During the recent decades, a lot of research has been performed concerning the so-called "endocrine disruptors", which are widespread in the environment. These compounds of anthropogenic or natural origin mimic the action of sex hormones and can interfere with the endocrine system. The largest body of evidence exists for those compounds that are estrogenic in nature, but the amount of experimental data on other types of interactions, especially anti-androgenic, steadily increases. Because of the growing public and scientific concern, epidemiological studies have been initiated to analyse the short and long-term effects of endocrine disruptors. In addition, a number of assays have been developed and are undergoing validation, aiming at high throughput screening of chemical agents with suspected endocrine disrupting properties. In the present review, we briefly describe the results of epidemiological studies dealing with observed time trends in male fertility disorders. In the second part of the article, an overview is given of the different classes of endocrine disruptors, followed by a description of the most important in vitro and in vivo bioassays, used to screen for the possible endocrine disruptive capacity of chemicals, together with future research needs for in vitro test development.

Animals↗

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Epidemiological study of the effects of carbon disulfide on male sexuality and reproduction.

One hundred sixteen male viscose rayon workers exposed to carbon disulfide and 79 other workers, who were not exposed to any toxic agent in the working environment, were asked about their sexual behavior and reproductive record. Forty-three exposed and 35 nonexposed men provided a semen sample. The relationship with occupational exposure was analyzed with univariate and multivariate methods. The results indicate a significant effect of carbon disulfide exposure on libido and potency, but no effects were noted on fertility nor on semen quality.

Adult↗

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Comparison between cell motion analyser, autosperm, and conventional semen analysis.

With the aim of explaining some of the controversy on the value of computer-assisted methods of semen analysis, a study was conducted comparing the fully automated cell motion analyzer (CMA), the semi-computerized autosperm system (AS) and the conventional manual method. The CMA equipment gave higher values for sperm concentration than the mean of the three methods. Sperm concentration estimated with the conventional method was below the average of the three methods. The conventional method overestimated sperm motility, which was underestimated by CMA. The correlation between sperm velocity characteristics estimated by CMA and AS was significant, but only 18% of variability of one method could be explained by variability of the other. The reasons for the discrepancy between velocity measurements in the two methods are discussed in relation to possible shortcomings in sperm paths smoothing using the CMA method and the effect of technician training in the AS method. The AS method was found to provide more reproducible results which correlated better with those of the manual method as recommended by the World Health Organization.

Autoanalysis↗

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Assessment of sperm function in fertile and infertile men.

The sperm function of fertile men (control), infertility patients (experimental), and men with varicocele were compared. The bioassays used were the follicular fluid-induced acrosome reaction, the binding to the zona pellucida, and the penetration of zona-free hamster oocytes. The percentage (mean +/- SEM) of reacted spermatozoa was 35 +/- 3 in the control, 22 +/- 1 in the experimental, and 22 +/- 3 in the varicocele. The minimum value of acrosome reaction in control men was 20%. The mean number of zona-bound spermatozoa was 250 +/- 30 in the control, 160 +/- 28 in the experimental, and 196 +/- 44 in the varicocele. The minimum number of zona bound spermatozoa in control men was 50. The mean number of hamster oocytes penetrated was 50 +/- 8 in the control, 19 +/- 3% in the experimental, and 10 +/- 3 in the varicocele. The minimum number of oocytes penetrated in control men was 6%. In the experimental group, 22 men had a normal sperm function, 58 had 1 or 2 bioassays below the minimum (relative dysfunction), and 10 had all bioassay below the minimum (abnormal sperm function). The results of these bioassays could help to reclassify the infertile men in several subgroups.

Acrosome↗

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The effective cumulative pregnancy rate of different modes of treatment of male infertility.

The clinical efficacy of conventional and advanced methods of treatment was assessed in 814 couples with infertility due to a male factor. The monthly and effective cumulative rate of ongoing or term pregnancies was calculated during 4712 couple-months. Treatment of varicocele by transcatheter embolization, resulting in 3.9% pregnancies per cycle and an effective cumulative pregnancy rate of 41% after 1 year, is more effective than counselling and timed intercourse (9% pregnancies after 12 months). Intrauterine insemination (IUI) of washed spermatozoa produced 17% pregnancies in the initial 4 months, but the success rate of the subsequent cycles (1.7% per cycle) was not different from that of the controls. In vitro fertilization (IVF) resulted in 16% pregnancies per attempt, but the effective cumulative pregnancy rate was only 31% in 12 months due to the long interval between treatment attempts and the high drop-out rate. With subzonal microinjection of sperm, the fertilization rate was higher (71%) than with regular IVF (29%) but both the pregnancy rate per attempt (9%) and the effective cumulative pregnancy rate (17% after 12 months) were low. The 10th percentile of sperm characteristics (cut-off values) of successful cases showed intrauterine insemination to be advantageous in cases with a lower percentage of spermatozoa with progressive motility (9%) than in the controls (15%). The cut-off value of sperm morphology in IVF (4%) is lower than that of IUI (8%) and of the controls (9%), but higher than that of subzonal insemination (1%). Treatment strategy must be defined selecting or combining conventional and assisted reproductive technology for each individual couple with male factor infertility.

Female↗

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Declining sperm quality in European men.

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Europe↗

PubMedDate not supplied

Cytokines in semen of normal men and of patients with andrological diseases.

PROBLEM: The potential value of assessment of cytokine concentrations for the diagnosis of certain pathological conditions of male reproduction has not been fully evaluated. METHOD: The concentrations of interleukin 6 (IL-6, pg/mL), its soluble receptor (IL-6 sR, ng/mL), and of interleukin 1 beta (IL-1 beta, pg/mL) have been measured in semen samples of 114 men and 12 corresponding blood sera. RESULTS: The concentration of IL-6 was unrelated to that of its receptor. Both IL-6 and IL-6 sR were higher in the first (mean: 69 and 31 resp.) than in the second fraction (39 and 13) of split ejaculates, and were within normal limits in vasectomised men. The Interleukin 1 beta concentration presented a strong positive correlated with that of IL-6 (r = 0.74, P < 0.001). The concentrations of IL-6 and IL-1 beta were unrelated to sperm concentration, motility and morphology, and they were within normal limits in immunological cases. Both IL-6 and IL-1 beta were higher (P < 0.01) in cases with accessory gland inflammation. CONCLUSIONS: Measurement of in particular IL-6 in semen may contribute to the diagnosis of inflammatory disease of the accessory sex glands (positive predictive value = 98%, sensitivity = 72%, specificity = 94%), but it is not relevant for the diagnosis of immunological disease.

Genital Diseases, Male↗