Vimentin expression during altered spermatogenesis in rats

Structural gonadal lesions observed in Japanese quail (Coturnix coturnix japonica) following exposure during puberty to the neonicotinoid pesticide, imidacloprid

Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.

Nicotinamide Mononucleotide Improves Spermatogenic Disorders in Aluminum-Exposed Rats by Modulating the Glycolytic Pathway

This study aimed to investigate the protective effect of nicotinamide mononucleotide (NMN) on testicular spermatogenesis in aluminum chloride (AlCl3)-exposed rats and to elucidate the potential underlying mechanism. The results indicated that AlCl3-induced testicular damage, leading to reduced sperm quality, increased apoptosis, decreased cell proliferation, and impaired Sertoli cell function in rats. Additionally, glycolytic metabolism was observed to be hindered. However, after NMN treatment, there was a noticeable improvement in testicular damage among the rats, marked by increased sperm quality, reduced apoptosis, enhanced cell proliferation, improved Sertoli cell function, and an activated glycolytic metabolism. The findings of this study suggest that NMN alleviates testicular spermatogenesis impairment induced by AlCl3 exposure through the inhibition of spermatogenic cell apoptosis, promotion of spermatogenic cell proliferation, and activation of glycolytic pathways. The study contributes an experimental foundation for potential future clinical applications of NMN in cases of AlCl3-exposed spermatogenic dysfunction.

Omega-3 polyunsaturated fatty acids and its metabolite 12-HEPE rescue busulfan disrupted spermatogenesis via target to GPR120

Busulfan is an antineoplastic, which is always accompanied with the abnormal of spermatogonia self-renewal and differentiation. It has been demonstrated that the omega-3 polyunsaturated fatty acids (PUFAs) benefits mature spermatozoa. However, whether omega-3 can protect endogenous spermatogonia and the detailed mechanisms are still unclear. Evaluate of spermatogenesis function (in vivo) were examined by histopathological analysis, immunofluorescence staining, and western blotting. The levels of lipid metabolites in testicular tissue were determined via liquid chromatography. We investigated the effect of lipid metabolites on Sertoli cells provided paracrine factors to regulate spermatogonia proliferation and differentiation using co-culture system. In our study, we showed that omega-3 PUFAs significantly improved the process of sperm production and elevated the quantity of both undifferentiated Lin28+ spermatogonia and differentiated c-kit+ spermatogonia in a mouse model where spermatogenic function was disrupted by busulfan. Mass spectrometry revealed an increase in the levels of several omega-3 metabolites in the testes of mice fed with omega-3 PUFAs. The eicosapentaenoic acid metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE) up-regulated bone morphogenic protein 4 (BMP4) expression through GPR120-ERK1/2 pathway activation in Sertoli cells and restored spermatogonia proliferation and differentiation. Our study provides evidence that omega-3 PUFAs metabolite 12-HEPE effectively protects spermatogonia and reveals that GPR120 might be a tractable pharmacological target for fertility in men received chemotherapy or severe spermatogenesis dysfunction.

Sericin and melatonin mitigate diethylnitrosamine-instigated testicular impairment in mice: Implications of oxidative stress, spermatogenesis, steroidogenesis, and modulation of Nrf2/WT1/SF-1 signaling pathways

AIMS

This study aimed to investigate the therapeutic influence of combination therapy with sericin and melatonin on attenuating diethylnitrosamine (DEN)-instigated testicular dysfunction in mice and defining the molecular mechanisms involved in orchestrating redox signaling pathways and restoring spermatogenesis and steroidogenesis.

MATERIALS AND METHODS

Different groups of male Swiss albino mice were established and injected with respective drugs intraperitoneally. Semen analysis, hormonal assays, and oxidative stress biomarkers were evaluated. Additionally, melatonin and its receptors, WT1, SF-1, vimentin, Nrf2, and ANXA1 expressions were assessed. Histopathological and ultrastructural features of the testes were investigated by semithin, SEM, and TEM analyses.

KEY FINDINGS

Exposure to DEN exhibited pathophysiological consequences, including a remarkable increase in lipid peroxidation associated with substantial diminutions in SOD, CAT, GPx, GSH, GSH:GSSG, and GST. Furthermore, it disrupted spermatozoa integrity, testosterone, FSH, LH, melatonin, and its receptors (MT1 and MT2) levels, implying spermatogenesis dysfunction. By contrast, treatment with sericin and melatonin significantly restored these disturbances. Interestingly, the combination therapy of sericin and melatonin noticeably augmented the Nrf2, WT1, and SF-1 expressions compared to DEN-treated mice, deciphering the amelioration perceived in antioxidant defense and spermatogenesis inside cells. Furthermore, immunohistochemical detection of ANXA1 alongside histopathological and ultrastructural analyses revealed evident maintenance of testicular structures without discernible inflammation or anomalies in mice administered with sericin and melatonin compared to the DEN-treated group.

SIGNIFICANCE

Our findings highlighted that treatment with sericin and melatonin alleviated the testicular tissues in mice from oxidative stress and dysregulated spermatogenesis and steroidogenesis engendered by DEN.

Immunohistochemical analysis of the vimentin filaments in Sertoli cells is a powerful tool for the prediction of spermatogenic dysfunction

The close interaction between male germ cells and Sertoli cells, a type of somatic cell found in the seminiferous tubules of mammalian testis, is essential for the normal progression of spermatogenesis in mammals. Vimentin is an intermediate filament protein that primarily provides mechanical support, preserves cell shape, and maintains the nuclear position, and it is often used as a marker to identify Sertoli cells. Vimentin is known to be involved in many diseases and aging processes; however, how vimentin is related to spermatogenic dysfunction and the associated functional changes is still unclear. In a previous study, we reported that vitamin E deficiency affected the testes, epididymis, and spermatozoa of mice, accelerating the progression of senescence. In this study, we focused on the Sertoli cell marker vimentin and explored the relationship between the cytoskeletal system of Sertoli cells and spermatogenic dysfunction using testis tissue sections that caused male reproductive dysfunction with vitamin E deficiency. The immunohistochemical analysis showed that the proportion of the vimentin-positive area in seminiferous tubule cross-sections was significantly increased in testis tissue sections of the vitamin E-deficient group compared with the proportion in the control group. The histological analysis of testis tissue sections from the vitamin E-deficient group showed that vimentin-positive Sertoli cells were greatly extended from the basement membrane, along with an increased abundance of vimentin. These findings suggest that vimentin may be a potential indicator for detecting spermatogenic dysfunction.

Immunohistochemical Changes in the Testicular Excurrent Duct System of Healthy, Male Japanese Quail (Coturnix coturnix japonica) Observed at 4, 6-7, 12, and 52 Weeks of Age

The immunolocalization of the cytoskeletal and the extracellular matrix proteins was investigated in the testicular excurrent duct system of healthy Japanese quail at 4, 6−7, 12 and 52 weeks of age. TdT dUTP Nick End Labeling (TUNEL) assay was used to assess apoptotic cell formation. The epithelia of the testicular excurrent duct system in birds of all age groups displayed various immunolabeling intensities and localization of cytokeratin 5 and beta-tubulin, while α-SMA was observed in epithelia only of 4-week-old birds. In all age groups, vimentin immunostaining was observed in the rete testes and efferent ductular epithelia, but not in the epididymal duct unit. The periductal smooth muscle cells of the excurrent duct system displayed variably intense immunopositivity with cytokeratin 5, desmin, fibronectin, α-SMA, and beta-tubulin. Furthermore, beta-tubulin and vimentin immunolabeled endothelial cells and fibroblasts with various intensities, while fibronectin immunostained extracellular matrices surrounding these cells. TUNEL-positive apoptotic cells were observed in the rete testes and efferent ductular epithelia, with increased frequency (p < 0.001) in 52-week-old birds. The study serves as a baseline normal for this region in healthy birds at 4, 6−7, 12, and 52 weeks of age, for comparison in future similar immunohistochemical studies involving environmental toxins affecting this region.

Localization of Xenobiotic Transporters Expressed at the Human Blood-Testis Barrier

The blood-testis barrier (BTB) is formed by basal tight junctions between adjacent Sertoli cells (SCs) of the seminiferous tubules and acts as a physical barrier to protect developing germ cells in the adluminal compartment from reproductive toxicants. Xenobiotics, including antivirals, male contraceptives, and cancer chemotherapeutics, are known to cross the BTB, although the mechanisms that permit barrier circumvention are generally unknown. This study used immunohistological staining of human testicular tissue to determine the site of expression for xenobiotic transporters that facilitate transport across the BTB. Organic anion transporter (OAT) 1, OAT2, and organic cation transporter, novel (OCTN) 1 primarily localized to the basal membrane of SCs, whereas OCTN2, multidrug resistance protein (MRP) 3, MRP6, and MRP7 localized to SC basal membranes and peritubular myoid cells (PMCs) surrounding the seminiferous tubules. Concentrative nucleoside transporter (CNT) 2 localized to Leydig cells (LCs), PMCs, and SC apicolateral membranes. Organic cation transporter (OCT) 1, OCT2, and OCT3 mostly localized to PMCs and LCs, although there was minor staining in developing germ cells for OCT3. Organic anion transporting polypeptide (OATP) 1A2, OATP1B1, OATP1B3, OATP2A1, OATP2B1, and OATP3A1-v2 localized to SC basal membranes with diffuse staining for some transporters. Notably, OATP1C1 and OATP4A1 primarily localized to LCs. Positive staining for multidrug and toxin extrusion protein (MATE) 1 was only observed throughout the adluminal compartment. Definitive staining for CNT1, OAT3, MATE2, and OATP6A1 was not observed. The location of these transporters is consistent with their involvement in the movement of xenobiotics across the BTB. Altogether, the localization of these transporters provides insight into the mechanisms of drug disposition across the BTB and will be useful in developing tools to overcome the pharmacokinetic and pharmacodynamic difficulties presented by the BTB. SIGNIFICANCE STATEMENT: Although the total mRNA and protein expression of drug transporters in the testes has been explored, the localization of many transporters at the blood-testis barrier (BTB) has not been determined. This study applied immunohistological staining in human testicular tissues to identify the cellular localization of drug transporters in the testes. The observations made in this study have implications for the development of drugs that can effectively use transporters expressed at the basal membranes of Sertoli cells to bypass the BTB.

Effect of spermidine on ameliorating spermatogenic disorders in diabetic mice via regulating glycolysis pathway

Diabetes mellitus (DM), a high incidence metabolic disease, is related to the impairment of male spermatogenic function. Spermidine (SPM), one of the biogenic amines, was identified from human seminal plasma and believed to have multiple pharmacological functions. However, there exists little evidence that reported SPM's effects on moderating diabetic male spermatogenic function. Thus, the objective of this study was to investigate the SPM's protective effects on testicular spermatogenic function in streptozotocin (STZ)-induced type 1 diabetic mice. Therefore, 40 mature male C57BL/6 J mice were divided into four main groups: the control group (n = 10), the diabetic group (n = 10), the 2.5 mg/kg SPM-treated diabetic group (n = 10) and the 5 mg/kg SPM-treated diabetic group (n = 10), which was given intraperitoneally for 8 weeks. The type 1 diabetic mice model was established by a single intraperitoneal injection of STZ 120 mg/kg. The results showed that, compare to the control group, the body and testis weight, as well the number of sperm were decreased, while the rate of sperm malformation was significantly increased in STZ-induced diabetic mice. Then the testicular morphology was observed, which showed that seminiferous tubule of testis were arranged in mess, the area and diameter of which was decreased, along with downregulated anti-apoptotic factor (Bcl-2) expression, and upregulated pro-apoptotic factor (Bax) expression in the testes. Furthermore, testicular genetic expression levels of Sertoli cells (SCs) markers (WT1, GATA4 and Vimentin) detected that the pathological changes aggravated observably, such as the severity of tubule degeneration increased. Compared to the saline-treated DM mice, SPM treatment markedly improved testicular function, with an increment in the body and testis weight as well as sperm count. Pro-apoptotic factor (Bax) was down-regulated expression with the up-regulated expression of Bcl-2 and suppression of apoptosis in the testes. What's more, expression of WT1, GATA4, Vimentin and the expressions of glycolytic rate-limiting enzyme genes (HK2, PKM2, LDHA) in diabetic testes were also upregulated by SPM supplement. The evidence derived from this study indicated that the SMP's positive effect on moderating spermatogenic disorder in T1DM mice's testis. This positive effect is delivered via promoting spermatogenic cell proliferation and participating in the glycolytic pathway's activation.

Low concentrations of glyphosate alone affect the pubertal male rat meiotic step: An in vitro study

Glyphosate is the most used herbicide in the world. Controversial studies exist on its effect on the male reproductive system. We used the validated BioAlter® model to test the effects of low concentrations of Glyphosate. Pubertal rat seminiferous tubules were treated with Glyphosate 50 nM, 500 nM, 5 μM or 50 μM over a 3-week culture period. The Trans-Epithelial Electrical Resistance was not modified by any of the concentrations. The decrease of Clusterin mRNAs suggested that glyphosate would target the integrity of Sertoli cells. The decrease of the numbers of germ cells from day 14 onward highlighted the chronic effect of glyphosate at 50 nM, 500 nM or 5 μM. No consistent effect of glyphosate was observed on the numbers of spermatogonia or on their specific mRNA levels. However, those low concentrations of glyphosate targeted young spermatocytes and middle to late pachytene spermatocytes resulting in a decrease of the numbers of round spermatids, the direct precursors of spermatozoa. This study underlines that the effect of a toxicant should be also studied at low doses and during the establishment of the blood-testis barrier.

Comparative study of the ameliorative effects of omega-3 versus selenium on etoposide-induced changes in Sertoli cells and ectoplasmic specialization of adult rat testes: immunohistochemical and electron microscopic study

Etoposide (Eto) is an anti-cancer drug that is associated with serious adverse effects on male reproductive function. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and selenium (Se) are known as anti-inflammatory, anti-apoptotic and anti-oxidant agents. This work was designed to investigate changes in the biochemical parameters as well as alterations in Sertoli cell vimentin expression, ultrastructure and ectoplasmic specializations (ESs) following Eto treatment and to assess the ameliorative effect of ω-3 versus Se on these alterations. Eighty four adult male albino rats were used and classified into four groups: group I (control group), group II (Eto group) received Eto in a single intra-peritoneal (IP) dose (60 mg/kg B.W.), group III (Eto & ω-3 group) received the single IP dose of Eto as well as ω-3 (300 mg/kg B.W./day by intra-gastric intubation) starting 5 days before Eto injection till the time of sacrifice & group IV (Eto & Se group) received the single IP dose of Eto as well as Se (0.5 mg/kg B.W./day IP) starting 5 days before Eto injection till the time of sacrifice. The rats were subdivided into 2 subgroups (a) and (b) that were sacrificed 3 and 7 days after Eto injection respectively. Eto administration in group II induced increase in malondialdehyde (MDA), decrease in superoxide dismutase (SOD), collapse of Sertoli cell vimentin filaments and ultrastructural degenerative changes in both Sertoli cells and ESs. Se (group IV) reversed Eto toxic effects potently, while ω-3 (group III) had some limited protective effects.

Busulfan impairs blood-testis barrier and spermatogenesis by increasing noncollagenous 1 domain peptide via matrix metalloproteinase 9

BACKGROUNDS

Sterility induced by anti-cancer treatments has caused significant concern, yet the mechanism and treatment exploration are little for male infertility after cancer therapy. Busulfan, the antineoplastic that was widely applied before bone marrow transplantation, was known to induce male reproductive disorder.

OBJECTIVES

To investigate the effect of busulfan on blood-testis barrier function in adult rats and determine whether noncollagenous 1 domain peptide, the biologically active fragment proteolyzed from the collagen α3 chain (IV) by matrix metalloproteinase 9, was involved during this process.

MATERIALS AND METHODS

Adult male rats were treated with one-dose or double-dose of busulfan (10 mg/kg) before euthanized at day 35. Blood-testis barrier integrity assay, HE staining, immunofluorescence, and Western blot were used to validate the effect of busulfan on blood-testis barrier permeability and spermatogenesis. JNJ0966 was applied to specifically inhibit the matrix metalloproteinase 9 activity. The polymerization activity of F-actin/G-actin and microtubule/tubulin in the testis were assessed by using commercial kits.

RESULTS

A noteworthy blood-testis barrier injury and significant up-regulation of matrix metalloproteinase 9 activity and noncollagenous 1 level after a single-dose busulfan (10 mg/kg) treatment in adult rat testis were revealed. The application of JNJ0966 was found to decrease noncollagenous 1 level and rescue the busulfan-induced blood-testis barrier injury including the mis-localization of junction proteins across the seminiferous epithelium, by recovering the organization and polymerization of both F-actin and microtubule. The busulfan-induced spermatogenesis impairment was also improved by JNJ0966.

CONCLUSION

These findings thus demonstrate that the elevation in matrix metalloproteinase 9 and noncollagenous 1 might participate in busulfan-induced blood-testis barrier disruption in adult male rats. As such, busulfan-induced male infertility could possibly be managed through interventions on noncollagenous 1 production.

Common markers of testicular Sertoli cells

INTRODUCTION

Sertoli cells play central roles in the development of testis formation in fetuses and the initiation and maintenance of spermatogenesis in puberty and adulthood, and disorders of Sertoli cell proliferation and/or functional maturation can cause male reproductive disorders at various life stages. It's well documented that various genes are either overexpressed or absent in Sertoli cells during the conversion of an immature, proliferating Sertoli cell to a mature, non-proliferating Sertoli cell, which are considered as Sertoli cell stage-specific markers. Thus, it is paramount to choose an appropriate Sertoli cell marker that will be used not only to identify the developmental, proliferative, and maturation of Sertoli cell status in the testis during the fetal period, prepuberty, puberty, or in the adult, but also to diagnose the mechanisms underlying spermatogenic dysfunction.

AREAS COVERED

In this review, we principally enumerated 5 categories of testicular Sertoli cell markers - including immature Sertoli cell markers, mature Sertoli cell markers, immature/mature Sertoli cell markers, Sertoli cell functional markers, and others.

EXPERT OPINION

By delineating the characteristics and applications of more than 20 Sertoli cell markers, this review provided novel Sertoli cell markers for the more accurate diagnosis and mechanistic evaluation of male reproductive disorders.

Effects of nicotine on porcine pre-pupertal sertoli cells: An in vitro study

Smoke components, such as nicotine and its major metabolites, cross the blood-testis barrier and are detectable in the seminal plasma of both active smokers and individuals exposed to cigarette smoke. In vivo studies in a rat model have further demonstrated that nicotine exposure reduces the weight of the testis, as well as the number of spermatocytes and spermatids, and affects the ultrastructure of Sertoli cells (SC) - which serve as sentinels of spermatogenesis - causing intense germ cell sloughing in the tubular lumen that compromises offspring fertility. This study sought to determine the effects of nicotine on the viability and function of purified pig pre-pubertal SC. Nicotine exposure reduced the mRNA expression and protein levels of anti-Mullerian hormone (AMH) and inhibin B and impaired FSH-r sensitivity via the downregulation of FSH-r and aromatase gene expression compared to untreated SC. Overall, our study suggests that nicotine can significantly alter extracellular matrix and tight junction protein gene expression (e.g., laminin, integrin, and occludin), thus compromising cross-talk between the interstitial and tubular compartments and enhancing blood-testis barrier (BTB) permeability via downregulation of the mitogen-activated protein kinase (MAPK) pathway. These findings further elucidate a potential mechanism of action underlying nicotine exposure's detrimental effects on SC function in vivo.

Characteristics of seasonal spermatogenesis in the soft-shelled turtle

Spermatogenesis in reptiles is a seasonally dependent physiological process that is not temporally associated with male mating behavior. Characteristics of seasonal spermatogenesis in reptiles, however, remain largely unknown. In this review, there is a coverage of the characteristics of soft-shelled turtle, Pelodiscus sinensis, during seasonal spermatogenesis that provides insights into spermatogenesis of testudines. The seminiferous epithelium of P. sinensis are undergoing spermatogenesis during the summer and fall, but are quiescent throughout the rest of the year; germ cells progress through spermatogenic stages in a temporal rather than a spatial pattern. While apoptotic germ cells mainly appear in the non-spermatogenic phase, these are seldom present during active spermatogenesis. It is inferred that apoptosis may be one of the reasons for germ cell loss during the resting phase of spermatogenesis. During the period when spermatogenesis is occurring, Sertoli cells become very narrow and are in contact with several round/elongated spermatids. Many residual spermatozoa can be internalized and degraded within Sertoli cells by entosis during the non-spermatogenic phase, which precedes the next reproductive cycle in P. sinensis. In the late spermatogenic phase, round-shaped mitochondria of spermatids become elongated and swollen, subsequently forming a crescent-like shape and develop into "onion-like" shaped mitochondria. As spermiogenesis progresses, the endoplasmic reticulum of spermatids is transferred into a specialized structure called the "Chrysanthemum flower center", which may be a source of autophagosomal membranes. The information provided in this review will help improve understanding of characteristics of seasonal spermatogenesis, which will hopefully promote interest in the study of reptilian species.

Sertoli Cell Alterations in Peripubertal Varicocelized Rats: Evidence of Primary Damage on Spermatogenesis

Idiopathic varicocele is closely associated with male infertility or subfertility. Sertoli cell is a very important regulator of spermatogenesis. We investigated the morphofunctional alterations in the Sertoli cell and its possible involvement in the establishment of testicular primary lesion in experimental left-sided varicocele, induced from peripuberty. Twenty-five male peripubertal rats (44 days postpartum [dpp]) were distributed into two groups: control (C) and varicocele (V). Experimental left varicocele was induced in rats through the partial ligature of the left renal vein. Euthanasia was performed at 100 dpp. Testicular histopathology and testosterone plasmatic level were evaluated. Transferrin and vimentin proteins were, respectively, used as immunomarkers of Sertoli cell function and structure. Significant reductions in vimentin and transferrin expressions were noticed in androgen-dependent stages (VII and VIII) of the seminiferous epithelium cycle in V rats; testosterone plasmatic level was also reduced. Bilateral testicular histopathological alterations were found in V rats, mainly massive germ cell desquamation. The histological damage and changes in protein expressions occurred bilaterally. The relevant impairment of the functional and structural characteristics of the Sertoli cell, together with the typical massive germ cell desquamation, indicates that Sertoli cell changes can primarily contribute to the significant testicular dysfunction associated with varicocele.

Altered hormonal milieu and dysregulated protein expression can cause spermatogenic arrest in ectopic xenografted immature rat testis

Testis tissue xenografting complemented with cryopreservation is a feasible technique for fertility preservation in children with malignancy receiving gonadotoxic therapy and for endangered species with high neonatal mortality rate. However, xenografted testis of human and most endangered species are known to undergo spermatogenic arrest. In this study, we xenografted immature rat testis onto immunodeficient male mice to investigate the plausible underlying causes of spermatogenic arrest. Histological analysis of xenografted testes collected 8-wk post-grafting showed incomplete spermatogenesis with pachytene-stage spermatocytes as the most advanced germ cells. Although the levels of serum luteinizing hormone and testosterone were normal in recipient mice, those of follicle stimulating hormone (FSH) were significantly high, and specific receptors of FSH were absent in the xenografts. The xenografts demonstrated dysregulated expression of Sertoli cell-transcriptional regulators (WT1 and SOX9) and secretory proteins (SCF and GDNF). In conclusion, results from our study suggested that an altered hormonal milieu in recipients and dysregulated protein expression in xenografts could be a potential cause of spermatogenic arrest in xenografted immature rat testis. Further stereological analysis of xenografts can demonstrate precise cellular composition of xenografts to decipher interactions between germ and somatic cells to better understand spermatogenic arrest in xenografted testis.

Progress on the study of the mechanism of busulfan cytotoxicity

The preparation of spermatogonial stem cell (SSC) transplant recipients laid the technical foundation for SSC transplant technology and the understanding of spermatogenesis mechanisms. Busulfan is commonly used to prepare recipients for mouse SSC transplantation; however, its safety and efficiency have been questioned. This review summarizes the relationship between SSCs and Sertoli cells (SCs), and the mechanism of busulfan toxicity against sperm cells. We concluded that the proliferation, differentiation, and apoptosis of SSCs are regulated by SCs. The endogenous spermatogenic cells are depleted by busulfan treatment via alkylation of DNA, destruction of vimentin filament distribution, disruption of SSC differentiation, promotion of SSC dormancy, and generation of oxidative stress. However, the mechanisms require further exploration. The recent establishment of a model in vitro culture system has provided a good technical foundation to further explore these mechanisms, which will help us to find more efficient methods of recipient preparation and optimal transplantation times.

Comparative proteomic analysis of different developmental stages of swamp buffalo testicular seminiferous tubules

With ageing, many protein components change markedly during mammalian spermatogenesis. Most of these proteins have yet to be characterized and verified. Here, we have employed two-dimensional electrophoresis coupled to tandem mass spectrometry to explore the different proteins from pre-pubertal, pubertal and post-pubertal swamp buffalo testicular seminiferous tubules. The results showed that 25 protein spots were differentially expressed among developmental stages, and 13 of them were successfully identified by mass spectrometry. Of which four proteins were up-regulated and three proteins were down-regulated with age, and the remaining six proteins were fluctuated among developmental stages. Bioinformatics analysis indicates that these proteins were probably related to cellular developmental process (53.8%), cell differentiation (53.8%), spermatogenesis (15.4%), apoptotic process and cell death (30.8%). Expression profiles of calumenin (CALU) and galectin-1 (LGALS1) were further verified via Western blotting. In summary, the results help to develop an understanding of molecular mechanisms associated with buffalo spermatogenesis.

In vitro toxicity evaluation of melamine on mouse TM4 Sertoli cells

The male reproductive toxicity of melamine (MA) has been recognized in recent years excepted for its renal toxicity. Our previous in vivo studies revealed that the damages of Sertoli cell barrier played a critical role in MA-induced testicular toxicity in mice. Herein, we performed an in vitro study to comprehensively evaluate the toxicity of MA on Sertoli cell by examining the influences of MA on the viability, morphology, mortality and intercellular junctions of mouse TM4 Sertoli cells (TM4 cells). The results showed that MA suppressed cell viability, induced obvious ultrastructural changes and cell apoptosis in concentration-dependent manner. Moreover, MA down-regulated the expressions of junction-associated proteins including occludin, N-cadherin, and vimentin, suggesting that MA disrupted the integrity of Sertoli cell barrier. Thus, these results indicated that Sertoli cell might be an important cellular target for MA-induced male reproductive toxicity.

Seminiferous epithelium damage after short period of busulphan treatment in adult rats and vitamin B12 efficacy in the recovery of spermatogonial germ cells

Several different strategies have been adopted in attempt to recover from chemotherapy-damaged spermatogenesis that is often seen in oncologic patients. In this study, we have evaluated the impact of short period of exposure to busulphan on the haemogram and seminiferous epithelium of adult rats, focusing on spermatogonial depletion and Sertoli cell (SC) integrity. We then examined whether vitamin B₁₂ supplementation improves the haematological parameters and spermatogonia number. The animals received 10 mg/kg of busulphan (BuG) or busulfan+vitamin B₁₂ (Bu/B₁₂ G) on the first and fourth days of treatment. In H.E.-stained testicular sections, the areas of the seminiferous tubule (ST) and seminiferous epithelium were measured. The number of spermatogonia in H.E-stained and PCNA-immunolabelled testicular sections was quantified. The frequency of tubules with abnormal SC nuclei or TUNEL-positive SC was evaluated. Vimentin immunofluorescence in ST was also evaluated. In BuG and Bu/B₁₂ G, the animals showed leukopenia and thrombocytopenia, but the body weight reduced only in BuG. The areas of ST and seminiferous epithelium decreased in Bu/B₁₂ G and BuG. In BuG, the number of H.E.-stained and PCNA-immunolabelled spermatogonia reduced significantly. The frequency of tubules containing abnormal SC nuclei and TUNEL-positive SC increased and the vimentin immunoexpression pattern changed. In Bu/B₁₂ G, the number of H.E.-stained or PCNA-immunolabelled spermatogonia increased fourfold in comparison with BuG. The structural changes in ST after 6 days of busulphan exposure may be associated with the potential effect of this anti-neoplastic agent on SC. The increased number of spermatogonia in the busulphan-treated animals receiving vitamin B₁₂ indicates that this vitamin can be an adjuvant therapy to improve the fertility in male cancer patients.

Seasonal Changes in the Immunolocalization of Cytoskeletal Proteins and Laminin in the Testis of the Black-Backed Jackal (Canis mesomelas)

Manipulation of the reproductive activity of jackals is dependent on a thorough understanding of the reproductive biology of this species. This study describes seasonal morphological changes in the adult testis of the black-backed jackal in relation to the immunoexpression of the basement membrane marker, laminin and the cytoskeletal proteins, cytokeratin, smooth muscle actin and vimentin. Laminin was immunolocalized in basement membranes surrounding seminiferous tubules, as well as in basement membranes associated with Leydig, peritubular myoid and vascular smooth muscle cells. Scalloped basement membranes enclosed seminiferous tubules in regressing testes. The seminiferous epithelium and interstitial tissue in all animals studied were cytokeratin immunonegative. Smooth muscle actin was demonstrated in vascular smooth muscle cells, as well as in peritubular myoid cells encircling seminiferous tubules. Vimentin immunoreactivity was exhibited in the cytoplasm of Sertoli cells, Leydig cells, vascular endothelial cells, vascular smooth muscle cells and fibrocytes. Vimentin immunostaining in Sertoli, Leydig and peritubular myoid cells varied depending on the functional state of the testis. The results of the study have shown that dramatic seasonal histological changes occur in the testes of the jackal. In addition, the use of immunohistochemistry accentuates these morphological changes.

Cytological study on Sertoli cells and their interactions with germ cells during annual reproductive cycle in turtle

Sertoli cells (SCs) play a central role in the development of germ cells within functional testes and exhibit varying morphology during spermatogenesis. This present study investigated the seasonal morphological changes in SCs in the reproductive cycle of Pelodiscus sinensis by light microscopy, transmission electron microscopy (TEM), and immunohistochemistry. During hibernation period with the quiescent of spermatogenesis, several autophagosomes were observed inside the SCs, the processes of which retracted. In early spermatogenesis, when the germ cells started to proliferate, the SCs contained numerous lipid droplets instead of autophagosomes. In late spermatogenesis, the SCs processes became very thin and contacted several round/elongated spermatids in pockets. At this time, abundant endoplasmic reticulum and numerous mitochondria were present in the SCs. The organization of the tight junctions and the adherens junctions between the SCs and germ cells also changed during the reproductive cycle. Moreover, SCs were involved in the formation of cytoplasmic bridges, phagophores, and exosome secretions during spermatogenesis. Tubulobulbar complexes (TBC) were also developed by SCs around the nucleus of the spermatid at the time of spermiation. Strong, positive expression of vimentin was noted on the SCs during late spermatogenesis compared with the hibernation stage and the early stage of spermatogenesis. These data provide clear cytological evidence about the seasonal changes in SCs, corresponding with their different roles in germ cells within the Chinese soft‐shelled turtle Pelodiscus sinensis.

Prenatal and lactation nicotine exposure affects Sertoli cell and gonadotropin levels in rats

Nicotine is largely consumed in the world as a component of cigarettes. It can cross the placenta and reach the milk of smoking mothers. This drug induces apoptosis, affects sex hormone secretion, and leads to male infertility. To investigate the exposure to nicotine during the whole intrauterine and lactation phases in Sertoli cells, pregnant rats received nicotine (2 mg/kg per day) through osmotic minipumps. Male offsprings (30, 60, and 90 days old) had blood collected for hormonal analysis (FSH and LH) and their testes submitted for histophatological study, analysis of the frequency of the stages of seminiferous epithelium cycle, immunolabeling of apoptotic epithelial cells (TUNEL and Fas/FasL), analysis of the function and structure of Sertoli cells (respectively using transferrin and vimentin immunolabeling), and analysis of Sertoli-germ cell junctional molecule (β-catenin immunolabeling). The exposure to nicotine increased the FSH and LH plasmatic levels in adult rats. Although nicotine had not changed the number of apoptotic cells, neither in Fas nor FasL expression, it provoked an intense sloughing of epithelial cells and also altered the frequency of some stages of the seminiferous epithelium cycle. Transferrin and β-catenin expressions were not changed, but vimentin was significantly reduced in the early stages of the seminiferous cycle of the nicotine-exposed adult rats. Thus, we concluded that nicotine exposure during all gestational and lactation periods affects the structure of Sertoli cells by events causing intense germ cell sloughing observed in the tubular lumen and can compromise the fertility of the offspring.

A detailed protocol for a rapid analysis of testicular cell populations using flow cytometry

Accurate analysis and quantification of different testicular cell populations are of central importance in studies of male reproductive biology. The traditional histomorphometric and immunohistochemical methods remain the gold standard in studying the complex dynamics of the testicular tissue. Through past years advances have been made in the application of flow cytometry for the rapid analysis of testicular cell populations. Detection of DNA content and of surface antigens and fluorescent reporters have been widely used to analyze and sort cells. Detection of intracellular antigens can broaden the possibilities of applying flow cytometry in studies of male reproduction. Here, we report a detailed protocol for the preparation of rat testicular tissue for detection of intracellular antigens by flow cytometry, and a pipeline for subsequent data analysis and troubleshooting. Rat testicular ontogenesis was chosen as the experimental model to validate the performance of the assay using vimentin and γH2AX as intracellular markers for the somatic and spermatogenic cells, respectively. The results show that the assay is reproducible and recapitulates the rat testis ontogenesis.

Immunohistochemical Characterization of Spontaneous Sertoli Cell Clusters in the Seminiferous Tubules of C57BL/6J Mice

Cell clusters were observed in the seminiferous tubules of C57BL/6J mice as a spontaneous lesion in a 2-week toxicity study, and they were demonstrated to be basically composed of Sertoli cells by immunohistochemistry for claudin-11 and GATA-4 (GATA-binding protein 4), which are both Sertoli cell markers. The clusters were composed of about 5 to 50 cells, which had eosinophilic and occasionally vacuolated cytoplasm with an unclear cell boundary. The cell clusters involved some sperm. No mitotic figures were observed and no immunoreactivity for proliferating cell nuclear antigen (PCNA) was detected in the clusters. In most cases, the cell clusters were observed in seminiferous tubules that also showed degenerative changes. In rare instances, cell aggregates immunohistochemically positive for claudin-11 were observed in the lumen of the epididymis, suggesting that some of the Sertoli cell clusters were sloughed off from the seminiferous epithelium into the epididymal ducts. To our knowledge, this is the first report of Sertoli cell clusters in any animal species except for transgenic or surgically altered animals.

Disruption of Sertoli cell vimentin filaments in prepubertal rats: an acute effect of butylparaben in vivo and in vitro

Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. We have recently shown that butylparaben induces spermatogenic cell apoptosis in prepubertal rats. We have conducted the present study for further information. Three-week-old male Sprague-Dawley rats (n=8) were given a single oral dose of 1,000 mg/kg butylparaben. The rats were sacrificed under anesthesia at 3, 6 and 24h after administration and their testes were collected for histopathological and immunohistochemical examination. Results showed a gradual collapse of Sertoli cell vimentin filaments and decreased actin staining intensity without accompanying changes in the pattern of tubulin expression, while spermatogenic cells became separated from the basement membrane and sloughed into the lumen in the butylparaben-treated rats, compared to the controls. To determine the direct effects of butylparaben on Sertoli cells, primary Sertoli cell cultures with and without butylparaben treatment were examined. Toluidine blue staining in butylparaben treated-cultured Sertoli cells showed an increased number and size of vacuoles in their cytoplasm. In agreement with the in vivo experiment, the in vitro study also clearly demonstrated disruption of vimentin filaments in Sertoli cells after butylparaben treatment. Considering both our present and previous reports, we can speculate that butylparaben-induced disruption of Sertoli cell vimentin filaments may lead to precocious release of spermatogenic cells from underlying Sertoli cells, and the released cells may undergo apoptosis owing to loss of support provided by the Sertoli cells.

Genome-wide identification of AR-regulated genes translated in Sertoli cells in vivo using the RiboTag approach

An understanding of the molecular mechanisms by which androgens drive spermatogenesis has been thwarted by the fact that few consistent androgen receptor (AR) target genes have been identified. Here, we addressed this issue using next-generation sequencing coupled with the RiboTag approach, which purifies translated mRNAs expressed in cells that express cyclic recombinase (CRE). Using RiboTag mice expressing CRE in Sertoli cells (SCs), we identified genes expressed specifically in SCs in both prepubertal and adult mice. Unexpectedly, this analysis revealed that the SC-specific gene program is already largely defined at the initiation of spermatogenesis despite the subsequent dramatic maturational changes known to occur in SCs. To identify AR-regulated genes, we generated triple-mutant mice in which the SCs express the RiboTag but lack ARs. RNA sequencing analysis revealed hundreds of SC-expressed AR-regulated genes that had previously gone unnoticed, including suppressed genes involved in ovarian development. Comparison of the SC-enriched dataset with that from the whole testes allowed us to classify genes in terms of their degree of expression in SCs. This revealed that a greater fraction of AR-up-regulated genes than AR-down-regulated genes were expressed predominantly in SCs. Our results also revealed that AR signaling in SCs causes a large number of genes not detectably expressed in SCs to undergo altered expression, thereby providing genome-wide evidence for wide-scale communication between SCs and other cells. Taken together, our results identified novel classes of genes expressed in a hormone-dependent manner in different testicular cell subsets and highlight a new approach to analyze cell type-specific gene regulation.

Protective effects of ginsenosides against Bisphenol A-induced cytotoxicity in 15P-1 Sertoli cells via extracellular signal-regulated kinase 1/2 signalling and antioxidant mechanisms

Numerous studies have demonstrated that Bisphenol A (BPA) can cause reproductive toxicity. Ginseng has wide range of pharmacological actions and, more importantly, has proven its worth with respect to reproductive function in several reports. We have suggested that ginsenosides, the main active components of ginseng, may protect against BPA-induced cell damage. Therefore, an in vitro culture model of 15P-1 Sertoli cells was employed to investigate whether ginsenosides have protective effects on BPA-stimulated 15P-1 Sertoli cells. The results revealed that ginsenosides (75 μg/ml) significantly inhibited BPA-induced decreases in cell viability and increases in apoptosis. Immunofluorescence staining showed that BPA exposure-induced collapse of vimentin intermediate filaments was prevented by the application of ginsenosides. Ginsenosides also inhibited extracellular signal-regulated kinase (ERK1/2) phosphorylation and BPA-induced alterations of Bcl-2 and Bax protein expression in 15P-1 Sertoli cells. Furthermore, the alterations of T-AOC, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione and malondialdehyde levels in BPA-stimulated cells were partially prevented with pre-treatment with ginsenosides. Taken together, these results suggest that ginsenosides have protective effects against BPA-induced cell damage and that these effects are mediated by preventing ERK1/2 phosphorylation and through the enhancement of cellular antioxidant capacity. Ginsenosides may therefore be beneficial in the prevention of environmental BPA-induced, reproduction-related toxicity.

Altered phosphorylation and distribution status of vimentin in rat seminiferous epithelium following 17β-estradiol treatment

Vimentin, type III intermediate filament, has stage-specific localization in the Sertoli cell. In the rat, during stages I-V and XI-XIV of the seminiferous epithelium, vimentin is localized in the perinuclear area with filaments projecting into the apical region toward the developing germ cells. These filaments decrease in length at stages VI-VII with perinuclear staining in stages VIII-IX, when spermiation occurs. Our earlier studies following 17β-estradiol treatment to adult male rats demonstrated an increase in germ cell apoptosis, spermiation failure and disruption of Sertoli cell microfilaments and microtubules. The present study was undertaken to determine the stage-specific distribution of vimentin and its involvement in spermiation failure and germ cell apoptosis. Immunofluorescence studies revealed that in contrast to the perinuclear localization with small extensions in control stages VII-IX, long extensions radiating apically to the spermatids in deep recess were observed in the treated group. Immunoprecipitation studies showed marked absence of phosphorylated vimentin in stages VII-VIII in the treated group. Further, localization of plectin, cytoskeletal linker protein, showed decrease in all the stages of spermatogenesis following estradiol treatment. Interestingly, for the first time the localization of plectin in the tubulobulbar complex was observed. In conclusion, the study suggests that estradiol treatment leads to an effect on vimentin phosphorylation, which could have inhibited the disassembly of vimentin leading to retention of apical projection in stages VII-VIII. These effects could be presumably due to a decrease in plectin, affecting the reorganization of vimentin and therefore the apical movement of spermatids, leading to spermiation failure.

Effects of di-n-butyl phthalate on male rat reproduction following pubertal exposure

Di-n-butyl phthalate (DBP) is an endocrine-disrupting chemical that has the potential to affect male reproduction. However, the reproductive effects of low-dose DBP are still not well known, especially at the molecular level. In the present study, pubertal male Sprague-Dawley rats were orally administered DBP at a wide range of doses (0.1, 1.0, 10, 100 and 500 mg kg⁻¹ day⁻¹) for 30 days. The selected end points included reproductive organ weights, testicular histopathology and serum hormonal levels. Additionally, proteomic analysis was performed to identify proteins that are differentially expressed as a result of exposure to DBP at low doses (0.1, 1.0 and 10 mg kg⁻¹ day⁻¹). Toxic effects were observed in the high-dose groups, including anomalous development of testes and epididymides, severe atrophy of seminiferous tubules, loss of spermatogenesis and abnormal levels of serum hormones. Treatment with low doses of DBP seemed to exert a 'stimulative effect' on the serum hormones. Proteomics analysis of rat testes showed 20 differentially expressed proteins. Among these proteins, alterations in the expression of HnRNPA2/B1, vimentin and superoxide dismutase 1 (SOD1) were further confirmed by Western blot and immunohistochemistry. Taken together, we conclude that high doses of DBP led to testicular toxicity, and low doses of DBP led to changes in the expression of proteins involved in spermatogenesis as well as changes in the number and function of Sertoli and Leydig cells, although no obvious morphological changes appeared. The identification of these differentially expressed proteins provides important information about the mechanisms underlying the effects of DBP on male rat reproduction.

Controlled release of chitosan/heparin nanoparticle-delivered VEGF enhances regeneration of decellularized tissue-engineered scaffolds

Regeneration deficiency is one of the main obstacles limiting the effectiveness of tissue-engineered scaffolds. To develop scaffolds that are capable of accelerating regeneration, we created a heparin/chitosan nanoparticle-immobilized decellularized bovine jugular vein scaffold to increase the loading capacity and allow for controlled release of vascular endothelial growth factor (VEGF). The vascularization of the scaffold was evaluated in vitro and in vivo. The functional nanoparticles were prepared by physical self-assembly with a diameter of 67–132 nm, positive charge, and a zeta potential of ∼30 mV and then the nanoparticles were successfully immobilized to the nanofibers of scaffolds by ethylcarbodiimide hydrochloride/hydroxysulfosuccinimide modification. The scaffolds immobilized with heparin/chitosan nanoparticles exhibited highly effective localization and sustained release of VEGF for several weeks in vitro. This modified scaffold significantly stimulated endothelial cells’ proliferation in vitro. Importantly, utilization of heparin/chitosan nanoparticles to localize VEGF significantly increased fibroblast infiltration, extracellular matrix production, and accelerated vascularization in mouse subcutaneous implantation model in vivo. This study provided a novel and promising system for accelerated regeneration of tissue-engineering scaffolds.

Altered differentiation and clustering of Sertoli cells in transgenic mice showing a Sertoli cell specific knockout of the connexin 43 gene

Histological analysis revealed that Sertoli cell specific knockout of the predominant testicular gap junction protein connexin 43 results in a spermatogenic arrest at the level of spermatogonia or Sertoli cell-only syndrome, intratubular cell clusters and still proliferating adult Sertoli cells, implying an important role for connexin 43 in the Sertoli and germ cell development. This study aimed to determine the (1) Sertoli cell maturation state, (2) time of occurrence and (3) composition, differentiation and fate of clustered cells in knockout mice. Using immunohistochemistry connexin 43 deficient Sertoli cells showed an accurate start of the mature markers androgen receptor and GATA-1 during puberty and a vimentin expression from neonatal to adult. Expression of anti-Muellerian hormone, as a marker of Sertoli cell immaturity, was finally down-regulated during puberty, but its disappearance was delayed. This observed extended anti-Müllerian hormone synthesis during puberty was confirmed by western blot and Real-Time PCR and suggests a partial alteration in the Sertoli cell differentiation program. Additionally, Sertoli cells of adult knockouts showed a permanent and uniform expression of GATA-1 at protein and mRNA level, maybe caused by the lack of maturing germ cells and missing negative feedback signals. At ultrastructural level, basally located adult Sertoli cells obtained their mature appearance, demonstrated by the tripartite nucleolus as a typical feature of differentiated Sertoli cells. Intratubular clustered cells were mainly formed by abnormal Sertoli cells and single attached apoptotic germ cells, verified by immunohistochemistry, TUNEL staining and transmission electron microscopy. Clusters first appeared during puberty and became more numerous in adulthood with increasing cell numbers per cluster suggesting an age-related process. In conclusion, adult connexin 43 deficient Sertoli cells seem to proliferate while maintaining expression of mature markers and their adult morphology, indicating a unique and abnormal intermediate phenotype with characteristics common to both undifferentiated and differentiated Sertoli cells.

Gene expression profiling of rat spermatogonia and Sertoli cells reveals signaling pathways from stem cells to niche and testicular cancer cells to surrounding stroma

Background

Stem cells and their niches are studied in many systems, but mammalian germ stem cells (GSC) and their niches are still poorly understood. In rat testis, spermatogonia and undifferentiated Sertoli cells proliferate before puberty, but at puberty most spermatogonia enter spermatogenesis, and Sertoli cells differentiate to support this program. Thus, pre-pubertal spermatogonia might possess GSC potential and pre-pubertal Sertoli cells niche functions. We hypothesized that the different stem cell pools at pre-puberty and maturity provide a model for the identification of stem cell and niche-specific genes. We compared the transcript profiles of spermatogonia and Sertoli cells from pre-pubertal and pubertal rats and examined how these related to genes expressed in testicular cancers, which might originate from inappropriate communication between GSCs and Sertoli cells.

Results

The pre-pubertal spermatogonia-specific gene set comprised known stem cell and spermatogonial stem cell (SSC) markers. Similarly, the pre-pubertal Sertoli cell-specific gene set comprised known niche gene transcripts. A large fraction of these specifically enriched transcripts encoded trans-membrane, extra-cellular, and secreted proteins highlighting stem cell to niche communication. Comparing selective gene sets established in this study with published gene expression data of testicular cancers and their stroma, we identified sets expressed genes shared between testicular tumors and pre-pubertal spermatogonia, and tumor stroma and pre-pubertal Sertoli cells with statistic significance.

Conclusions

Our data suggest that SSC and their niche specifically express complementary factors for cell communication and that the same factors might be implicated in the communication between tumor cells and their micro-enviroment in testicular cancer.

Effects of di-iso-butyl phthalate on testes of prepubertal rats and mice

Di-iso-butyl phthalate (DiBP), a special plasticizer, is used as a substitute for di(n-butyl) phthalate (DBP). The effects of DiBP on testes in prepubertal rodents still remain to be obscure. Testicular toxicity of DiBP was investigated in 21-day-old Sprague-Dawley rats and C57BL/6N mice, using with in situ TUNEL method. For an acute exposure experiment, animals were once given DiBP at various concentrations by oral gavage. For a subchronic exposure experiment, they were daily given DiBP at various concentrations for consecutive 7 days. Controls were treated with corn oil under the same condition. For a recovery experiment, rats were once given DiBP (1000 mg/kg), and were sacrificed at day 1 to 8 after administration. Furthermore, the disorder of vimentin filaments in Sertoli cells after daily administration of DiBP (500 mg/kg) for consecutive 7 days in rats also identified by immunohistochemistry using anti-vimentin antibody. As a result, the present study demonstrated that DiBP can induce testicular atrophy in rats due to the increase of TUNEL-positive spermatogenic cells in both acute and subchronic exposure experiments. At the same time, the disorder of vimentin filaments in Sertoli cells was recognized. However, no such damages could be found in mouse testis. For the recovery experiment, the testis weight and testicular morphology returned to normal at day 6 after administration. In conclusion, the present study indicates that DiBP causes the significant increase of TUNEL-positive spermatogenic cells and the disorder of vimentin filaments in Sertoli cells in rats and that DiBP shows a species-specific toxicity.

Claudin 11 deficiency in mice results in loss of the Sertoli cell epithelial phenotype in the testis

Tissue integrity relies on barriers formed between epithelial cells. In the testis, the barrier is formed at the initiation of puberty by a tight junction complex between adjacent Sertoli cells, thereby defining an adluminal compartment where meiosis and spermiogenesis occur. Claudin 11 is an obligatory protein for tight junction formation and barrier integrity in the testis. It is expressed by Sertoli cells, and spermatogenesis does not proceed beyond meiosis in its absence, resulting in male sterility. Sertoli cell maturation--arrest of proliferation and expression of proteins to support germ cell development--parallels tight junction assembly; however, the pathophysiology underlying the loss of tight junctions in the mature testis remains largely undefined. Here, using immunohistochemistry and microarrays we demonstrate that adult Cldn11(-/-) mouse Sertoli cells can proliferate while maintaining expression of mature markers. Sertoli cells detach from the basement membrane, acquire a fibroblast cell shape, are eliminated through the lumen together with apoptotic germ cells, and are found in epididymis. These changes are associated with tight junction regulation as well as actin-related and cell cycle gene expression. Thus, Cldn11(-/-) Sertoli cells exhibit a unique phenotype whereby loss of tight junction integrity results in loss of the epithelial phenotype.

Fibroblasts from the new-born male testicle of Guangxi Bama mini-pig ( Sus scrofa) can support nuclear transferred embryo development in vitro

Miniature pigs are valuable for research in xenotransplantation and as models for investigating human diseases. Although many mammalian species have been cloned, the success rates have been very low, especially in the pig. In the present study, an attempt was made to optimize somatic cell nuclear transfer (SCNT) protocols for use in the production of the Guangxi Bama mini-pig. Firstly, mini-pig fibroblast cells from a new-born Guangxi Bama piglet were isolated and cultured. Cell type was identified by fluorescence immunocytochemistry (ICC); the cells expressed cimentin, but not cytoceratin and follicular stimulation hormone receptor (FSHR). Secondly, the optimal cell cycle synchronization protocol for treating fibroblast cells from the newborn piglet's testicle was investigated by contact inhibition and serum starvation. When fibroblast cells were treated by contact inhibition, a higher fusion (66.0% vs. 58.3%, p > 0.05) and blastocyst production (20.8% vs. 15.1, p > 0.05) rates were obtained than with serum starvation. Thirdly, to examine the ability of old cells to be morphologically remodelled after activation, testicular fibroblasts (passage 10-14) were introduced into enucleated oocytes; enlarged nuclei were formed in most of the reconstructed embryos at 6 h and enlarged nuclei or distinct pseudopronuclei were formed in nearly all the reconstructed embryos at 12 h. The old donor cell could be morphologically remodelled correctly and was competent to support embryo development to the blastocyst in vitro. Fourthly, the in vitro development potential of the cloned embryos was investigated using two types of donor cell: ear fibroblasts and low or high passage testicular fibroblasts. The rate of fusion was highest using low passage testicle fibroblasts (84.5% vs. 69.8% and 80.0%, p < 0.05), as was development to the blastocyst stage (14.6% vs. 7.7% and 6.3%, p < 0.05). Finally, the effect of phytohaemagglutinin (PHA) on parthenogenetic and cloned embryo development was examined. The PHA had no significant effect on the parthenogenetic embryos, but cloned embryo development to the blastocyst stage was significantly increased by PHA (10 microg/ml), (13.4% vs. 5.6% and 5.6%, p < 0.05).

Changes in the expression of P-cadherin in the normal, cryptorchid and busulphan-treated rat testis

Adhesion between Sertoli cells and germ cells is important for spermatogenesis. Cadherins are Ca(2+)-dependent transmembrane proteins that mediate cell-cell adhesion. The aim of this study was to compare the expression of P-cadherin in unilaterally cryptorchid and busulphan-treated rat testes using immunohistochemistry. The pattern of expression of P-cadherin in the seminiferous epithelium changed with the stage of the seminiferous epithelium. The membranes of round spermatids and membranes and cytoplasm of spermatocytes were strongly positive. Our experiments revealed that busulphan treatment (2 doses - 10 mg/kg of body weight - 21 days apart) and cryptorchism led to destructive changes in the structure of seminiferous tubules, together with the decrease in P-cadherin expression. The expression of P-cadherin disappeared in the spermatids segregated from the epithelium while segregated spermatocytes remained still positive for P-cadherin during the 3- to 11-day cryptorchid period. In busulphan-treated animals, the expression of P-cadherin was dependent on the presence or absence of the spermatocytes and spermatids in the tubules. Strong positivity for P-cadherin was observed in the spermatocytes that re-appeared in the regenerating seminiferous epithelium. We suggest that P-cadherin participates in the architecture of adherens junctions in testis, plays an important role in maintaining normal spermatogenesis and that cryptorchism and busulphan treatment lead to adherens junction disintegration.

β-nerve growth factor participates in an auto/paracrine pathway of regulation of the meiotic differentiation of rat spermatocytes

NGF appears to be involved in spermatogenesis. However, mice lacking NGF or TrkA genes do not survive more than a few days whereas p75(NTR) knockout mice are viable and fertile. Therefore, we addressed the effect of betaNGF on spermatogenesis by using the systems of rat germ cell culture we established previously. betaNGF did not modify the number of Sertoli cells, pachytene spermatocytes, secondary spermatocytes nor the half-life of round spermatids, but increased the number of secondary meiotic metaphases and decreased the number of round spermatids formed in vitro. These effects of betaNGF were reversible and maximal at about 4 x 10(-11) M. Conversely, K252a, a Trk-specific kinase inhibitor, enhanced the number of round spermatids above that of control cultures. The presence of betaNGF and its receptors TrkA and p75(NTR) was investigated in testis sections, in Sertoli cell and germ cell fractions, and in germ cell and Sertoli cell co-cultures. betaNGF was detected only in germ cells from pachytene spermatocytes of stages VII up to spermatids of stages IX-X. TrkA and p75(NTR) were detected in Sertoli cells and in these germ cells. Taken together, these results indicate that betaNGF should participate in an auto/paracrine pathway of regulation of the second meiotic division of rat spermatocytes in vivo.