCl, 10 mM Tris, with pH 8.0 and 206 mOsm/kg proved to be optimal for perch gametes. The addition of ammonium molybdate (AcP inhibitor) caused no significant reduction in the percentage of fertilised eggs. On the other hand, the addition of 0.25 mM gossypol (LDH inhibitor) and 0.125 M acetamide (β-N-acetylglucosaminidase inhibitor) significantly decreased the fertilisation percentage to 41.1% and 52.4%, respectively, in contrast to the control (89.9 %). Both LDH and β-NAGase thus seem to play a very important role in the perch fertilisation process.

A trifunctional contraceptive gel enhances the safety and quality of sexual intercourse

Current contraceptive methods come with a number of drawbacks, including low efficacy, in the case of commercial contraceptive gels, and a reduction in the quality of sexual intercourse, in the case of condoms. Adding pharmacologically-active agents to contraceptive gels holds the potential to improve sexual experience, and hardbor safety and hygiene. In this study, we fabricated a Carbomer-based contraceptive gel consisting of three agents: tenofovir, gossypol acetate, and nitroglycerin (TGN), with pH adjusted to 4.5 (to be compatible with the vagina). In vitro, the gossypol component of the contraceptive gel proved to be a significantly effective spermicide. When the concentration of gossypol acetate was 10 mg/ml, the spermicidal ability reached 100% after 30s. In addition, tenofovir in the gel significantly inhibited lentiviral transfection efficiency in cell-containing media. In 6 pairs of rats, the gel successfully prevented all females from conceiving after successful mating. Moreover, increased sexual frequency and enhanced erection, which were promoted by the nitroglycerin in the components, were observed in male rats that had the gel applied to their penises. This novel TGN contraceptive gel yielded a higher contraceptive success rate than that of the commercial contraceptive gel (Contragel®). In addition, it has the added benefits to prevent sexually transmitted diseases and improve male libido and erection function during sexual intercourse. Combining three FDA-approved and marketed agents together, our trifunctional TGN gel has a great potential for further translation and commercialization.

Computer-Assisted Sperm Analysis to Test Environmental Toxicants

Fish sperm show many measurable parameters which react sensitively in a dose- and time-dependent way to toxic exposure. Fish sperm is therefore used as an in vitro toxicology test system. One of the most sensitive and easily detectable parameters is progressive motility which can be measured by a computer-assisted sperm analysis (CASA) system. Here we describe a simple protocol to test the effect of environmental toxicants by using zebrafish (Danio rerio) sperm.

Investigation of Fertilizing Capacity of Zebrafish (Danio rerio) Sperm Exposed to Heavy Metals

The objective of our study was to investigate the effects of heavy metals on the fertilizing capacity of exposed zebrafish sperm, on embryonic survival, and on occurrence of embryonic deformities following fertilization with exposed sperm. It is important to test heavy metals because they are well-known pollutants. Sperm of externally fertilizing species can get in contact with pollutants found in aquatic environment. Zebrafish sperm, despite its advantages, has seldom been used in in vitro toxicological studies and no reports are available regarding the fertilizing capacity of exposed sperm. Zebrafish sperm was stripped and exposed to concentrations of the tested heavy metals (Zn²⁺, Cd²⁺, Cr³⁺, Cu²⁺, Ni²⁺, Hg²⁺, As³⁺) for 30 or 120 minutes. Calculated half-maximal effective concentration (EC₅₀) values do not differ significantly from those calculated for motility for any of the tested heavy metals, which means fertilization rate can indicate the toxicity of the given substance following exposure of sperm. Thus, its application as in vitro toxicological end point is reasonable. The survival of embryos and embryonic development have not been affected by the exposure of spermatozoa, which means all alterations in spermatozoa caused by heavy metals have been expressed before 24 hours post fertilization.

Sperm quality in fish: Determinants and affecting factors

Fish sperm quality assessment is helpful for optimizing production and for monitoring the environmental state. Sperm can be monitored relatively easy and, to date, various analyses have been applied and proven to be helpful in this task. Among them, sperm motility parameters such as sperm speed are one of the main performance traits during assisted fish reproduction. Apart from motility the sperm concentration, volume, and seminal plasma pH and osmolality are also frequently evaluated and are the main sperm quality indicators measured in fish sperm. However, other parameters also determine sperm fertilization potential. Recent knowledge reveals several additional parameters of high importance for sperm function. Among them are DNA integration, membrane stability, mitochondria status and enzymatic activity. Measuring all these parameters in fish sperm provides complex knowledge regarding male fertility and helps to improve broodstock maintenance protocols as well as gamete handling and fertilization processes. This review focuses on the presentation of the sperm quality measures for freshwater and marine species of the fish and provides information regarding recent methods of sperm quality evaluation.

In vitro toxicology test system based on common carp (Cyprinus carpio) sperm analysis

The effect of heavy metals on the motility parameters of common carp sperm was investigated. In vitro test systems are widespread in ecotoxicology, and fish sperm can be a suitable model. For this reason, studies had been carried out in this topic; however, the published methods are not standard in several aspects (donor species, measured endpoint, etc.). In this study, a previously published toxicology-aimed sperm analysis protocol was tested to examine the effect of heavy metals (arsenic, cadmium, chromium, copper, mercury, nickel, zinc,) on common carp sperm. According to our results, PMOT is the most sensitive of the investigated parameters: dose-response was observed in case of each metal at low concentrations, already after 30 min of exposure. VCL was less sensitive: lower effects were observed at the same concentrations compared to PMOT. Among the examined parameters, LIN was the least affected: a dose-response was observed only in case of arsenic and mercury. The same sensitivity of motility parameters was observed on zebrafish sperm previously. Moreover, we found that PMOT, VCL, and LIN of common carp sperm were affected at the same concentrations as it had been observed in zebrafish, when the identical analytical protocol was applied. The only exception was As³⁺, where common carp sperm proved to be more sensitive: lower concentrations already reduced its motility parameters. Consequently, PMOT of common carp sperm is an accurate and fast bioindicator of aquatic pollution.

Gamete quality in fish: evaluation parameters and determining factors

The quality of fish gametes, both male and female, are determined by several factors (age, management, feeding, chemical and physical factors, water quality, etc.) that have an impact on the survivability of embryos, larvae and/or fry in the short or long term. One of the most important factors is gamete ageing, especially for those species that are unable to spawn naturally in hatcheries. The chemical and physical factors in hatcheries and the nutrition that they provide can significantly alter harvest quality, especially from females; as a rule, males are more tolerant of stress conditions produced by inadequate feeding, management and/or poor water conditions. The stress produced on broodstock by inadequate conditions in hatcheries can produce adverse effects on gamete quality, survival rates, and the embryonic eggs after hatching.

Toxicity of environmental contaminants to fish spermatozoa function in vitro--a review

In vitro techniques for investigating the toxic effects of environmental contaminants (EC) on fish spermatozoa motility kinetics and fertilizing ability are valuable tools to understand toxicity mechanisms and sites of action. In vitro techniques may also be well-suited to studies of endocrine disruption in male fertility in vivo. This review shows ECs to decrease or suppress spermatozoa motility kinetics and fertilizing ability in a dose-dependent manner, with toxic concentrations being much higher than those reported in the aquatic environment. Sites of action depend on EC concentration and duration of exposure. Both instant (immediate) and incubated exposure of spermatozoa to ECs results in damage to the plasma membrane and the axoneme, while disruption of energy metabolism appears only during incubated exposure. Spermatozoa lose fertilizing ability following exposure to ECs in vitro, not only due to inhibition or suppression of the initiation of motility, but also through damage to DNA. This review highlights the significant lack of information about disruption of spermatozoa function associated with exposure to water from polluted areas as well as combined effects of ECs. Specifics of alterations in intracellular signaling cascades involved in the initiation of spermatozoa motility following exposure to sublethal concentrations of ECs remain unknown. Further studies are also needed to elucidate in vitro EC effects during spermatozoa maturation, when spermatozoa acquire the potential for motility.

In vitro gossypol induced spermatozoa motility alterations in rabbits

The objectives of the present study were to: (i) examine the in vitro dose response of rabbit spermatozoa motility to the antifertility agent gossypol (GOS) and (ii) determine whether filtered (FIL) and unfiltered (UNFIL) GOS differ in their magnitude of effect. Rabbit semen belonging to adult males (n = 5; 12-14 months) were cultured with UNFIL GOS and FIL GOS (5% solution) and subsequently diluted (1:1-7) for analysis using a Computer Assisted Semen Analyzer (CASA) system in 5 time periods (0, 60, 120, 180 and 360 minutes). At Time 0, no significant change in rabbit spermatozoa motility (MOT) and progressive motility (PROG) with GOS FIL was noted, while increases were observed with GOS UNFIL. At Time 60, weak changes were noted for MOT and PROG. After 120 minutes of culture with both GOS FIL and GOS UNFIL, MOT and PROG decreased significantly in some experimental groups. However, no differences were recorded for both the parameters at Times 180 and 360, with the exception of PROG in the GOS UNFIL category (groups A, B, E, F and G), where a significant decrease was noticed. Detailed evaluation of the distance and velocity parameters revealed reduction in all these studied markers after 60 and 120 minutes of in vitro culture with both GOS FIL and GOS UNFIL, indirectly confirming the PROG decrease. Straightness (STR), linearity (LIN), wobble (WOB), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF) mostly remained unaltered at all time periods for GOS FIL, where as some minor alterations were noticed in GOS UNFIL category for STR, LIN, WOB, ALH and BCF parameters at Time 0, 60 and 120. The present study confirms the dose and time dependent alterations of rabbit spermatozoa motility parameters by GOS. The GOS dynamics in our experiment shows that rabbit spermatozoa as a biological material can indicate a GOS inhibition of motility. Obtained data for the first time indicates a higher immobilizing potential of unfiltered GOS in comparison to filtered GOS in its inhibitory action of spermatozoa motility parameters in rabbits.

Gossypol and gossypolone enantiomers in tissues of rainbow trout fed low and high levels of dietary cottonseed meal

Gossypol is an antifertilizing agent in males and females. However, gossypol and its metabolite, gossypolone, have also gained interest because of their anticarcinogenic activities. This paper examines for the first time both enantiomers of tissue gossypol and gossypolone in mature rainbow trout fed two diets containing low (15%) and high (60%) levels of cottonseed meal (CM) for 9 months. The gossypol concentration was highest in liver followed by kidney, intestine, testis, blood plasma, stomach, and muscle. Gossypol was detected in muscles of fish fed low- and high-CM diets (0.31 +/- 0.03 and 1.95 +/- 0.59 microg of total gossypol/g, wet basis, respectively). The (+)-gossypol enantiomer was predominantly retained in all tissues. The ratio of (-)- to total gossypol ranged from 30 to 44% in fish fed the high-CM diet and from 23 to 30% in fish fed the low-CM diet except for muscle tissue (44%). Higher gossypolone concentrations were found in intestine than in liver. Gossypolone, however, was not detected in blood plasma, muscle, and testis of fish fed the low-CM diet. The ratio of gossypolone to gossypol was highest in muscle (1.75), followed by intestine (1.59), stomach (1.50), kidney (0.43), liver (0.34), testis (0.28), and blood plasma (0.27). This study indicated that the retention of the (-)-gossypol enantiomer is dependent on dietary concentrations and that the oxidative conversion of gossypol to gossypolone occurs more actively in the digestive tract and muscle than in other tissues in rainbow trout.

Gossypol isomers bind specifically to blood plasma proteins and spermatozoa of rainbow trout fed diets containing cottonseed meal

We investigated the role of gossypol isomers binding to blood plasma, seminal plasma and spermatozoa to elucidate gossypol anti-fertility action in the teleost fish, rainbow trout (Oncorhynchus mykiss). Growth and hematological indicators of males were depressed when fish meal protein in diets was completely replaced with cottonseed meal. The cottonseed meal contained equal proportions of (-) (47.8+/-1.6%) and (+) gossypol isomers. Concentrations of spermatozoa were decreased with increasing proportions of gossypol in diets (from 0.22% to 0.95%); however, sperm motility and fertilizing ability were not affected. In contrast to mammals, steroid hormone concentrations were not suppressed in fish given diets with gradual increase of gossypol level. Gossypol concentrations were 100-fold higher in blood plasma than in seminal plasma, confirming a barrier in gossypol transfer between the general circulation and the testis. Spermatozoa accumulated predominantly (+) enantiomer (65-75%) with decreasing proportions as dietary gossypol concentrations increased. Spermatozoa bound most of the gossypol contained in the semen; however, this did not result in impairment of the sperm motility apparatus. Teleost fish sperm rely on ATP stores that accumulate during maturation as a source of energy during activation. In addition, the duration of sperm movement is short in these fish. As such, we hypothesize that the major action of gossypol on mammalian sperm, which is uncoupling of oxidative phosphorylation, does not impair the energy supply required for flagellar beating in fish spermatozoa.