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Biomedical subjects

M Rossato

Publications and source records attributed to M Rossato.

At least 19 recordsLinked to original sources
PubMed2006

The polymorphic polyglutamine repeat in the mitochondrial DNA polymerase gamma gene is not associated with oligozoospermia.

The POLG1 nuclear gene, encoding for the catalytic subunit of the mitochondrial polymerase gamma, has been reported to play a role in male infertility. In fact, genotypes showing alleles different from the common ten repeat CAG allele have been detected in patients with oligozoospermia or in patients with normal spermiograms and unexplained infertility. However, these results have been debated by other studies. To verify these data, we analyzed 625 individuals in three groups of case-controls from three different Italian regions. In these series, the frequency of the different genotypes was not statistically different in oligozoospermic vs normal subjects. Even considering the pooled controls and patients (348 and 277, respectively), no significant difference was shown (p = 0.11). Our findings, in agreement with other studies from Italy and France, suggest that, at least in these countries, the POLG1 CAG-repeat polymorphisms do not contribute to oligozoospermia.

Adult↗
PubMed2005

Review article: adipocytokines and insulin resistance.

Insulin resistance has been implicated as one possible factor that links visceral obesity to unfavourable metabolic and cardiovascular consequences. However, the mechanism whereby adipose tissue causes alterations in insulin action remains unclear. White adipose tissue is secreting several hormones, particularly leptin and adiponectin, and a variety of other protein signals: the adipocytokines. They include proteins involved in the regulation of energy balance, lipid and glucose metabolism as well as angiogenesis, vascular and blood pressure regulation. Visceral obesity and inflammation within white adipose tissue may be a crucial step contributing to the emergence of insulin resistance, type 2 diabetes and atherosclerosis. A growing list of adipocytokines involved in inflammation (IL-1beta, IL-6, IL-8, IL-10, TNF-alpha, TGF-beta,) and the acute-phase response (serum amyloid A, PAI-1) have been found to be increased in the metabolic syndrome. It is, however, unclear as to the extent adipose tissue contributes quantitatively to the elevated circulating levels of these factors in obesity and how they may affect the insulin-dependent tissues. This review describes the role of the currently known adipocytokines and hormones released by adipose tissue in generating the insulin resistance state and the chronic inflammatory profile which frequently goes together with visceral obesity.

Adiponectin↗
PubMed2004

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.

Acrosome Reaction↗
PubMed2004

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.

Acrosome Reaction↗
PubMed2004

Suppression of the high endogenous levels of plasma FSH in infertile men are associated with improved Sertoli cell function as reflected by elevated levels of plasma inhibin B.

BACKGROUND: In vitro continuous stimulation of Sertoli cells with FSH leads to a desensitization of these cells to FSH action. To evaluate the presence of a desensitization of FSH receptor on Sertoli cells in vivo, we performed a controlled clinical study in 97 men affected by severe oligozoospermia. METHODS: On the basis of FSH and inhibin B plasma concentrations, these subjects were divided into three groups: group A, 33 subjects with high FSH and low inhibin B plasma levels; group B, 32 subjects with high FSH plasma levels and inhibin B concentrations at the lower limit of the normal range; and group C, 32 subjects with normal FSH and inhibin B plasma levels. Patients with high FSH plasma levels (groups A and B) were prospectively randomized into two subgroups, called A1, A2, B1 and B2. Patients of groups A1 and B1 were treated with a GnRH agonist, leuprolide acetate, to induce a hypogonadotrophic state and then were treated with recombinant human FSH (r-hFSH; 100 IU/day) and hCG (2000 IU/twice a week) for 2 months. Subjects of groups A2, B2 and C were treated only with r-hFSH for the same period. RESULTS: In patients of group A1, inhibin B remained unmodified during the whole period of study, whereas in subjects of group B1, we observed a significant reduction of this hormone during the hypogonadotrophic period and then an increase of inhibin B plasma levels that were higher that those observed before therapy. In patients of groups A2 and B2, FSH treatment did not induce a significant increase in inhibin B concentrations. In patients of group C, FSH induced a significant increase in inhibin B plasma levels. CONCLUSIONS: In infertile men, suppression of the high endogenous levels of plasma FSH associated with much lower exogenous FSH levels is able to evoke higher inhibin B production, which may indicate improved Sertoli cell function and the possibility that this could have a positive effect on spermatogenesis.

Adult↗
PubMed2004

Erectile dysfunction: symptom or disease?

Erectile dysfunction (ED) has been defined by the National Institute of Health (NIH) as the inability to achieve and/or to maintain an erection for a sufficiently long period of time so as to permit satisfactory sexual intercourse. ED affects millions of men throughout the world and could have a negative influence on the individual's well-being as well as on the quality of life of affected subjects. Discordant data have been reported on ED epidemiology with prevalence ranging from 12% to 52%, probably depending on the different criteria utilized in the different studies for patient selection. ED is a symptom, sometimes the first, of different pathological conditions. In 15.7% of 45-yr-old patients with vascular ED a dynamic ergometric test has shown electrocardiographic alterations in the absence of any cardiac symptom. In 15% of the patients with ED, high fasting glucose plasma levels are discovered for the first time and in patients with ED and normal fasting glucose plasma levels the prevalence of undiagnosed diabetes mellitus is 12.1% after an oral glucose tolerance test (OGTT). The different risk factors are often additive in the possible development of systemic vasculopathy, neuropathy and ED. ED, underestimated in clinical practice due to archaic prejudice which hinders the patient in spontaneously revealing the problem and the physicians in investigating it, can mark the point where evaluation and prevention of important diseases (such as diabetes, arterial hypertension, atherosclerosis) hitherto unknown by the patients, can begin. The physicians' cultural baggage must include the ability to identify the pathology that can determine ED and the ability to program a specific diagnostic workup. In this paper the different specialists involved in ED diagnosis agreed that a clinical approach which allows the identification of systemic pathologies contributing to the development of ED constitutes an improvement in disease prognosis and may either induce a spontaneous reduction of ED or facilitate its specific treatment.

Adult↗
PubMed2004

Self-protection against aminoglycoside ototoxicity in guinea pigs.

BACKGROUND: Amikacin is a semisynthetic aminoglycoside. It acts against most of the microbial species. Amikacin limitation of the therapeutic application is the ototoxicity which promotes permanent lesions in the cochlear system. Aminoglycoside antibiotics have ototoxic potential. The target cells are preferentially the outer hair cells in the cochlear basal turns. Amynoglicoside antibiotics can quelate iron forming a complex with oxidate properties and promotes the formation of free radicals. Responsible for production of lesions in the hair cells. OBJECTIVE: The objective of the present investigation was to determine whether the use of the aminoglycoside amikacin at small doses may lead to the occurrence of some types of resistance to or protection against ototoxicity of the drug by analyzing lesions to the organ of Corti by scanning electron microscopy. METHODS: The study was conducted on 31 guinea pigs that were divided into 4 groups, amikacin was administered intramuscularly. The groups consisted of: group A = control group: 5 animals (10 cochleae); group B = 5 animals (10 cochleae), amikacin 20 mg/kg/day for 30 days; group C = 7 animals (13 cochleae), amikacin 400 mg/kg/day for 12 days; group d = 14 animals (26 cochleae) amikacin 20 mg/kg/day for 30 days, followed by 400 mg/kg/day for 12 days. Histological studies were performed by scanning electron microscopy. Three cochleae were excluded. RESULTS: In groups A and B, the cells were normal in all cochleae, in group C there were extensive lesions of the 2 more basal turns, and in group D there was a significant reduction of lesions in the 2 more basal turns compared with group C, which had received the ototoxic dose of amikacin alone. CONCLUSION: We conclude that the non-ototoxic dose of amikacin administered before the ototoxic dose of the same antibiotic had a statistically significant protective effect on the 2 more basal turns of the guinea pig cochlea.

Amikacin↗
PubMed2004

Role of androgens in erectile function.

PURPOSE: Erectile response in mammals is centrally and peripherally regulated by androgens. Severe hypogonadism in men usually results in loss of libido and potency. The present studies were designed to evaluate the possible influence of circulating androgens in the regulation of sexual function. MATERIALS AND METHODS: A total of 15 men with severe hypogonadism (testosterone less than 2.0 ng/ml) were recruited. The control group consisted of 20 patients with psychogenic erectile dysfunction. All subjects underwent nocturnal penile tumescence (NPT) and rigidity monitoring during 2 consecutive nights, evaluation of cavernous artery flow using penile color duplex ultrasound (P-CDU), and real-time visually stimulated erection evaluation at baseline and after administration of 50 mg sildenafil or 3 mg apomorphine. NPT, P-CDU and visually stimulated erection were evaluated after 6 months of therapy with a 5 mg daily testosterone patch. RESULTS: NPT analysis in subjects with severe hypogonadism showed a significant decrease in sleep related erections. P-CDU showed a partial erectile response with an alteration of the parameters analyzed, and the visually stimulated erections test was pathological. Administration of 3 mg apomorphine and 50 mg sildenafil has no influence on erectile function. Testosterone treatment for 6 months induced normalization of NPT and P-CDU parameters, and of visually stimulated erection effects with the restoration of a normal response to pharmacological stimulation with apomorphine or sildenafil. CONCLUSIONS: Our results show that testosterone has a key role in the central and peripheral modulation of erectile function even if the accurate testosterone plasma level threshold that may influence these processes remains to be established.

Adult↗
PubMed2003

Erectile function in elderly: role of androgens.

Erectile function progressively declines with age, although most old men's erectile rigidity remains adequate for vaginal intercourses. Recently it has been demonstrated that a significant proportion of men over 60 years of age has a biochemical hypogonadism (defined as below the 2.5th percentile for young men). It is generally accepted that erectile response in mammals is regulated by androgens both centrally and peripherically, but in male ageing a casual relationship between androgen levels and erectile function has not been established yet. The present study was designed to evaluate the possible relationships between circulating androgens and sexual activity in a group of healthy old men without erectile dysfunction. Forty men with a mean age of 68 +/- 6 years (range 61-75 years) were recruited among healthy subjects undergoing periodic health screening. The control group consisted of 30 young volunteers with a mean age of 33 +/- 5 years (range 26-40 years). These subjects had good general health and stable relationship with at least one successful intercourse for week. All subjects performed: 1) hormonal assessment (total testosterone, free testosterone, DHT, FSH and LH); 2) nocturnal penile tumescence monitoring during two consecutive nights. The findings of this study show a significant decrease in frequency, duration and degree of nocturnal erectile episodes in old men with respect to those observed in young controls. The alteration of these parameters was more evident in old subject showing a reduction of testosterone plasma levels. In hypotestosteronemic subjects DHT treatment significantly improved nocturnal penile tumescence parameters even if these still differed from those of controls (p<0.001). On the basis of these observations we hypothesize that hypoandrogenism in old men, also in presence of normal sexual activity, may influence locally the erectile mechanisms. However hypoandrogenism, associated to other conditions negatively influencing the erectile activity, may be an important co-factor in the induction of erectile dysfunction in aging.

Adult↗
PubMed2002

Role of seminal osmolarity in the reduction of human sperm motility.

Mammalian sperm at ejaculation are suspended in the seminal plasma, a heterogeneous mixture deriving from the testicular/epididymal fluid and from secretions of seminal vesicles, prostate and bulbourethral glands. Biochemical characteristics of seminal fluid change along the male reproductive tract when considering its inorganic and organic composition and pH but it is known that in each region of the male genital tract seminal osmolarity is higher than that of serum. It has been previously demonstrated that in invertebrate and vertebrate sperm, seminal plasma osmolarity influences sperm motility and activity, and human sperm have been shown to possess osmosensitive calcium entry pathway that controls important functions such as acrosome reaction and oocyte penetration. In the present study, we have determined seminal plasma osmolarity in a large number of normozoospermic fertile and asthenozoospermic infertile subjects correlating it with sperm motility percentages and kinematic characteristics determined utilizing a computerized motion analysis system. Our results confirm that seminal plasma osmolarity is higher than that of serum (336.1 +/- 20.2 vs. 291.1 +/- 6.9 mOsm/L, respectively). Normozoospermic subjects show seminal osmolarity values that are significantly lower with respect to asthenozoospermic patients (317.8 +/- 12.2 vs. 345.2 +/- 22.6 mOsm/L, p<0.001), irrespective of the cause of asthenozoospermia. Seminal plasma osmolarity negatively correlates with sperm progressive motility percentages and kinetic characteristics (curvilinear velocity, linear velocity, linear coefficient and lateral displacements of sperm head). Furthermore, when sperm from fertile subjects were suspended in medium with an osmolarity increasing from 300 to 600 mOsm, sperm motility percentages and kinetics characteristics were progressively reduced and nearly abolished when medium osmolarity was 600 mOsm. On the contrary, when sperm from asthenozoospermic subjects with high semen osmolarity were resuspended in medium with lower osmolarity, sperm motility parameters improved significantly. Sperm motility parameters did not correlate with seminal plasma concentrations of sodium, potassium, chloride with a weak correlation only with seminal calcium concentration. No correlations are present between seminal plasma osmolarity and ionic composition. In conclusion, the present study confirms and extends the knowledge that, in human, seminal plasma osmolarity is higher than that of serum and demonstrates that seminal osmolarity influences sperm motility characteristics and then it may contribute to the pathogenesis of some forms of asthenozoospermia and male infertility.

Humans↗
PubMed2001

Extracellular ATP stimulates estradiol secretion in rat Sertoli cells in vitro: modulation by external sodium.

In this study, we examined the effects of extracellular ATP (ATPe) on [Ca(2+)](i), [Na(+)](i), plasma membrane potential changes and estradiol secretion in rat Sertoli cells. ATPe caused a rapid rise of [Ca(2+)](i) with an initial spike followed by a long lasting plateau. The first rapid spike was dependent on the release of Ca(2+) from internal stores as it also occurred in Ca(2+)-free medium while the long lasting plateau phase was dependent on Ca(2+) influx from the external medium. ATPe stimulated a rapid plasma membrane depolarization that was dependent on an influx of Na(+) from the external medium as demonstrated by plasma membrane potential monitoring in Na(+)-free medium and by [Na(+)](i) measurement with the Na(+)-sensitive fluorescent dye SBFI. ATPe stimulated estradiol secretion in a dose dependent manner and was fully dependent on the presence of Na(+) in the external medium while the presence of Ca(2+) was not necessary. Among the different nucleotides tested, only ATP, ATP-5'-[gamma-thio]triphosphate, UTP, alpha,beta-methylene-ATP were effective in stimulating estradiol secretion. These results demonstrate that rat Sertoli cells possess P2-purinergic receptors belonging to the P2X and P2Y subfamily which activation induces [Ca(2+)](i) and [Na(+)](i) rise and Na(+)-dependent plasma membrane depolarization leading to estradiol secretion.

Adenosine Triphosphate↗
PubMed2001

Intracellular calcium store depletion and acrosome reaction in human spermatozoa: role of calcium and plasma membrane potential.

We evaluated the presence and role of internal calcium stores in human uncapacitated spermatozoa by determining the effects of two inhibitors of Ca2+ ATPase of the sarco-endoplasmic reticulum (SERCA-ATPase), thapsigargin and cyclopiazonic acid (CPA) on intracellular calcium concentrations, [Ca2+](i), plasma membrane potential and acrosome reaction. Using a fluorescent conjugate of thapsigargin, we localized internal Ca2+ stores on the acrosome, post-acrosomal region and sperm midpiece. SERCA-ATPase inhibitors induced a rise in [Ca2+](i) both in Ca2+ and Ca2+-free media but under these latter conditions it was reduced with a progressive decline to baseline values; the re-addition of Ca2+-stimulated a rise in [Ca2+](i). This demonstrated that internal Ca2+ store depletion can evoke the opening of Ca2+-channels on sperm plasma membrane, thus showing the existence of "capacitative" Ca2+ entry into these specialized cells. The addition of thapsigargin to human spematozoa induced a dose-dependent increase in acrosome reaction percentages, but only when Ca2+ was present in the external medium. Plasma membrane potential monitoring showed that these inhibitors induced a depolarization dependent on Ca2+ influx from external medium and that this was preceded by a transient hyperpolarization caused by activation of Ca2+-dependent K+ channels. When K+-dependent plasma membrane hyperpolarization was inhibited, the thapsigargin- and CPA-stimulated rise in [Ca2+](i) plasma membrane depolarization and acrosome reaction were abolished. In conclusion, the present study demonstrates that human spermatozoa possess internal Ca2+ stores and that the capacitative Ca2+ entry pathway present in these cells regulates important biological processes that are fundamental for the acrosome reaction.

Acrosome Reaction↗
PubMed2001

Store-operated calcium influx and stimulation of steroidogenesis in rat Leydig cells: role of Ca(2+)-activated K(+) channels.

This study evaluates the role of internal calcium store depletion in the activation of ionic fluxes and steroidogenesis in adult rat Leydig cells. Thapsigargin and cyclopiazonic acid, two inhibitors of Ca(2+)-adenosine triphosphatase of internal Ca(2+) stores induced a dose-dependent rise in intracellular Ca(2+) concentrations following kinetics that would not be expected if the calcium rise was dependent only on internal calcium store depletion, but it was in keeping with the presence of calcium influx from the external medium. In fact, chelation of external calcium with EGTA during the plateau phase reduced the intracellular calcium concentration to basal levels. When added in calcium-free medium, thapsigargin and cyclopiazonic acid still induced a rise in the intracellular calcium concentration that was transient, and when calcium was added back to the medium, a rapid and sustained intracellular calcium increase was observed. Thapsigargin and cyclopiazonic acid induced a dose-dependent rise in testosterone secretion in the presence and absence of calcium in the external medium, although in calcium-free medium this stimulatory effect was lower. Leydig cell plasma membrane potential monitoring demonstrated that thapsigargin and cyclopiazonic acid induced first a rapid hyperpolarization, followed by a sustained depolarization phase that was reversed by the addition of the calcium-chelating agent EGTA. In the absence of calcium in the external medium the first phase of hyperpolarization was still present, but it was not followed by plasma membrane depolarization but by the slow return of plasma membrane potential to resting levels. The readdition of calcium to the external medium induced the rapid plasma membrane depolarization. Plasma membrane hyperpolarization was completely abolished by Leydig cell preincubation with the K(+) channel blockers tetraethylammonium and charybdotoxin. Leydig cell preincubation with K(+) channel inhibitors reduced the thapsigargin-stimulated Ca(2+) influx from the external medium and testosterone secretion. These results suggest that internal Ca(2+) stores depletion in rat Leydig cells induces a rise in intracellular Ca(2+), determining important plasma membrane potential variations that influence testosterone secretion.

Animals↗
PubMed2000

FSH in the treatment of oligozoospermia.

The aim of this study was to individuate parameters able to distinguish oligozoospermic subjects who will respond to follicle-stimulating hormone (FSH) therapy. A group of 135 oligozoospermic subjects was divided in three groups considering basal FSH and inhibin B concentrations: group A (normal FSH and inhibin B) characterized by moderate hypospermatogenesis sometimes associated to partial spermatidic arrest; group B (high FSH and normal inhibin B) characterized by hypospermatogenesis associated or not to spermatogonial/spermatocytic arrest; group C (high FSH and low inhibin B) characterized by severe hypospermatogenesis. Seventy-eight patients were treated with FSH at the dose of 75 IU on alternate days while 57 were treated with the same dose every day for 3 months. After FSH treatment a significant increase in ejaculated sperm concentration was observed only in oligozoospermic subjects with normal basal FSH and inhibin B plasma levels (group A) showing a testicular cytological picture of moderate hypospermatogenesis. In these subjects no differences in sperm production were observed between the two protocols of therapy. In the remaining patients of group A, characterized by hypospermatogenesis associated with maturation arrest at spermatidic level and in group B and C, no increase in sperm concentration was observed after therapy. These data suggest that FSH treatment may have a role in oligozoospermic subjects only when the spermatogenetic alterations consist in germ cell depopulation without maturative disturbances and with normal FSH concentrations.

Adult↗
PubMed2000

Role of the AZFa candidate genes in male infertility.

The AZFa region on the Y-chromosome long arm has been recently assembled in a complete sequence map contained in a contig and shown to span more than 1 Mb. It contains three genes, USP9Y, DBY and UTY, but only the former two can be at present considered candidate genes for the infertile phenotype associated with deletion of this interval. These genes have X-homologues and are expressed in many tissues, even if DBY has a shorter transcript expressed in the testis only, strengthening its role in spermatogenesis. Only few patients with gene-specific deletion have been reported and a clear genotype-phenotype relation is still lacking. While deletions or even smaller mutations in USP9Y seem to be associated with a testicular phenotype of severe hypospermatogenesis, patients with deletions of DBY may present both Sertoli cell-only syndrome and severe hypospermatogenesis. On the contrary, the phenotype of patients with deletion of both USP9Y and DBY seem to be invariably azoospermia with a testicular histology of Sertoli cell-only.

Chromosome Mapping↗
PubMed2000

Variables of stimulation and placebo in acupuncture reflexotherapy.

Placebo can be defined as "the idea of recovery." It represents the natural impulse toward recovery that is catalyzed by treatment or even simply by the idea of treatment. Therefore, placebo is not an "active" treatment; it is used in scientific research to discriminate between the actual effect of a drug or therapeutic technique and the result of chance or the will to recover. Even though it is only an idea, placebo can cause improvement and recovery in approximately 30% of the subjects treated with any therapeutic program and for very different pathologies. Acute pathologies are more sensitive to placebo than chronic ones; functional disorders respond better than organic alterations, and so on. The main controversial issues in the methodology of acupuncture research are: placebo, double-blinding, and the intensity of stimulation of needles. The most used placebo method is sham acupuncture, which is the insertion of the needles outside acupuncture points. It is argued that this methodologically incorrect choice leads to studying the importance of the acupuncture point, rather than that of acupuncture as a transdermic stimulation technique.

Acupuncture Therapy↗
PubMed2000

Effects of cryopreservation on progesterone-induced ion fluxes and acrosome reaction in human spermatozoa.

The present study evaluated the effects of cryopreservation on progesterone-induced variations of calcium ion concentration [Ca(2+)](i), plasma membrane potential and acrosome reaction in human spermatozoa. Spermatozoa from 10 fertile donors were divided in two equivalent aliquots, one used as control (fresh spermatozoa) and the other used after freezing-thawing. Measurement of spermatozoa [Ca(2+)](i) before and after freezing-thawing showed a significant reduction of basal [Ca(2+)](i) in thawed spermatozoa (P < 0.01). Progesterone induced a rise of [Ca(2+)](i) both in fresh and thawed spermatozoa with a significant reduction after freezing-thawing (P < 0.01). The monitoring of sperm plasma membrane potential demonstrated that progesterone induced plasma membrane depolarization in fresh spermatozoa that was absent in thawed spermatozoa. The inhibitory effects of freezing-thawing on progesterone induced [Ca(2+)](i) and plasma membrane potential variations in human spermatozoa were closely related to the inhibition of the acrosome reaction. In conclusion the present study demonstrates that freezing-thawing procedures reduce the responsiveness of human spermatozoa to progesterone in terms of [Ca(2+)](i) rise and completely inhibit its effects on plasma membrane potential variations, thus supporting the hypothesis that freezing-thawing procedures may differently modify the plasma membrane receptors for progesterone in human spermatozoa which are known to express at least two receptors for this steroid in their plasma membrane.

Acrosome Reaction↗