P–104 Assessment of sperm motility according to WHO classification using convolutional neural networks

Study question

How does convolutional neural network (CNN)-predicted sperm motility correlate with manual assessment according to the WHO guidelines.

Summary answer

CNN predicts sperm motility comparable to reference laboratories in the ESHRE-SIGA External Quality Assessment Programme for Semen Analysis.

What is known already

Manual sperm motility assessment according to WHO guidelines is regarded as the gold standard. To obtain reliable and reproducible results, comprehensive training is essential as well as running internal and external quality control. Prediction based on artificial intelligence can potentially transfer human-level performance into models that perform the task faster and can avoid human assessor variations. CNNs have been groundbreaking in image processing. To develop AI models with high predictive power, the data set used should be of high quality and sperm motility assessment based on WHO guidelines.

Study design, size, duration

Videos of 65 fresh semen samples obtained from the ESHRE-SIGA External Quality Assessment Programme for Semen Analysis (from the period 2006–2018) were used in the development of the model. One video was captured for each semen sample. Sperm motility data was obtained from manual assessment of the videos according to WHO criteria by reference laboratories in the programme. Rapid progressive motility was also included. Ten-fold cross-validation was used to compensate for the relatively small dataset.

Participants/materials, setting, methods

The mean values of the reference laboratories were used. Sparse optical flow of the sperm videos was generated from each second of each video and fed into a ResNet50 convolutional neural network. For training, Adam was used to optimize the weights and mean squared error (MSE) to measure loss. For baseline, ZeroR (pseudo regression) was performed. Results are reported as MAE. For correlation analysis, Pearson’s r was used.

Main results and the role of chance

Predicting sperm motility based on the optical flow generated from the videos, achieved an average MAE of 0.05 across progressive (0.06), non-progressive (0.04) and immotile sperm (0.05). The ZeroR baseline was 0.09, indicating that the method is able to capture the movement of the spermatozoa and predict motility with low error. Pearson’s correlation between manually and AI-predicted motility showed r of 0.88, p < 0.001 for progressive, 0.59, p < 0.001 for non-progressive and 0.89, p < 0.001 for immotile sperm. When predicting rapid progressive motility, the average MAE was 0.07 across rapid progressive (0.11), slow progressive (0.09), non-progressive (0.04) and immotile sperm (0.05). Pearson’s correlation analysis between manually and AI-predicted motility showed r of 0.67, p < 0.001 for rapid progressive, 0.41, p < 0.001 for slow progressive, 0.51, p < 0.001 for non-progressive and 0.88, p < 0.001 for immotile sperm. The results show that differentiating between rapid progressive and slow progressive motility is difficult, but the model is still able to do this better than the ZeroR baseline, which was 0.15 for rapid progressive and 0.11 for slow progressive. This is interesting since rapid progressive motility has been regarded challenging to assess. The next step would be to compare the results of the algorithm to the human performance.

Limitations, reasons for caution

The sample size is small. The model is based on videos of high quality, and the performance may not transfer well to videos of lower quality. The performance for rapid progressive motility, which may have an important clinical value, has to be improved.

Wider implications of the findings: This CNN model has a potential to assess sperm motility according to WHO guidelines for progressive motility and immotility. The error values for the automatic predictions are low, and the model shows a good performance taking into account that only videos were used to perform the prediction.

Trial registration number

Not applicable

P–029 Identification of spermatozoa by unsupervised learning from video data

Study question

Can artificial intelligence (AI) algorithms identify spermatozoa in a semen sample without using training data annotated by professionals?

Summary answer

Unsupervised AI methods can discriminate the spermatozoon from other cells and debris. These unsupervised methods may have a potential for several applications in reproductive medicine.

What is known already

Identification of individual sperm is essential to assess a given sperm sample’s motility behaviour. Existing computer-aided systems need training data based on annotations by professionals, which is resource demanding. On the other hand, data analysed by unsupervised machine learning algorithms can improve supervised algorithms that are more stable for clinical applications. Therefore, unsupervised sperm identification can improve computer-aided sperm analysis systems predicting different aspects of sperm samples. Other possible applications are assessing kinematics and counting of spermatozoa.

Study design, size, duration

Three sperm-like paint images were manipulated using a graphic design tool and used to train our AI system. Two paintings have an ash colour background and randomly distributed white colour circles, and one painting has a predefined pattern of circles. Selected semen sample videos from a public dataset with videos obtained from 85 participants were used to test our AI system.

Participants/materials, setting, methods

Generative adversarial networks (GANs) have become common AI methods to process data in an unsupervised way. Based on single image frames extracted from videos, a GAN (SinGAN) can be trained to determine and track locations of sperms by translating the real images into localization paintings. The resulting model showed the potential of identifying the presence of sperms without any prior knowledge about data.

Main results and the role of chance

Visual comparisons of localization paintings to real sperm images show that inverse training of SinGANs can track sperms. Converting colour frames into grayscale frames and using grayscale synthetic sperm-like frames showed the best visual quality of generated localization paintings of sperm frames. Feeding real sperm video frames to the SinGAN at different scaling factors, which is defining the resolution of the input image, showed different quality levels of generated sperm localization paintings. A sperm frame given to the algorithm with a scaling factor of one leads to random sperm tracking, while the scales two to four result in more accurate localization maps than scaling levels five to eight. In contrast, scales from six to eight result in an output close to the input frame. The proposed method is robust in terms of the number of spermatozoa, meaning that the detection works well for samples with a low or high sperm count. For visual comparisons, visit our Github page: https://vlbthambawita.github.io/singan-sperm/. The sperm tracking speed of our SinGAN using an NVIDIA 1080 graphic processing unit, is around 17 frames per second, which can be improved by using parallel video processing capabilities. This shows the capability of using this method for real-time analysis.

Limitations, reasons for caution

Unsupervised methods are hard to train, and the results need human verification. The proposed method will need quality control and must be standardized. Unsupervised sperm tracking SinGAN may identify blurry bright spots as non-existing sperm heads which may restrict the use of SinGAN sperm tracking for sperm counting.

Wider implications of the findings: Assessment of semen samples according to the WHO guidelines is subjective and resource-demanding. This unsupervised model might be used to develop new systems for less time-consuming and more accurate evaluation of semen samples. It may also be used for real-time analysis of prepared spermatozoa for use in assisted reproduction technology.

Trial registration number

N/A

Artificial intelligence in the fertility clinic: status, pitfalls and possibilities

In recent years, the amount of data produced in the field of ART has increased exponentially. The diversity of data is large, ranging from videos to tabular data. At the same time, artificial intelligence (AI) is progressively used in medical practice and may become a promising tool to improve success rates with ART. AI models may compensate for the lack of objectivity in several critical procedures in fertility clinics, especially embryo and sperm assessments. Various models have been developed, and even though several of them show promising performance, there are still many challenges to overcome. In this review, we present recent research on AI in the context of ART. We discuss the strengths and weaknesses of the presented methods, especially regarding clinical relevance. We also address the pitfalls hampering successful use of AI in the clinic and discuss future possibilities and important aspects to make AI truly useful for ART.

Association between semen parameters and chance of fatherhood - a long-term follow-up study

BACKGROUND

Evaluation of male fertility includes standard semen analysis; however, there is uncertainty about the value of sperm parameters in predicting fertility.

OBJECTIVE

To evaluate the association between semen parameters and fatherhood during a long-time period.

MATERIALS AND METHODS

Semen parameters (total sperm count, concentration, motility, and morphology) and sperm DNA fragmentation Index (DFI) assessed on samples collected from 195 Norwegian men from the general population in 2001/2002 were matched with information about fatherhood until 2015, obtained from the Medical Birth Register. The parameters were dichotomized as normal vs. abnormal according to the WHO reference values from 1999 and 2010. Cut-offs at 20% and 30% were used for DFI.

RESULTS

Among men who had no children before 2003, those with normal progressive sperm motility had more often become fathers (WHO 1999, cut-off ≥50%, adjusted OR 2.8, 95% CI 1.3-6.1 and WHO 2010, cut-off ≥32%; aOR 4.2, 95% CI 1.1-15). Based on the WHO 1999 reference value, men with normal sperm concentration (≥20 × 10⁶ /mL) had more often become fathers (aOR 3.1, 95% CI 1.1-8.6). Men with progressive sperm motility ≥50% and concentration ≥20 × 10⁶ /mL did more often achieve fatherhood (aOR 8.4, 95% CI 2.1-34). For DFI, there was a borderline significance at cut-off 20% in the group of men who had ever been fathers (OR 2.7, 95% CI 1.0-7.0 p < 0.05).

DISCUSSION

The results indicate that sperm progressive motility, sperm concentration, and DFI are associated with fatherhood during a longer time period, with sperm motility being most consistent. Although the sample size is relatively small and our results should be replicated in larger studies, they may be of clinical relevance.

CONCLUSION

Semen parameters may have a diagnostic value not only in a short time frame but also for predicting future fertility potential.

Fatty acid composition of spermatozoa is associated with BMI and with semen quality

High body mass index (BMI) is negatively associated with semen quality. In addition, the composition of fatty acids of spermatozoa has been shown to be important for their function. The aim of the study was to examine the association between BMI and the composition of spermatozoa fatty acids in men spanning a broad BMI range. We also analysed the relation between fatty acid composition of spermatozoa and semen characteristics, and the relationship between serum fatty acids and spermatozoa fatty acids. One hundred forty-four men with unknown fertility status were recruited from the general population, from couples with identified female infertility and from morbid obesity centres. Standard semen analysis (WHO) and sperm DNA integrity (DFI) analysis were performed. Fatty acid compositions were assessed by gas chromatography. When adjusted for possible confounders, BMI was negatively associated with levels of sperm docosahexaenoic acid (DHA) (p < 0.001) and palmitic acid (p < 0.001). The amount of sperm DHA correlated positively with total sperm count (r = 0.482), sperm concentration (r = 0.469), sperm vitality (r = 0.354), progressive sperm motility (r = 0.431) and normal sperm morphology (r = 0.265). A negative association was seen between DHA levels and DNA fragmentation index (r = -0.247). Levels of spermatozoa palmitic acid correlated positively with total sperm count (r = 0.227), while levels of linoleic acid correlated negatively (r = -0.254). When adjusted for possible confounders, only the levels of arachidonic acid showed positive correlation between spermatozoa and serum phospholipids (r = 0.262). Changes in the fatty acid composition of spermatozoa could be one of the mechanisms underlying the negative association between BMI and semen quality. The relationship between fatty acids of spermatozoa and serum phospholipids was minor, which indicates that BMI affects fatty acid composition of spermatozoa through regulation of fatty acid metabolism in the testis. The role of dietary intake of fatty acids on the spermatozoa fatty acid composition remains to be elucidated.

Profiling of the small RNA populations in human testicular germ cell tumors shows global loss of piRNAs

Background

Small non-coding RNAs play essential roles in gene regulation, however, the interplay between RNA groups, their expression levels and deregulations in tumorigenesis requires additional exploration. In particular, a comprehensive analysis of microRNA (miRNA), PIWI-interacting RNAs (piRNAs), and tRNA-derived small RNAs in human testis and testicular germ cell tumor (TGCT) is lacking.

Results

We performed small RNA sequencing on 22 human TGCT samples from 5 histological subtypes, 3 carcinoma in situ, and 12 normal testis samples. miRNA was the most common group among the sequences 18–24 nt in length and showed histology-specific expression. In normal samples, most sequences 25–31 nucleotides in length displayed piRNA characteristics, whereas a large proportion of the sequences 32–36 nt length was derived from tRNAs. Expression analyses of the piRNA population demonstrated global loss in all TGCT subtypes compared to normal testis. In addition, three 5′ small tRNA fragments and 23 miRNAs showed significant (p < 10⁻⁶) differential expression in cancer vs normal samples.

Conclusions

We have documented significant changes in the small RNA populations in normal adult testicular tissue and TGCT samples. Although components of the same pathways might be involved in miRNA, piRNA and tRNA-derived small RNA biogenesis, our results showed that the response to the carcinogenic process differs between these pathways, suggesting independent regulation of their biogenesis. Overall, the small RNA deregulation in TGCT provides new insight into the small RNA interplay.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0411-4) contains supplementary material, which is available to authorized users.

Genetic variations associated with the effect of testicular cancer treatment on gonadal hormones

STUDY QUESTION

Do genetic variations in the testosterone pathway genes modify the effect of treatment on the levels of testosterone and LH in long-term testicular cancer (TC) survivors (TCSs)?

SUMMARY ANSWER

Variations in LH receptor (LHR) and in 5α-reductase II (SRD5A2) genes may modify the effect of TC treatment on testosterone levels, whereas genetic variations in the androgen receptor (AR) may modify the effect on LH levels.

WHAT IS KNOWN ALREADY

TCSs experience variable degrees of long-term reduction in gonadal function after treatment. This variability can in part be explained by treatment intensity, but may also be due to individual variations in genes involved in the function and metabolism of reproductive hormones.

STUDY DESIGN, SIZE, DURATION

Cross-sectional study on testosterone and LH levels in 637 Norwegian TCSs in relation to genetic variants and TC treatment.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The single nucleotide polymorphisms LHR Asn291Ser (rs12470652) and Ser312Asn (rs2293275), as well as SRD5A2 Ala49Thr (rs9282858) and Val89Leu (rs523349) were analyzed by allele-specific PCR. The insertion polymorphism LHR InsLQ (rs4539842) was analyzed by sequencing. The numbers of AR CAG and GGN repeats were determined by capillary electrophoresis. Blood samples were collected 5-21 years after diagnosis (median 11 years) and serum total testosterone and LH were analyzed by commercial immunoassays. The TCSs were divided into four groups according to their treatment; surgery only, radiotherapy and chemotherapy with ≤850 or >850 mg of cisplatin. Polymorphisms presenting P < 0.1 for the interaction term with treatment in an initial two-way analysis of covariance (ANCOVA) were investigated further in two consecutive one-way ANCOVA analyses to elucidate the interaction between treatment and genotype.

MAIN RESULTS AND THE ROLE OF CHANCE

For the whole group of TCSs, there were no significant differences between the hormone levels in homozygotes for the wild type and carriers of at least one polymorphic allele for the investigated polymorphisms. Three of the polymorphisms showed signs of interaction with treatment, i.e. LHR InsLQ, SRD5A2 A49T and the AR CAG repeat. Follow-up analyses revealed three situations where only one of the genotypes of the polymorphism where associated with significantly different hormone levels after surgery compared with after additional cytotoxic treatment: For LHR InsLQ, only the wild-type allele was associated with lower testosterone levels after cisplatin > 850 mg compared with after surgery (24% lower, P < 0.001). For SRD5A2 A49T, testosterone levels were lower after radiotherapy compared with after surgery, but only for the heterozygotes for the polymorphism (39% lower, P = 0.001). In comparison, the testosterone levels were just slightly lower after radiotherapy (6% lower, P = 0.039) or cisplatin ≤ 850 mg (7% lower, P = 0.041), compared with surgery, independent of genotypes. For AR CAG, only the reference length of CAG = 21-22 had significantly higher LH levels after cisplatin ≤ 850 mg compared with after surgery (70% higher, P < 0.001). Independent of genotypes, however, LH levels after cisplatin ≤ 850 mg were only 26% higher than after surgery (P = 0.005).

LIMITATIONS, REASONS FOR CAUTION

Unadjusted P-values are presented. For analysis involving genotypes, the level of statistical significance was adjusted for the total number of polymorphisms tested, n = 7, i.e. to P < 0.007 (0.5/7). The rather weak associations indicate that additional polymorphisms are involved in the modulation.

WIDER IMPLICATIONS OF THE FINDINGS

To our knowledge, this is the first study supporting the notion that polymorphisms may explain at least some of the inter-individual differences in endocrine response to TC treatment. Our findings suggest that individuals with certain genotypes may be more vulnerable to certain treatments. Knowledge on genetic predisposition concerning treatment-related endocrine gonadotoxicity to different treatment regimens may help tailoring TC therapy when possible.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the Research Council of Norway (Grant No. 160619). There were no competing interests.

Genetic variation in AKT1, PTEN and the 8q24 locus, and the risk of testicular germ cell tumor

STUDY QUESTION

Is there an association between testicular germ cell tumor (TGCT) and genetic polymorphisms in AKT1, PTEN and the 8q24 locus?

SUMMARY ANSWER

Our findings suggest that genetic variation in PTEN may influence the risk of TGCT.

WHAT IS KNOWN ALREADY

There is strong evidence that genetic variation influences the risk of TGCT. The oncogene, AKT1, the tumor suppressor gene, PTEN and the chromosome 8q24 locus play important roles in cancer development in general.

STUDY DESIGN, SIZE, DURATION

We have conducted a population-based Norwegian-Swedish case-parent study, based on cases diagnosed in 1990-2008, including 831 triads (TGCT case and both parents), 474 dyads (TGCT case and one parent) and 712 singletons (only the TGCT case). In addition we expanded the study to include 3922 unrelated male controls from the TwinGene project.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We genotyped 26 single nucleotide polymorphisms (SNPs) in AKT1, PTEN and the 8q24 locus. First, triads and dyads were included in a likelihood-based association test. To increase the statistical power, case singletons and controls from the TwinGene project were included in a single test for association. We examined if the allelic effect on TGCT risk differed by histological subgroup, country of origin or parent of origin. Odds ratios (ORs) and 95% confidence intervals (CI) were calculated with Bonferroni correction (P bonf) for multiple testing.

MAIN RESULTS AND THE ROLE OF CHANCE

In the case-parent analyses, none of the 26 SNPs were significantly associated with TGCT. Of the 23 SNPs investigated in the combined study, one SNP in PTEN (rs11202586) remained associated with TGCT risk after adjusting for multiple testing (OR = 1.16, 95% CI = 1.06-1.28, P bonf = 0.040). We found no difference in risk according to histological subgroup, parent of origin or between countries.

LIMITATIONS, REASONS FOR CAUTION

Our study is strengthened by the population-based design and large sample size, which gives high power to detect risk alleles. The reported association was not highly significant, and although it was based on an a priori hypothesis of this tumor suppressor gene being implicated in the etiology of TGCT, replication studies, as well as functional studies of this polymorphism, are warranted.

WIDER IMPLICATIONS OF THE FINDINGS

We report, to our knowledge, a novel association between TGCT and a marker in the tumor suppressor gene PTEN. Previous studies have linked PTEN to TGCT etiology, and there is also a link between PTEN and KITLG, which contains TGCT susceptibility loci revealed through recent genome-wide studies.

CYP1A1, CYP3A5 and CYP3A7 polymorphisms and testicular cancer susceptibility

Testicular cancer (TC) incidence is increasing worldwide, but the aetiology remains largely unknown. An unbalanced level of oestrogens and androgens in utero is hypothesized to influence TC risk. Polymorphisms in genes encoding cytochrome P450 (CYP) enzymes involved in metabolism of reproductive hormones, such as CYP1A1, CYP3A5 and CYP3A7, may contribute to variability of an individual's susceptibility to TC. The aim of this case-control study was to investigate possible associations between different CYP genotypes and TC, as well as histological type of TC. The study comprised 652 TC cases and 199 controls of Norwegian Caucasian origin. Genotyping of the CYP1A1*2A (MspI), CYP1A1*2C (I462V), CYP1A1*4 (T461N), CYP3A5*3C (A6986G) and CYP3A7*2 (T409R) polymorphisms was performed using TaqMan allelic discrimination or sequencing. The CYP1A1*2A allele was associated with 44% reduced risk of TC with each polymorphic allele [odds ratio (OR) = 0.56, 95% confidence interval (CI) = 0.40-0.78, p(trend) = 0.001], whereas the CYP1A1*2C allele was associated with 56% reduced risk of TC with each polymorphic allele (OR = 0.44, 95% CI = 0.25-0.75, p(trend) = 0.003). The decreased risk per allele was significant for seminomas (OR = 0.46, 95% CI, 0.31-0.70, p(trend) < 0.001 and OR = 0.31, 95% CI = 0.14-0.66, p(trend) = 0.002, respectively), but only borderline significant for non-seminomas (OR = 0.65, 95% CI = 0.45-0.95, p(trend) = 0.027 and OR = 0.55, 95% CI = 0.30-1.01, p(trend) = 0.052, respectively). There were no statistically significant differences in the distribution of the CYP3A5*3C and CYP3A7*2 polymorphic alleles between TC cases and controls. This study suggests that polymorphisms in the CYP1A1 gene may contribute to variability of individual susceptibility to TC.

Risk factors for testicular cancer – differences between pure non-seminoma and mixed seminoma/non-seminoma?

The origin of testicular germ cell cancer (TGCC) is believed to be carcinoma in situ cells developed in utero. Clinically, TGCCs are divided into two major histological groups, seminomas and non-seminomas, where the latter group includes non-seminomatous TGCCs with seminomatous components (mixed S/NS TGCC). Recent studies, however, have suggested that non-seminomas and mixed S/NS TGCCs could have certain differences in aetiology, and in this study the TGCCs were divided into three, rather than the conventional two histological groups. A large case-control study was undertaken on data on all live-born boys registered in the Medical Birth Registry of Norway during the period 1967-1998 (n=961 396). Among these were 1087 TGCC cases registered in the Cancer Registry of Norway until February 2004. We found several risk factors for TGCC, including low parity, low gestational age, epilepsy and retained placenta. Several of the variables studied seemed to be risk factors for specific histological groups, e.g. parity 0 vs. 2 and low gestational age being associated with increased risk of non-seminomas, but not of mixed S/NS TGCC, and low maternal age being associated with increased risk of mixed S/NS TGCC, but not of non-seminomatous TGCC. Therefore, our results might suggest that non-seminomas and mixed S/NS TGCCs have partially different risk factors, whose associations may be obscured by combining these two histological groups. The histological groups were not significantly different, however. Most of our findings on risk factors for TGCC are in agreement with at least some previous studies. An unexplainable exception is low birth weight being associated with reduced risk of TGCC in our study.

Twenty Years Experience with Semen Cryopreservation in Testicular Cancer Patients: Who Needs It?

PURPOSE

To evaluate the role of semen cryopreservation (SCP) in the fertility saving management of testicular cancer (TC) patients, treated at the Norwegian Radium Hospital between 1983 and 2002.

PATIENTS AND METHODS

422 of 1388 newly diagnosed TC patients had SCP All patients were followed up for post-treatment paternity.

RESULTS

During the 20 years study period, by 2002 an increasing percentage of patients had pre-treatment SCP, reaching 43% after 1994. Twenty-nine (7%) of the 422 patients with SCP had used their frozen semen for assisted reproductive techniques (ART) at least once to achieve fatherhood. Pregnancies were achieved in 16 of these patients' partners, but two of these pregnancies ended in abortions. 67(17%) of 393 men with SCP fathered at least one child without use of frozen semen. The comparable figures for those without SCP were 205 out of 966(21%). Twenty years after orchiectomy the cumulative incidence of first post-treatment fatherhood was 47% for the 393 patients who had SCP but did not use it for ART, and 34% for the 966 patients without SCP (p=0.12).

CONCLUSION

If offered, about 50% of the young and middle-aged patients newly diagnosed with TC are interested in pre-treatment SCP. Though our study reveals that a considerable number of TC patients referred to SCP, achieve fatherhood without the use of frozen semen, the psychological impact of pre-treatment cryopreservation is undeniable. Furthermore, for some TC survivors ART with cryopreserved sperm offers the only chance of post-treatment paternity.

Differential distribution of splice variants of estrogen receptor beta in human testicular cells suggests specific functions in spermatogenesis

A growing number of estrogen receptor beta (ER beta) splice variants are reported. Several of these have been discovered in testis, but with few exceptions little is known about their cellular localization. The aim of this study was to identify and elucidate the mRNA expression pattern of the different ER beta splice variants in human testicular cells. Northern analysis was performed on whole testis and fractions enriched in germ cells from untreated men and from estrogen-treated men undergoing sex change surgery. Probes were constructed in order to systematically screen for and identify various ER beta splice variants. Several ER beta bands were observed in the human testis, in which splice variants constituted the major part of total ER beta transcripts. Interestingly, only two ER beta wild-type transcripts were detected. These seem to be virtually absent from the haploid germ cells and are probably mainly located in somatic cells and/or primary spermatocytes. Several novel ER beta deletion variants were found in high levels in the haploid germ cell fractions and were nearly absent in testicular cells from the estrogen-treated men. The cell-dependent distribution raises the question whether splice variants may have specific functions in spermatogenesis, and whether the differential splicing of ER beta is regulated in a cell-specific manner.

Alterations in semen parameters in men with epilepsy treated with valproate or carbamazepine monotherapy

Men with epilepsy are known to have reduced fertility. Whether this is drug-induced or a result of the epilepsy itself is still under debate. Few studies have been carried out on semen from men with epilepsy. The aim of the present study was first to investigate possible drug-specific effects of long-term treatment with either valproate or carbamazepine on semen quality and testicular size, and secondly to see whether the results in epilepsy patients differed from healthy fertile males. Men with epilepsy, 20-40 years old, having used either valproate (n = 16) or carbamazepine (n = 20) for >2 years, were included. The semen data of healthy fertile men without epilepsy in the same age group (n = 90) were used as controls. The semen was examined according to WHO (1999). No significant differences in semen quality were seen between men receiving either valproate or carbamazepine. However, semen from the valproate-treated, as opposed to the carbamazepine-treated, differed from controls with regard to tail abnormalities. Absolute testicular size was not significantly different between the two treatment groups. However, after correcting for changes in body mass index (BMI), the testicular size/BMI ratio was lower in the valproate-treated patients. The valproate-treated patients gained significantly more weight than the carbamazepine-treated patients after start of current medication. No differences between the patient groups were found in terms of libido/potency or number of pregnancies fathered. When comparing all epilepsy patients with healthy fertile males, there was a significant reduction in the percentage of rapidly progressive motile sperms in the semen from epileptic patients. The semen from men with epilepsy also showed significant differences from the controls regarding neck and head abnormalities of the spermatozoa.

Tissue-specific transcriptional regulation of the cholesterol biosynthetic pathway leads to accumulation of testis meiosis-activating sterol (T-MAS)

Lanosterol 14alpha-demethylase (CYP51) produces follicular fluid meiosis-activating sterol (FF-MAS), which is converted further to testis meiosis-activating sterol (T-MAS). MAS are intermediates in the cholesterol biosynthetic pathway, with the ability to trigger resumption of oocyte meiosis in vitro. In contrast to the liver, where pre- and post-MAS genes are upregulated coordinately at the level of transcription by a cholesterol feedback mechanism through sterol regulatory element-binding proteins (SREBP), regulation differs in the testis. Genes encoding pre-MAS enzymes [HMG-CoA synthase (SYN), HMG-CoA reductase (RED), farnesyl diphosphate synthase (FPP), squalene synthase (SS), and CYP51] are upregulated during sexual development of the testis, although not all genes are turned on at the same time. Furthermore, two post-MAS genes, C-4 sterol methyl oxidase and sterol Delta(7)-reductase, are expressed at low levels and are not upregulated either in rat or human. This transcriptional discrepancy seems to be SREBP independent. Besides cAMP/cAMP-responsive element modulator, other unknown transcription factors control expression of individual cholesterogenic genes during spermatogenesis. HPLC analysis shows an 8-fold increase in T-MAS during development of rat testis whereas MAS is barely detectable in livers of the same animals. We propose that the lack of a coordinate transcriptional control over the cholesterol biosynthetic pathway contributes importantly to overproduction of the signaling sterol T-MAS in testis.

Placental transfer of the estrogenic mycotoxin zearalenone in rats

In order to study the possible placental transfer of the Fusarium mycotoxin zearalenone (ZON), Sprague Dawley rats were treated with a single dose (0.74 mg/kg b.w.) of ZON i.v. on day 12 or day 18 of pregnancy, or intragastrically (i.g.) on day 18 of pregnancy. Samples of placenta, foetus, and maternal liver and spleen were collected for chemical analyses 0.3 h after treatment on day 12, and 0.3, 4, and 24 h after treatment on day 18. Three rats were used for each pregnancy day, administration route, and exposure time. The concentrations of ZON and its metabolites alpha- and beta-zearalenol (-ZOL) were determined quantitatively by high-performance liquid chromatography (HPLC) after incubation with beta-glucuronidase and purification on immunoaffinity columns. Tissue distribution was studied by means of whole body autoradiography at 4 and 24 h after treatment with tritiated ZON (750 microCi/kg b.w; 7.4 mg/kg b.w.) on day 18 of pregnancy. ZON and alpha-ZOL were transferred into the foetus on both gestational days. However, a delay in distribution into the foetus, relative to the maternal tissue, was observed. Beta-ZOL was below the detection limit in the foetus. No specific site of foetal accumulation of ZON or its metabolites was apparent. In the maternal tissues, the highest levels of ZON and of alpha- and beta-ZOL were found in the liver.

Metabolism of very long chain polyunsaturated fatty acids in isolated rat germ cells

Which cell type is responsible for the high levels of very long chain polyunsaturated fatty acids in testis and whether this fatty acid pattern is a result of a local synthesis are not presently known. In this study, fatty acid conversion from 20:4n-6 to 22:5n-6 and from 20:5n-3 to 22:6n-3 was investigated in isolated rat germ cells incubated with [1-14C]-labeled fatty acids. The germ cells elongated the fatty acids from 20- to 22-carbon atoms and from 22- to 24-carbon atoms but had a low delta6 desaturation activity. Thus, little [14C]22:5n-6 and [14C]22:6n-3 were synthesized. When Sertoli cells were incubated with [1-14C]20:5n-3 for 24 h, an active fatty acid elongation and desaturation were observed. In vivo germ cells normally have a higher content of 22:5n-6 or 22:6n-3 than Sertoli cells. An eventual transport of essential fatty acids from Sertoli cells to germ cells was thus studied. Different co-culture systems were used in which germ cells were on one side of a filter and Sertoli cells on the opposite side. When isolated pachytene spermatocytes or round spermatids were added to the opposite side of a semipermeable filter, approximately 1 nmol [14C]22:6n-3 crossed the filter. Little of this was esterified in the germ cells. Similarly, in using [1-14C]20:4n-6 in identical experiments, very little [14C]22:5n-6 was esterified in germ cells on the opposite side of the filter. Although the very active synthesis of 22:5n-6 and 22:6n-3 observed in Sertoli cells suggests a transport of these compounds to germ cells, this was not experimentally determined.

Studies on the metabolism of essential fatty acids in isolated human testicular cells

The essential fatty acid 22:6(n-3) is a minor component of the Western diet, but a major fatty acid in human testis and semen. In mature spermatozoa, the physical and fusogenic properties of the plasma membrane are probably influenced by its particular fatty acid composition. In this study, the synthesis of 22:6(n-3) and 22:5(n-6) was investigated in isolated human testicular cells. [1-(14)C]20:4(n-6), [1-(14)C]20:5(n-3), [1-(14)C]22:4(n-6) and [1-(14)C]22:5(n-3) were incubated in a 'crude' cell suspension (consisting of a mixture of the cells in the seminiferous tubule), and in fractionated pachytene spermatocytes and round spermatids. The esterification of fatty acids in lipid and phospholipid classes and the fatty acid chain elongation and desaturation were measured. The crude cell suspension metabolized the fatty acids more actively than did the fractionated germ cell suspension, indicating that types of cell other than the germ cells are important for fatty acid elongation and desaturation and thus the production of 22:6(n-3). This finding is in agreement with previous results in rats that indicated that the Sertoli cells are the most important type of cell for the metabolism of essential fatty acids in the testis. Some [1-(14)C]20:5(n-3) was elongated to [(14)C]22:5(n-3) in the fractionated germ cells, but very little was elongated further to [(14)C]24:5(n-3),possibly restricting the formation of [(14)C]22:6(n-3). In the fractionated germ cells, the fatty acid substrates were recovered primarily in the phospholipid fraction, indicating an incorporation in the membranes, whereas in the crude cells, more substrates were esterified in the triacylglycerol fraction. In the phospholipids, more radioactivity was recovered in phosphatidylcholine than in phosphatidylethanolamine and more radioactivity was recovered in phosphatidylethanolamine than in phosphatidylinositol or phosphatidylserine.

Reproductive function in male rats after brief in utero exposure to diethylstilboestrol

Long-term effects of brief in utero exposure to diethylstilboestrol (DES) during a foetal period known to be critical for gonadal development were evaluated. Rats were exposed to DES (100 microg/kg body-weight) from day 17 to 19 of pregnancy. All of the DES-treated pregnant rats (11/11) ate parts or whole of their offspring during the first day after birth (p=0.03). Surviving male offspring were examined on day 63 post-partum. DES induced a reduction in weight of the testis (p=0.06) and ventral prostate (p=0.07), even after this short exposure. DES tended to reduce the number of Sertoli cells (p=0.13). Our findings indicate that even a short in utero exposure of rats to DES during a critical period for gonadal development results in cannibalism and reduced testis and ventral prostate weight.

A novel isoform of human cyclic 3',5'-adenosine monophosphate-dependent protein kinase, c alpha-s, localizes to sperm midpiece

Using rapid amplification of cDNA ends, a cDNA encoding a novel splice variant of the human C alpha catalytic subunit of cAMP-dependent protein kinase (PKA) was identified. The novel isoform differed only in the N-terminal part of the deduced amino acid sequence, corresponding to the part encoded by exon 1 in the previously characterized murine C alpha gene. Sequence comparison revealed similarity to an ovine C alpha variant characterized by protein purification and micropeptide sequencing, C alpha-s, identifying the cloned human cDNA as the C alpha-s isoform. The C alpha-s mRNA was expressed exclusively in human testis and expression in isolated human pachytene spermatocytes was demonstrated. The C alpha-s protein was present in ejaculated human sperm, and immunofluorescent labeling with a C alpha-s-specific antibody indicated that C alpha-s was localized in the midpiece region of the spermatozoon. The majority of C alpha-s was particulate and could not be released from the sperm midpiece by cAMP treatment alone. Furthermore, detergent extraction solubilized approximately two-thirds of the C alpha-s pool, indicating interaction both with detergent-resistant cytoskeletal and membrane structures. In addition, we recently identified the regulatory subunit isoforms RI alpha, RII alpha, and an A-kinase anchoring protein, hAKAP220 in this region in sperm that could target C alpha-s. This novel C alpha-s splice variant appeared to have an independent anchor in the human sperm midpiece as it could not be completely solubilized even in the presence of both detergent and cAMP.

Localization of a novel human A-kinase-anchoring protein, hAKAP220, during spermatogenesis

Using a combination of protein kinase A type II overlay screening, rapid amplification of cDNA ends, and database searches, a contig of 9923 bp was assembled and characterized in which the open reading frame encoded a 1901-amino-acid A-kinase-anchoring protein (AKAP) with an apparent SDS-PAGE mobility of 220 kDa, named human AKAP220 (hAKAP220). The hAKAP220 amino acid sequence revealed high similarity to rat AKAP220 in the 1167 C-terminal residues, but contained 727 residues in the N-terminus not present in the reported rat AKAP220 sequence. The hAKAP220 mRNA was expressed at high levels in human testis and in isolated human pachytene spermatocytes and round spermatids. The hAKAP220 protein was present in human male germ cells and mature sperm. Immunofluorescent labeling with specific antibodies indicated that hAKAP220 was localized in the cytoplasm of premeiotic pachytene spermatocytes and in the centrosome of developing postmeiotic germ cells, while a midpiece/centrosome localization was found in elongating spermatocytes and mature sperm. The hAKAP220 protein together with a fraction of PKA types I and II and protein phosphatase I was resistant to detergent extraction of sperm tails, suggesting an association with cytoskeletal structures. In contrast, S-AKAP84/D-AKAP1, which is also present in the midpiece, was extracted under the same conditions. Anti-hAKAP220 antisera coimmunoprecipitated both type I and type II regulatory subunits of PKA in human testis lysates, indicating that hAKAP220 interacts with both classes of R subunits, either through separate or through a common binding motif(s).

Regulation of tissue inhibitor of metalloproteinases-1 in rat Sertoli cells: induction by germ cell residual bodies, interleukin-1alpha, and second messengers

In the testis, FSH has been shown to induce the expression and secretion of tissue inhibitor of metalloproteinases-1 (TIMP-1) from Sertoli cells in vitro. This study was performed to elucidate further the cellular origin of testicular TIMP-1 and its expression by hormonal and paracrine factors. This is the first report on the expression of testicular TIMP-1 in vivo. TIMP-1 mRNA in whole testis was decreased after hypophysectomy and strongly increased by the injection of FSH-S17 to hypophysectomized rats. Primary cultures of both peritubular and Sertoli cells showed basal expression of TIMP-1 mRNA. In contrast, we were unable to detect TIMP-1 mRNA in Leydig cells, freshly isolated immature germ cells (primary spermatocytes and spermatids), or residual bodies. We further show that treatment of Sertoli cells with 8-(4-chlorophenyl)thio-cAMP (8-CPTcAMP) in combination with 12-O-tetradecanoylphorbol 13-acetate (TPA) or Ca(2+) inducers (calcium ionophore A23187 or thapsigargin) had additive (TPA) and synergistic effects (Ca(2+)) on the level of TIMP-1 mRNA and secreted protein. We also show that both the level of TIMP-1 mRNA and secreted protein from Sertoli cells were strongly increased by residual bodies, as well as by the cytokine interleukin-1alpha. TIMP-1 was not up-regulated by either 8-CPTcAMP or interleukin-1alpha in peritubular cells. In contrast to the regulated secretory fraction of TIMP-1, we also detected constitutively expressed immunoreactive TIMP-1 in the nucleus of Sertoli cells, suggesting a role of nuclear TIMP-1 in these cells. In conclusion, our data show that secretion of TIMP-1 from Sertoli cells is highly regulated by hormonal and local processes in the testis, indicating that TIMP-1 is of physiological importance during both testicular development and spermatogenesis.

The pathway from arachidonic to docosapentaenoic acid (20:4n-6 to 22:5n-6) and from eicosapentaenoic to docosahexaenoic acid (20:5n-3 to 22:6n-3) studied in testicular cells from immature rats

The concentration-dependent metabolism of 1-(14)C-labelled precursors of 22:5n-6 and 22:6n-3 was compared in rat testis cells. The amounts of [(14)C]22- and 24-carbon metabolites were measured by HPLC. The conversion of [1-(14)C]20:5n-3 to [3-(14)C]22:6n-3 was more efficient than that of [1-(14)C]20:4n-6 to [3-(14)C]22:5n-6. At low substrate concentration (4 microM) it was 3.4 times more efficient, reduced to 2.3 times at high substrate concentration (40 microM). The conversion of [1-(14)C]22:5n-3 to [1-(14)C]22:6n-3 was 1.7 times more efficient than that of [1-(14)C]22:4n-6 to [1-(14)C]22:5n-6 using a low, but almost equally efficient using a high substrate concentration. When unlabelled 20:5n-3 was added to a cell suspension incubated with [1-(14)C]20:4n-6 or unlabelled 22:5n-3 to a cell suspension incubated with [1-(14)C]22:4n-6, the unlabelled n-3 fatty acids strongly inhibited the conversion of [1-(14)C]20:4n-6 or [1-(14)C]22:4n-6 to [(14)C]22:5n-6. In the reciprocal experiment, unlabelled 20:4n-6 and 22:4n-6 only weakly inhibited the conversion of [1-(14)C]20:5n-3 and [1-(14)C]22:5n-3 to [(14)C]22:6n-3. The results indicate that if both n-6 and n-3 fatty acids are present, the n-3 fatty acids are preferred over the n-6 fatty acids in the elongation from 20- to 22- and from 22- to 24-carbon atom fatty acids. In vivo the demand for 22-carbon fatty acids for spermatogenesis in the rat may exceed the supply of n-3 precursors and thus facilitate the formation of 22:5n-6 from the more abundant n-6 precursors.

Fish model for assessing the in vivo estrogenic potency of the mycotoxin zearalenone and its metabolites

The in vivo estrogenic potency of zearalenone (ZEA), a mycotoxin produced by different strains of Fusarium fungi, and its metabolites (alpha- and beta-zearalenol), have been studied in fish. Estrogenicity was evaluated using an in vitro competitive receptor binding assay and in vivo induction of vitellogenesis and zonagenesis, two estrogen receptor (ER)-mediated responses that are integral aspects of fish oogenesis. The ER binding affinities of alpha-zearalenol and ZEA in rainbow trout (Oncorhynchus mykiss) were approximately 1/150 and 1/300 to that of estradiol, respectively. Juvenile salmon (Salmo salar) were exposed to a single intraperitoneal injection of ZEA, alpha-zearalenol and beta-zearalenol (each at 1 and 10 mg/kg) and compared to fish injected with estradiol-17 beta (E2; 5 mg/kg) and controls. Using indirect enzyme-linked immunosorbent assay (ELISA) with homologous antibodies, a dose-dependent induction of vitellogenin (Vtg) and eggshell zona radiata proteins (Zr-proteins) were observed 7 days after exposure to ZEA and alpha-zearalenol. beta-Zearalenol did not elevate plasma Vtg levels, but a non-significant elevation of plasma Zr-proteins levels was observed at the highest dose (10 mg/kg). Generally, alpha-zearalenol and ZEA possess estrogenic potencies that are approximately 50% compared to that of E2, and their order of estrogenic potency (in both in vitro receptor competitive binding and in vivo induction of Vtg and Zr-proteins levels) is: alpha-zearalenol > ZEA > beta-zearalenol. Our results show that blood plasma analysis of Vtg and Zr-proteins levels provides a suitable in vivo fish model for assessing the estrogenic potencies of ZEA and its metabolites.

A sensitive zonagenetic assay for rapid in vitro assessment of estrogenic potency of xenobiotics and mycotoxins

Mounting evidence confirms that hepatic biosynthetic processes are essential for female sexual maturation in fish, which is directly controlled by estrogens. These oogenetic events (zonagenesis and vitellogenesis) are induced in both sexes by estrogens. In this paper, we report the induction of zona radiata (zr) proteins and vitellogenin in primary hepatocytes from Atlantic salmon (Salmo salar L.) exposed to xenoestrogens and mycotoxins. Cells were treated with doses of 1, 5, and 10 microM 4-nonylphenol (4-NP), o, p'-DDT, lindane ([gamma]-HCH), and bisphenol A (BPA), which all induced zr proteins and vitellogenin in an approximate dose-dependent manner. Hepatocytes were also treated with combinations of xenoestrogens at 1 or 2 microM, resulting in elevated levels of both zr proteins and vitellogenin, compared to single treatment. The estrogenic activity of the mycotoxin zearalenone (ZEA) and its metabolites [alpha]-ZEA) and ss-zearalenol (ss-ZEA)], with regard to zonagenesis and vitellogenesis, was assessed in this assay system. Mycotoxins were used at concentrations of 10, 100, or 1,000 nM. All induced zr proteins and vitellogenin, with [alpha]-ZEA being the strongest inducer. When cells were treated with xenoestrogens or mycotoxins in combination with an estrogen receptor inhibitor (ICI 182,780), the induction of both zr proteins and vitellogenin was inhibited in all cases. Thus, the reported estrogen effects are bonafide estrogen responses. Zona radiata proteins were more responsive than vitellogenin to both xenoestrogens and mycotoxins. The versatility and sensitivity of the hepatocyte assay demonstrates that biosynthesis of zr proteins provides a new supplementary method for estimating xenoestrogenicity and mycotoxin action.

A comparative study of the metabolism of n-9, n-6 and n-3 fatty acids in testicular cells from immature rat

Dietary 18 and 20-carbon fatty acids of the n-6 and the n-3 families are metabolized to 22:5,n-6 and 22:6,n-3 by a sequence of specific desaturases and chain elongation via 24-carbon intermediates. This pathway is regulated so that more 22:6,n-3 than 22:5,n-6 is found in the tissues. Rat testis is an exception since 22:5,n-6 is present in large proportions in this organ. Therefore rat testis appears to be interesting for studies of the detailed synthesis of 22:5,n-6 compared with that of 22:6,n-3. By using fresh preparations of rat testicular cells from 19-day-old rats enriched in Sertoli cells, we compared the metabolism of 1-14C-labelled n-3, n-6 and n-9 fatty acids. The testicular cells actively synthesized 22:6,n-3 and 22:5, n-6, but not 22:4,n-9 from the 18 and 20-carbon precursors. Of 200 mol 14C-labelled C18 and C20 fatty acids added initially, approximately 20-40 mol were found as 24-carbon intermediates after 24 h of incubation. This indicates that the balanced capacity of elongation, desaturation and chain shortening favours the accumulation of 24-carbon intermediates in these cells. One exception was [1-14C]20:3,n-9 which was efficiently elongated to 22:3,n-9 but not to C24 fatty acids. Our data suggests that the poor elongation of n-9 fatty acids from C22- to C24 may be an important hindrance in the synthesis of 22:4,n-9. The efficient synthesis of 22:5,n-6 may also partly explain why this is the major 22-carbon fatty acid in rat testis.

Elevated expression of lanosterol 14alpha-demethylase (CYP51) and the synthesis of oocyte meiosis-activating sterols in postmeiotic germ cells of male rats

Mammalian CYP51 encodes lanosterol 14alpha-demethylase (P45014DM) that is involved in the postsqualene part of cholesterol biosynthesis. This enzyme removes the 14alpha-methyl group from lanosterol and 24,25-dihydrolanosterol producing intermediates in cholesterol biosynthesis, the oocyte meiosis-activating sterols FF-MAS and MAS-412. Human and rat CYP51 messenger RNAs (mRNAs) are expressed in all tissues, with highest levels in the testis due to the presence of an additional shorter CYP51 transcript in this tissue. In situ hybridization shows the highest CYP51 mRNA levels in seminiferous tubules, with only background levels in Leydig cells. The rat testis-specific CYP51 mRNA arises from the use of an upstream polyadenylation site and is restricted to germ cells, being most abundant in elongating spermatids in stages VII-XIV, whereas somatic CYP51 transcripts are present in all cells. In contrast, the mRNA levels of squalene synthase are maximal in round spermatids, and no germ cell-specific transcript is observed. The rat male germ cell-specific CYP51 transcript is translated in vitro to two proteins of approximately 55 and 53.5 kDa. CYP51 activity is higher in protein extracts of testes and germ cells of sexually mature rats than in prepubertal animals, in which postmeiotic germ cells are not yet present. This shows increased capacity for the production of MAS sterols by male germ cells that have already completed meiosis, suggesting that they serve a role different from meiosis activation.

The gene encoding the C gamma catalytic subunit of cAMP-dependent protein kinase is a transcribed retroposon

Three different catalytic isoforms of cAMP-dependent protein kinase have been identified (C alpha, C beta, and C gamma). We report the cloning and characterization of the human and rhesus monkey genes encoding the testis-specific C gamma subunit. The human C gamma gene is intronless with an open reading frame similar to the previously published cDNA sequence. The 3' and 5' flanking regions share high similarity with the C alpha nontranslated regions (82%) also outside the regions corresponding to the C gamma cDNA. The human gene is flanked by an Alu-related sequence in the 5'-end and there are insertions of two Alu-related sequences in the 3' nontranslated region. The observation that the C gamma gene is intronless and colinear with C alpha mRNA, together with the presence of remnants of a poly(A) tail and flanking direct repeats, indicates that the C gamma gene is a C alpha-derived retroposon. The 5' flanking region of this gene has a high G/C content and a putative TATA box situated at -138 compared to the translation initiation codon. Cloning and sequencing of a partial C gamma rhesus monkey gene demonstrate conservation of the sequence in primates. Northern analysis on isolated and fractionated human germ cells of testes from normal and estrogen-treated individuals demonstrates that the C gamma gene is expressed only in germ cells in the human testis. Our results indicate that the C gamma gene is a retroposon specifically transcribed in primate testicular germ cells.

pH of human semen

The World Health Organization (WHO) laboratory manual (1992) states the normal values for pH in liquefied semen to be between 7.2 and 8.0. This implies an adjustment compared with the previous version (WHO, 1987) in which the upper limit was 7.8, whereas in the WHO clinical manual (1993) the normal range of values is still stated to be in the range of 7.2-7.8. In this study pH was measured in ejaculates from 207 men in couples undergoing infertility examination. The pH was measured within 30 and 60 min after ejaculation with both pH paper and pH meter. The mean pH values were consistently well above 8.0 regardless of analysis method and time after ejaculation. Since semen analysis is part of clinical assessment of male infertility and includes pH measurement, our findings suggest that the range of normal values needs to be revised further.

Residual bodies and IL-1alpha stimulate expression of mRNA for IL-1alpha and IL-1 receptor type I in cultured rat Sertoli cells

The cytokine interleukin (IL)-1alpha may be produced both by Sertoli cells and immature male germ cells from rat and is thought to play a role in autocrine and/or paracrine regulation of the spermatogenesis. The localization of IL-1 receptors in seminiferous tubules is unknown. In this study we found a constitutive expression of IL-1 receptor type I (IL-I RI) mRNA in cultured Sertoli cells and peritubular cells from rat, whereas no such transcripts were observed in immature germ cells (pachytene spermatocytes and round spermatids). An autostimulation of IL-1alpha mRNA synthesis has previously been described in other cell types. Stimulation of Sertoli cells with recombinant IL-1alpha for 0-7 h resulted in a rapid increase in both IL-1alpha and IL-1 RI mRNA. When Sertoli cells were cultured with residual bodies for 0-48 h, mRNA levels for both IL-1alpha and IL-1 RI were increased in a biphasic manner. We suggest that phagocytosis of residual bodies triggers an autocrine IL-1alpha loop in Sertoli cells where both IL-1alpha and one of its receptors are stimulated.

The alpha-subunit mRNAs for Gs and Go2 are differentially regulated by protein kinase A and protein kinase C in rat Sertoli cells

In the present study, we have examined regulatory effects of protein kinase A and protein kinase C activation by 8-CPTcAMP and TPA, respectively, on mRNAs for various G protein alpha-subunits and corresponding immunoreactive proteins in rat Sertoli cells. Gs alpha and Go alpha mRNA levels were transiently increased 1.5-fold and 4-fold, respectively, by 8-CPTcAMP in cultured Sertoli cells. This up-regulation of mRNAs for Gs alpha and Go alpha was also observed when Sertoli cells were incubated in the presence of FSH. When protein synthesis was inhibited by cycloheximide, the cAMP-mediated stimulation of Gs alpha mRNA was abolished, whereas Go alpha mRNA was superinduced to a 50- to 100-fold higher level than basal. Activation of protein kinase C with TPA had a strong, synergistic effect on cAMP-mediated stimulation of Gs alpha mRNA, whereas the cAMP-mediated stimulation of Go alpha mRNA was completely blocked. Surprisingly, changes in mRNA levels were not accompanied by any alterations in the levels of immunoreactive Gs alpha and Go alpha proteins.

The mature form of interleukin-1 alpha is constitutively expressed in immature male germ cells from rat

In the present study we show that immature germ cells from rat testis contain both interleukin-1 alpha (IL-1 alpha) mRNA and immunoreactive proteins. In contrast, in primary cultures of Sertoli cells and peritubular cells. IL-1 alpha mRNA and immunoreactive protein were below the levels of detection. Immunoblots of lysates from these germ cells showed the presence of strong 17 kDa bands (mature forms of IL-1 alpha) and a much weaker 33 kDa band (precursor form). The finding of cell-associated mature forms of IL-1 alpha in germ cells indicates that immature male germ cells are able to process IL-1 alpha independent of its secretion. Data from isolated cell fractions, as well as from whole testis tissue from rats of various ages, indicate that IL-1 alpha expression takes place in late pachytene spermatocytes and early round spermatids. Whether IL-1 alpha plays a role intracellularly in germ cells or exerts its effects on neighboring Sertoli cells remains to be shown.

Cell-specific expression of Gq/11 protein and mRNA in rat seminiferous tubules

As part of a study to elucidate the involvement of G proteins in signal transduction in testicular cells, we have examined the cellular localization of Gq/11 within the seminiferous tubules. The somatic cells (Sertoli cells, peritubular cells) contain high amounts of both Gq/11 alpha mRNA and immunoreactive protein. In contrast, very low levels of these G proteins and the corresponding mRNAs are present in the germ cells (pachytene spermatocytes, round spermatids). Thus, in the germ cells, receptor-regulated inositol phospholipid hydrolysis is not likely to be regulated via Gq/11, but rather through the Go protein, which has been previously shown to be abundant in rat germ cells. Since the somatic cells are nearly devoid of Go, the Gpp(NH)p-stimulated phospholipase C in these cells is probably regulated by Gq and/or G11.

Serum factors induce messenger ribonucleic acid levels for cellular retinol-binding protein in rat Sertoli cells

This report shows that serum factors dramatically increase the levels of mRNA for cellular retinol-binding protein (CRBP) in cultured rat Sertoli cells. Incubation of rat Sertoli cells (0-24 h) with 10% fetal calf serum (FCS) was associated with a time-dependent increase in CRBP mRNA levels. A significant increase (6-fold) was observed after 3 h of incubation. Maximal levels (15- to 50-fold) were reached after 9-12 h and were maintained for as long as serum was present. The effect was concentration dependent, with maximal induction at 10% FCS. Removal of FCS resulted in a decline in the CRBP mRNA levels, with a t1/2 of approximately 7 h. The CRBP mRNA stimulating activity (CMSA) was completely removed from FCS by precipitation with 5% trichloroacetic acid, but was only partly (50%) inhibited by heating at 100 C or trypsin treatment. Removal of retinol from FCS by repeated ether extractions did not alter the CMSA of FCS. Both the induction and degradation of CRBP mRNA were inhibited by the protein synthesis inhibitor cycloheximide. A nuclear protein binding to the 5'-flanking region of the CRBP gene was detected in nuclear extracts from untreated Sertoli cells, but not in nuclear extracts from Sertoli cells treated with 10% FCS for 3 h. Thus, serum factors, different from retinoids, dramatically stimulate the levels of CRBP mRNA in rat Sertoli cells. This is associated with the loss of protein binding to the 5'-flanking region of the CRBP gene.

Evidence for a novel splice variant of the alpha subunit of Go in rat male haploid germ cells

Northern analysis shows that Go alpha mRNA is highly expressed in immature germ cells from rat. Whereas alpha o2 mRNA is the major form in pachytene spermatocytes, a message of shorter chain length is present in large amount in haploid germ cells. This mRNA was detected with an oligonucleotide specific for the 3'-coding region of alpha o2, but did not hybridize to oligonucleotides specific for the 5'-untranslated and 5'-coding regions. The results indicate the presence of a novel splice variant of alpha o mRNA, which may code for a Go alpha protein important for germ cell development.

Regulation of G protein mRNA levels by thyroliberin, vasoactive intestinal peptide and somatostatin in prolactin-producing rat pituitary adenoma cells

We have investigated the regulation of mRNA levels of alpha- and beta-subunits of guanine nucleotide-binding regulatory proteins (G proteins) by peptide hormones in prolactin producing rat pituitary adenoma cells (GH3 cells) in culture. The cells were treated with thyroliberin (1 microM), vasoactive intestinal peptide (1 microM) or somatostatin (10 microM) for 6 to 48 hours. Thyroliberin and vasoactive intestinal peptide increased the levels of Gs alpha Go alpha, Gi-2 alpha, Gi-3 alpha, Gx alpha, G beta 36 and mRNAs. The effect of vasoactive intestinal peptide was however earlier and more pronounced. Gi-2 alpha mRNA levels showed the quantitatively largest alterations. Somatostatin upregulated Gs alpha and downregulated Go alpha and Gi-2 mRNAs. G protein mRNAs for Gi-2 alpha and Go alpha were increased by exposure of the cells to a medium devoid of serum. We conclude that G protein mRNA levels are subjected to alterations by hormones that act through the corresponding G proteins in the regulation of prolactin synthesis and secretion.

Cell-specific expression of guanine nucleotide-binding proteins in rat testicular cells

Guanine nucleotide-binding proteins (G proteins) are key components in membrane signal transduction that may play an important role in testis function. The present study is the first description of cell-specific differences in the contents of G protein alpha-subunits and their mRNAs in isolated rat testicular cells (pachytene spermatocytes, round spermatids, Sertoli cells, peritubular cells). By using Western blot techniques G1-3 alpha was shown to be the only pertussis toxin (PTX) substrate present in all the testicular cells examined. Surprisingly, we observed a lack of immunoreactive Gi-1 alpha/Gi-2 alpha protein in pachytene spermatocytes and round spermatids in spite of significant levels of the corresponding mRNAs as revealed by Northern analysis. No immunoreactive Gs alpha was detected in germ cells, in agreement with previous findings that the hormone-sensitive adenylyl cyclase is absent in these cell types. Peritubular cells and Sertoli cells contained no Go alpha, whereas high levels of both immunoreactive protein and mRNA were found in pachytene spermatocytes. This indicates that the Go protein may play a role at this stage of spermatogenesis. The stimulation of phospholipase C (PLC) in germ cell membranes by 5'-guanylyl imidophosphate indicates that PTX-sensitive PLC activation may be mediated by Go alpha or Gi-3 alpha.

Cell specific distribution of guanine nucleotide-binding regulatory proteins in rat pituitary tumour cell lines

To investigate the effects of guanine nucleotide-binding regulatory proteins (G proteins) on hormonal regulation of prolactin (PRL) synthesis and secretion, the qualitative distribution of G protein alpha-subunits and their mRNAs was studied in three functionally different pituitary tumour cell lines (GH cells) and normal rat pituitary tissue. Levels of basal and modulated adenylyl cyclase (AC) and phospholipase C (PLC) activities are also included. GH cells and pituitary tissue contained various amounts of mRNAs and protein for Gs alpha, Gi-2 alpha, Gi-3 alpha and Go alpha, while mRNA for Gi-1 alpha was only detected in normal pituitary tissue. Gz alpha/Gx alpha mRNA was expressed in all pituitary cell lines as well as in pituitary tissue. Go alpha mRNA and Gz alpha/G x alpha mRNA displayed size heterogeneity. These findings may have importance in the understanding of hormone regulation of second messenger systems.

A unique mRNA species for the alpha subunit of Gs is present in rat haploid germ cells

The 1.9 kb mRNA encoding the alpha subunit of Gs observed in the somatic cells of the rat testis was not seen in the germ cells (pachytene spermatocytes and round spermatids) as revealed by Northern blot analysis. Interestingly, the cDNA probe for Gs alpha detected a mRNA of shorter chain length (0.9 kb) exclusively in the haploid germ cells (round and elongated spermatids). However, no ADP ribosylated protein was detected in membranes from germ cells after cholera toxin treatment. The 0.9 kb transcript may represent a haploid germ cell-specific variant of Gs alpha, which is functionally different from the stimulatory component of the adenylate cyclase system.

[G proteins: GTP binding proteins in signal transduction]

A family of GTP-binding proteins (G proteins) couples receptors for hormones and neurotransmitters to diverse effectors in the cell. G proteins are membrane-bound GTPases composed of three distinct polypeptides. Cyclic AMP production, phosphoinositide breakdown, and ion channels are all known to be regulated via G proteins. Functional characterization, protein purification, labelling with bacterial toxins, specific antibodies and molecular cloning are tools which have helped to provide information on these proteins. Although the molecular properties of several G proteins are well known, the correct functional assignments are complex. Furthermore, we do not know how the various signal systems are involved in regulation of G protein activity.

Cellular distribution, developmental changes and effects of cryptorchidism on uridine kinase in the rat testis

High specific activity of uridine kinase was found in cultured peritubular cells (3.0 nmol/min per mg protein) which was more than 3-fold higher than that found in cultured Sertoli cells (0.79 nmol/min per mg protein). In the various classes of germ cells a decrease in specific uridine kinase activity was associated with increased maturity of the cells, primary spermatocytes, round spermatids and spermatozoa showing 1.3, 0.65 and 0.16 nmol/min per mg protein, respectively. A relationship between uridine kinase activity and the rate of RNA synthesis in these cells is suggested. A decrease in specific uridine kinase activity in testis with increasing age supports the finding of lower uridine kinase in mature germ cells than in earlier germ cells and somatic cells. This finding is further supported by the observation that cryptorchidism, which is associated with a time-dependent depletion of germ cells, resulted in an increase in specific uridine kinase activity. The results indicate that pyrimidine salvage is important in earlier germ cells, as well as in somatic cells in the testis, to produce substrates for nucleic acid synthesis.

Effects of cryptorchidism and orchidopexy on deoxyribonucleoside-activated nucleotidase (DAN) in the rat testis

1. Unilateral cryptorchidism was associated with an increase in specific DAN activity in the abdominal testis of adult rats. 2. In the scrotal, immature testis, there was an age-dependent decrease in specific DAN activity similar to that normally seen in rats. This decrease was less pronounced in the abdominal testis of unilaterally cryptorchid rats. 3. Total DAN activity in the abdominal testis showed a decrease in both immature and adult rats, when compared to that of the scrotal testis. 4. Orchidopexy following cryptorchidism in adult rats, resulted in complete restoration of DAN activity in spite of poor recovery of spermatogenesis.

Cellular localization and developmental changes of deoxyribonucleoside-activated nucleotidase in the rat testis

Specific deoxyribonucleoside-activated nucleotidase (DAN) activity showed a rapid decline during the exponential increase in testis weight between 25 and 35 days of age. Specific DAN activity in Sertoli cells was dependent on the amount of cytosol in the enzyme assay. At optimal cytosol concentration the measured value was 50 units/mg of protein. Specific DAN activity in peritubular cells, primary spermatocytes and round spermatids was 13, 3.7 and 3.1 units/mg, respectively, and was independent of the cytosol concentration in the assay.

The presence and activity in normal and regenerating rat liver postmicrosomal supernatant fraction of an enzyme with properties similar to those of membrane-bound 5'-nucleotidase

An alkaline 5'-nucleotidase with properties similar to those of membrane-bound 5'-nucleotidase was recovered in soluble form in the postmicrosomal supernatant fraction (cytosol) of rat liver. The enzyme seems to constitute a quantitatively distinct fraction, since the activity in postmicrosomal supernatants was increased by a further 10% by additional homogenization of livers. Lysosomal acid phosphatase activity increased similarly, whereas other membrane-bound marker enzymes alkaline phosphatase, phosphodiesterase I and glucose-6-phosphatase showed no increase when homogenization of liver tissue was continued. Gel-permeation chromatography and pH-dependence studies indicated that enzyme activity in the supernatant fraction with 0.3 mM-UMP or -AMP as substrate at pH 8.1 was about 85 or 100% specific respectively. In regenerating liver the enzyme recovered in soluble form showed decreased specific activity, in contrast with alkaline phosphatase measured for comparison. The nucleotidase activity per mg of cytosolic protein was 2.1 nmol/min with AMP as substrate. The total activity measured in the postmicrosomal supernatant was 1.5% of the homogenate activity measured in the presence of detergent.

Measurement and activity of cytosolic deoxyribonucleoside-activated nucleotidase in various cell types from rat liver and spleen

The enzyme activity was measured in hepatocytes, Kupffer cells, endothelial cells and spleen cells. Hepatocytes showed proportionality between enzyme activity and cytosol concentration, but with Kupffer cells, endothelial cells and spleen cells the specific activity decreased with decreasing cytosol concentration when the amount of cytosol protein in 250 microliters incubation mixture was below 80, 60 and 20 micrograms, respectively. The specific activities in hepatocytes, Kupffer cells, endothelial cells and spleen cells were 2, 16, 18 and 115 nmol/min per mg of cytosol protein, respectively.