Sperm storage in the female reproductive tract after mating and before ovulation is a reproductive strategy used by many species. When insemination and ovulation are poorly synchronized, the formation and maintenance of a functional sperm reservoir improves the possibility of fertilization. In mammals, the oviduct regulates sperm functions, such as Ca2+ influx and processes associated with sperm maturation, collectively known as capacitation. A fraction of the stored sperm is released by unknown mechanisms and moves to the site of fertilization. There is an empirical association between the hormonal milieu in the oviduct and sperm detachment; therefore, we tested directly the ability of progesterone to induce sperm release from oviduct cell aggregates. Sperm were allowed to bind to oviduct cells or an immobilized oviduct glycan and then challenged with progesterone, which stimulated the release of 48% of sperm from oviduct cells or 68% of sperm from an immobilized oviduct glycan. The effect of progesterone on sperm release was specific; pregnenolone and 17α-OH-progesterone did not affect sperm release. Ca2+ influx into sperm is associated with capacitation and development of hyperactivated motility. Progesterone increased sperm intracellular Ca2+, which was abrogated by blocking the sperm–specific Ca2+ channel CatSper with NNC 055-0396. NNC 055-0396 also blocked the progesterone-induced sperm release from oviduct cells or immobilized glycan. An inhibitor of the non-genomic progesterone receptor that activates CatSper similarly blocked sperm release. This is the first report indicating that release of sperm from the sperm reservoir is induced by progesterone action through CatSper channels.
Internal fertilization is part of a reproductive strategy that requires male and female gametes to meet in the female reproductive tract. In mammals, fertilization occurs in the upper oviduct. Upon semen deposition in the female reproductive tract, a subpopulation of the ejaculated spermatozoa is transported to the lower oviduct, also called isthmus, where sperm are stored for variable periods, hours to months, depending on the species1,2. Retention in the lower oviduct is accomplished in swine by epithelial glycoproteins that contain either of two motifs, a Lewis X trisaccharide (LeX) or a biantennary 6-sialylated structure that bind sperm3,4. While in the oviduct, sperm complete several maturational changes that allow them to develop fertilizing ability and are referred to collectively as capacitation5. Binding to epithelial cells of the isthmus results in functional changes in sperm that enable sperm-egg binding and fertilization even if there is some asynchrony between semen deposition and ovulation. Interaction of sperm with oviduct epithelial cells decreases calcium uptake and suppresses the capacitation-associated increase in protein tyrosine phosphorylation6,7,8,9. Formation of a “functional sperm reservoir” in the mammalian oviductal isthmus is most likely to allow gradual release of a finite number of competent sperm sub-populations to the fertilization site10, lengthening the duration that fertile sperm are provided and reducing the chances of polyspermy11. In addition to the peri-ovulatory release of sub-populations of competent sperm, there is evidence for a post-ovulatory release of larger numbers of sperm12.
How sperm are released from the oviduct reservoir is controversial. It is not clear whether release is activated by changes in the oviduct fluid, oviduct cells, or sperm. One hypothesis is that sperm detachment is due to a change in oviduct fluid components13 or volume. It may also be affected by oviduct peristaltic contractions13 or altered oviduct epithelial cell transcription14,15. Finally, a change in sperm function may contribute to release. Release may be promoted by the development of hyperactivated motility that may overcome the adhesive forces that otherwise bind sperm to the oviduct epithelium16,17,18. Hyperactivated motility can be activated in human sperm by the sex steroid progesterone19,20,21,22. The source of the elevated progesterone may be the peri-ovulatory follicle via a counter-current mechanism23. The concentration of progesterone is 5–10 fold or more greater in the arterioles near the oviduct23,24 and hundreds of times more concentrated in the peri-follicular capillary network25 than in systemic circulation.
Progesterone has well-studied effects on human sperm. Progesterone stimulates Ca2+ entry in human sperm in a fast and non-genomic fashion26,27. Over the last decade, it has been demonstrated that progesterone stimulates Ca2+ influx in human sperm by binding to a non-genomic receptor, α/β hydrolase domain-containing protein 2 (ABHD2), a serine hydrolase that depletes membrane 2-arachidonylglycerol, releasing inhibition of sperm Ca2+ channels known as CatSper channels19,20,21,28,29,30. CatSper channels are localized in the principal piece of the sperm flagellum and are essential for male fertility19,20,21,29,31. Functional CatSper channels are necessary for development of human and mouse sperm hyperactivated motility and fertility22,32,33,34,35. Although there is evidence that CatSper channel subunit genes are expressed in the porcine testis and localized in porcine sperm36,37, much less is known of CatSper function outside of human and mouse sperm.
This work was designed to determine the role of progesterone in the release of sperm from the reservoir in the oviduct. Because progesterone is involved in CatSper activation in human and macaque sperm19,20,22,38,39, we explored the function of CatSper channels in progesterone-activated porcine sperm release.
Materials and Methods
Collection and processing of sperm
Semen was provided by Prairie State Semen Supply and Birchwood Genetics. No live animals were used for these experiments. For each replicate, semen samples were collected from 3–5 different mature boars and diluted in extender. Samples were stored at 16° to 18 °C up to 24 hr prior to use. Three ml of pooled extended semen were washed through a Percoll cushion containing 5.4 ml Percoll, 0.6 ml 10X HBS (1.3 M NaCl, 40 mM KCl, 10 mM CaCl2, 5 mM MgCl2), and 4 ml dmTALP (2.1 mM CaCl2, 3.1 mM KCl, 1.5 mM MgCl2, 100 mM NaCl, 0.29 mM KH2PO4, 0.36% lactic acid, 25 mM NaHCO3, 0.6% BSA, 1 mM pyruvic acid, 20 mM HEPES pH 7.3, and sterile filtered) at 800 x g for 10 min. Sperm were washed with 5 ml dmTALP and pelleted for 5 min at 600 x g. Samples with greater than 80% motility were used immediately for experiments. Sperm concentration was determined by hemocytometer and adjusted according to the experiment.
Collection of oviduct epithelial cells
Oviducts were provided by Rantoul Foods. No live animals were used. For each experiment, the isthmus of 15–20 oviducts were collected from pre- and post-pubertal females and transported in PBS in a sterile 50 ml conical tube on ice. After 2–20 hr on ice, the oviducts were processed at the lab. The isthmus was trimmed and the edge of a microscope slide was used to apply pressure to the outside of the oviduct to strip sheets of oviduct epithelial cells from the isthmus. Epithelial sheets in PBS were transferred to a 15 ml conical tube and centrifuged at 100 × g for 1 min. After removing the supernatant, the cells were disaggregated by passage through a 1 ml pipette tip 10 times. After bringing the volume to 15 ml with PBS, the suspension was centrifuged again. The partially disaggregated cells in the pellet were passed through a 22-gauge needle ten times. After adjusting the volume to 12 ml with dmTALP, the cells were divided evenly into three 100-mm tissue culture dishes. Cells were allowed to re-aggregate for 90 min at 39 °C. Spherical aggregates that were 100–150 µm in diameter were selected for experiments.
Assay of sperm binding to and release from oviduct epithelial cells
Spherical oviduct cell aggregates were selected and washed twice in 100 µL drops of fresh dmTALP. A Stripper Pipette (MidAtlantic Diagnostics, Inc., Mount Laurel, NJ) with a 250 µm internal diameter tip was used to collect oviduct epithelial cell aggregates and wash them. Sperm at a final concentration of 5 × 105 cells/mL were added to 50 µL droplets (total volume) containing oviduct cell aggregates. Sperm and oviduct cell aggregates were pre-incubated at 39 °C for 15 min to allow sperm binding. When testing the necessity for CatSper channels in sperm release, 2 µM of NNC 055–0396, a Cav channel blocker that blocks CatSper20, was also added to this step. Then, the sperm-oviduct cell complexes were transferred in 3 µL to a fresh 47 µL-droplet containing either 800 nM of progesterone or 80 nM of progesterone, pregnenolone, and 17α-OH-progesterone for 30 min at 39 °C or vehicle control. Ten aggregates were added to each droplet in triplicate droplets. After co-incubation, free and loosely attached sperm were removed by washing with 30 µl of dmTALP. Aggregates were transferred onto a microscope slide in a volume of 3 µl. Each droplet with 10 aggregate-sperm complexes was considered an experimental unit for statistical analysis. Images were captured using a Zeiss Axioskop and AxioCam HRc digital camera (Carl Zeiss, Thornwood, NY). The number of sperm bound to the periphery of each aggregate was enumerated and the circumference of the aggregate calculated using AxioVision V 4.5 software (Carl Zeiss, Thornwood, NY). The number of sperm bound per mm circumference was calculated for each aggregate. The average number of sperm bound to the aggregates counted in each droplet was used for statistical analysis.
Sperm binding and release from 3-O-sulfated lewis X trisaccharide (suLeX) coupled beads
Glycan-coated streptavidin-Sepharose High-Performance beads (GE Healthcare Bio-Sciences, Pittsburgh, PA, average diameter of 34 µm) were used to test the ability of sperm to release from an oviduct glycan suLeX in the presence of progesterone. To link the glycan to beads, approximately 60 µg of glycan covalently attached to a biotinylated 30 kDa polyacrylamide core40 was incubated with 20 µL of streptavidin-Sepharose beads for 90 min at room temperature. Each molecule of polyacrylamide had 20% glycan and 5% biotin, by molarity41. Beads with attached suLeX were washed twice in dmTALP and re-suspended in 100 µl of dmTALP. Once the glycan-coupled beads were ready for use, a 50-µL droplet containing 1.5 million sperm/mL was prepared to receive 1 µL of glycan-coated beads in triplicate droplets. Sperm and beads were co-incubated at 45 min at 39 °C in dmTALP after which the steroid hormones were added. Progesterone (P4), pregnenolone (P5), and 17α-OH-progesterone (17-OHP) at 80 and 800 nM were added to sperm bound to beads. After 30 min of incubation with steroids, the number of sperm bound to the glycan-coated beads was counted. In some experiments, the T channel blocker NCC 55–0396 that inhibits CatSper or a blocker (methoxy arachidonyl fluorophosphonate; MAFP) of the non-genomic progesterone receptor (ABHD2) was added prior to addition of steroid hormone. For each treatment, 25 beads were randomly selected and the total number of bound sperm was enumerated in the triplicate droplets. Sperm that were self-aggregated were not included in the counts. Each experiment was repeated at least 3 times and documented using a Zeiss Axioskop and Axiocam (Zeiss, Thornwood, NY).
Effects of NNC 55–0396 and methoxy arachidonyl fluorophosphonate on sperm motility
The motility of sperm incubated with 80 nM progesterone, progesterone and CatSper inhibitor NNC 55–0396 (2 µM), 2 µM NNC 55–0396 alone, progesterone and progesterone receptor blocker methoxy arachidonyl fluorophosphonate (2 µM), and methoxy arachidonyl fluorophosphonate (2 µM) alone was assessed using a Hamilton Thorne Semen Analysis CASA system (Hamilton Thorne, Beverly, MA, USA). Sperm were incubated with the treatments at 39 °C in dmTALP for 30 min. For each experimental condition, 5 random fields were evaluated for a minimum total of 100 cells (in each field) in 5 replicates.
Measurement of intracellular Ca2+ in sperm populations
Calcium influx in sperm populations was assessed by a spectrofluorometric assay using a probe that detects intracellular Ca2+. These experiments were repeated at least three times. Fluo-4 AM, a Ca2+-sensitive reporter, was added at a final concentration of 4 µM to a sperm suspension (5 × 106 sperm/mL in dmTALP) and incubated in the dark for 30 min at room temperature. This incubation was necessary to allow hydrolysis of the acetoxymethyl (AM) ester group by cytoplasmic esterases, enabling Fluo-4 molecules to bind to Ca2+. Sperm treated with 80 nM of progesterone or control were incubated at 39 °C and measurements were taken at 0, 15, and 30 min. The actual time of sampling for 0 min was approximately 1–2 min after progesterone addition. In experiments assessing the involvement of CatSper channels during the progesterone-mediated Ca2+ influx, either 2 µM of NNC 055–0396 or 500 nM of RU-486 were added 15 min prior to progesterone supplementation. In order to measure strictly intracellular Ca2+ signal and account for probe leaking and extrusion from cells, we used 8.4 mM EGTA to chelate extracellular Ca2+. Differences in concentrations of free intracellular Ca2+ due to binding to Fluo-4 were detected upon argon-ion laser excitation at 494 nm and emission at 516 nm in a QuantaMaster 4CW fluorescence spectrophotometer (Photo Technology International, NJ).
For statistical analysis of sperm binding assay and Ca2+ influx is sperm populations, we used SAS software (v. 9.1 SAS Institute, Inc, Cary, NC) to run a one-way analysis of variance using a PROC GLM (General Linear Models) procedure following the general model: Yij = µ + αi + εij (where Yij is the jth sample observation from population i; µ is the overall mean; α is an effect due to population i; and ε is the random deviation of Yij about the ith population mean). Results are depicted as means ± SEM. Differences were considered to be significant if p < 0.05 using Tukey’s test for multiple comparisons.
Progesterone promotes sperm release from oviduct cell aggregates
We used an in vitro assay to test the ability of progesterone to release porcine sperm from oviduct isthmic cell aggregates. Sperm were allowed to bind the isthmic aggregates for 15 min and then challenged with 80 and 800 nM of progesterone (Fig. 1). Treatment with progesterone stimulated the release of up to 48% of sperm from aggregates within 30 min of addition, compared to the vehicle control group. A higher concentration of progesterone (800 nM) did not stimulate further release of sperm from aggregates. To ensure that progesterone’s effect on sperm release was specific, we treated sperm bound to oviduct aggregate cells with 80 nM of the related steroid hormones pregnenolone and 17α-hydroxyprogesterone. Neither of the two steroid hormones stimulated sperm release; the number of sperm bound to oviduct cell aggregates was not different than the vehicle control (Fig. 2), indicating a specific effect of progesterone on sperm release from oviduct aggregate cells.
When added to sperm bound to oviduct cells, progesterone could act on either sperm or oviduct cells. To confirm progesterone was acting on sperm, the oviduct glycan 3-O-sulfated Lewis X trisaccharide (suLeX) was covalently attached to biotinylated polyacrylamide and then coupled to streptavidin-beads. Sperm were allowed to bind the beads. Either progesterone or 17α-hydroxyprogesterone was added. Both 80 nM and 800 nM progesterone induced release of 68% of sperm from beads whereas 800 nM 17α-hydroxyprogesterone had no effect (Fig. 3).
Because progesterone stimulates Ca2+ influx into human sperm42 and an increase in intracellular Ca2+ is linked to hyperactivation43, we assessed intracellular Ca2+ in response to progesterone, using the fluorescent Ca2+ indicator Fluo-4 AM. The initial measurement (0 min) was taken as soon as possible after adding progesterone (about 1–2 min after progesterone). Although 0 and 15 min incubation with progesterone did not result in significant fluctuations in intracellular free Ca2+, treatment of sperm with 80 nM of progesterone for 30 min resulted in a 13% increase in Fluo-4 fluorescence when compared to vehicle controls (Fig. 4).
CatSper channels are involved in sperm detachment from oviduct cell aggregates
We investigated the possibility that progesterone influences sperm release from oviductal cells by activating CatSper channels. Although CatSper channel activation in porcine sperm is unclear, CatSper channels in human sperm but not mouse sperm are responsive to progesterone19,20,28,44 and are essential for male fertility33,35,39,45,46,47,48. To test the functional importance of CatSper, we used a T-type channel blocker (NNC 055–0396) that abolishes CatSper currents in human sperm19,20. We treated the sperm with 0.4 and 2 µM of NNC 055–0396 and free intracellular Ca2+ was measured at 0, 15, and 30 min after progesterone addition. Blocking CatSper with 2 µM NNC suppressed the progesterone-induced increase in Fluo-4 fluorescence by 10% when compared to sperm treated with 80 nM progesterone alone (Fig. 5). To rule out the involvement of the genomic progesterone receptor, we used RU-486 (mifepristone), a genomic progesterone receptor antagonist. Mifepristone at a final concentration of 0.5 μM did not affect Ca2+ influx (Fig. 6).
Once the association between progesterone and Ca2+ influx was established (Figs. 4 and 5), we tested whether functional CatSper channels were involved in sperm release from oviduct cell aggregates. Blocking CatSper with 2 µM NNC 055–0396 inhibited 94% of sperm release induced by progesterone (Fig. 7). The same concentration (2 μM) of NNC 055-0396 also blocked sperm release from suLeX-coated beads, demonstrating that the NNC compound was not acting on oviduct cells but rather, sperm (Fig. 8). The non-genomic progesterone receptor in human sperm is α/β hydrolase domain-containing protein 2 (ABHD2), a serine hydrolase that cleaves 2-arachidonylglycerol into glycerol and arachidonic acid19,20,21,28,29,30. An inhibitor of serine hydrolases, methoxy arachidonyl fluorophosphonate (MAFP), was tested for its ability to abrogate the progesterone-induced sperm release. Concentrations from 5 to 2000 nM of MAFP blocked from 20 to 70% of sperm release (Fig. 9).
One possible explanation for the reduction in sperm release due to NNC or MAFP is that NNC or MAFP reduced the percentage of motile sperm thereby reducing the tension applied to the adhesion between sperm and oviduct glycans and blocking sperm release. To address this possibility, the motility of free sperm exposed to progesterone, NNC and MAFP was assessed. There were no differences in sperm motility characteristics during the 30 min required for sperm release (Table 1). Therefore, sperm release was not blocked due to an effect of NNC and MAFP on sperm motility. This demonstrates that porcine sperm release from isthmic epithelial cells was promoted by progesterone using a mechanism that requires functional CatSper channels.
This report documents the importance of progesterone and CatSper channels in the release of porcine sperm from oviduct cells. We demonstrated that progesterone stimulates the detachment of porcine sperm from oviduct cell aggregates in vitro through an influx of Ca2+ through CatSper channels. These findings indicate that when intracellular free Ca2+, a central regulator of sperm function, is increased by addition of progesterone, it promotes sperm release from the oviduct within 30 min.
Although not conclusive, earlier experiments to study sperm release from the isthmus in mammals suggested that ovarian steroids might be involved12. There is evidence supporting a role for progesterone, at least some extent, in sperm detachment from the isthmus in vivo although the target of progesterone was unclear, either sperm or oviduct cells11,49,50,51,52. Outside of mammals, there is also evidence that progesterone promotes the release of avian sperm from the storage tubules in the uterovaginal junction53. Results herein are the first support for the hypothesis that progesterone acts directly on sperm to release them from oviduct epithelial cells. The progesterone biosynthetic precursor pregnenolone and downstream derivative 17α-hydroxyprogesterone, used as specificity controls, did not cause sperm release. Previous studies demonstrated that estradiol had no effect on sperm binding to oviductal vesicles in vitro50. Our results are consistent with the findings of an in vivo study that reported that injecting progesterone in the isthmic subserosa of gilts in the pre-ovulatory period caused high rates of polyspermic fertilization51, presumably by causing a massive release of sperm bound to the oviduct. Although progesterone concentrations are very high during the pre-ovulatory period, especially near the oviduct25, how this steroid reaches sperm in the oviduct is unclear. There is a counter-current mechanism that could supply progesterone from the ovary to the oviduct23,54. In this model, ovarian steroid hormones diffuse from the ovarian vein to the utero-tubal arteries, redirecting the flow of progesterone toward the oviduct reservoir. Besides the counter-current theory, cumulus-oocyte complexes and detached cumulus cells are likely to synthesize progesterone55,56, which, if produced in adequate amounts, could modify the oviductal environment and elicit changes in sperm behavior, including release from the isthmic epithelium.
We demonstrated that nanomolar concentrations of progesterone trigger a rise in intracellular Ca2+ in porcine sperm. Although there are many reports of the effect of progesterone on human sperm44,57,58, reports of the effects of progesterone on porcine sperm are very limited. Progesterone increased intracellular Ca2+ in porcine sperm 0.5 to 1.0 min after addition and stimulated a more gradual secondary increase 30 min later59,60. Although the time resolution of our spectrophotometric measurements was insufficient to detect the initial increase, we detected an increase in intracellular Ca2+ within 30 min, a time coincident with sperm release (Figs. 1, 3 and 4). Increases in intracellular Ca2+ concentrations are commonly associated with a variety of changes that occur during capacitation61.
The mechanism by which progesterone increases intracellular Ca2+ through CatSper is best described in human sperm. Progesterone binds to ABHD2, a serine hydrolase that, after progesterone binding, removes CatSper inhibitors allowing the channel to open28. But in mouse sperm, CatSper is activated by an increase in intracellular pH62,63. This mere change in pH appears inadequate to activate human CatSper. There is also evidence that other voltage-gated Ca2+ channels (CaV2.3) have a role in mouse sperm function64. Outside of human and mouse sperm, the function of CatSper is less clear. Bovine and equine sperm hyperactivation is promoted by intracellular alkalinization-induced activation of Ca2+ influx, presumably occurring through CatSper65,66. We tested the functional importance of CatSper in porcine sperm release by blocking the progesterone-mediated Ca2+ entry in sperm using NNC 55-0396, a T-type calcium channel inhibitor19,20,67 and by blocking ABHD2. Blocking CatSper was sufficient to suppress the Ca2+ influx induced by progesterone (Fig. 5). Progesterone-mediated Ca2+ entry in sperm was CatSper-specific; mifepristone, a classical progesterone receptor antagonist, did not modify Ca2+ influx (Fig. 6). These results suggest that the Ca2+ entry in porcine sperm that is influenced by progesterone is occurring by activation of CatSper channels, which are essential for the development of sperm hyperactivated motility and sperm fertilizing ability34,68.
Not only did blocking CatSper abrogate the increase in intracellular Ca2+, it completely blocked sperm release from oviduct cells and an immobilized oviduct glycan. Similarly, inhibition of ABHD2 also suppressed sperm release. These results suggested that sperm hyperactivation is critical and sufficient for sperm release, in contrast to a previous report that addition of a glycosaminoglycan in the medium was necessary for release13. Our results also suggest that oviduct fluid flow or oviduct peristaltic contractions are not necessary for sperm release because release occurred from isolated epithelial cells and beads in droplets that have minimal fluid flow (Fig. 1). The inhibition of sperm release from oviduct cells was not due to reduction in the percentage of motile sperm or other motility characteristics evaluated by CASA (Table 1). We also did not detect changes in hyperactivation, as determined by CASA, in response to progesterone. But it is challenging for CASA to discern traits in porcine sperm that are associated with hyperactivation in other species (i.e. changes in BCF, ALH, straightness and linearity) because of the very asymmetrical full-type hyperactivated motility that porcine sperm display69,70.
It is highly unlikely that NNC 55-0396, a T-type calcium channel inhibitor, prevented sperm release by acting on oviduct cells rather than sperm. Although ciliated oviduct cells have TRPV4 channels that are likely affected by the NNC compound, TRPV4 channels of oviduct ciliated cells are activated by high fluid viscosity71. But NNC 55-0396 blocked sperm release under conditions in which fluid viscosity was not changed. Furthermore, the NNC compound blocked sperm release from an immobilized oviduct cell glycan, suLeX in the absence of oviduct cells. Finally, an inhibitor of ABHD2 also blocked release from the immobilized oviduct cell glycan.
Our data support the model that release of porcine sperm from oviduct isthmic cells is activated by progesterone and requires ABHD2 and CatSper channels. Increasing progesterone concentrations in the sperm reservoir might be one of the signals that accompanies ovulation and facilitates release of sperm from the oviduct epithelium so that they can be freed to fertilize oocytes. These are the first results showing that progesterone is sufficient to release mammalian sperm from oviduct epithelial cells. This work helps explain the intricate communication necessary for successful mammalian fertilization.
Birkhead, T. R. & Moller, A. P. Sexual selection and the temporal separation of reproductive events - sperm storage data from reptiles, birds and mammals. Biol J Linn Soc 50, 295–311, https://doi.org/10.1111/J.1095-8312.1993.Tb00933.X (1993).
Holt, W. V. & Fazeli, A. Sperm storage in the female reproductive tract. Annu Rev Anim Biosci 4, 291–310, https://doi.org/10.1146/annurev-animal-021815-111350 (2016).
Kadirvel, G. et al. Porcine sperm bind to specific 6-sialylated biantennary glycans to form the oviduct reservoir. Biol Reprod 87, 147, https://doi.org/10.1095/biolreprod.112.103879 (2012).
Machado, S. A. et al. LewisX-containing glycans on the porcine oviductal epithelium contribute to formation of the sperm reservoir. Biol Reprod 91, 140, https://doi.org/10.1095/biolreprod.114.119503 (2014).
Puga Molina, L. C. et al. Molecular basis of human sperm capacitation. Front Cell Dev Biol 6, 72, https://doi.org/10.3389/fcell.2018.00072 (2018).
Boilard, M., Bailey, J., Collin, S., Dufour, M. & Sirard, M. A. Effect of bovine oviduct epithelial cell apical plasma membranes on sperm function assessed by a novel flow cytometric approach. Biol Reprod 67, 1125–1132 (2002).
Dobrinski, I., Smith, T. T., Suarez, S. S. & Ball, B. A. Membrane contact with oviductal epithelium modulates the intracellular calcium concentration of equine spermatozoa in vitro. Biol Reprod 56, 861–869, https://doi.org/10.1095/biolreprod56.4.861 (1997).
Dobrinski, I., Suarez, S. S. & Ball, B. A. Intracellular calcium concentration in equine spermatozoa attached to oviductal epithelial cells in vitro. Biol Reprod 54, 783–788 (1996).
Teijeiro, J. M., Cabada, M. O. & Marini, P. E. Sperm binding glycoprotein (sbg) produces calcium and bicarbonate dependent alteration of acrosome morphology and protein tyrosine phosphorylation on boar sperm. J Cell Biochem 103, 1413–1423, https://doi.org/10.1002/jcb.21524 (2008).
Hunter, R. H., Nichol, R. & Crabtree, S. M. Transport of spermatozoa in the ewe: Timing of the establishment of a functional population in the oviduct. Reprod Nutr Dev 20, 1869–1875 (1980).
Hunter, R. H. & Leglise, P. C. Polyspermic fertilization following tubal surgery in pigs, with particular reference to the role of the isthmus. J Reprod Fertil 24, 233–246 (1971).
Hunter, R. H. Sperm release from oviduct epithelial binding is controlled hormonally by peri-ovulatory graafian follicles. Mol Reprod Dev 75, 167–174, https://doi.org/10.1002/mrd.20776 (2008).
Ardon, F. et al. Dynamics of bovine sperm interaction with epithelium differ between oviductal isthmus and ampulla. Biol Reprod 95, 90, https://doi.org/10.1095/biolreprod.116.140632 (2016).
Seytanoglu, A. et al. Oviductal cell proteome alterations during the reproductive cycle in pigs. J Proteome Res 7, 2825–2833 (2008).
Alminana, C. et al. The battle of the sexes starts in the oviduct: Modulation of oviductal transcriptome by x and y-bearing spermatozoa. BMC Genomics 15, 293, https://doi.org/10.1186/1471-2164-15-293 (2014).
Chang, H. & Suarez, S. S. Unexpected flagellar movement patterns and epithelial binding behavior of mouse sperm in the oviduct. Biol Reprod 86(140), 141–148, https://doi.org/10.1095/biolreprod.111.096578 (2012).
Curtis, M. P., Kirkman-Brown, J. C., Connolly, T. J. & Gaffney, E. A. Modelling a tethered mammalian sperm cell undergoing hyperactivation. Journal of theoretical biology 309C, 1–10, https://doi.org/10.1016/j.jtbi.2012.05.035 (2012).
Simons, J., Olson, S., Cortez, R. & Fauci, L. The dynamics of sperm detachment from epithelium in a coupled fluid-biochemical model of hyperactivated motility. Journal of theoretical biology 354C, 81–94, https://doi.org/10.1016/j.jtbi.2014.03.024 (2014).
Lishko, P. V., Botchkina, I. L. & Kirichok, Y. Progesterone activates the principal ca2+ channel of human sperm. Nature 471, 387–391, https://doi.org/10.1038/nature09767 (2011).
Strunker, T. et al. The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm. Nature 471, 382–386, https://doi.org/10.1038/nature09769 (2011).
Alasmari, W. et al. The clinical significance of calcium-signalling pathways mediating human sperm hyperactivation. Hum Reprod 28, 866–876, https://doi.org/10.1093/humrep/des467 (2013).
Smith, J. F. et al. Disruption of the principal, progesterone-activated sperm Ca2+ channel in a CatSper2-deficient infertile patient. Proc Natl Acad Sci USA 110, 6823–6828, https://doi.org/10.1073/pnas.1216588110 (2013).
Hunter, R. H., Cook, B. & Poyser, N. L. Regulation of oviduct function in pigs by local transfer of ovarian steroids and prostaglandins: A mechanism to influence sperm transport. Eur J Obstet Gynecol Reprod Biol 14, 225–232 (1983).
Novak, S., Almeida, F. R., Cosgrove, J. R., Dixon, W. T. & Foxcroft, G. R. Effect of pre- and postmating nutritional manipulation on plasma progesterone, blastocyst development, and the oviductal environment during early pregnancy in gilts. J Anim Sci 81, 772–783, https://doi.org/10.2527/2003.813772X (2003).
Eiler, H. & Nalbandov, A. V. Sex steroids in follicular fluid and blood plasma during the estrous cycle of pigs. Endocrinology 100, 331–338, https://doi.org/10.1210/endo-100-2-331 (1977).
Blackmore, P. F., Neulen, J., Lattanzio, F. & Beebe, S. J. Cell surface-binding sites for progesterone mediate calcium uptake in human sperm. J Biol Chem 266, 18655–18659 (1991).
Falkenstein, E. et al. Specific progesterone binding to a membrane protein and related nongenomic effects on ca2+ -fluxes in sperm. Endocrinology 140, 5999–6002 (1999).
Miller, M. R. et al. Unconventional endocannabinoid signaling governs sperm activation via the sex hormone progesterone. Science 352, 555–559, https://doi.org/10.1126/science.aad6887 (2016).
Lishko, P. V. et al. The control of male fertility by spermatozoan ion channels. Annu Rev Physiol 74, 453–475, https://doi.org/10.1146/annurev-physiol-020911-153258 (2012).
Lishko, P. V. & Mannowetz, N. Catsper: A unique calcium channel of the sperm flagellum. Curr Opin Physiol 2, 109–113, https://doi.org/10.1016/j.cophys.2018.02.004 (2018).
Chung, J. J. et al. Structurally distinct Ca(2+) signaling domains of sperm flagella orchestrate tyrosine phosphorylation and motility. Cell 157, 808–822, https://doi.org/10.1016/j.cell.2014.02.056 (2014).
Carlson, A. E. et al. Pharmacological targeting of native CatSper channels reveals a required role in maintenance of sperm hyperactivation. PLoS One 4, e6844, https://doi.org/10.1371/journal.pone.0006844 (2009).
Hildebrand, M. S. et al. Genetic male infertility and mutation of CatSper ion channels. Eur J Hum Genet 18, 1178–1184, https://doi.org/10.1038/ejhg.2010.108 (2010).
Qi, H. et al. All four CatSper ion channel proteins are required for male fertility and sperm cell hyperactivated motility. Proc Natl Acad Sci USA 104, 1219–1223, https://doi.org/10.1073/pnas.0610286104 (2007).
Ren, D. et al. A sperm ion channel required for sperm motility and male fertility. Nature 413, 603–609 (2001).
Song, C. et al. Molecular cloning, spatial and temporal expression analysis of CatSper genes in the chinese meishan pigs. Reprod Biol Endocrinol 9, 132, https://doi.org/10.1186/1477-7827-9-132 (2011).
Vicente-Carrillo, A., Alvarez-Rodriguez, M. & Rodriguez-Martinez, H. The CatSper channel modulates boar sperm motility during capacitation. Reprod Biol, https://doi.org/10.1016/j.repbio.2017.01.001 (2017).
Sumigama, S. et al. Progesterone accelerates the completion of sperm capacitation and activates CatSper channel in spermatozoa from the rhesus macaque. Biol Reprod, https://doi.org/10.1095/biolreprod.115.129783 (2015).
Williams, H. L. et al. Specific loss of CatSper function is sufficient to compromise fertilizing capacity of human spermatozoa. Hum Reprod 30, 2737–2746, https://doi.org/10.1093/humrep/dev243 (2015).
Bovin, N. V. et al. Synthesis of polymeric neoglycoconjugates based on n-substituted polyacrylamides. Glycoconj J 10, 142–151 (1993).
Galanina, O. et al. Fluorescent carbohydrate probes for cell lectins. Spectrochim Acta A Mol Biomol Spectrosc 57, 2285–2296 (2001).
Blackmore, P. F., Beebe, S. J., Danforth, D. R. & Alexander, N. Progesterone and 17 alpha-hydroxyprogesterone. Novel stimulators of calcium influx in human sperm. J Biol Chem 265, 1376–1380 (1990).
Ho, H. C., Granish, K. A. & Suarez, S. S. Hyperactivated motility of bull sperm is triggered at the axoneme by Ca2+ and not cAMP. Dev Biol 250, 208–217 (2002).
Servin-Vences, M. R. et al. A caged progesterone analog alters intracellular Ca2+ and flagellar bending in human sperm. Reproduction 144, 101–109, https://doi.org/10.1530/REP-11-0268 (2012).
Avenarius, M. R. et al. Human male infertility caused by mutations in the CatSper1 channel protein. Am J Hum Genet 84, 505–510, https://doi.org/10.1016/j.ajhg.2009.03.004 (2009).
Avidan, N. et al. CatSper2, a human autosomal nonsyndromic male infertility gene. Eur J Hum Genet 11, 497–502, https://doi.org/10.1038/sj.ejhg.5200991 (2003).
Jin, J. et al. CatSper3 and CatSper4 are essential for sperm hyperactivated motility and male fertility in the mouse. Biol Reprod 77, 37–44, https://doi.org/10.1095/biolreprod.107.060186 (2007).
Quill, T. A. et al. Hyperactivated sperm motility driven by CatSper2 is required for fertilization. Proc Natl Acad Sci USA 100, 14869–14874, https://doi.org/10.1073/pnas.21366541002136654100 (2003).
Alasmari, W. et al. Ca2+ signals generated by CatSper and Ca2+ stores regulate different behaviors in human sperm. J Biol Chem 288, 6248–6258, https://doi.org/10.1074/jbc.M112.439356 (2013).
Bureau, M., Bailey, J. L. & Sirard, M. A. Binding regulation of porcine spermatozoa to oviductal vesicles in vitro. J Androl 23, 188–193 (2002).
Hunter, R. H. Local action of progesterone leading to polyspermic fertilization in pigs. J Reprod Fertil 31, 433–444 (1972).
Hunter, R. H., Petersen, H. H. & Greve, T. Ovarian follicular fluid, progesterone and Ca2+ ion influences on sperm release from the fallopian tube reservoir. Mol Reprod Dev 54, 283–291 (1999).
Ito, T. et al. Progesterone is a sperm-releasing factor from the sperm-storage tubules in birds. Endocrinology 152, 3952–3962, https://doi.org/10.1210/en.2011-0237 (2011).
Einer-Jensen, N. & Hunter, R. Counter-current transfer in reproductive biology. Reproduction 129, 9–18, https://doi.org/10.1530/rep.1.00278 (2005).
Brussow, K. P., Torner, H., Ratky, J., Manabe, N. & Tuchscherer, A. Experimental evidence for the influence of cumulus-oocyte-complexes on sperm release from the porcine oviductal sperm reservoir. J Reprod Dev 52, 249–257 doi:JST.JSTAGE/jrd/17085 [pii] (2006).
Schuetz, A. W. & Dubin, N. H. Progesterone and prostaglandin secretion by ovulated rat cumulus cell-oocyte complexes. Endocrinology 108, 457–463 (1981).
Sanchez-Cardenas, C. et al. Acrosome reaction and Ca(2)(+) imaging in single human spermatozoa: New regulatory roles of [Ca(2)(+)]i. Biol Reprod 91, 67, https://doi.org/10.1095/biolreprod.114.119768 (2014).
Achikanu, C., Pendekanti, V., Teague, R. & Publicover, S. Effects of pH manipulation, CatSper stimulation and Ca2+-store mobilization on [Ca2+]i and behaviour of human sperm. Hum Reprod 33, 1802–1811, https://doi.org/10.1093/humrep/dey280 (2018).
Kim, J. C. et al. Effects of cryopreservation on Ca2+ signals induced by membrane depolarization, caffeine, thapsigargin and progesterone in boar spermatozoa. Molecules and cells 26, 558–565 (2008).
Yeste, M. et al. Intracellular calcium movements of boar spermatozoa during ‘in vitro’ capacitation and subsequent acrosome exocytosis follow a multiple-storage place, extracellular calcium-dependent model. Andrology 3, 729–747, https://doi.org/10.1111/andr.12054 (2015).
Sagare-Patil, V. et al. Differential concentration and time dependent effects of progesterone on kinase activity, hyperactivation and acrosome reaction in human spermatozoa. Int J Androl 35, 633–644, https://doi.org/10.1111/j.1365-2605.2012.01291.x (2012).
Miller, M. R., Mansell, S. A., Meyers, S. A. & Lishko, P. V. Flagellar ion channels of sperm: Similarities and differences between species. Cell calcium 58, 105–113, https://doi.org/10.1016/j.ceca.2014.10.009 (2015).
Hwang, J. Y. et al. Dual sensing of physiologic pH and calcium by efcab9 regulates sperm motility. Cell, https://doi.org/10.1016/j.cell.2019.03.047 (2019).
Cohen, R. et al. Lipid modulation of calcium flux through Cav2.3 regulates acrosome exocytosis and fertilization. Dev Cell 28, 310–321, https://doi.org/10.1016/j.devcel.2014.01.005 (2014).
Loux, S. C. et al. CatSper and the relationship of hyperactivated motility to intracellular calcium and pH kinetics in equine sperm. Biol Reprod 89, 123, https://doi.org/10.1095/biolreprod.113.111708 (2013).
Marquez, B. & Suarez, S. S. Bovine sperm hyperactivation is promoted by alkaline-stimulated Ca2+ influx. Biol Reprod 76, 660–665, https://doi.org/10.1095/biolreprod.106.055038 (2007).
Huang, L. et al. Nnc 55-0396 [(1 s,2 s)-2-(2-(n-[(3-benzimidazol-2-yl)propyl]-n-methylamino)ethyl)-6-fluoro-1,2, 3,4-tetrahydro-1-isopropyl-2-naphtyl cyclopropanecarboxylate dihydrochloride]: A new selective inhibitor of t-type calcium channels. J Pharmacol Exp Ther 309, 193–199, https://doi.org/10.1124/jpet.103.060814 (2004).
Ho, K., Wolff, C. A. & Suarez, S. S. CatSper-null mutant spermatozoa are unable to ascend beyond the oviductal reservoir. Reprod Fertil Dev 21, 345–350, RD08183 [pii] (2009).
Harayama, H. Flagellar hyperactivation of bull and boar spermatozoa. Reprod Med Biol 17, 442–448, https://doi.org/10.1002/rmb2.12227 (2018).
Kojima, A. et al. Roles of extracellular Ca(2+) in the occurrence of full-type hyperactivation in boar ejaculated spermatozoa pre-incubated to induce the camp-triggered events. Andrology 3, 321–331, https://doi.org/10.1111/andr.12005 (2015).
Andrade, Y. N. et al. Trpv4 channel is involved in the coupling of fluid viscosity changes to epithelial ciliary activity. J Cell Biol 168, 869–874, https://doi.org/10.1083/jcb.200409070 (2005).
This project was supported by the Agriculture and Food Research Initiative Competitive Grant no. 2015-67015-23228 from the USDA National Institute of Food and Agriculture and R01 HD095841 from the National Institutes of Health to DM, and by grant #14-50-00131 from the Russian Science Foundation to NB. Semen was provided generously by Prairie State Semen Supply and Birchwood Genetics. Oviducts were provided by Rantoul Foods in Rantoul, IL. The authors thank Rebecca Winters for assistance with statistical analysis. Much of this work is also in Sergo Machado’a thesis “Regulation of boar sperm function by the oviduct – formation of a sperm reservoir, modulation of Ca 2+ influx, and release from storage”.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Machado, S.A., Sharif, M., Wang, H. et al. Release of Porcine Sperm from Oviduct Cells is Stimulated by Progesterone and Requires CatSper. Sci Rep 9, 19546 (2019). https://doi.org/10.1038/s41598-019-55834-z
Scientific Reports (2022)
The role of semen and seminal plasma in inducing large-scale genomic changes in the female porcine peri-ovulatory tract
Scientific Reports (2020)
Bovine sperm-oviduct interactions are characterized by specific sperm behaviour, ultrastructure and tubal reactions which are impacted by sex sorting
Scientific Reports (2020)