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From the * Centre de Recherche en Biologie de la
Reproduction, Département des sciences animales, and
Département d'obstétrique et
gynécologie, Université Laval, Québec, Québec
Canada.
| Correspondence to: Janice L. Bailey PhD, Centre de Recherche en Biologie de la Reproduction, Département des sciences animales, Université Laval, Québec, Québec G1K 7P4, Canada (e-mail: janice.bailey{at}crbr.ulaval.ca). |
| Received for publication May 29, 2001; accepted for publication July 25, 2002. |
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Abstract |
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Key words: Vinpocetine, rolipram, cyclic AMP, in vitro fertilization, motility
Cyclic nucleotide metabolism consists of a dynamic steady state between synthesis and degradation. Cyclic AMP is produced from adenosine triphosphate (ATP) by adenylyl cyclase (AC) and is degraded by cyclic nucleotide phosphodiesterases (PDE) to adenosine monophosphate (AMP). To date, 11 PDE families or types have been identified (Beavo, 1995; Conti et al, 1995; Fisher et al, 1998a,b; Soderling et al, 1998a,b; 1999; Fawcett et al, 2000). The families differ in their amino acid composition, substrate specificities and affinities, their sensitivity to activators and inhibitors, subcellular distribution, and cell and tissue expression (Conti et al, 1995). Many studies have suggested the presence of PDE in male gametes (Gray et al, 1971; Hoskins et al, 1975; Stephens et al, 1979; Rossi et al, 1985) and their implication in sperm motility (McKinney et al, 1994; Jaiswal and Majumder, 1996; Nassar et al, 1999), capacitation (Visconti et al, 1995; Galantino-Homer et al, 1997; de Lamirande et al, 1997) and the acrosome reaction (Tesarik et al, 1992). Richter et al (1999) demonstrated that ejaculated human sperm contain an extended pattern of PDE messenger RNA (mRNA) transcripts corresponding to types 1, 2, 3, 4, 5, and 8. PDEs 1 and 4 are expressed in mammalian sperm and may play a special role in sperm function (Geremia et al, 1982, 1984; Naro et al, 1996). The PDE 1, calcium/calmodulin (Ca2+/CaM)-dependent, preferentially cleaves cyclic guanosine monophosphate (cGMP) but can also degrade cAMP (Beavo, 1995). PDE 4 is cAMP-specific and may be regulated by phosphorylation (Conti et al, 1995). By using specific inhibitors, Fisch et al (1998) showed that in human sperm, PDEs 1 and 4 favor the acrosome reaction and motility, respectively.
Because cAMP and Ca2+ regulate capacitation and motility, it is possible that PDE 1 and PDE 4 are also involved (Tash and Means, 1983; Parrish et al, 1994). We hypothesize that separate cAMP pools regulate sperm capacitation and motility, such that one or more specific PDEs regulate capacitation without affecting sperm motility and vice versa. The objectives of this study were to determine the role of PDE 1 and PDE 4 on bovine sperm capacitation and motility using specific inhibitors. These effects are compared with those observed using heparin, which is recognized to induce bovine sperm capacitation in vitro (Parrish et al, 1988).
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Materials and Methods |
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Culture Media
Two basic media were prepared as described by Galantino-Homer et al
(1997): a modified Tyrodes
Hepes-buffered medium (Talp-H; 100 mM NaCl, 3.1 mM KCl, 0.3 mM
NaH2PO4, 21.6 mM sodium lactate, 0.4 mM
MgCl2·6H2O, 2.0 mM
CaCl2·2H2O, 40.0 mM Hepes, 1.0 mM pyruvate, 50
µg/mL gentamycin sulfate, 1 mg/mL PVA, and 10 mM NaHCO3) and a
modified Tyrodes bicarbonate-buffered medium (Sp-Talp; 100 mM NaCl, 3.1 mM
KCl, 0.3 mM NaH2PO4, 21.6 mM sodium lactate, 0.4 mM
MgCl2·6H2O, 2.0 mM
CaCl2·2H2O, 10.0 mM Hepes, 1.0 mM pyruvate, 6
mg/mL BSA, and 25 mM NaHCO3). The pHs were adjusted to 7.4 at
23°C and both media were sterilized by passage through a 0.22-µm pore
filter (Millipore Corporation, Bedford, Mass).
Collection and Preparation of Semen
Fresh bovine semen collected using an artificial vagina was generously
donated by the Centre d'Insémination Artificielle du Québec (St
Hyacinthe, QC, Canada). Semen was diluted 1:1 into egg yolk-Tris diluent
without glycerol (0.25 M Tris, 60 mM citric acid, 69 mM fructose, 25% [v/v]
egg yolk and an antibiotic cocktail containing tylosin, gentamicin, and
lincospin) and was transported in a thermos (25°C) to the university
laboratory within 2.5 hours of collection. The sperm were isolated by Percoll
centrifugation as described by Parrish et al
(1995). Two milliliters of
semen were layered on the top of a gradient composed of 4-mL fractions each of
90% and 45% isotonic Percoll. After a 30-minute centrifugation at 700 x
g (25°C), the supernatant was discarded and the pellet was washed
twice at 280 x g for 10 minutes (38°C) with Talp-H. After
the second centrifugation, the supernatant was removed and 3 mL of Sp-Talp
were added. The concentration of sperm was estimated using a hemocytometer and
adjusted with Sp-Talp to 50 x 106 sperm/mL for evaluation of
capacitation and motility and to 1 x 106 sperm/mL for in
vitro fertilization (IVF). The inhibitor treatments were added to the sperm
suspension immediately before incubation. The sperm samples (1 mL) in 15-mL
conical tubes were incubated in conditions to promote capacitation (39°C,
5% CO2, 100% humidity) for up to 5 hours. At 0, 3, and 5 hours,
200-µL aliquots were removed for evaluation of capacitation, motility, and
viability.
Eosin-Nigrosin Staining
Sperm viability was determined by eosin-nigrosin staining
(Barth and Oko, 1989). Ten-microliter samples were mixed with 10 µL of modified eosin-nigrosin
solution containing 0.5% (w/v) sodium citrate
(Hancock, 1951) and 10 µL
of this mixture was smeared onto a clean slide at room temperature. After
drying, the slides were covered with Permount S-15 (Fisher, Montreal, QC,
Canada) and mounted on a glass slide under a coverslip. At least 200 cells per
slide were counted by light microscopy (400x) and the percentage of live
sperm (unstained) was evaluated.
Evaluation of Capacitation by the Chlortetracycline Assay
The fluorescent antibiotic CTC was used to assess sperm capacitation. A
modification of the technique described by Ward and Storey
(1984) was used
(Collin et al, 2000). The CTC
solution contained 750 µM CTC and 5 mM DL-cysteine dissolved in 20 mM Tris
and 130 mM NaCl (TN stock), and the pH was adjusted to 7.8. The CTC solution
was prepared daily and kept at 4°C in foil to protect it from the light.
Fifteen microliters of CTC solution and 10 µL of spermatozoa were mixed in
a warmed glass well; 0.5 µL of 12.5% glutaraldehyde in TN stock (pH 7.4)
was then added. Ten microliters of this suspension were placed on a clean
slide at 37°C. After mounting with a coverslip, the slides were stored in
dark at 4°C until counting within 24 hours. The slides were assessed with
a Nikon microscope equipped with phase contrast and epifluorescence optics;
cells were observed under blue-violet illumination (excitation at 400-440 nm
and emission at 470 nm). Two hundred spermatozoa per slide were counted and
classified as one of three distinct CTC staining patterns as described by
Fraser et al (1995). The
precapacitated sperm had uniform fluorescence over the head (pattern F),
capacitated sperm had a fluorescence-free band in the postacrosomal region
(pattern B), and acrosome-reacted sperm had dull head fluorescence except for
a thin band of fluorescence along the equatorial segment (pattern AR).
Motility Studies
To assess sperm motion, an HTM IVOS unit (Hamilton-Thorne Research,
Beverly, MA) was used with MicroCell slides (20 µm deep; Conception
Technologies, San Diego, Calif) essentially as described by Chamberland et al
(2001). Ten microliters of
sperm solution were deposited in the chamber (prewarmed to 37°C). The
slide was placed on the stage of the motility analyzer and both chambers on
each slide were evaluated as duplicates. Five fields per chamber were selected
for computer-assisted analysis. The values of computer settings were
determined by examining the sample of fresh bull sperm with the
"playback" screen: frame acquired, 20 Hz; frame rate, 30/second;
minimum contrast, 7; minimum size, 7; low and high size gates, 0.3 and 1.5,
respectively; low and high intensity gates, 0.3 and 1.5, respectively; medium
and low average path velocities, 80 µm/s and 20 µm/s, respectively; no
motile head size, 14 pixels; no motile brightness, 14 pixels; threshold
straightness, 80%; temperature, 38.5°C. Nine characteristics were
evaluated: the percentage of motile sperm, progressive motility (PROG),
average path velocity (VAP), curvilinear velocity (VCL), straight line or
progressive velocity (VSL), linearity (LIN = VSL/VCL x 100),
straightness (STR = VSL/VAP x 100), amplitude of lateral head
displacement (ALH), and beat cross frequency (BCF).
In Vitro Fertilization
Bovine ovaries were collected at a slaughterhouse and transported to the
laboratory within 2-3 hours in saline (0.9% w/v NaCl, 35°C).
Cumulus-oocyte complexes (COCs) were aspirated from 1-5 mm follicles. After
selection, isolated (intact) COCs were washed three times in Hepes-buffered
Tyrodes medium (TLH; Bavister et al,
1983) supplemented with 10% heat-treated fetal calf serum (FCS;
Flow Laboratories, McLean, Va), 0.2 mM pyruvate, and 50 µg/mL gentamicin
(Sigma) then matured in vitro for 22-24 hours as described by Chian and Sirard
(1995). The matured oocytes
were used for IVF according to Blondin and Sirard
(1995) and were modified to
assess sperm fertility by Cormier et al
(1997). Fresh semen was used
for treatments and cryopreserved semen as an internal control to confirm
oocyte quality. Treated sperm were added at 1 x 106/mL to
each droplet containing five COCs and incubated for 6 hours at 39°C in
fertilization medium (TALP containing 20 mM pyruvate, 1 mM hypotaurine, 2 mM
penicillamine, 250 µM epinephrine, and 0.6% BSA ± 15 µg/mL
heparin, ± 150 µM vinpocetine). After 6 hours, surplus sperm were
removed and COCs were placed in FCS-enriched medium (TCM-199 supplemented with
10% FCS, 0.2 mM pyruvate, and 50 µg/mL gentamicin) for 12 hours. The COCs
with cryopreserved sperm (internal control) were incubated in fertilization
medium with 2 µg/mL heparin for a full 18 hours. This internal control
assured the quality of the COCs and other experimental conditions. At the end
of incubation (18 hours from the initial addition of sperm), the oocytes were
denuded of the attached cumulus cells by gentle vortexing, fixed in
ethanol:acetic acid (3:1), and stained with 1% orcein (w/v) in 40% acetic acid
(v/v). An oocyte was judged as fertilized when either an enlarged spermatozoa
head or two pronuclei were seen within cytoplasm by light microscopy
(200x).
Statistical Analysis
For the CTC assay, motility, IVF, and the eosin-nigrosin staining, we
conducted analysis of variance with the general linear models procedure using
the Statistical Analysis System (SAS,
1990). The models included ejaculate; concentration of heparin,
vinpocetine, or rolipram; and their interactions. When main effects were
significant (P < .05), preplanned comparisons among treatments
were conducted using the protected Fisher least significant difference
test.
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Results |
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Determination of Sperm Viability by Eosin-Nigrosin Staining
Sperm viability in the presence of vinpocetine or heparin is displayed in
Table 1. After 3 hours of
incubation, vinpocetine did not significantly affect the viability of sperm,
however, more dead sperm were observed with heparin than with control or
vinpocetine treatments (P < .05). Following 5 hours of incubation,
sperm treated with either heparin or vinpocetine (100 and 150 µM) were less
viable than control sperm (P < .05). Rolipram treatments did not
affect sperm viability during incubation for 5 hours (P > .05;
data not shown).
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Evaluation of Sperm Motility
Among the nine characteristics of sperm motion evaluated by
computer-assisted sperm analysis, the specific PDE inhibitors affected only
PROG and LIN. The effects of the PDE 1 inhibitor vinpocetine on the percentage
of progressive sperm compared to those of heparin are presented in
Figure 3. At 3 hours, PROG with
vinpocetine (100 and 150 µM) was different than that of controls but only
the 150 µM dose was significantly lower than heparin (P < .01).
After 5 hours of incubation, a decrease of the percentage of PROG was observed
with heparin and vinpocetine (100 and 150 µM), and PROG with 150 µM
vinpocetine was still lower than that of heparin (P < .01). The
PDE 4 inhibitor rolipram affected only the percentage of LIN sperm
(Figure 4). After 3 hours of
incubation, 200 µM rolipram increased the LIN of sperm (P <
.05) in a manner observed in neither the negative nor positive (heparin)
controls.
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Determination of Capacitation by IVF
The effect of blocking sperm PDE 1 on IVF rates is shown in
Table 2. The presence of
heparin increased nearly fivefold the percentage of oocytes penetrated by
sperm compared with controls (P < .05). Compared with the positive
heparin controls, inclusion of the PDE 1 inhibitor vinpocetine (without
heparin) did not promote fertilization because more than seven times fewer
oocytes were penetrated (P < .05), which was similar to negative
(heparin-free) controls. However, there was no difference in fertility between
the combination of vinpocetine plus heparin and heparin alone (P >
.05), indicating that vinpocetine did not negatively affect oocyte
function.
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Discussion |
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It is recognized that sperm capacitation (Visconti et al, 1995, 1997; Leclerc et al, 1996; Galantino-Homer et al, 1997; Aitken et al, 1998) and motility (Tash and Means, 1983) are regulated by a cAMP-dependent pathway. Therefore, the control of cAMP levels in sperm is very important to properly regulate the effects of this messenger. In human sperm, the degradation of cyclic nucleotides by PDE occurs at a rate 9-fold to 600-fold faster than that of their synthesis by adenylyl cyclase (Cheng and Boettcher, 1982). It is thus probable that PDE plays a role in sperm functions. Fisch et al (1998) demonstrated the presence of two distinct PDE families in human sperm, PDE 1 and PDE 4, which appear to regulate the acrosome reaction and motility, respectively. These two PDE families may be implicated in these critical sperm functions by regulating separate pools of cAMP, which could explain why this second messenger can control several different sperm functions at different times, such as progressive motility (Tash and Means, 1983), capacitation (Visconti et al, 1998) and the acrosome reaction (Leclerc and Kopf, 1995).
Regarding the effects on capacitation, rolipram, a PDE 4 inhibitor, has no effect, whereas vinpocetine, a specific inhibitor of the Ca2+/CaM-dependent PDE 1, increased the rate of capacitation according to CTC pattern B fluorescence in a dose-response manner. The Ca2+/CaM complex regulates a large number of enzymes in many cell types (Cheung, 1980; Means et al, 1982). Calmodulin is present in both the acrosomal region and the flagellum of sperm (Manjunath et al, 1993; Leclerc and Goupil, 2000) and is necessary for PDE 1 activity. The implication of PDE 1 in capacitation is supported by the observation that CaM intracellular concentration decreases during heparin-induced capacitation of bull sperm (Leclerc et al, 1992). As sperm CaM declines during capacitation, PDE 1 would not be activated to hydrolyze cAMP, and is thus in agreement with an increased cAMP pool observed during capacitation (White and Aitken, 1989; Parrish et al, 1994; Parinaud and Milhet, 1996).
PDE 1 inhibition induced a rapid appearance of the CTC pattern B in a dose-response manner supporting the hypothesis that this enzyme family mediates membrane changes associated with capacitation. The rapid appearance of pattern B was not an artifact due to a fluorescent interaction between CTC and the vinpocetine because this compound is not fluorescent at the wavelengths used (data not shown). Our results suggest that an increase in sperm cAMP concentration by PDE 1 inhibition is responsible for the rapid appearance of CTC pattern B. Harrison and Miller (2000) proposed that plasma membrane lipid architecture in boar sperm during capacitation is controlled via a target protein phosphorylated by PKA and is dephosphorylated by a protein phosphatase type 1. The PKA can be activated by the high cAMP level and increase membrane fluidity leading to capacitation. Furthermore, in boar sperm, these changes are extremely rapid, resulting in increased membrane fluidity within minutes and in the present study, vinpocetine increased the proportion of bull sperm showing pattern B (capacitated) fluorescence immediately. The mechanism of the CTC assay reflects the location of membrane calcium, which in turn is dependent on the characteristics of bilayer phospholipids. Therefore, in the presence of an inhibitor of a capacitation-specific PDE 1 family (according to our hypothesis), any PKA-mediated plasma membrane modifications would be reflected in the elevated percentage of sperm displaying CTC pattern B even at the beginning of the incubation.
In contrast, sperm treated with high concentrations of the PDE 1 inhibitor vinpocetine did not penetrate COCs as those treated with heparin. Our findings resemble those of Lefièvre et al (2000), who observed that sildenfafil, an inhibitor of PDE 5, a cGMP-dependent PDE, promoted the sperm protein tyrosine phosphorylation that is associated with capacitation in humans, but is inadequate to promote the acrosome reaction. Clearly, PDE inhibition favors certain events associated with capacitation, but not all of them. A possible explanation for the results of the present study (Figure 1 and Table 2) is that the regulation of cAMP by PDE 1 occurs early during capacitation, however, full capacitation is prevented from prematurely occurring by downstream events. For example, the dephosphorylation of capacitation-related molecules by phosphatases that regulate lipid architecture (Harrison and Miller, 2000) or of tyrosine-phosphorylated sperm proteins (Visconti et al, 1998) could prevent premature capacitation. The aim of PDE 1 inhibition is to increase the cAMP concentration, which itself represents an important step of capacitation, yet on its own, elevated cAMP may be insufficient to support complete capacitation. Alternatively, perhaps another type of PDE is activated in the sperm to compensate for the inhibition of PDE 1 in an effort to restrict premature cAMP elevation. Capacitation has been reported to be a reversible phenomenon, largely due to the ability of components from the male reproductive tract to restabilize the membranes of capacitated sperm after their reintroduction (discussed in Yanagamachi, 1994). However, based on the observations that PDE 1 inhibition leads to membrane changes that resemble capacitation (as indicated by the pattern B staining), one can also speculate that some internal process, perhaps a phosphatase or another PDE type, rapidly reversed the vinpocetine-induced capacitation. Consequently, vinpocetine would not be sufficient to induce functional capacitation in its entirety because its effects are too transient to be functional (ie, oocyte fertilization during IVF). However, this is a weak speculation; if vinpocetin even temporarily induced functional capacitation, the oocyte penetration rate would, in theory, be greater than that of the negative control sperm, which did not happen (Table 2).
Numerous studies have demonstrated that the addition of heparin is essential to induce bovine sperm capacitation in vitro (Parrish et al, 1988; Miller et al, 1990; Galantino-Homer et al, 1997; Chamberland et al, 2001). In this study, heparin reduced sperm viability relative to vinpocetine, the PDE 1 inhibitor. Capacitation is an ongoing destabilization process and sperm become increasingly fragile owing to various alterations in the plasma membrane (Harrison, 1996). In this sense, a drop in sperm survival can be an indirect indicator of full capacitation such that the changes induced by the PDE 1 inhibitor do not fully correspond to complete capacitation (as heparin) because vinpocetine maintained sperm viability. By these observations, the present study shows that the CTC assay is representative of sperm physiology indicating the early stages of a series of molecular changes leading to capacitation. However, the CTC pattern B does not necessarily indicate full capacitation because the sperm treated with the PDE 1 inhibitor showed a CTC pattern B yet could not penetrate COC, as discussed earlier.
During incubation with heparin, sperm progressive motility is reduced. Vinpocetine induced similar change in the percentage of progressively motile sperm, supporting the hypothesis that PDE 1 mimics heparin. Although the mechanisms of the motility changes in sperm due to heparin are unclear, an increase of cAMP during capacitation may lead to hyperactivation. Heparin elevates cAMP and intracellular Ca2+ in bull sperm (Handrow et al, 1989; Parrish et al, 1989, 1994) and these molecules are directly implicated in the regulation of sperm motility (Garbers and Kopf, 1980; Tash and Means, 1983; Garty and Salomon, 1987). Chamberland et al (2001) observed greater BCF and ALH in bull sperm treated with heparin. These parameters are believed to be related to sperm hyperactivation that occurs in vivo and favors sperm oocyte penetration (Suarez et al, 1991; Suarez and Dai, 1992; Stauss et al, 1995). In the present study, however, the PDE 1 inhibitor did not affect these parameters. The inhibition of PDE 1 altered sperm motility but contrary to heparin, it did not affect the parameters associated with hyperactivation. PDE 1 clearly does not affect all molecular changes implicated in motility that favors fertilization.
The inhibition of PDE 4 with rolipram slightly changed motility parameters, but in a manner different from heparin. Rolipram induces a minor but significant increase in the percentage of linear motile sperm, although the high concentration required to induce these changes renders the physiological relevance of the results somewhat questionable. Tash and Means (1983) postulated that in highly motile noncapacitated sperm (such as the heparin-free fresh sperm used in this study), the PKA activity is already at maximal levels. Thus it is possible that using PDE inhibitors to increase cAMP has no additional effect on PKA activity in the absence of heparin. This may be why rolipram did not markedly alter sperm motion, however, it would be interesting to repeat this experiment using poor motility sperm like those from cryopreserved semen.
In summary, the present study demonstrates that PDE 1 inhibition mimics certain effects of heparin (the membrane modifications reported by CTC pattern B fluorescence and motility changes) but can not support complete capacitation (fertilization of homologous oocytes during IVF). Our experiments do support the hypothesis that multiple PDE families in sperm affect different sperm functions by regulating separate pools of cAMP (Fisch et al, 1998). This study also supports the role of a cAMP-dependent signaling pathway in capacitation (Visconti et al, 1995; Leclerc et al, 1996; Galantino-Homer et al, 1997; Aitken et al, 1998) via increased cAMP levels. Furthermore, these results reinforce the hypothesis that a loss of calmodulin accompanies capacitation of bull sperm (Leclerc et al, 1992), thereby favoring the increased cAMP levels necessary to drive the signaling events associated with this phenomenon.
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Footnotes |
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References |
|---|
|
TopAbstractMaterials and MethodsResultsDiscussionReferences |
|---|
Austin CR. Observations on the penetration of the sperm into the mammalian egg. Aust J Sci Res B.1951; 4:581 -596.
Austin CR. The "capacitation" of the mammalian sperm. Nature. 1952;170:326 .[Medline]
Barth A, Oko RJ. Abnormal Morphology of Bovine Spermatozoa. Ames, Iowa: Iowa Sate University Press;1989 .
Bavister BD, Leibfried ML, Lieberman G. Development of preimplantation embryos of the golden hamster in a defined culture medium. Biol Reprod.1983; 28:235 -247[Abstract]
Beavo JA. Cyclic nucleotide phosphodiesterases: functional implications of multiple isoforms. Am J Physiol.1995; 75:725 -748.
Blondin P, Sirard MA. Oocyte and follicular morphology as determining characteristics for developmental competence in bovine oocytes. Mol Reprod Dev.1995; 41:54 -62.[Medline]
Chamberland A, Fournier V, Tardif S, Sirard MA, Sullivan R, Bailey JL. The effect of heparin on motility parameters and protein phosphorylation during bovine sperm capacitation. Theriogenology.2001; 55:823 -835.[Medline]
Chang MC. Fertilizing capacity of spermatozoa deposited into the fallopian tubes. Nature.1951; 168:697 -698.[Medline]
Cheng CY, Boettcher B. Partial characterization of human spermatozoal phosphodiesterase and adenylate cyclase and the effects of steroids on their activities. Int J Androl.1982; 5:253 -266.[Medline]
Cheung MY. Calmodulin plays a pivotal role in cellular regulation. Science NY.1980; 207:19 -27.
Chian RC, Sirard MA. Fertilizing ability of bovine spermatozoa cocultured with oviduct epithelial cells. Biol Reprod.1995; 52:156 -162.[Abstract]
Collin S, Sirard MA, Dufour M, Bailey JL. Sperm calcium levels and chlortetracycline fluorescence patterns are related to the in vivo fertility of cryopreserved bovine semen. J Androl.2000; 21:938 -943.[Abstract]
Conti M, Nemoz G, Sette C, Vicini E. Recent progress in understanding the hormonal regulation of phosphodiesterase. Endocr Rev. 1995;16:370 -389.[Medline]
Cormier N, Sirard MA, Bailey JL. Premature capacitation of bovine
spermatozoa is initiated by cryopreservation. J
Androl. 1997;18:461
-468.
Das Gupta S, Mills CL, Fraser LR. Ca2+-related changes in the capacitation state of human spermatozoa assessed by chlortetracycline fluorescence assay. J Reprod Fertil.1993; 99:135 -143.
de Lamirande E, Leclerc P, Gagnon C. Capacitation as a regulatory
event that primes spermatozoa for the acrosome reaction and fertilization.
Mol Hum Reprod.1997; 3:175
-194.
Fawcett L, Baxendale R, Stacey P, McGrouther C, Harrow I, Soderling
S, Hetman J, Beavo JA, Phillips SC. Molecular cloning and characterization of
a distinct human phosphodiesterase gene family: PDE11A. Proc Natl
Acad Sci USA. 2000;97:3702
-3707.
Fisch JD, Behr B, Conti M. Enhancement of motility and acrosome
reaction in human spermatozoa: differential activation by type-specific
phosphodiesterase inhibitors. Hum Reprod.1998; 13:1248
-1254.
Fisher DA, Smith JF, Pillar JS, St Denis SH, Cheng JB. Isolation and characterization of PDE8A, a novel human cAMP-specific phosphodiesterase. Biochem Biophys Res Commun.1998a; 246:570 -577.[Medline]
Fisher DA, Smith JF, Pillar JS, St Denis SH, Cheng JB. Isolation
and characterization of PDE9A, a novel human cGMP-specific phosphodiesterase.
J Biol Chem.1998b; 273:15559
-15564.
Florman HM, First NL. The regulation of acrosomal exocytosis. I. Sperm capacitation is required for the induction of acrosome reactions by the bovine zona pellucida in vitro. Dev Biol.1988; 128:453 -463.[Medline]
Fraser LR, Abeydeera LR, Niwa K. Ca2+-regulating mechanisms that modulate bull sperm capacitation and acrosome exocytosis as determined by chlortetracycline analysis. Mol Reprod Dev. 1995;40:233 -241.[Medline]
Furuya S, Endo Y, Oba M, Nozawa S, Suzuki S. Effect of modulators of protein kinases and phosphatases on mouse sperm capacitation. J Assist Reprod Genet. 1992;9:391 -399.[Medline]
Galantino-Homer H, Visconti PE, Kopf GS. Regulation of protein tyrosine phosphorylation during bovine sperm capacitation by a cyclic adenosine 3',5'-monophosphate-dependent pathway. Biol Reprod. 1997;56:707 -719.[Abstract]
Garbers DL, Kopf GS. The regulation of spermatozoa by calcium and cyclic nucleotides. Adv Cyclic Nucleotide Res.1980; 22:251 -306.
Garty NB, Salomon Y. Stimulation of partially purified adenylate cyclase from bull sperm by bicarbonate. FEBS Lett.1987; 218:148 -152.[Medline]
Geremia R, Rossi P, Pezzotti R, Conti M. Cyclic nucleotide phosphodiesterase in developing rat testis. Identification of somatic and germcell forms. Mol Cell Endocrinol.1982; 28:37 -53.[Medline]
Geremia R, Rossi P, Mocini D, Pezzotti R, Conti M. Characterization of a calmodulin-dependent high-affinity cyclic AMP and cyclic GMP phosphodiesterase from male mouse germ cells. Biochem J. 1984;217:693 -700.[Medline]
Gray JP, Hardman JG, Hammer JL, Hoos RT, Sutherland EW. Adenyl cyclase, phosphodiesterase and cyclic AMP of human sperm and seminal plasma. Fed Proc. 1971;30:1267 -1269.
Hancock JL. A staining technique for the study of temperature shock in semen. Nature.1951; 167:323 -324.
Handrow RR, First NL, Parrish JJ. Calcium requirement and increased association with bovine sperm during capacitation by heparin. J Exp Zool. 1989;252:174 -182.[Medline]
Harrison RA. Capacitation mechanisms, and the role of capacitation as seen in eutherian mammals. Reprod Fertil Dev.1996; 8:581 -594.[Medline]
Harrison RA, Miller NG. cAMP-dependent protein kinase control of plasma membrane lipid architecture in boar sperm. Mol Reprod Dev. 2000;55:220 -228.[Medline]
Hoskins DD, Hall ML, Musterman D. Induction of motility in immature bovine spermatozoa by cyclic AMP phosphodiesterase inhibitors and seminal plasma. Biol Reprod.1975; 13:168 -176.[Abstract]
Jaiswal BS, Majumder GC. Cyclic AMP phosphodiesterase: a regulator of forward motility initiation during epididymal sperm maturation. Biochem Cell Biol.1996; 74:669 -674.[Medline]
Kopf GS, Gerton GL. The mammalian sperm acrosome and the acrosome reaction. In: Wassarman PM, ed. Elements of Mammalian Fertilization. Boca Raton, Fla: CRC Press; 1991:153 -203.
Leclerc P, Goupil S. Distribution and localization of
calmodulin-binding proteins in bull spermatozoa. Biol
Reprod. 2000;62:1875
-1881.
Leclerc P, Kopf GS. Mouse sperm adenylyl cyclase: general properties and regulation by the zona pellucida. Biol Reprod. 1995;52:1227 -1233.[Abstract]
Leclerc P, de Lamirande E, Gagnon C. Cyclic adenosine 3',5' monophosphate-dependent regulation of protein tyrosine phosphorylation in relation to human sperm capacitation and motility. Biol Reprod.1996; 55:684 -692.[Abstract]
Leclerc P, Langlais J, Lambert RD, Sirard MA, Chafouleas JG. Effect of heparin on the expression of calmodulin-binding proteins in bull spermatozoa. J Reprod Fertil.1989; 85:615 -622.
Leclerc P, Sirard MA, Chafouleas JG, Lambert RD. Decreased binding of calmodulin to bull sperm proteins during heparin-induced capacitation. Biol Reprod.1990; 42:483 -489.[Abstract]
Leclerc P, Sirard MA, Chafouleas JG, Lambert RD. Decrease in calmodulin concentrations during heparin-induced capacitation in bovine spermatozoa. J Reprod Fertil.1992; 94:23 -32.
Lee MA, Trucco GS, Bechtol KB, Wummer N, Kopf GS, Blasco L, Storey BT. Capacitation and acrosome reactions in human spermatozoa monitored by a chlortetracycline fluorescence assay. Fertil Steril.1987; 48:649 -658.[Medline]
Lefievre L, de Lamirande E, Gagnon C. The cyclic GMP-specific phosphodiesterase inhibitor, sildenafil, stimulates human sperm motility and capacitation but not acrosome reaction. J Androl.2000; 21:929 -937.[Abstract]
Lindemann CB, Kanous KS. Regulation of mammalian sperm motility. Arch Androl.1989; 23:1 -22.[Medline]
Manjunath P, Chandonnet L, Baillargeon L, Roberts KD. Calmodulin-binding proteins in bovine semen. J Reprod Fertil. 1993;97:75 -81.
McKinney KA, Lewis SEM, Thompson W. Persistent effects of pentoxifylline on human sperm motility, after drug removal, in normozoospermic and athenozoospermic individuals. Andrologia.1994; 26:235 -240.[Medline]
Means AR, Tash JS, Chafoulas JG. Physiological implications of the
presence, distribution and regulation of calmodulin in eukaryotic cells.
Physiol Rev.1982; 62:1
-38.
Miller DJ, Winer MA, Ax RL. Heparin-binding proteins from seminal plasma bind to bovine spermatozoa and modulate capacitation by heparin. Biol Reprod.1990; 42:899 -915.[Abstract]
Naro F, Zhang R, Conti M. Developmental regulation of unique adenosine 3',5'-monophosphate-specific phosphodiesterase variants during rat spermatogenesis. Endocrinology.1996; 137:2464 -2472.[Abstract]
Nassar A, Morshedi M, Mahony M, Srisombut C, Lin MH, Dehninger S. Pentoxifylline stimulates various sperm motion parameters and cervical mucus penetrability in patients with asthenozoospermia. Andrologia.1999; 31:9 -15.[Medline]
Parinaud J, Milhet P. Progesterone induces Ca2+-dependent 3',5'-cyclic adenosine monophosphate increase in human sperm. J Clin Endocrinol Metab.1996; 81:1357 -1360.[Abstract]
Parrish JJ, Krogenaes A, Susko-Parrish JL. Effect of bovine sperm separation by either swim-up or percoll method on success of in vitro fertilization and early embryonic development. Theriogenology.1995; 44:859 -869.
Parrish JJ, Susko-Parrish JL, First NL. Capacitation of bovine sperm by heparin: inhibitory effect of glucose and role of intracellular pH. Biol Reprod.1989; 41:683 -699.[Abstract]
Parrish JJ, Susko-Parrish J, Uguz C, First NL. Differences in the role of cyclic adenosine 3',5'-monophosphate during capacitation of bovine sperm by heparin or oviduct fluid. Biol Reprod. 1994;51:1099 -1108.[Abstract]
Parrish JJ, Susko-Parrish J, Winer MA, First NL. Capacitation of bovine sperm by heparin. Biol Reprod.1988; 38:1171 -1180.[Abstract]
Richter W, Dettmer D, Glander HJ. Detection of mRNA transcripts of
cyclic nucleotide phosphodiesterase subtypes in ejaculated human spermatozoa.
Mol Hum Reprod.1999; 5:732
-736.
Rossi P, Pezzotti R, Conti M, Geremia R. Cyclic nucleotide phosphodiesterases in somatic and germ cells of mouse seminiferous tubules. J Reprod Fertil.1985; 74:317 -327.
Saling PM, Storey BT. Mouse gamete interactions during
fertilization in vitro: chlortetracycline as fluorescent probe for the mouse
sperm acrosome reaction. J Cell Biol.1979; 83:544
-555.
Saling PM, Sowinski J, Storey BT. An ultrastructural study of epididymal mouse spermatozoa binding to zonae pellucidae in vitro: sequential relationship to the acrosome reaction. J Exp Zool.1979; 209:229 -238.[Medline]
SAS Institute, Inc. SAS Procedures Guide, Version 6, 3rd ed. Cary, NC: SAS Institute; 1990.
Si Y, Olds-Clarke P. Mice carrying two t haplotypes: sperm
populations with reduced zona pellucida binding are deficient in capacitation.
Biol Reprod.1999; 61:305
-311.
Soderling SH, Bayuga SJ, Beavo JA. Identification and
characterization of a novel family of cyclic nucleotide phosphodiesterase.
J Biol Chem.1998a; 273:15553
-15558.
Soderling SH, Bayuga SJ, Beavo JA. Cloning and characterization of
a cAMP-specific cyclic nucleotide phosphodiesterase. Proc Natl Acad
Sci USA. 1998b;95:8991
-8996.
Soderling SH, Bayuga SJ, Beavo JA. Isolation and characterization
of a dual-substrate phosphodiesterase gene family: PDE10A. Proc
Natl Acad Sci USA. 1999;96:7071
-7076.
Stein DM, Fraser LR. Cyclic nucleotide metabolism in mouse epididymal spermatozoa during capacitation in vitro. Gamete Res. 1984;10:283 -299.
Stephens DT, Wang JL, Hoskins DD. The cyclic AMP phosphodiesterase of bovine spermatozoa: multiple forms, kinetic properties and changes during development. Biol Reprod.1979; 20:483 -491.[Abstract]
Stauss CR, Votta TJ, Suarez SS. Sperm motility hyperactivation facilitates penetration of the hamster zona pellucida. Biol Reprod. 1995;53:1280 -1285.[Abstract]
Suarez SS, Dai XB. Hyperactivation enhances mouse sperm capacity for penetrating viscoelastic media. Biol Reprod.1992; 46:686 -691.[Abstract]
Suarez SS, Katz DF, Owen DH, Andrew JB, Powell RL. Evidence for the function of hyperactivated motility in sperm. Biol Reprod. 1991;44:375 -381.[Abstract]
Tardif S, Dube C, Chevalier S, Bailey JL. Capacitation is
associated with tyrosine phosphorylation and tyrosine kinase-like activity of
pig sperm proteins. Biol Reprod.2001; 65:784
-792.
Tash JS, Means AR. Cyclic adenosine 3',5' monophosphate, calcium and protein phosphorylation in flagellar motility. Biol Reprod.1983; 28:75 -104.[Abstract]
Tesarik J, Mendoza C, Carreras A. Effects of phosphodiesterase inhibitors caffeine and pentoxifylline on spontaneous and stimulus-induced acrosome reactions in human sperm. Fertil Steril.1992; 58:1185 -1190.[Medline]
Topper EK, Killian GJ, Way A, Engel B, Woelders H. Influence of capacitation and fluids from the male and female genital tract on the zona binding ability of bull spermatozoa. J Reprod Fertil.1999; 115;175 -183.
Visconti PE, Galantino-Homer H, Moore GD, Bailey JL, Ning X, Fornes
M, Kopf GS. The molecular basis of sperm capacitation. J
Androl. 1998;19:242
-248.
Visconti PE, Johnson L, Oyaski M, Fornès M, Moss SB, Gerton GL, Kopf GS. Regulation, localization, and anchoring of protein kinase A subunits during mouse sperm capacitation. Dev Biol.1997; 192:351 -363.[Medline]
Visconti PE, Moore GD, Bailey JL, Leclerc P, Connors SA, Pan D, Olds-Clarke, Kopf GS. Capacitation of mouse spermatozoa. II. Protein tyrosine phosphorylation and capacitation are regulated by a cAMP-dependent pathway. Development.1995; 121:1139 -1150.[Abstract]
Visconti PE, Tezon JG. Phorbol esters stimulate cyclic adenosine 3',5'-monophosphate accumulation in hamster spermatozoa during in vitro capacitation. Biol Reprod.1989; 40:223 -231.[Abstract]
Ward CR, Storey BT. Determination of the time course of capacitation in mouse spermatozoa using a chlortetracycline fluorescence assay. Dev Biol.1984; 104:287 -296.[Medline]
White DR, Aitken RJ. Relationship between calcium, cyclic AMP, ATP, and intracellular pH and the capacity of hamster spermatozoa to express hyperactivated motility. Gamete Res.1989; 22:163 -177.[Medline]
Yanagimachi R. Mammalian fertilization. In: Knobil E, Neill JD, eds. The Physiology of Reproduction. New York: Raven Press; 1994: 189-317.
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