Aromatization and antioxidant capacity in the testis of seasonally breeding bank voles: Effects of LH, PRL and IGF-I

Toward understanding the role of the interstitial tissue architects: Possible functions of telocytes in the male gonad

Telocytes represent a relatively recently discovered population of interstitial cells with a unique morphological structure that distinguishes them from other neighboring cells. Through their long protrusions extending from the cell body, telocytes create microenvironments via tissue compartmentalization and create homo- and hetero-cellular junctions. These establish a three-dimensional network enabling the maintenance of interstitial compartment homeostasis through regulation of extracellular matrix organization and activity, structural support, paracrine and juxtracrine communication, immunomodulation, immune surveillance, cell survival, and apoptosis. The presence of telocytes has also been confirmed in testicular interstitial tissue of many species of animals. The objective of this review is to summarize recent findings on telocytes in the male gonad, on which conclusions have been deduced that indicate the involvement of telocytes in maintaining the cytoarchitecture of the testicular interstitial tissue, in the processes of spermatogenesis and steroidogenesis, and photoperiod-mediated changes in the testes in seasonally reproductive animals.

Association between levels of insulin-like growth factor-1 in serum and seminal plasma with fresh and frozen-thawed semen characteristics in Beetal bucks

The aim of this study was to investigate the relationship between the levels of insulin-like growth factor-1 (IGF-1) in serum and seminal plasma and the characteristics of semen in Beetal bucks (Capra hircus). A total of 12 adult Beetal bucks were involved in the study, with each buck providing six ejaculates collected using a standard artificial vagina (n = 72 total). Only qualified semen samples (volume of 0.7 mL, a mass motility rating of 3+ or higher on a 0-+ scale, and individual progressive motility of 80% or more) divided into three fractions were processed for estimation of IGF-1 and other seminal parameters like motility, viability, acrosome integrity, sperm abnormality and superoxide dismutase (SOD) activity. The first and second fraction were diluted and extended with Optixcell extender (1:15 ratio). The first ejaculate fraction was processed for studying fresh semen parameters and the second fraction was cryopreserved for evaluating frozen semen parameters. French mini straws (0.25 mL) were used for semen filling, and polyvinyl alcohol powder of different colours was used for sealing the extended semen. The third fraction of each ejaculate was centrifuged at room temperature (1100 × g for 7 min) to separate the seminal plasma. Additionally, blood samples were taken from each buck on the same day as semen collection, resulting in a total of 36 blood samples. The results revealed a significant positive correlation (r = .4243; p < .05) between the concentration of IGF-1 in both serum and seminal plasma of the Beetal bucks. Furthermore, the concentration of IGF-1 in serum showed significant positive correlations with sperm viability (r = .554; p < .05), acrosome integrity (r = .527; p < .05), post-thaw sperm motility (r = .407; p < .01), post-thaw sperm viability (r = .426; p < .01) and post-thaw acrosome integrity (r = .333; p < .05). However, it had a significant negative correlation with SOD activity in fresh semen (r = -0.458; p < .01). Moreover, the concentration of IGF-1 in seminal plasma demonstrated significant positive correlations with individual progressive motility (r = .341; p < .05), sperm viability (r = .527; p < .05), acrosome integrity (r = .539; p < .05), sperm plasma membrane integrity (r = .464; p < .05), post-thaw sperm motility (r = .644; p < .01), post-thaw sperm viability (r = .643; p < .01), post-thaw acrosome integrity (r = .487; p < .01) and post-thaw sperm plasma membrane integrity (r = .521; p < .01). Additionally, it showed a significant negative correlation with SOD activity in both fresh semen (r = -0.714; p < .01) and frozen semen (r = -0.558; p < .01) of Beetal bucks. Based on these findings, IGF-1 in seminal plasma can be considered as a potential biomarker for the selection of bucks for breeding purposes.

Flutamide treatment reveals a relationship between steroidogenic activity of Leydig cells and ultrastructure of their mitochondria

Our present knowledge on interrelation between morphology/ultrastructure of mitochondria of the Leydig cell and its steroidogenic function is far from satisfactory and needs additional studies. Here, we analyzed the effects of blockade of androgen receptor, triggered by exposure to flutamide, on the expression of steroidogenic proteins (1) and ultrastructure of Leydig cells' constituents (2). We demonstrated that increase in the expression level of steroidogenic (StAR, CYP11A1, 3β-HSD, and CYP19A1) proteins (and respective mRNAs) in rat testicular tissue as well as elevation of intratesticular sex steroid hormone (testosterone and estradiol) levels observed in treated animals correspond well to morphological alterations of the Leydig cell ultrastructure. Most importantly, up-regulation of steroidogenic proteins' expression apparently correlates with considerable multiplication of Leydig cell mitochondria and subsequent formation of local mitochondrial networks. Interestingly, we showed also that the above-mentioned processes were associated with elevated transcription of Drp1 and Mfn2 genes, encoding proteins implicated in mitochondrial dynamics. Collectively, our studies emphasize the importance of mitochondrial homeostasis to the steroidogenic function of Leydig cells.

Seasonal expression of insulin-like growth factor 1 (IGF-1), its receptor IGF-1R and klotho in testis and epididymis of the European bison (Bison bonasus, Linnaeus 1758)

The European bisons are the largest mammals of Europe that are still in danger of extinction. The species conservation is associated with their continuous reproduction, and bisons are characterized by the well-pronounced seasonality of reproductive processes. However, the exact mechanisms regulating their reproduction still remain unknown. Our previous studies indicated the involvement of some of the growth factors in the regulation of male seasonal reproductive activities in bison, showing expression patterns that seemed to be regulated by the length of the daylight. In the present study, using RT-PCR and Western blot approaches, we verified the expression and possible relationship between the insulin-like growth factor (IGF-1), its receptor (IGF-1R), and klotho in testis and epididymis of the European bison in pre- and post-reproductive periods, i.e., in June and in December. The observed expression of IGF-1 and IGF-1R mRNA in testis and epididymis was higher in June than in December. At the same time, klotho mRNA expression in both testis and epididymis did not differ between the analyzed seasons. However, along with the higher levels of IGF-1R protein observed in June, klotho protein levels for the membrane form and for the secrete form were higher in December than in June. Finally, the messenger and protein expression profiles presented herein indicate the importance of both the IGF-system and klotho in reproductive processes in the European bison, implying their involvement in the regulation of seasonal testicular activity in males of this threatened species.

Differences in aromatase expression and steroid hormone concentrations in the reproductive tissues of male domestic turkeys (Meleagris gallopavo) with white and yellow semen

1. To show hormonal differences between male turkeys with yellow semen syndrome (YSS) and white, normal semen (WNS), the expression of aromatase, oestrogen receptor α (ERα), and oestrogen receptor β (ERβ) as well as testosterone and oestradiol concentrations in YSS and WNS testes, epididymis, and ductus deferens were examined. 2. To measure gene expression levels of aromatase and oestrogen receptors (ERs), three complementary techniques (real-time PCR, Western blot, and immunohistochemistry) were used, whereas steroid hormone levels were determined radio-immunologically. 3. Upregulation of aromatase and ERα mRNAs in YSS testes (P < 0.05; P < 0.01), epididymis (P < 0.001; P < 0.001), and ductus deferens (P < 0.05; P < 0.01) compared to those of WNS tissues was detected. Significant increases in the levels of aromatase and ERα proteins were detected in YSS testes (P < 0.001; P < 0.05), epididymis (P < 0.001; P < 0.001), and ductus deferens (P < 0.001; P < 0.05). The expression of ERβ mRNA and protein level was upregulated in the testes (P < 0.05; P < 0.01) and epididymis (P < 0.001; P < 0.01) but not in ductus deferens where it was downregulated (P < 0.01; P < 0.01). Increased intensity of immunoreactive proteins in YSS versus WNS reproductive tissues corroborated gene expression results. 4. Testosterone concentration diminished in YSS epididymis (P < 0.05) and ductus deferens (P < 0.05), but not in the testes, remaining at high level (P < 0.05) compared to WNS values. Concomitantly, increased oestradiol concentration was found in YSS testes (P < 0.05) and epididymis (P < 0.05) but decreased in the ductus deferens (P < 0.05). 5. From the published literature, this study is the first to demonstrate the ability for androgen aromatisation in the turkey reproductive tissues and to show the cellular targets for locally produced oestrogens. The data suggested that the androgen/oestrogen ratio is a mechanistic basis for amplification of differences between turkeys with white and yellow semen and that these results can have a relevance in applied sciences to widen the knowledge on domestic bird reproduction.

Are aryl hydrocarbon receptor and G-protein-coupled receptor 30 involved in the regulation of seasonal testis activity in photosensitive rodent-the bank vole (Myodes glareolus)?

Within the reproductive system both aryl hydrocarbon receptor (AHR) and G-protein-coupled receptor 30 (GPR30) contribute to estrogen signaling and controlling of reproductive physiology. The specific question is whether and how AHR and GPR30 are involved in regulation of testis function in seasonally breeding rodents. Bank vole testes were obtained from animals reared under 18 hours light:6 hours dark (LD) and 6 hours light:18 hours dark (SD) conditions. Aryl hydrocarbon receptor and GPR30 expression were analyzed by quantitative reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry and/or immunofluorescent staining. In addition, the activity of enzymes involved in the intracellular signal transduction; extracellular signal-regulated kinase (ERK), protein kinase (PKA), matrix metalloproteinase 9 (MMP 9) and the concentrations of cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), and calcium (Ca(2+)) were examined by immunohistochemical, immunoenzymatic, and colorimetric assays, respectively. Aryl hydrocarbon receptor and GPR30 were expressed in testes of actively reproducing voles and regressed ones although their expression at the messenger RNA and AHR also at protein level appeared to be photoperiod-dependent. A specific cellular localization and expression of AHR and GPR30 correlated with the expression of ERK, PKA, and MMP 9. Moreover, we found robust differences in the levels of cAMP, cGMP, and Ca(2+) in testicular homogenates between LD and SD voles. In the testes of LD voles, the levels of second messengers were always higher compared to SD. In vole testis, AHR and GPR30 can induce signaling pathways that involve ERK, PKA, MMP 9 and cAMP, cGMP, Ca(2+). In addition, in AHR, signaling the engagement of both photoperiod and estrogens, whereas in GPR30, signaling only estrogens is reported. It is likely that in vole, because of a differential activity of signaling molecules, signal transduction via AHR rather than through GPR30 plays a role in regulation of seasonal changes of testis physiology.

Effect of stallion age on the expression of LH and FSH receptors and aromatase P450 in equine male reproductive tissues

The aim of the present study was to characterise receptors for LH and FSH (LHR and FSHR, respectively) and aromatase in epididymal and testicular tissue from stallions of different ages (prepubertal, young, mature and old). Gene and protein expression were assessed by real-time quantitative polymerase chain reaction (real-time qPCR), immunohistochemistry and multiple immunofluorescence labelling. There were no differences in LHR mRNA expression in epididymal and testicular parenchyma in stallions of different age. In contrast, expression of FSHR and CYP19A1 in caput, corpus and cauda epididymis and in testicular parenchyma increased with age (P < 0.001). Immunolabelling for LHR, FSHR and aromatase was influenced by puberty. In postpubertal stallions, positive staining for LHR and aromatase was detected in Leydig cells, whereas protein expression of FSHR was present in Sertoli cells and primary spermatocytes. In prepubertal colts, staining for LHR, FSHR and aromatase was detected in seminiferous tubules. In epididymal tissue, aromatase was present in the cauda epididymis only, regardless of age. In conclusion, the results highlight the significance of gonadotropin action and oestrogen production for the maturation of male reproductive tissue in the horse. The presence of FSHR in the seminiferous tubules suggests effects of FSH on spermatogenesis in this species. The importance of oestrogen production for maintenance of testicular function in stallions was confirmed.

Do photoperiod and endocrine disruptor 4-tert-octylphenol effect on spermatozoa of bank vole (Clethrionomys glareolus)?

Photoperiod is an environmental signal that controls physiology and behavior of all organisms. Bank voles, which are seasonal breeders, are stimulated to reproduce by the long photoperiod associated with spring and summer. To date, physiology of bank vole spermatozoa has not been explored, although they constitute an interesting model for examining the relationship between photoperiod and xenoestrogen on spermatozoa function. In an attempt to evaluate the acute effect of 4-tert-octylphenol (OP) an in vitro system was used. Spermatozoa isolated from the cauda epididymidies of long-day (LD; 18 h light: 6 h darkness) and short-day (SD; 6 h light: 18 h darkness) bank voles were treated with two OP concentrations (10(-4) M and 10(-8)M, respectively). OP-treated spermatozoa were used for the examination of motility parameters (computer-assisted semen analyzer CEROS), acrosome integrity (Commassie blue staining), cAMP production (immunoenzymatic assay) and cell viability (flow-cytometry analysis). The study revealed the photoperiod-dependent effect of short OP-treatment on motility parameters of vole spermatozoa. In LD spermatozoa, an increase of velocities: (curvilinear velocity [VCL], average path velocity [VAP] straight line velocity [VSL]) and head activity (amplitude of the lateral head displacement, [ALH]) was found. Interestingly, in SD spermatozoa opposite effect on VCL, VAP, VSL and ALH was observed, however only after treatment with 10(-4)M OP. The dose-dependent influence of OP upon acrosome integrity, as well as cAMP levels, in relation to the reproductive status of voles was observed. Moreover, OP exposure affected spermatozoa morphology rather than spermatozoa viability.

Detection of aromatase, androgen, and estrogen receptors in bank vole spermatozoa

Spermatozoa are highly specialized cells which transport a single-copy haploid genome to the site of fertilization. Before this, spermatozoa undergo a series of biochemical and functional modifications. In recent years, the crucial role of androgens and estrogens in proper germ cell differentiation during spermatogenesis has been demonstrated. However, their implication in the biology of mature male gametes is still to be defined. Our study provides evidence for the first time that aromatase, the androgen receptor (AR), as well as the estrogen receptors α and β (ERα and ERβ), are present in bank vole spermatozoa. We demonstrated the region-specific localization of these proteins in bank vole spermatozoa using confocal microscopy. Immunoreactive aromatase was observed in the proximal head region and in both the proximal and distal tail regions, whereas steroid hormone receptors were found only in the proximal region of the sperm head. Protein expression in sperm lysates was detected by Western blot analysis. Immunohistochemical results were analyzed quantitatively. Our results show that bank vole spermatozoa are both a source of estrogens and a target for steroid hormone action. Moreover, the presence of aromatase and steroid hormone receptors in the bank vole spermatozoa indicates a potential function of these proteins during capacitation and/or the acrosome reaction.

Prenatal and neonatal exposure to flutamide affects function of Leydig cells in adult boar

In this study, flutamide, an androgen receptor antagonist, was used as a tool to better understand the role of androgen receptor signaling and androgen signaling disruption during fetal and neonatal periods on porcine Leydig cell development and function. Flutamide, 50 mg kg(-1) d(-1) was administered into pregnant gilts during gestational days 20 to 28 and days 80 to 88 and into male piglets on postnatal days 2 to 10 (PD2). Leydig cells of flutamide-exposed boars, especially those of PD2 males, displayed morphologic alterations, increased size, and occupied increased area (P < 0.001) of the testes when compared with the control. Despite this, testosterone concentrations were reduced significantly in comparison with those of controls (P < 0.05, P < 0.001). Reduced testosterone production in response to flutamide exposure appeared to be related to changes in testosterone metabolism, as shown by increased aromatase mRNA (P < 0.05, P < 0.01), protein expression (P < 0.01, P < 0.001), and elevated estradiol concentrations (P < 0.001). Moreover, impaired Leydig cell responsiveness to LH was indicated by the decreased expression of LH receptor (P < 0.05, P < 0.001). No significant effect of flutamide was found on LH and FSH concentrations. Taken together, our data indicate that flutamide when administered during prenatal or neonatal period have a long-term effect on Leydig cell structure and function, leading to androgen-estrogen imbalance. Leydig cell failure was most evident in adult boars neonatally exposed to flutamide, suggesting that androgen action during neonatal development is of pivotal importance for the differentiation and function of porcine adult Leydig cell population.

Addition of IGF-I to storage-cooled boar semen and its effect on sperm quality

OBJECTIVE

To evaluate in vitro IGF-I treatment during warming of storage-cooled boar semen and its effect on seminal quality parameters and metabolism in spermatic cells.

DESIGN

Semen samples (n=7) warmed after stored at 15°C for 24 or 72h were divided into four equal parts. Different IGF-I concentrations (0, 50, 100 and 150ng/mL) were added to the semen samples. The samples were incubated at 37°C, and assessments were made after 0 and 120min of incubation.

RESULTS

For semen samples that were stored for 24h, the addition of IGF-I had no effect (p>0.05) on the total motility and intensity of movements by spermatic cells, osmotic resistance, live:dead cell ratio or total spermatic abnormalities. However, incubation with 150ng/mL IGF-I did decrease glutathione peroxidase activity (p<0.05) and reduce lipid peroxidation after 120min of incubation. For semen samples stored for 72h and incubated with IGF-I for 120min, there was a linear relationship between the IGF-I concentration and the live:dead ratio (p<0.05). There was a quadratic relationship between the IGF-I concentration and both the osmotic resistance (peak results at IGF-I=62.4ng/mL) and glutathione peroxidase activity (peak results at IGF-I=77.8ng/mL). There was no effect on lipid peroxidation (p>0.05) after 120min of incubation. Addition of IGF-I also decreased fructose utilization by spermatic cells regardless of semen storage time (p<0.05).

CONCLUSION

This study suggests that IGF-I may be beneficial to semen stored for longer periods of time. Adding 150ng/mL IGF-I improved the quality of semen stored for 24h, and adding 78ng/mL IGF-I improved the quality of semen stored for 72h.

Connexin 43 gene expression in male and female gonads of porcine offspring following in utero exposure to an anti-androgen, flutamide

The aim of this study was to show the effect of maternal exposure to flutamide on connexin 43 (Cx43) gene expression in testes and ovaries of 2-day-old piglets. Additionally, anogenital distance (AGD) was measured both in male and female offspring. Immunohistochemistry, Western blotting, and RT-PCR were performed to assess the immunoreactivity and the presence of Cx43 protein and it's mRNA, respectively. Following flutamide exposure strong immunostaining for Cx43 was observed between testicular Leydig cells, between granulosa cells of primary follicles, and between interstitial cells surrounding clusters of oocyte nests in the ovarian cortex as in the respective controls. Differences between the flutamide-treated groups and the controls obtained by qualitative immunohistochemistry were confirmed by quantitative image analysis (*P<0.05; **P<0.01). In Western blotting, Cx43 appeared as a band of 43kDa, whereas electrophoresis revealed PCR products of the predicted sizes. Screening for Cx43 expression revealed the presence of a transcript, both in control and in flutamide-treated pigs. The AGD values differed significantly from the control (*P<0.05). Overall, since no obvious changes in gonad morphology were observed and the Cx43 signal was present in all the examined tissues, it seems likely that androgens acting through ARs are not involved in the control of Cx43 gene expression in neonatal pig gonads.

Hormones and antioxidant systems: role of pituitary and pituitary-dependent axes

Oxidative stress, a condition defined as unbalancing between production of free radicals and antioxidant defenses, is an important pathogenetic mechanism in different diseases. Despite the abundant literature, many aspects of hormone role in regulating antioxidant synthesis and activity still remain obscure. Therefore, we reviewed experimental data, in vivo and in vitro, about the effects of the different pituitary- dependent axes on antioxidant levels, trying to give a broad view from hormones which also have antioxidant properties to the classic antioxidants, from the lipophilic antioxidant Coenzyme Q10, strictly related to thyroid function, to total antioxidant capacity, a measure of non-protein non-enzymatic antioxidants in serum and other biological fluids. Taken together, these data underline the importance of oxidative stress in various pituitary-dependent disorders, suggesting a possible clinical usefulness of antioxidant molecules.

Protective effects of estrogens and caloric restriction during aging on various rat testis parameters

AIM

To investigate the effects of 17beta-estradiol (E2), Peganum harmala extract (PHE) and caloric restriction (CR) on various testis parameters during aging.

METHODS

Twelve month-old male rats were treated for 6 months with either E2 or PHE, or submitted to CR (40%).

RESULTS

Our results show that estrogens and CR are able to protect the male gonad by preventing the decrease of testosterone and E2 levels as well as the decrease of aromatase and estrogen receptor gene expressions. Indeed, E2, PHE and CR treatments induced an increase in the superoxide dismutase activities and decreased the activity of testicular enzymes: gamma-glutamyl transferase, alkaline phosphatase, lactate deshydrogenase as well as the aspartate and lactate transaminases in aged animals. In addition, the testicular catalase and gluthatione peroxidase activities were enhanced in E2, PHE and CR-treated rats compared to untreated animals at 18 months of age. Moreover, the positive effects of estradiol, PHE and CR were further supported by a lower level of lipid peroxidation. Recovery of spermatogenesis was recorded in treated rats.

CONCLUSION

Besides a low caloric diet which is beneficial for spermatogenesis, a protective antioxydant role of estrogens is suggested. Estrogens delay testicular cell damage, which leads to functional senescence and, therefore, estrogens are helpful in protecting the reproductive functions from the adverse effects exerted by reactive oxygen species (ROS) produced in large quantities in the aged testis.

Immunoexpression of aromatase in immature and adult males of the European bison (Bison bonasus, Linnaeus 1758)

Based on recent literature dealing with the role of oestrogens in the male gonad, attempts were undertaken to reveal the site of aromatization within the testis of the European bison (Bison bonasus). Testes were collected from culled animals living in free-ranging populations in Bialowieza Forest, Poland (nine males aged 8 months to 10 years). Moreover, to check for any alterations in the expression of testicular aromatase between American bison (Bison bison) and European bison, testes from one adult 10-year-old individual were also chosen for this study. For immunohistochemistry, 4% formaldehyde fixative was used. Both qualitative and quantitative evaluations of immunohistochemical staining were performed. Leydig cells, Sertoli cells and germ cells exhibited a positive immunoreaction for aromatase in testes of immature and sexually mature bison. A marked increase in aromatase expression was observed in three adult European individuals with impaired spermatogenesis. Consistent with recent data and those of our own, it might be suggested that the strong expression of aromatase negatively affects spermatogenic function in bison testes and may serve as a possible explanation of specific sperm defects observed in European bison bulls. On the contrary, one cannot exclude that differences in the aromatase immunoexpression levels are attributed to the homozygosity, the cause of frequent disease in European bison.

Morphofunctional alterations in testicular cells of deslorelin-treated boars: an immunohistochemical study

In this study we thoroughly scrutinized testes morphology and investigated whether treatment of recipient boars with gonadotropin-releasing hormone (GnRH)-agonist deslorelin could alter the expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), luteinizing hormone receptors (LHRs), and androgen receptors (ARs) in testicular cells. An implant containing 4.7 mg of the GnRH-agonist deslorelin was subcutaneously inserted into crossbred male pigs at 91 and 147 days of age. Testicular traits, morphology of the testes, the proteins' expression, and testosterone concentration in blood plasma were analyzed in all boars after slaughter at 175 days of age. Histological analysis revealed significant alterations in both the interstitial tissue and seminiferous tubules of experimental animals after 28 and 84 days of deslorelin treatment. The intensity of the AR immunostaining within the testis appeared as a function of the severity of testicular dysgenesis. Time-dependent action of deslorelin on the expression of LHR and 3beta-HSD in Leydig cells was also detected. Staining for LHR and 3beta-HSD was very weak or the Leydig cells were immunonegative. Concomitantly, a significant decrease in plasma testosterone level was found in both groups of deslorelin-treated boars when compared with the control group. This is the first report showing the cellular distribution of AR, LHR, and 3beta-HSD in testicular cells of deslorelin-treated boars. It is concluded that morphological and immunohistochemical studies are important for the evaluation of testicular histoarchitecture and steroidogenic function. Subsequently, the endocrine control of reproduction in the GnRH-agonist deslorelin-treated males will be better understood.