Biomedical subjects

A Zini

Publications and source records attributed to A Zini.

At least 37 records · Page 2Linked to original sources

PubMed2000

Influence of initial semen quality on the integrity of human sperm DNA following semen processing.

OBJECTIVE: To examine and compare the effects of density-gradient centrifugation on the integrity of sperm DNA from the semen of both fertile and infertile men. DESIGN: Prospective, observational study. SETTING: University infertility clinic. PATIENTS: Forty-four nonazoospermic, infertile men and nine fertile controls. INTERVENTIONS: Semen samples were processed by density-gradient centrifugation. Sperm motility and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa) were monitored before and after semen was processed. MAIN OUTCOME MEASURES: Sperm motility and DNA integrity. RESULTS: Following density-gradient centrifugation, mean sperm motility (+/-SEM) improved significantly compared to whole semen in samples from fertile and infertile men, respectively (71 +/- 6 vs. 49 +/- 7% and 56 +/- 3 vs. 44 +/- 3%, P<0.05). However, the percentage of sperm with denatured DNA increased compared to whole semen after processing of samples from infertile (25 +/- 3 vs. 15 +/- 2%, P<0. 01) but not fertile men (9 +/- 3 vs. 8 +/- 2%, P>0.05). CONCLUSIONS: Our data indicate that the potential detrimental effect of density-gradient centrifugation on sperm DNA integrity is related to the initial semen quality. These data urge us to examine our current sperm-processing techniques to minimize sperm DNA damage.

Acridine Orange↗

PubMed2000

Antioxidant activity in the semen of fertile and infertile men.

OBJECTIVES: To evaluate catalase- and superoxide dismutase (SOD)-like activities in the seminal plasma of fertile and infertile men. METHODS: Semen samples were obtained from consecutive men presenting for vasectomy (n = 12) and infertility evaluation (n = 105) at our institution. Catalase-like activity was measured by the decrease in hydrogen peroxide after incubation with seminal plasma. SOD-like activity was measured as the inhibition of nitroblue tetrazolium reduction due to superoxide anion generation by xanthine plus xanthine oxidase. RESULTS: Mean seminal catalase-like activity (+/-SEM) in fertile men was not significantly different from that of infertile men (369 +/- 49 versus 326 +/- 17 U/mL, respectively). Mean SOD-like activity in the semen of infertile men was significantly greater than in the semen of fertile controls (46.7 +/- 1.5 versus 37.0 +/- 2.8 U/mL, respectively, P <0.05). CONCLUSIONS: Our data show that infertile men do not have deficient seminal plasma SOD- and/or catalase-like activity (two key antioxidants). These findings suggest that the high semen ROS levels in some infertile men are likely due to excessive generation of ROS rather than deficient ROS scavenging activity in semen.

Adult↗

PubMed2000

Effect of adult microsurgical varicocelectomy on testicular volume.

OBJECTIVES: To re-examine the potential influence of varicocelectomy on testicular volume using scrotal ultrasonography, because it has been reported that total testicular volume (assessed by physical examination) increases after adult varicocele ligation. METHODS: A retrospective review of the testicular volume and semen parameters of 61 men who underwent microsurgical varicocelectomy between 1996 and 1998 was performed. Ultrasound-derived testicular volumes and total motile sperm counts were compared before varicocelectomy and at a mean of 7.2 months postoperatively. RESULTS: Bilateral varicocelectomy was performed in 22 men; 39 men underwent a left-sided procedure only. Overall, no significant change was found in the mean total testicular volume after varicocelectomy compared with preoperatively (24.0 versus 23.9 mL, respectively; P = 0.74). Similarly, the testicular volumes did not change significantly after left or bilateral varicocelectomy (P >0.05). Overall, the mean total motile sperm count increased significantly after varicocelectomy (17. 9 to 25.4, P = 0.05). CONCLUSIONS: This was the first study to examine the effect of adult varicocelectomy on testicular volume using ultrasound-derived measurements of volume. Unlike previous findings, our data suggest that although adult varicocelectomy improves semen quality in most infertile men, it does not result in a significant increase in testicular volume.

Adult↗

PubMed2000

Cystic fibrosis gene mutations and infertile men with primary testicular failure.

It has been proposed that the gene responsible for cystic fibrosis, called the cystic fibrosis transmembrane conductance regulator (CFTR) gene, may play an important role in the process of spermatogenesis. A group of azoospermic men with primary testicular failure underwent CFTR mutation analysis, including assessment of the intron 8 polythymidine tract (IVS8-T tract). An association was not found between CFTR mutations or the 5T variant of the IVS8-T tract and the primary testicular failure phenotype. This finding suggests that CFTR does not play a significant role in the aetiopathogenesis of primary spermatogenic dysfunction. Therefore, the abnormal testicular histological findings in some post-pubertal men with cystic fibrosis may be a result of nutritional deficiency or testicular obstruction rather than a primary defect in spermatogenesis. In addition, the decreased sperm count in oligozoospermic men with CFTR mutations may be secondary to partial reproductive tract obstruction and not abnormal spermatogenesis. Lastly, routine screening of men with primary testicular failure for CFTR gene mutations is not warranted.

Adult↗

PubMed1999

Proportion of cystic fibrosis gene mutations not detected by routine testing in men with obstructive azoospermia.

CONTEXT: Infertile men with obstructive azoospermia may have mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, many of which are rare in classic cystic fibrosis and not evaluated in most routine mutation screening. OBJECTIVE: To assess how often CFTR mutations or sequence alterations undetected by routine screening are detected with more extensive screening in obstructive azoospermia. DESIGN: Routine screening for the 31 most common CFTR mutations associated with the CF phenotype in white populations, testing for the 5-thymidine variant of the polythymidine tract of intron 8 (IVS8-5T) by allele-specific oligonucleotide hybridization, and screening of all exons through multiplex heteroduplex shift analysis followed by direct DNA sequencing. SETTING: Male infertility clinic of a Canadian university-affiliated hospital. SUBJECTS: Of 198 men with obstructive (n = 149) or nonobstructive (n = 49; control group) azoospermia, 64 had congenital bilateral absence of the vas deferens (CBAVD), 10 had congenital unilateral absence of the vas deferens (CUAVD), and 75 had epididymal obstruction (56/75 were idiopathic). MAIN OUTCOME MEASURE: Frequency of mutations found by routine and nonroutine tests in men with obstructive vs nonobstructive azoospermia. RESULTS: Frequency of mutations and the IVS8-5T variant in the nonobstructive azoospermia group (controls) (2% and 5.1% allele frequency, respectively) did not differ significantly from that in the general population (2% and 5.2%, respectively). In the CBAVD group, 72 mutations were found by DNA sequencing and IVS8-5T testing (47 and 25, respectively; P<.001 and P = .002 vs controls) vs 39 by the routine panel (P<.001 vs controls). In the idiopathic epididymal obstruction group, 24 mutations were found by DNA sequencing and IVS8-5T testing (12 each; P=.01 and P=.14 vs controls) vs 5 by the routine panel (P=.33 vs controls). In the CUAVD group, 2 mutations were found by routine testing (P=.07 vs controls) vs 4 (2 each, respectively; P=.07 and P=.40 vs controls) by DNA sequencing and IVS8-5T testing. The routine panel did not identify 33 (46%) of 72, 2 (50%) of 4, and 19 (79%) of 24 detectable CFTR mutations and IVS8-5T in the CBAVD, CUAVD, and idiopathic epididymal obstruction groups, respectively. CONCLUSIONS: Routine testing for CFTR mutations may miss mild or rare gene alterations. The barrier to conception for men with obstructive infertility has been overcome by assisted reproductive technologies, thus raising the concern of iatrogenically transmitting pathogenic CFTR mutations to the progeny.

Adult↗

PubMed1999

Potential adverse effect of semen processing on human sperm deoxyribonucleic acid integrity.

OBJECTIVE: To examine the effect of standard Percoll density-gradient centrifugation on human sperm DNA denaturation. DESIGN: Prospective, observational study. SETTING: University-based infertility clinic. PATIENT(S): Twenty-five nonazoospermic men. INTERVENTION(S): Semen samples (n = 25) were obtained from consecutively seen nonazoospermic men presenting for infertility evaluation. Samples were processed by two-layer and four-layer Percoll density gradients. Sperm motility and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa) were monitored before and after semen processing. Sperm chromatin integrity was expressed as the percentage of spermatozoa that demonstrated denatured DNA. MAIN OUTCOME MEASURE(S): Sperm motility and DNA integrity. RESULT(S): Mean sperm motility improved significantly after processing with two-layer and four-layer Percoll gradients compared with whole semen (54% and 57% motility versus 44% motility, respectively). In contrast, the percentage of sperm with denatured DNA increased after processing with two-layer and four-layer Percoll gradients compared with whole semen (34% and 32% versus 18%, respectively). CONCLUSION(S): Our data demonstrate that the improvement seen in sperm motility after Percoll processing is not associated with a similar improvement in sperm DNA integrity. These data suggest that we reexamine current sperm processing techniques to minimize sperm DNA damage and the potential transmission of genetic mutations in assisted reproductive cycles.

Acridine Orange↗

PubMed1999

Restoration of spermatogenesis after scrotal replacement of experimentally cryptorchid rat testis: assessment of germ cell apoptosis and eNOS expression.

OBJECTIVES: Cryptorchidism has been shown to induce germ cell apoptosis. Nitric oxide (NO), a ubiquitous free radical produced by the nitric oxide synthases (NOSs), has been associated with apoptosis in a number of cell types. We examined the effect of experimental cryptorchidism and subsequent orchidopexy on germ cell apoptosis and endothelial NOS (eNOS) expression. METHODS: Prepubertal rats were rendered unilaterally cryptorchid, and 14 days later, orchidopexy was performed on a subset of these rats. Forty days after the initial procedure, testes were harvested from experimental and sham-operated rats for immunohistochemical studies. Apoptosis was detected by in situ 3'-end-labeling of DNA with digoxigenin-ddUTP, and eNOS protein was detected using an eNOS monoclonal antibody. RESULTS: Cryptorchid testes were characterized by diffuse hypospermatogenesis and had a 25-fold increase in apoptotic germ cells per cross-sectional area compared with sham-operated testes (P < 0.05). By contrast, the number of apoptotic germ cells per cross-sectional area in orchidopexied testes was not significantly different from that of sham-operated testes. In addition to its known expression in Leydig, Sertoli, and vascular endothelial cells, eNOS was detected in the cytoplasm of degenerating germ cells. Consecutive testis sections stained for eNOS and cellular DNA fragmentation demonstrated co-localization of eNOS protein and germ cell apoptosis. CONCLUSIONS: In our experimental model, cryptorchidism induced germ cell apoptosis, and orchidopexy lowered the levels of germ cell apoptosis. Our data also support a role of eNOS in germ cell degeneration.

Animals↗

PubMed1999

Effect of varicocelectomy on the abnormal retention of residual cytoplasm by human spermatozoa.

Abnormal retention of cytoplasmic residues by human spermatozoa is associated with the generation of reactive oxygen species (ROS) in semen and defective sperm function. We have examined the effect of varicocelectomy on the retention of residual cytoplasm by human spermatozoa. Clinical reports of 43 men who underwent microsurgical varicocelectomy at our institution during a 1 year period beginning July 1996 were reviewed. Standard semen parameters (concentration, motility and morphology) and residual cytoplasm retention (monitored by Papanicolaou stain) were assessed before and 6 months after varicocelectomy. The percentage of spermatozoa with residual cytoplasm decreased significantly following varicocelectomy compared to pre-operatively (25.8 versus 18.1% respectively). The percentages of motile spermatozoa and normal forms increased significantly (P = 0.0003, P = 0.005 respectively) following varicocelectomy (22.6 versus 32.9% and 46.4 versus 54.4% respectively). Our data suggest that varicocelectomy can improve the disposal of residual sperm cytoplasm by the testis and/or epididymis in infertile men with varicocele. These data also suggest that varicocelectomy reduces the potential for ROS generation by human spermatozoa in these men.

Adult↗

PubMed1998

Human sperm endothelial nitric oxide synthase expression: correlation with sperm motility.

OBJECTIVE: To characterize the pattern of endothelial nitric oxide synthase (eNOS) expression on human spermatozoa and to determine whether sperm eNOS expression correlates with sperm function. DESIGN: Prospective, observational study. SETTING: University infertility clinic. PATIENT(S): Twelve nonazoospermic infertile men. INTERVENTION(S): Semen samples (n=12) obtained from nonazoospermic infertile men were fractionated on discontinuous Percoll gradients. Endothelial nitric oxide synthase staining on spermatozoa was correlated with sperm motility in Percoll gradient-fractionated spermatozoa. Endothelial nitric oxide synthase protein was detected with the use of a previously characterized monoclonal antibody. Control slides were incubated with preabsorbed antibody or mouse immunoglobulin G. MAIN OUTCOME MEASURE(S): Localization of eNOS on human spermatozoa and correlation between the pattern of sperm eNOS expression and sperm motility. RESULT(S): Morphologically normal spermatozoa exhibited postacrosomal and equatorial eNOS immunostaining. However, abnormally shaped spermatozoa often exhibited aberrant staining (in the midpiece and/or head region). A significant negative correlation was observed between the percentage of sperm with aberrant eNOS immunostaining and the percentage of motile sperm (r=-.46). CONCLUSION(S): The specific localization of eNOS to human spermatozoa suggests that nitric oxide may be involved in normal sperm physiology. However, aberrant patterns of sperm eNOS expression are associated with decreased sperm motility, possibly through the generation of excessive cytotoxic oxidants.

Humans↗

PubMed1998

Human sperm NADH and NADPH diaphorase cytochemistry: correlation with sperm motility.

OBJECTIVES: We have examined the correlation between the retention of residual sperm cytoplasm and sperm motility in semen from men presenting for infertility evaluation. METHODS: Semen samples (n = 12) were obtained from nonazoospermic men presenting for infertility evaluation at our institution. Samples were fractionated into high-, intermediate-, and low-density subpopulations by Percoll gradients in order to examine the correlation between the retention of residual sperm cytoplasm and sperm motility. Residual sperm cytoplasm retention was detected by cytochemical staining of sperm for nicotinamide adenine dinucleotide (NADH)- or nicotinamide adenine dinucleotide phosphate (NADPH)-dependent diaphorase activity. RESULTS: The different sperm subpopulations (low, intermediate, and high density) had significantly different percentages of sperm with droplet retention (analysis of variance, P < 0.05). Using either NADH or NADPH diaphorase staining as a marker of the cytoplasmic space, a significant negative correlation was observed between the percentage of sperm with residual cytoplasmic droplets and the percentage of motile sperm (r = -0.58 and -0.61, respectively, P < 0.05). CONCLUSIONS: Assessment of residual sperm cytoplasm retention is a simple diagnostic test. Although this test is of unproven value in the management of infertile men, this and other studies suggest that it may provide useful data on sperm function.

Dihydrolipoamide Dehydrogenase↗

PubMed1998

Population-based patterns of radical retropubic prostatectomy use.

OBJECTIVES: To examine the use of radical retropubic prostatectomy (RRP) in a large population-based study. METHODS: Identification of all RRPs performed in the province of Quebec between the years 1988 and 1993 was accomplished by relying on the Quebec Healthcare Plan Database. RESULTS: Overall, 2861 RRPs have been performed during the study period. On average, 80% of surgeries have been performed by urologists using this surgery 12 times or less annually. Of all surgeries, 420 (15%) RRPs have been performed in individuals 71 years of age or older. CONCLUSIONS: Each year, most RRPs (80%) in this population-based study were performed by urologists performing this procedure 12 times or less annually. A substantial proportion (15%) of RRPs have been performed in men 71 years of age or older, in whom the detriments of radical surgery may outweigh its benefits. These findings could potentially contribute to suboptimal outcomes when radical prostatectomy is compared with alternative treatment modalities.

Aged↗

PubMed1998

Outcome of microsurgical reconstruction in men with suspected epididymal obstruction.

PURPOSE: Approximately 3 to 6% of all men presenting with infertility (excluding those with a history of vasectomy) are suspected of having epididymal obstruction. However, other anatomical abnormalities within the male reproductive tract are often encountered. In this study we attempted to define the range and frequencies of anatomical abnormalities in the reproductive tract and the outcome of surgical reconstruction in men with suspected epididymal obstruction and no history of vasectomy. MATERIALS AND METHODS: Between July 1992 and July 1996, 80 azoospermic men with suspected epididymal obstruction underwent scrotal exploration. The anatomical findings and outcomes of reconstructive surgery were reviewed. RESULTS: Of a possible 160 reproductive tract units (2 per patient) we thoroughly examined 147 with suspected epididymal obstruction. Epididymal obstruction was found in 52.7% of the cases with other anatomical abnormalities accounting for the remaining 47.3%. Of the patients 49 (61%) had sperm identified in the epididymis on at least 1 side and underwent vasoepididymostomy, and 3 (4%) had sperm unilaterally in the proximal vas but had ipsilateral distal vasal obstruction. These 3 men underwent crossed vasovasostomy. We were more likely able to perform reconstruction in men whose obstruction was due to an infectious etiology (13 of 14, 93%) compared to either a surgical (5 of 7, 71%) or idiopathic (34 of 59, 58%) etiology. In 28 patients (35%) no sperm was identified in the epididymis or they had no other abnormalities that precluded successful reconstruction on either side. Of those patients who underwent vasoepididymostomy for epididymal obstruction 61% had sperm in the ejaculate postoperatively. CONCLUSIONS: In nearly half the men with suspected epididymal obstruction other reproductive tract abnormalities were detected, most of which precluded successful vasoepididymostomy. Other reproductive tract abnormalities are much less likely to be found, and the outcomes of reconstruction are better if the cause of the obstruction is infectious compared to surgical or idiopathic.

Epididymis↗

PubMed1998

Adverse effects on vasoepididymostomy outcomes for men with concomitant abnormalities in the prostate and seminal vesicle.

PURPOSE: Following microsurgical vasoepididymostomy as many as 85% of men have sperm in the ejaculate, yet only 30 to 50% will spontaneously father children. We examined the possibility that there may be concomitant abnormalities in the prostate and seminal vesicle, which may be associated with low pregnancy rates. MATERIALS AND METHODS: Transrectal ultrasound was performed in azoospermic men with suspected epididymal obstruction, excluding those who had undergone vasectomy, to identify abnormalities of the seminal vesicles and ejaculatory ducts. Microsurgical vasoepididymostomy was attempted in all men. RESULTS: Transrectal ultrasound revealed ejaculatory duct dilatation in 13 of 40 men (33%), although only 3 had accompanying seminal vesicle dilatation. Two men had atrophic seminal vesicles with normal ejaculatory ducts. At surgery 8 of 40 patients (20%) were deemed to have irreparable conditions. For the 27 men followed at least 6 months postoperatively patency and pregnancy rates were 75 and 22%, respectively. Mean sperm counts plus or minus standard deviation were significantly higher in men without compared to those with seminal vesicle or ejaculatory duct abnormalities (43 +/- 68 versus 5.7 +/- 6.9 x 10(6) sperm per ml., respectively), and so was the percentage of motile sperm (30 +/- 16% versus 1.2 +/- 2.2%, respectively). Pregnancy rates were also higher in men without (6 of 19, 32%) than with (0 of 8, 0%) seminal vesicle or ejaculatory duct abnormalities. CONCLUSIONS: Transrectal ultrasound detected abnormalities of the seminal vesicles and ejaculatory ducts are common in men with suspected epididymal obstruction. These abnormalities are associated with a poor outcome for vasoepididymostomy. We recommend that all men with suspected epididymal obstruction undergo transrectal ultrasound before any attempted reconstruction.

Epididymis↗

PubMed1997

Expression of glutathione peroxidases in the adult male rat reproductive tract.

OBJECTIVE: To evaluate the messenger RNA (mRNA) expression of three glutathione peroxidase isoforms in the male reproductive tract and to further characterize testicular glutathione peroxidase expression. DESIGN: Analysis of glutathione peroxidase levels in untreated animals. INTERVENTION(S): 32P-labeled DNA probes were derived from known complementary DNA (cDNA) sequences for classic cellular glutathione peroxidase, phospholipid hydroperoxide glutathione peroxidase, and secretory epididymal glutathione peroxidase, and used to evaluate mRNA levels in each tissue by Northern blot hybridization. MAIN OUTCOME MEASURE(S): Glutathione peroxidase mRNA concentrations. RESULT(S): A 0.8-kb transcript was identified in liver, testis, prostate, seminal vesicle, vas deferens, and epididymis using the cDNA probe for classic cellular glutathione peroxidase. Using the probe for phospholipid hydroperoxide glutathione peroxidase, a 0.9-kb transcript was identified in the epididymis, vas deferens, prostate, seminal vesicle, and liver. In the testis, the phospholipid hydroperoxide glutathione peroxidase transcript was highly abundant and longer, measuring 1.1 kb. The phospholipid hydroperoxide glutathione peroxidase mRNA transcript was expressed in 40-, 60-, and 90-day-old rat testes, but was undetectable in testes of 10- and 20-day-old rats. Epididymal glutathione peroxidase was detected as a single 1.9-kb transcript in the caput epididymis only. CONCLUSION(S): Male rat reproductive tissues express at least three different isozymes of glutathione peroxidase. Phospholipid hydroperoxide glutathione peroxidase and classic cellular glutathione peroxidase are primarily found in testis, whereas epididymal glutathione peroxidase is expressed in the epididymis.

Animals↗

PubMed1997

The influence of clinical and subclinical varicocele on testicular volume.

OBJECTIVE: To examine the possible loss of testicular volume in infertile men with clinical and subclinical varicocele by using ultrasound (US)-derived measurements of testicular volume. DESIGN: Retrospective review of clinical and scrotal US reports. SETTING: University infertility clinic. PATIENT(S): Infertile men (n = 404) presenting for evaluation from 1992 to 1996. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Presence of clinical or subclinical varicocele, US-derived measurements of testicular volume. RESULT(S): In men with clinical left or subclinical left varicocele, left testicular volume was significantly less than right testicular volume (12.9 versus 14.1 and 13.2 versus 14.7 mL, respectively). This finding was not observed in men with bilateral clinical or bilateral subclinical varicoceles or in men without varicocele. CONCLUSION(S): Our data confirm previous reports showing that a clinical left varicocele can negatively impact on left testicular volume and for the first time show that a subclinical varicocele is also associated with decreased left testicular volume.

Adult↗

PubMed1997

Identification and characterization of antioxidant enzyme mRNAs in the rat epididymis.

Spermatozoa are highly sensitive to oxidative stress. The epididymis, a natural sperm reservoir, has maturational and storage functions. The epididymis may also protect spermatozoa from oxidative injury by elaborating scavengers of reactive oxygen species (ROS). Therefore, we have evaluated the mRNA expression of antioxidant enzymes in the normal rat epididymis and the effects of efferent duct ligation no the expression of these enzymes. Adult rat epididymides were harvested, divided into caput, corpus and cauda and processed for RNA extraction. Additional adult rats were subjected to unilateral efferent duct ligation and the epididymides harvested at 1, 4, 8, 16 or 28 days after the procedure. Antioxidant enzyme mRNA expression was assessed by Northern blot analysis using 32P-labelled DNA probes derived from known cDNA sequences for classical cellular glutathione peroxidase (GSHPx), phospholipid hydroperoxide glutathione peroxidase (PHGPX), secretory epididymal glutathione peroxidase (E-GPX), copper-zinc superoxide dismutase (SOD), secretory epididymal superoxide dismutase (E-SOD) and catalase. Specific mRNA levels were measured, with gene expression evaluated relative to total RNA, not per organ. Variations in lane loading were controlled by measuring the levels of 28S ribosomal RNA. GSHPx, PHGPX, SOD and catalase mRNA were detected in the caput, corpus and cauda epididymis. E-GPX mRNA was only detected in the caput, whereas E-SOD mRNA was primarily detected in the corpus. At 28 days after efferent duct ligation, epididymal weight decreased by 34% relative to controls (p < 0.05). With the exception of PHGPX, the relative mRNA levels of the antioxidant enzymes studied did not change after efferent duct ligation. This study demonstrates that mRNAs for multiple antioxidant enzymes are expressed in the epididymis and that the relative expression of these enzymes remains largely unchanged in response to efferent duct ligation. Taken together, these results suggest that antioxidant enzymes may play an important, region-specific role in epididymal function. Expression of the secretory antioxidant enzymes E-SOD and E-GPX is region-specific, indicating that the need for antioxidant enzymes may vary along the length of the epididymis.

Animals↗

PubMed1997

Reactive oxygen species and sperm physiology.

Although high concentrations of reactive oxygen species (ROS) cause sperm pathology (ATP depletion leading to insufficient axonemal phosphorylation, lipid peroxidation and loss of motility and viability), recent evidence demonstrates that low and controlled concentrations of these ROS play an important role in sperm physiology. Reactive oxygen species, such as the superoxide anion, hydrogen peroxide and nitric oxide, induce sperm hyperactivation, capacitation or the acrosome reaction in vitro. The ROS involved in these processes may vary depending on experimental conditions, but all the evidence converges to describe these events as 'oxidative' or 'redox regulated'. Human sperm capacitation and acrosome reaction are associated with extracellular production of a superoxide anion that is thought to originate from a membrane 'oxidase'. The enzymes responsible for tyrosine phosphorylation-dephosphorylation of sperm proteins are possible targets for ROS since mild oxidative conditions cause increases in protein tyrosine phosphorylation and acrosome reaction. The lipid peroxidation resulting from low concentrations of ROS promotes binding to the zona pellucida and may trigger the release of unesterified fatty acids from the sperm plasma membrane. The fine balance between ROS production and scavenging, as well as the right timing and site for ROS production are of paramount importance for acquisition of fertilizing ability.

Animals↗

PubMed1997

Cu/Zn superoxide dismutase, catalase and glutathione peroxidase mRNA expression in the rat testis after surgical cryptorchidism and efferent duct ligation.

The testis is known to be highly sensitive to a number of physical stresses. Previous investigations suggest that oxidative stress may be an important mediator of testicular injury. The ability of the testis to manage oxidative stress may be limited by enzymatic clearance of reactive oxygen species (ROS). To evaluate the ability of the testis to withstand the common pathologic conditions of cryptorchidism and obstruction, we measured mRNA levels of testicular antioxidant enzymes. Prepubertal rats were rendered unilaterally cryptorchid and 40 days after the procedure, cryptorchid, contralateral and control (sham) testes were harvested for RNA extraction. Adult rats were subjected to unilateral efferent duct ligation and the obstructed testes harvested 1 to 28 days after the procedure. Antioxidant enzyme mRNA expression was assessed by Northern blot analysis using 32P-labeled DNA probes for classical cellular glutathione peroxidase (GSHPx), phospholipid hydroperoxide glutathione peroxidase (PHGPX), Cu/Zn superoxide dismutase (SOD) and catalase. In both cryptorchid and contralateral testes, the germ cell-specific 0.9 kb SOD and PHGPX mRNA transcript levels were significantly decreased compared to control testes (p < 0.05). Similarly, after efferent duct ligation, the 0.9 kb SOD and PHGPX mRNA transcript levels also decreased compared to control testes (p < 0.05). These findings suggest that the overall decline in testicular mRNA transcript levels after efferent duct ligation and cryptorchidism is primarily due to germ cell depletion. Reduced levels of antioxidant enzyme mRNAs in cryptorchid testes have been documented. Further experiments may elucidate the role of increased oxidative stress associated with decreased antioxidants in cryptorchidism. It remains to be determined whether oxidative stress has a causative role in the abnormal spermatogenesis and tumorigenesis associated with cryptorchidism.

Animals↗