scholarly journals Effect of calmodulin on the stimulation of capacitation and acrosome reaction of frozen thawed bull spermatozoa

2017 ◽  
Vol 45 (3) ◽  
pp. 1-9
Author(s):  
QS Akter ◽  
KMA Tareq ◽  
K Hamano ◽  
RB Gilchrist
Keyword(s):  
Acrosome Reaction ◽  
Specific Binding ◽  
Staining Technique ◽  
Inhibitory Effect ◽  
Free Medium ◽  
Inhibitory Effects ◽  
Specific Binding Protein ◽  
Bovine Spermatozoa ◽  
Mammalian Spermatozoa

Capacitation and acrosome reaction (AR) are the prerequisites for successful fertilization by mammalian spermatozoa. Intracellular calcium (Ca2+) has a regulatory role in sperm motility, capacitation, and AR. Calmodulin (CaM) antagonists calmidazolium (CZ) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W7) were used to investigate the possible role of CaM, a Ca2+ specific binding protein, on motility, capacitation and AR of frozen-thawed bovine spermatozoa. Capacitation and AR in sperm were evaluated by using chlortetracycline (CTC) staining technique. Addition of the 1 mM dibutyryl cAMP (dbcAMP) and 100 ?M 1-methy l-3-isobutylxanthine (IBMX) to CaM antagonists treated sperm incubated in the presence of NaHCO3 and CaCl2 in media overcome the inhibitory effects of these antagonists to support capacitation and AR at 4 h of incubation period. In contrast, addition of dbcAMP with IBMX induced AR in spermatozoa incubated with NaHCO3-free medium but these compounds did not induce AR in cells incubated in CaCl2-free medium. However, the addition of dbcAMP and IBMX partially, but significantly (p<0.01) reversed the inhibitory effect of W7 and CZ on the sperm capacitation and AR. These results suggest that CaM may play an important role in the regulation of capacitation and AR in frozen-thawed bovine spermatozoa.Bang. J. Anim. Sci. 2016. 45 (3): 1-9

Evidence that acrosin activity is important for the development of fusibility of mammalian spermatozoa with the oolemma: inhibitor studies using the golden hamster

Zygote ◽  
1993 ◽  
Vol 1 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Hiroko Takano ◽  
R. Yanagimachi ◽  
Umbert A. Urch
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Free Medium ◽  
Inhibitory Effects ◽  
Chloromethyl Ketone ◽  
Gamete Fusion ◽  
Sperm Plasma Membrane ◽  
Acrosomal Enzyme ◽  
Acrosin Activity ◽  
Mammalian Spermatozoa

SummaryThe sperm plasma membrane over the equatorial segment of the acrosome gains the ability to fuse with the oolemma some time during, or after, the acrosome reaction. Since acrosin is a major component of the acrosome matrix that dissolves during the acrosome reaction, we sought to determine the effect of acrosin inhibitors on the sperm's ability to fuse with the oolemma. Five acrosin inhibitors (soybean trypsin inhibitor (SBTI), leupeptin, benzamidine, N-p-tosyl-1-lysin-chloromethyl ketone (TLCK) and phenylmethylsulphonyl fluoride (PMSF) and one non-acrosin inhibitor (N-p-tosyl-1-phenylalanine chloromethyl ketone (TPCK) were tested at non-toxic levels (below motility-disturbing concentrations). These inhibitors were added at three different times: (1) during the acrosome reaction of spermatozoa, (2) during sperm-oocyte contact and fusion, and (3) soon after sperm-oocyte fusion was completed. TLCK prevented sperm-oocyte fusion by inhibiting the acrosome reaction.PMSF inhibited gamete fusion, without inhibiting the acrosome reaction. SBTI, leupeptin and benzamidine also inhibited gamete fusion, but they had no effect if spermatozoa were allowed to acrosome-react in inhibitor-free medium. TPCK was without any inhibitory effects, suggesting that chymotrypsin-like enzymes are not involved in gamete fusion. Although acrosin inhibitors prevented acrosome-reacted spermatozoa from becoming fusion-competent, acrosin (and trypsin) alone could not make the plasma membrane of acrosome-intact spermatozoa fusion-competent. The data suggest that (1) the plasma membrane of the acrosomal region first undergoes dramatic changes immediately before or during the acrosome reaction and (2) acrosin released from the acrosome during the acrosome reaction further alters biophysical and biochemical characteristics of the plasma membrane over the equatorial segment. Such dual changes make the plasma membrane of this specialised region of the spermatozoon competent to fuse with the oolemma. Acrosin may not be the only acrosomal enzyme to participate in these changes.

The Inhibitory Effect of Heparin and Related Glycosaminoglycans on Neutrophil Chemotaxis

1984 ◽  
Vol 52 (02) ◽  
pp. 134-137 ◽  
Author(s):  
Yaacov Matzner ◽  
Gerard Marx ◽  
Ruth Drexler ◽  
Amiram Eldor
Keyword(s):  
Specific Binding ◽  
Anticoagulant Activity ◽  
Neutrophil Migration ◽  
Inhibitory Effect ◽  
Chemotactic Factor ◽  
Human Neutrophils ◽  
Boyden Chamber ◽  
Neutrophil Chemotaxis ◽  
Inhibitory Effects ◽  
Chemotactic Factors

SummaryClinical observations have shown that heparin has antiinflammatory activities. The effect of heparin on neutrophil chemotaxis was evaluated in vitro in the Boyden Chamber. This method enabled differentiation between the direct effects of heparin on neutrophil migration and locomotion, and its effects on chemotactic factors. Heparin inhibited both the random migration and directed locomotion of human neutrophils toward zymosan-activated serum (ZAS) and F-met-leu-phe (FMLP). Inhibition was found to be dependent on the concentrations of the heparin and of the chemotactic factors. No specific binding of heparin to the neutrophils could be demonstrated, and heparin’s inhibitory effects were eliminated by simple washing of the cells. When added directly to the chamber containing chemotactic factor, heparin inhibited the chemotactic activity of ZAS but not that of FMLP, suggesting a direct inhibitory effect against C5a, the principal chemotactic factor in ZAS.Experiments performed with low-molecular-weight heparin, N-desulfated heparin, dextran sulfate, chondroitin sulfate and dextran indicated that the inhibitory effects of heparin on neutrophil chemotaxis are not related to its anticoagulant activity, but probably depend on the degree of sulfation of the heparin molecule.

scholarly journals Amphetamine-Decreased Progesterone and Estradiol Release in Rat Granulosa Cells: The Regulatory Role of cAMP- and Ca2+-Mediated Signaling Pathways

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 493
Author(s):  
 Chung-Yu Chen ◽  
Chien-Rung Chen ◽  
Chiao-Nan Chen ◽  
Paulus S. Wang ◽  
Toby Mündel ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Prostaglandin F2α ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Steroidogenic Enzyme ◽  
Estradiol Secretion ◽  
Basal Release ◽  
Ca2 Channels

The purpose of this study is to evaluate the amphetamine effects on progesterone and estradiol production in rat granulosa cells and the underlying cellular regulatory mechanisms. Freshly dispersed rat granulosa cells were cultured with various test drugs in the presence of amphetamine, and the estradiol/progesterone production and the cytosolic cAMP level were measured. Additionally, the cytosolic-free Ca2+ concentrations ([Ca2+]i) were measured to examine the role of Ca2+ influx in the presence of amphetamine. Amphetamine in vitro inhibited both basal and porcine follicle-stimulating hormone-stimulated estradiol/progesterone release, and amphetamine significantly decreased steroidogenic enzyme activities. Adding 8-Bromo-cAMP did not recover the inhibitory effects of amphetamine on progesterone and estradiol release. H89 significantly decreased progesterone and estradiol basal release but failed to enhance a further amphetamine inhibitory effect. Amphetamine was capable of further suppressing the release of estradiol release under the presence of nifedipine. Pretreatment with the amphetamine for 2 h decreased the basal [Ca2+]i and prostaglandin F2α-stimulated increase of [Ca2+]i. Amphetamine inhibits progesterone and estradiol secretion in rat granulosa cells through a mechanism involving decreased PKA-downstream steroidogenic enzyme activity and L-type Ca2+ channels. Our current findings show that it is necessary to study the possibility of amphetamine perturbing reproduction in females.

035. THE ROLE OF THE SERTOLI CELL IN REGULATING SPERMATOGENESIS, IMMUNE RESPONSES AND INFLAMMATORY DISEASE: MULTIPLE FUNCTIONS, COMMON MECHANISMS?

2009 ◽  
Vol 21 (9) ◽  
pp. 8
Author(s):  
M. P. Hedger ◽  
J. A. Muir ◽  
W. R. Winnall
Keyword(s):  
Sertoli Cell ◽  
Inflammatory Cytokines ◽  
Cell Function ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Tight Junction Formation ◽  
Interleukin 1Α ◽  
Factor Α ◽  
Necrosis Factor

There is increasing evidence that the Sertoli cell, in addition to modulating responses to direct antigenic challenges (eg. intratesticular allografts), is central to the response of the testis to inflammation and infection. Systemic inflammation exerts an inhibitory effect on spermatogenesis, which has been attributed to the effects of fever, vascular disturbances, or loss of androgenic support. However, recent studies point to more direct effects of inflammation on spermatogenesis. The discovery that Sertoli cells express Toll-like receptors (TLR), and react to TLR ligands by producing inflammatory cytokines and other mediators, provides a mechanism to account for this direct inhibition. Moreover, the pattern of cytokines produced by the Sertoli cell during inflammation is highly characteristic. For example, when stimulated with TLR ligands the Sertoli cell produces the pro-inflammatory cytokines, interleukin-1α (IL1α) and IL6, and the regulatory cytokine, activin A, but does not produce IL1β and tumour necrosis factor-α, which are major pro-inflammatory products of activated macrophages. The disruptive effects of inflammation on spermatogenesis may be attributed to the elevated production of these cytokines, all of which have stimulatory or inhibitory effects on germ cell mitosis, meiosis and apoptosis and Sertoli cell tight junction formation, In addition, activation of TLR/IL1 mediated inflammatory pathways in the Sertoli cell inhibits its ability to respond to its principal trophic hormone, follicle-stimulating hormone. Studies on the regulation of these interactions will further establish the role of the Sertoli cell in inflammation and infection. However, such studies also have important implications for normal Sertoli cell function, as TLRs can respond to endogenous ligands as well. Consequently, the Sertoli cell may be viewed as a sentinel cell, supporting and protecting spermatogenesis when conditions are optimal, but rapidly shutting down spermatogenesis in the presence of infection or illness. Intriguingly, these apparently disparate roles appear to involve common inflammation-related mechanisms.

Role of lipoxygenase in the mechanism of acrosome reaction in mammalian spermatozoa

1990 ◽  
Vol 1043 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Y. Lax ◽  
S. Grossman ◽  
S. Rubinstein ◽  
N. Magid ◽  
H. Breitbart
Keyword(s):  
Acrosome Reaction ◽  
Mammalian Spermatozoa

scholarly journals Expression and putative function of fibronectin and its receptor (integrin α5β1) in male and female gametes during bovine fertilization in vitro

Reproduction ◽  
2009 ◽  
Vol 138 (3) ◽  
pp. 471-482 ◽  
Author(s):  
Mirjan Thys ◽  
Hans Nauwynck ◽  
Dominiek Maes ◽  
Maarten Hoogewijs ◽  
Dries Vercauteren ◽  
...  
Keyword(s):  
Sperm Cell ◽  
Acrosome Reaction ◽  
Male Gamete ◽  
Inhibitory Effect ◽  
Fertilization In Vitro ◽  
Integrin Receptor ◽  
Male And Female ◽  
Sperm Penetration ◽  
Bovine Spermatozoa

Fibronectin (Fn) is a 440 kDa glycoprotein assumed to participate in sperm–egg interaction in human. Recently, it has been demonstrated that Fn – when present during bovine IVF – strongly inhibits sperm penetration. The present study was conducted firstly to evaluate the expression of Fn and its integrin receptor (α5β1) on male and female bovine gametes using indirect immunofluorescence and secondly, to determine the function of Fn during bovine IVF. Endogenous Fn was detected underneath the zona pellucida (ZP) and integrin α5 on the oolemma of cumulus-denuded oocytes. Bovine spermatozoa displayed integrin α5 at their equatorial segment after acrosome reaction. We established that the main inhibitory effect of exogenously supplemented Fn was located at the sperm–oolemma binding, with a (concurrent) effect on fusion, and this can probably be attributed to the binding of Fn to spermatozoa at the equatorial segment, as shown by means of Alexa Fluor 488-conjugated Fn. Combining these results, the inhibitory effect of exogenously supplemented Fn seemed to be exerted on the male gamete by binding to the exposed integrin α5β1 receptor after acrosome reaction. The presence of endogenous Fn underneath the ZP together with integrin α5 expression on oolemma and acrosome-reacted (AR) sperm cell surface suggests a ‘velcro’ interaction between the endogenous Fn ligand and corresponding receptors on both (AR) sperm cell and oolemma, initiating sperm–egg binding.

scholarly journals Role of cyclic GMP in the control of capacitative Ca2+ entry in rat pancreatic acinar cells

1995 ◽  
Vol 311 (2) ◽  
pp. 649-656 ◽  
Author(s):  
P Gilon ◽  
J F Obie ◽  
X Bian ◽  
G S J Bird ◽  
J W Putney
Keyword(s):  
Sodium Nitroprusside ◽  
Cyclic Gmp ◽  
Acinar Cells ◽  
Inhibitory Effect ◽  
Pancreatic Acinar Cells ◽  
Inhibitory Effects ◽  
Intracellular Cgmp ◽  
Agonist Stimulation ◽  
Ly 83583

We have investigated the possible roles of cyclic GMP (cGMP) in initiating or regulating capacitiative Ca2+ entry in rat pancreatic acinar cells. In medium containing 1.8 mM external Ca2+, thapsigargin activated Ca2+ entry and slightly but significantly increased intracellular cGMP concentration. This rise in cGMP levels was prevented by pretreating the cells with the guanylate cyclase inhibitor, LY-83583, or by omitting Ca2+ during stimulation by thapsigargin or methacholine. LY-83583 and NG-nitro-L-arginine (L-NA, an inhibitor of NO synthase) both had a small inhibitory effect on Ca2+ entry when they were added after thapsigargin in Ca2(+)-containing medium, and they reduced by 32 and 48% respectively the thapsigargin-induced capacitative Ca2+ entry when added to the cells during a 20 min preincubation period. However, neither dibutyryl cGMP (Bt2cGMP) nor sodium nitroprusside, an NO mimic, affected either basal intracellular Ca2+ concentration [Ca2+]i or thapsigargin-induced capacitative Ca2+ entry. Further, the inhibitory effects observed after preincubation with LY-83583 or L-NA could not be prevented by preincubation with Bt2cGMP, nor could they be reversed by adding Bt2cGMP, 8-bromo-cGMP or sodium nitroprusside acutely after activation of capacitative Ca2+ entry by thapsigargin. Finally, pretreatment of cells with LY-83583 or L-NA did not affect Ca2+ signalling in response to 1 microM methacholine, including the pattern of [Ca2+]i oscillations. In conclusion, in pancreatic acinar cells, the rise in cellular cGMP levels appears to depend on, rather than cause, the increase in [Ca2+]i with agonist stimulation.

scholarly journals THE INFLUENCE OF CORTISONE ON EXPERIMENTAL VIRAL INFECTION

1957 ◽  
Vol 106 (6) ◽  
pp. 883-892 ◽  
Author(s):  
Edwin D. Kilbourne ◽  
Keyword(s):  
Protein Synthesis ◽  
Influenza Virus ◽  
Potent Inhibitor ◽  
Inhibitory Effect ◽  
The Self ◽  
Inhibitory Effects ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
Experimental Viral Infection

Cortisone is a highly potent inhibitor of influenza virus synthesis in the chick embryo, inducing manifest inhibition in doses of 0.1 to 1.0 µg/egg. Inhibition of viral synthesis is only temporarily manifest. As infection continues, the negation by cortisone of the self-limiting effects of viral autointerference obscures the coincident cortisone effect on synthesis. The inhibitory effect of cortisone may be induced late in the course of viral multiplication, after conclusion of the latent period. It is proposed that inhibition of viral synthesis with cortisone is a corollary of the steroid's inhibitory effects on growth and protein synthesis of the infected host. The role of adrenal corticoids in the regulation of infection with obligate intracellular parasites deserves continued investigation.

scholarly journals Role of protein kinase C in the acrosome reaction of mammalian spermatozoa

1992 ◽  
Vol 281 (2) ◽  
pp. 473-476 ◽  
Author(s):  
H Breitbart ◽  
J Lax ◽  
R Rotem ◽  
Z Naor
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Acrosome Reaction ◽  
Specific Activity ◽  
Immunohistochemical Analysis ◽  
Mammalian Sperm ◽  
Kinase C ◽  
Low Concentrations ◽  
Bovine Spermatozoa ◽  
Mammalian Spermatozoa

Mammalian spermatozoa undergo a Ca(2+)-dependent exocytotic event before fertilization which is known as the acrosome reaction. The process of exocytosis in several cell systems is mediated by a protein kinase C (PKC)-catalysed phosphorylation. Addition of phorbol 12-myristate-13-acetate or the membrane-permeant diacylglycerol analogue 1-oleoyl-2-acetylglycerol, which are potent activators of PKC, to bovine spermatozoa resulted in stimulation of the acrosome reaction. This stimulation was inhibited by low concentrations (50% inhibition at 0.7 nM) of the PKC inhibitor staurosporine. PKC specific activity in bovine spermatozoa is extremely low in comparison with other cells; however, it is comparable with the activity found in human spermatozoa. Immunohistochemical analysis using anti-PKC antibodies revealed staining in the equatorial segment, the post-acrosomal region and the upper region of the head. We propose that PKC is involved in the mammalian sperm acrosome reaction.

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