Impact of seminal and serum zinc on semen quality and hormonal status: A population-based cohort study of Russian young men

BackgroundTrace elements are important factors in human reproductive health. Among them, special attention is paid to zinc, which is an essential trace element and is necessary for the normal functioning of the male reproductive system and the process of spermatogenesis. The aim of the study was to investigate the association between seminal and serum zinc concentrations and semen quality and reproductive hormone levels in population of Russian young men.MethodsThe study population consisted of 626 young Russian men (median age 22.5 years), recruited from the general population, regardless of their fertility status. Each participant provided semen and blood sample, information about his lifestyle and ethnicity. Semen quality (sperm concentration, motility and morphology), reproductive hormone levels (testosterone, estradiol, LH, FSH and inhibin B), and serum and seminal zinc concentrations were evaluated. The semen samples were analyzed according to the WHO laboratory manual (WHO, 2010). Serum hormones were measured by enzyme immunoassay, zinc concentrations were determined using spectrophotometry and direct colorimetry without deproteinization.ResultsZinc was present in the seminal plasma in a significantly higher concentration than in the blood serum (median serum Zn concentration was 23.6 μmol/L vs seminal Zn concentration 1571.8 μmol/L). The seminal zinc concentration was positively related to the total sperm count, sperm concentration, progressive motility and normal morphology (Spearman’s test: 0.221; 0.286; 0.269; 0.183, respectively, p < 0.001), while the serum Zn concentration was negatively related to serum testosterone and estradiol levels (r = −0.249 and r = −0.096, respectively, p < 0.001−0.05). It was found that the seminal Zn content in men with normal semen quality was higher compared to men with lowered semen quality (means: 6.37 and 5.03 μmol/ejaculate, respectively, p < 0.001). Similarly, the semen volume, total sperm count, sperm concentration, progressive motility, normal morphology and the serum testosterone level in men with the seminal Zn deficiency were lower than in men with the normal seminal Zn content.ConclusionBased on the results of our population-based study, seminal Zn levels were closely associated with semen parameters in young men, so Zn deficiency may be an important risk factor for lowered semen quality. Seminal Zn determinations should be considered as a useful tool in addition to other parameters in assessing male fertility.     

Interpretation of semen analysis among infertile couples.

Among the male partners of 1074 infertile couples the mean results of semen analysis were sperm count 78 X 10(6)/ml, seminal volume 4.0 ml, proportion of progressively motile sperm 54%, proportion of sperm with normal morphologic features 81.4% and total motile sperm count 152.3 X 10(6) per ejaculate. After excluding 65 couples who chose donor insemination and 300 with known female causes of infertility, the cumulative pregnancy rates in the remaining 709 couples were higher with increasing sperm density and motility and seminal volume, but the higher rates were significant only when these variables were combined into total motile sperm count per ejaculate. The cumulative pregnancy rates were 20% with a total motile sperm count of 9 X 10(6) or less, 37% with a count of 10 to 19 X 10(6) and 52% with a count of 20 X 10(6) or more (p = 0.001). Counts higher than 20 X 10(6) were not associated with a further improvement in pregnancy rates, but variability in the results was high, which suggests that the test should be repeated as necessary to determine the true range. Although standards for these and other seminal variables are ill defined, the total motile sperm count incorporates the most useful prognostic information from semen analysis, and the associated pregnancy rates can help guide clinical decisions.     

Semen parameters and level of microsatellite heterozygosity in Noriker draught horse stallions

It was the aim of the present study to determine physiological values for different semen parameters in an endangered draught horse breed, the Austrian Noriker. Because small population size is often believed to cause a decrease in fertility and/or semen quality through inbreeding and a reduction in genetic variation, the general genomic heterogeneity of the breed was estimated on the basis of microsatellite variation and correlated to semen parameters. Semen could be collected from 104 of 139 stallions with semen collection being more often successful in younger stallions. Mean volume of ejaculates was 90.8+/-55.1 ml, density 243+/-114 x 10(6)ml(-1), total sperm count 21.0+/-23.7 x 10(9), percentage of morphologically normal spermatozoa 38+/-18% and total motility 50+/-23%. Total sperm count and semen motility were significantly affected by age. Blood samples of 134 stallions were analysed for 12 microsatellite DNA markers. Genotypes of 110 stallions with at least 11 successfully typed markers were used for calculation of heterozygosity. A total of 82 alleles was identified with a mean of 6.8 alleles per marker. Heterozygosity varied between 35 and 76% for the different markers, mean heterozygosity was calculated to 63%. No correlation between heterozygosity and semen parameters was found.     

Semen characteristics of Muturu Bulls--Bos brachyceros

Six mature Muturu Bulls were elecroejaculated once a week for nine weeks to study their semen quality and ejaculate characteristics. The semen volume was 1.8 ml +/- 0.1, the sperm concentration 2.16 x 10(8)/ml +/- 0.29, and the progressive sperm motility 36.2% +/- 2.6. Morphologically normal sperm averaged 70.0% +/- 3.1, primary abnormalities 13.4% +/- 1.0 and secondary abnormalities 15.1% +/- 2.3. Except in one bull, no measurable levels of fructose were observed. The contents of major cations and chloride ions in whole semen and seminal plasma were also determined.     

Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years.

OBJECTIVE: To determine whether the quality of semen has changed in a group of over 500 Scottish men born between 1951 and 1973. DESIGN: Retrospective review of data on semen quality collected in a single laboratory over 11 years and according to World Health Organisation guidelines. SETTING: Programme of gamete biology research funded by Medical Research Council. SUBJECTS: 577 volunteer semen donors. Of these, 171 were born before 1959, 120 were born in 1960-4, 171 in 1965-9, and 115 in 1970-4. MAIN OUTCOME MEASURES: Conventional criteria of semen quality including semen volume (ml), sperm concentration (10(6)/ml), overall motility (% motile), total number of sperm in the ejaculate (10(6)), and total number of motile sperm in the ejaculate (10(6)). RESULTS: When the four birth cohort groups were compared a later year of birth was associated with a lower sperm concentration, a lower total number of sperm in the ejaculate, and a lower number of motile sperm in the ejaculate. The median sperm concentration fell from 98x10(6)/ml among donors born before 1959 to 78x10(6)/ml among donors born after 1970 (P=0.002). The total number of sperm in the ejaculate fell from 301x10(6) to 214x10(6) (P=0.0005), and the total number of motile sperm in the ejaculate fell from 169.7x10(6) to 129.0x10(6) (P=0.0065). CONCLUSION: This study provides direct evidence that semen quality is deteriorating, with a later year of birth being significantly associated with a reduced number of sperm in adult life.     

Relationship between semen characteristics and fertility in electroejaculated mice

Ejaculates were obtained from C57BL mice by applying two successive series of electrical stimuli which were delivered via a bipolar rectal probe. The ejaculates thus collected contained fertile spermatozoa as indicated by results from in-vitro fertilization. Once separated from the seminal plasma, ejaculated spermatozoa possessed the same in-vitro fertilization rate as epididymal sperm. Ejaculates were analysed for coagulum weight, ejaculate volume, sperm count, sperm motility, acid phosphatase content and fructose content. Significant differences were present between several of these values for fertile and infertile mice, and values were therefore empirically assigned to represent minimal amounts for 'normal' fertility (1.5 microliters ejaculate volume; 10.2 mg coagulum weight; 2.5 x 10(6) spermatozoa/ml; 2.3 x 10(3) motile spermatozoa/ejaculate). One half of the fertile animals had no deficiencies in any of the characteristics measured, whereas 97% of the infertile animals had at least one deficiency. No fertile male had more than 2 deficiencies. These data show that the characteristics of mouse semen obtained by the present method of electroejaculation are related to the fertility status of the animal.     

The development of a qualitative assay for male infertility from a study of enzymes in human semen.

Various enzymes in the semen of men were examined to see if any could be related to measures of fertility. Fumarase activity was highly correlated with sperm number and percentage motility. Diamine oxidase activity was higher in samples with sperm counts of less than 20 X 10(6)/ml and aperm motility of less than 20%. Monoamine oxidase, adenine deaminase and prostaglandin dehydrogenase were undetectable in significant amounts in all samples, while peroxidase and adenosine deaminase were not correlated with sperm count and motility. It is suggested that the simple spectrophotometric assays for fumarase and diamine oxidase could form the basis of a routine assessment of human semen samples for estimation of male infertility.     

Effect of trace elements on the seminal oxidative status and correlation to sperm motility in infertile Saudi males

The impact of trace elements, especially zinc, selenium, copper, and magnesium, on male fertility has gained great interest and significance. Increased oxidative stress and altered trace element levels are probable etiological factors underlying male reproductive dysfunction and infertility. The present study focused on the evaluation of seminal oxidative markers, such as reactive oxygen species (ROS), malondialdehyde (MDA), and total antioxidant capacity (TAC), and trace element levels in the normozoospermic fertile control group (n = 40) and asthenozoospermic infertile group (n = 30). Semen from infertile men exhibited significantly higher ROS and MDA levels accompanied with significant decline in TAC and trace element (zinc and magnesium) levels. Furthermore, a significant correlation was observed between trace elements and oxidative markers with sperm motility. The current study revealed increased lipid peroxidation and oxidant-reductant imbalance that leads to deterioration of semen quality and male infertility. Thus, oxidative stress and trace elements can be considered important biomarkers of male infertility. Measurement of seminal oxidative stress with conventional seminological parameters must be integrated in fertility assessment from early stages to ensure healthy semen characteristics and fertility in men.     

Measurement of intrascrotal temperature in normal and subfertile men

Intrascrotal temperatures were measured bilaterally by a non-invasive method in 300 subfertile men (mean sperm count 21.4 x 10(6)/ml) and 30 normospermic control men (mean sperm count 118.7 x 10(6)/ml). The subfertile men had mean (s.d.) temperatures of 34.7 degrees C (0.8) for the right and 34.8 degrees C (0.7) for the left testis. The value for both testes of the control men was 33.4 degrees C (0.6). The difference (1.3-1.4 degrees C) was significant (P = 0.03). An intrascrotal temperature of greater than 34.1 degrees C was found in greater than 83% of subfertile men, regardless of clinical diagnosis. This method can therefore be used to survey large numbers of men. We suggest that small intrinsic temperature increases may interfere with the ability of the testis to accommodate to environmental temperature stresses and so lead to abnormal semen and subfertility.     

Decline in seminal quality in Indian men over the last 37 years

Background

Since the first report of a decline in semen quality in 1974, there have been several reports of similar declines across populations. Despite some scattered reports of declining semen quality in the Indian sub-continent, comprehensive studies analyzing semen quality over the last few decades have not been undertaken. We undertook the present study to investigate the temporal trend in semen parameters in Indian populations over a period of 37 years (1979–2016).

Methods

Publications providing semen analysis details for fertile and infertile men from the Indian sub-continent were collected by a thorough literature search. Semen quality data for 6466 normal fertile or presumptive normal men (from 119 studies/data sets) and 7020 infertile men (from 63 studies/data sets) published between 1979 and 2016 were retrieved. We undertook systematic review and quantitative analysis of mean sperm count, motility, normal morphology and other available parameters. Data were analyzed to estimate semen parameters reference values for Indian men and to assess temporal trends in infertile, fertile and all subjects.

Results

Seminal quality shows a decreasing temporal trend and the decrease is higher in infertile than fertile males. In pooled analysis for all individuals, significant (p?<?0.05 or?<?0.001) declines in sperm concentration and normal morphology are observed; however, isolated analysis for each group shows declines without statistical significance. The mean (± SD) semen volume, sperm concentration, total motility, rapid linear progressive motility, normal sperm morphology and sperm viability for Indian fertile men are 2.88?±?0.77 ml, 81.08?±?29.21 million/ml, 66.37?±?10.95%, 52.64?±?15.78%, 56.68?±?20.23% and 72.63?±?8.31%, respectively, whereas in infertile these are 3.07?±?1.27 ml, 37.94?±?26.41 million/ml, 40.22?±?13.76%, 26.79?±?15.47%, 36.41?±?21.66% and 55.25?±?11.99%, respectively. The mean seminal parameter values were significantly lower (p?<?0.001) in infertile as compared to fertile men, except semen volume.

Conclusions

Semen parameters in Indian men have declined with time and the deterioration is quantitatively higher in the infertile group. The study also provides reference values for semen parameters in Indian men.

     

Fertility test of frozen boar semen.

The fertility results of two experiments are presented. In experiment 1, the semen was frozen in tris-fructose-EDTA or BF3 diluents at 0-25 X 10(9)/ml sperm concentration and extended after thawing with either seminal plasma (SP) or the freezing medium (FM) containing no cryoprotective agent. In the second experiment the semen was glycerolated by two methods, frozen at 1-0 X 10(9)/ml sperm concentration, and extended wtih FM before insemination. Fertility after double insemination within one oestrus with semen frozen in tris-fructose-EDTA or BF3 diluents varied depending on the medium used for extension of thawed semen. The farrowing rates for semen frozen in the former diluent with FM and SP post-thawing media were 4/8 and 1/8 respectively, and for semen frozen BF3 diluent with FM and SP post-thawing extenders 1/8 and 5/8. The mean farrowing for the 32 animals inseminasted was 34-4%. Pregnancies for semen frozen in tris-fructose-EDTA and glycerolated at 30 or 5 degrees C were 5/12 and 4/12 respectively, and for single and double inseminations 6/12 and 3/12 respectively. Of 24 animals inseminated 37-5% farrowed.     

Quality and fertility of cooled-shipped stallion semen at the time of insemination

Stallion semen processing is far from standardized and differs substantially between AI centers. Suboptimal pregnancy rates in equine AI may primarily result from breeding with low quality semen not adequately processed for shipment. It was the aim of the study to evaluate quality and fertility of cooled-shipped equine semen provided for breeding of client mares by commercial semen collection centers in Europe. Cooled shipped semen (n = 201 doses) from 67 stallions and 36 different EU-approved semen collection centers was evaluated. At arrival, semen temperature was 9.8 ± 0.2 °C, mean sperm concentration of AI doses was 68 ± 3 x 10⁶/ml), mean total sperm count was 1.0 ± 0.1 x 10⁹, total motility averaged 83 ± 1% and morphological defects 45 ± 2%. A total of 86 mares were inseminated, overall per season-pregnancy rate in these mares was 67%. Sperm concentration significantly influenced semen motility and morphology at arrival of the shipped semen. Significant effects of month of the year on volume, sperm concentration and total sperm count of the insemination dose were found. The collection center significantly influenced all semen parameters evaluated. Semen doses used to inseminate mares that became pregnant had significantly higher total and progressive motility of spermatozoa and a significantly lower percentage of morphological semen defects than insemination doses used for mares failing to get pregnant. Results demonstrate that insemination with semen of better quality provides a higher chance to achieve pregnancy. Besides the use of stallions with good semen quality, appropriate semen processing is an important factor for satisfying results in artificial insemination with cooled-shipped horse semen.     

Effect of L-carnitine administration on the seminal characteristics of oligoasthenospermic stallions

The effect of orally administered l-carnitine on the quality of semen obtained from stallions with different semen qualities was investigated. Four stallions with proven fertility (high motility group, HM) and with normal seminal characteristics (>50% progressive motility and > 80 x 10(6) spermatozoa/ml), and four questionable breeders (low motility group, LM) with <50% of sperm progressive motility and < 80 x 10(6) spermatozoa/ml, received p.o. 20 g of l-carnitine for 60 days. Blood and semen samples were collected before treatment (T0) and after 30 (T1) and 60 days (T2). Semen evaluation were performed on five consecutive daily ejaculates (n = 120 ejaculates) and conventional semen analysis was carried out on each ejaculate, both at collection and after refrigeration for 24, 48, and 72 h. Furthermore l-carnitine, acetylcarnitine, pyruvate, and lactate concentrations, and carnitine acetyltransferase activity (CAT) were determined both in raw semen and seminal plasma. There were an increase in progressive motile spermatozoa only in the LM group (26.8 +/- 12.9, 39.1 +/- 15.5, and 48.8 +/- 8.6 for T0, T1, and T2, respectively). Free seminal plasma carnitine concentration was higher in the LM group compared to the HM one. Both pyruvate and lactate were higher in the LM group. Raw semen and seminal plasma carnitine and acetylcarnitine levels correlate positively with both sperm concentration and progressive motility; moreover, acetylcarnitine content was positively correlated with total motile morphologically normal spermatozoa. In conclusion, oral administration of l-carnitine to stallions with questionable seminal characteristics may improve spermatozoa kinetics and morphological characteristics; whereas, it seem to be ineffective in normospermic animals.     

Semen changes in boars after experimental infection with porcine reproductive and respiratory syndrome (PRRS) virus

Eleven boars seronegative to porcine reproductive and respiratory syndrome virus (PRRSV) were trained for semen collection: five boars were inoculated intranasally with 6 x 10(6)TCID(50)/ml of PRRSV (Group A); four boars were inoculated intranasally with 6 x 10(4)TCID(50)/ml (Group B); and two boars were used as uninfected control (Group C). Semen samples were collected at 7-d intervals from 49 d prior to experimental inoculation with PRRSV to 70 d after inoculation, and were examined for sperm volume, sperm concentration, sperm morphology, sperm motility and for the presence of PRRSV. The infection in boars was demonstrated by the reisolation of PRRSV from the serum of all inoculated boars. Rectal temperatures and general health of the boars were clinically normal throughout the trial. Differences were observed in the quality of semen collected from boars after experimental infection with PRRSV. This infection induced a significant decrease in sperm motility and in spermatozoa with normal acrosomes. Of the semen samples tested for virus isolation in swine alveolar macrophages PRRSV was only isolated in 1 boar from Group B. The virus was detected in an additional semen sample in Group A by the production of an antibody titer in a biological assay. All attempts to detect PRRSV by RT-PCR in semen samples were unsuccessful. Nevertheless, from our study it is possible to suggest that the PRRSV can occasionally be transmitted in the semen during the initial phase of the disease.     

ATP contents of human semen, seminal plasma and isolated sperm at time intervals after ejaculation

1. ATP was estimated in 105 samples of human semen, seminal plasma and sperm of normozoospermic and oligozoospermic origins at time intervals after ejaculation. 2. In semen with sperm counts up to 40 millions per ml and in seminal plasma, ATP levels were lower than in specimens with higher sperm counts. 3. In isolated sperm, the ATP content decreased with the increase in sperm density. 4. The decrease in ATP after 24 hr was the highest in sperm, lower in semen and the lowest in seminal plasma, being maximal in specimens with high sperm counts.     

Seasonality of serum testosterone levels and sperm density in Tursiops truncatus

We trained a mature male bottlenose dolphin, Tursiops truncatus, to provide semen samples on command. After completion of the 10-week training period, semen was collected twice weekly and blood was sampled twice monthly for a period of 28 months. Total sperm per ejaculate ranged from near 0 to 54.6 x 10(9) (n = 1332). Sperm densities from each session ranged from no sperm to 1,587 x 10(6)/ml (n = 241). Testosterone levels ranged from 1.1 to 54.4 ng/ml (n = 79). Seasonal variations were observed in total sperm per ejaculate, sperm density per ml of ejaculate, and in serum testosterone levels. Peak sperm densities were detected during September and October of three consecutive breeding seasons. Serum testosterone levels peaked in June, decreased during July and August, and were lowest in September and October, the period of greatest sperm density. Peak sperm production and density were coincident with the peak period of breeding activity but at a time when serum testosterone levels were lowest.     

Tissue kallikrein activity in seminal plasma of bovine ejaculates with different quality

Tissue kallikrein activity was monitored in seminal plasma from 3 groups of bovine ejaculates: those with normal total sperm motility (78.43%), with reduced sperm motility (49.29%), and with reduced sperm count (0.68 x 10(9) cells/ml). The tissue kallikrein activity was measured spectrophotometrically by using the specific chromogenic substrate S-2266. It was found that the semen samples with normal sperm motility manifested 1.083 microkat/L, on an average, or 29% higher than the activity recorded in ejaculates with reduced sperm motility (P < 0.05). After storage of a group of ejaculates of normal quality for 5 h at room temperature, sperm motility dropped by approximately 80%, expressed as a percentage of the initial motility, while the tissue kallikrein activity in the respective seminal samples decreased by 23%. No significant differences were found in kallikrein activity between ejaculates with normal and reduced sperm counts. It is concluded that a relationship exists between the level of tissue kallikrein activity in the seminal plasma of bovine ejaculates and sperm motility.     

Characterization of semen collected from beagles and captive Japanese black bears (Ursus thibetanus japonicus)

This study characterized semen collected from the Japanese black bear, Ursus thibetanus aponicus, to provide information on semen cryopreservation for artificial breeding. Preliminary studies using a beagle dog as the model species showed that sperm concentration and total sperm count were lower in semen collected by electroejaculation than in semen collected by digital manipulation, but that sperm motility, viability and morphology were similar. Characterization of semen obtained from Japanese black bears by electroejaculation under general anesthesia revealed that semen volume and total number of spermatozoa collected were lower; but that sperm concentration, motility, viability and morphology were equivalent to those reported in other ursids. When semen was collected via a catheter inserted into the urethra during the stimulation for ejaculation, the sperm concentration, total sperm count and motility were relatively higher than when semen was collected directly in a test tube. Specific normal semen characteristics (mean +/- SEM) were pH, 7.6 +/- 0.0; volume, 0.212 +/- 0.038 mL; sperm concentration, 361 +/- 100 x 10(6)/mL; total sperm count, 84.0 +/- 32.2 x 106; +++ motility, 30 +/- 5%; motility, 77 +/- 3%; viability 77 +/- 2%; and abnormal morphology, 11+/- 2%. These results suggest that semen can be collected from Japanese black bears by electroejaculation.     

Selenium,Copper and Zinc in Seminal Plasma of Men with Varicocele,Relationship with Seminal Parameters

Varicocele has been associated with decrease in seminal parameters. Selenium (Se), copper (Cu), and zinc (Zn) are trace elements essential for normal spermatogenesis of mammals and play a critical role as antioxidant defense system enzymes. Se, Cu, and Zn are associated with sperm quality in fertile and infertile men. However, there is little information about Se, Cu, and Zn concentrations in semen in patients with varicocele and its association with seminal parameters. The purpose of this study was to determine the concentrations of Se, Cu, and Zn in semen of patients with varicocele and the relationship with seminal parameters. Total Reflection X-Ray Fluorescence was used for the fist time in the seminal fluid analysis. The concentration of selenium in men with varicocele was smaller than the normozoospermic group, while no differences were observed for both concentrations of zinc and copper. A significant positive correlation between zinc and selenium concentration was observed. Selenium in seminal plasma correlates with a good spermatozoa concentrations, motility, and morphology. Additionally, a significant positive correlation was observed between zinc levels and sperm count. In conclusion, a decrease in selenium concentration was associated with detriment of seminal parameters. A study should be conducted to evaluate the benefits of both zinc and selenium supplementation to improve seminal parameters in patients with varicocele.