Estradiol inhibits the effects of extracellular ATP in human sperm by a non genomic mechanism of action

Steroid hormones, beside their classical genomic mechanism of action, exert rapid, non genomic effects in different cell types. These effects are mediated by still poorly characterized plasma membrane receptors that appear to be distinct from the classic intracellular receptors. In the present study we evaluated the non genomic effects of estradiol (17βE2) in human sperm and its effects on sperm stimulation by extracellular ATP, a potent activator of sperm acrosome reaction. In human sperm 17βE2 induced a rapid increase of intracellular calcium (Ca2+) concentrations dependent on an influx of Ca2+ from the extracellular medium. The monitoring of the plasma membrane potential variations induced by 17βE2 showed that this steroid induces a rapid plasma membrane hyperpolarization that was dependent on the presence of Ca2+ in the extracellular medium since it was absent in Ca2+ free-medium. When sperm were pre-incubated in the presence of the K+ channel inhibitor tetra-ethylammonium, the 17βE2 induced plasma membrane hyperpolarization was blunted suggesting the involvement of K+ channels in the hyperpolarizing effects of 17βE2. Extracellular ATP induced a rapid plasma membrane depolarization followed by acrosome reaction. Sperm pre-incubation with 17βE2 inhibited the effects of extracellular ATP on sperm plasma membrane potential variations and acrosome reaction. The effects of 17βE2 were specific since its inactive steroisomer 17αE2 was inactive. Furthermore the effects of 17βE2 were not inhibited by tamoxifen, an antagonist of the classic 17βE2 intracellular receptor

Antisperm antibodies modify plasma membrane functional integrity and inhibit osmosensitive calcium influx in human sperm

BACKGROUND: The hypo-osmotic swelling (HOS) test evaluates the ability of the functional sperm plasma membrane to stretch following cell swelling when exposed to hypo-osmotic solutions. Sperm samples with low HOS scores show low fertilization and pregnancy rates during assisted reproductive techniques, though data are controversial. The aim of this study was to compare the results of the HOS test in a group of normozoospermic men with those in a group of subjects affected by autoimmune infertility due to the presence of antisperm antibodies (ASA) bound to the sperm surface. METHODS: Sperm from normozoospermic and from infertile subjects affected by autoimmune infertility were exposed to hypo-osmolar conditions to verify the effects on intracellular calcium concentrations and acrosome reaction. RESULTS: Sperm samples from infertile men with ASA showed HOS test scores that were significantly lower than those of normozoospermic subjects despite similar sperm viability percentages. Sperm with ASA bound to their plasma membrane showed a reduced rise in intracellular calcium concentrations and acrosome reaction after hypo-osmotic challenge with respect to sperm from normozoospermic subjects without ASA. CONCLUSIONS: Infertile subjects with ASA have a reduced sperm plasma membrane functional integrity that could explain, at least in part, the low fertilization and pregnancy rates observed in these subjects during assisted reproductive procedures. Evaluation for the presence of ASA in all sperm samples showing low HOS test scores in the presence of normal sperm viability percentages is suggested

Dose dependence of the inhibition by 17βE of the ATP induced plasma membrane depolarization in human sperm

<p><b>Copyright information:</b></p><p>Taken from "Estradiol inhibits the effects of extracellular ATP in human sperm by a non genomic mechanism of action"</p><p></p><p>Purinergic Signalling 2005;1(4):369-375.</p><p>Published online Jan 2005</p><p>PMCID:PMC2096547.</p><p></p> Isolated sperm were suspended in the presence of 200 nM bis-oxonol as described in the Materials and methods section. Sperm suspensions were stimulated with 17βE at different doses (0.01, 0.1, 1.0 and 10.0 µM) for 2 min before addition of ATP (2.5 mM). Plasma membrane depolarization is expressed as percentage of the plasma membrane depolarization induced by ATP determined in the absence of 17βE (100%). Results are mean T S.D. of three separate experiments

Effects of 17βE on ATP induced sperm plasma membrane potential variations

<p><b>Copyright information:</b></p><p>Taken from "Estradiol inhibits the effects of extracellular ATP in human sperm by a non genomic mechanism of action"</p><p></p><p>Purinergic Signalling 2005;1(4):369-375.</p><p>Published online Jan 2005</p><p>PMCID:PMC2096547.</p><p></p> Isolated motile human sperm (1.5 × 10 cells) were suspended in the presence of 200 nM bis-oxonol as described in the Material and Methods section in calcium containing medium before addition of the different agonists. Where indicated ATP (2.5 mM), gramicidin D (Gr, 1.0 µM), 17βE (1.0 µM), 17αE (1.0 µM) and tamoxifen (1.0 µM) were added. Traces represent the result of a single from three similar experiments

Human sperm express cannabinoid receptor Cb1, the activation of which inhibits motility, acrosome reaction, and mitochondrial function.

Cannabinoids and endocannabinoids negatively influence sperm functions. These substances have been demonstrated in many mammalian tissues, including male and female reproductive tracts, and previous studies have shown the presence of functional receptors for cannabinoids in human sperm. The present study, by means of RT-PCR and Western blot techniques, demonstrates that human sperm express the CB(1), but not CB(2), cannabinoid receptor (CB-R) subtype located in the head and middle piece of the sperm. The activation of this receptor by anandamide reduces sperm motility and inhibits capacitation-induced acrosome reaction. Activation of the CB(1)-R did not induce any variation in sperm intracellular calcium concentrations, but produced a rapid plasma membrane hyperpolarization that was reduced by the K(+) channel blocker tetraethylammonium. The effects of anandamide on human sperm motility were dependent on the reduction of sperm mitochondrial activity as determined by rhodamine 123 fluorescence. The specificity of anandamide effects in human sperm were confirmed by the effects of the CB(1)-R antagonist SR141716. These findings provide additional evidence that human sperm express functional CB(1)-R, the activation of which negatively influences important sperm functions, and suggest a possible role for the cannabinoid system in the pathogenesis of some forms of male infertility

PDE-5 inhibitor, Vardenafil, increases circulating progenitor cells in humans.

Bone marrow-derived endothelial progenitor cells (EPCs) originate from haematopoietic stem cells in bone marrow and migrate into the peripheral circulation to promote endothelial repair and neovascularization. The number of circulating progenitor cells is reduced in patients with cardiovascular risk factor. The aim of our study was to determine the number of these cells in healthy patients and to evaluate the effect of Vardenfil, a phosphodiesterases-5 (PDE-5) inhibitor, in the number of circulating EPCs. In our study, we found a significant increase in the number of these cells after the drug administration

Possible Anandamide and Palmitoylethanolamide involvement in human stroke

<p>Abstract</p> <p>Background</p> <p>Endocannabinoids (eCBs) are ubiquitous lipid mediators that act on specific (CB1, CB2) and non-specific (TRPV1, PPAR) receptors. Despite many experimental animal studies proved eCB involvement in the pathogenesis of stroke, such evidence is still lacking in human patients. Our aim was to determine eCB peripheral levels in acute stroke patients and evaluate their relationship with clinical disability and stroke volume.</p> <p>Methods</p> <p>A cohort of ten patients with a first acute (within six hours since symptoms onset) ischemic stroke and a group of eight age- and sex-matched normal subjects were included. Groups were also matched for metabolic profile. All subjects underwent a blood sample collection for anandamide (AEA), 2-arachidonoylglycerol (2-AG) and palmitoylethanolamide (PEA) measurement; blood sampling was repeated in patients on admission (T0), at 6 (T1) and 18 hours (T2) thereafter. Patients neurological impairment was assessed using NIHSS and Fugl-Meyer Scale arm subitem (FMSa); stroke volume was determined on 48 h follow-up brain CT scans. Blood samples were analyzed by liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry.</p> <p>Results</p> <p>1)T0 AEA levels were significantly higher in stroke patients compared to controls. 2)A significant inverse correlation between T0 AEA levels and FMSa score was found. Moreover a positive correlation between T0 AEA levels and stroke volume were found in stroke patients. T0 PEA levels in stroke patients were not significantly different from the control group, but showed a significant correlation with the NIHSS scores. T0 2-AG levels were lower in stroke patients compared to controls, but such difference did not reach the significance threshold.</p> <p>Conclusions</p> <p>This is the first demonstration of elevated peripheral AEA levels in acute stroke patients. In agreement with previous murine studies, we found a significant relationship between AEA or PEA levels and neurological involvement, such that the greater the neurological impairment, the higher were these levels.</p

D-Aspartic acid stimulates steroidogenesis through the delay of LH receptor internalization in a mammalian Leydig cell line

Recent experimental evidence on non-mammalian animal models showed that D-Aspartic acid (d-Asp) administration increases testosterone levels through upregulation of StAR in Leydig cells. In this study, we aimed to investigate in vitro the signaling pathway associated with d-Asp stimulation in MA-10 murine Leydig cells