Parathyroid Hormone-Related Protein Promotes Rat Stem Leydig Cell Differentiation

Patulin Stimulates Progenitor Leydig Cell Proliferation but Delays Its Differentiation in Male Rats during Prepuberty

Patulin is a mycotoxin with potential reproductive toxicity. We explored the impact of patulin on Leydig cell (LC) development in male rats. Male Sprague Dawley rats (21 days postpartum) were gavaged patulin at doses of 0.5, 1, and 2 mg/kg/day for 7 days. Patulin markedly lowered serum testosterone at ≥0.5 mg/kg and progesterone at 1 and 2 mg/kg, while increasing LH levels at 2 mg/kg. Patulin increased the CYP11A1+ (cholesterol side-chain cleavage, a progenitor LC biomarker) cell number and their proliferation at 1 and 2 mg/kg. Additionally, patulin downregulated Lhcgr (luteinizing hormone receptor), Scarb1 (high-density lipoprotein receptor), and Cyp17a1 (17α-hydroxylase/17,20-lyase) at 1 and 2 mg/kg. It increased the activation of pAKT1 (protein kinase B), pERK1/2 (extracellular signal-related kinases 1 and 2), pCREB (cyclic AMP response binding protein), and CCND1 (cyclin D1), associated with cell cycle regulation, in vivo. Patulin increased EdU incorporation into R2C LC and stimulated cell cycle progression in vitro. Furthermore, patulin showed a direct inhibitory effect on 11β-HSD2 (11β-hydroxysteroid dehydrogenase 2) activity, which eliminates the adverse effects of glucocorticoids. This study provides insights into the potential mechanisms via which patulin affects progenitor LC development in young male rats.

Nestin-dependent mitochondria-ER contacts define stem Leydig cell differentiation to attenuate male reproductive ageing

Male reproductive system ageing is closely associated with deficiency in testosterone production due to loss of functional Leydig cells, which are differentiated from stem Leydig cells (SLCs). However, the relationship between SLC differentiation and ageing remains unknown. In addition, active lipid metabolism during SLC differentiation in the reproductive system requires transportation and processing of substrates among multiple organelles, e.g., mitochondria and endoplasmic reticulum (ER), highlighting the importance of interorganelle contact. Here, we show that SLC differentiation potential declines with disordered intracellular homeostasis during SLC senescence. Mechanistically, loss of the intermediate filament Nestin results in lower differentiation capacity by separating mitochondria-ER contacts (MERCs) during SLC senescence. Furthermore, pharmacological intervention by melatonin restores Nestin-dependent MERCs, reverses SLC differentiation capacity and alleviates male reproductive system ageing. These findings not only explain SLC senescence from a cytoskeleton-dependent MERCs regulation mechanism, but also suggest a promising therapy targeting SLC differentiation for age-related reproductive system diseases.

The regulatory mechanisms contributing to male reproductive ageing are unknown. Here, the authors show that Nestin-dependent mito-ER contacts (MERCs) regulate stem Leydig cell (SLC) senescence and provide insights into SLCs-targeting therapies.

Bisphenol AF blocks Leydig cell regeneration from stem cells in male rats

Bisphenol A (BPA) is a ubiquitous environmental pollutant, mainly from the manufacture and use of plastics. The use of BPA is restricted, and its new analogs (including bisphenol AF, BPAF) are being produced to replace it. However, the effect of BPAF on the male reproductive system remains unclear. Here, we report the effect of BPAF on Leydig cell regeneration in rats. Leydig cells were eliminated by ethane dimethane sulfonate (EDS, i.p., 75 mg/kg) and the regeneration began 14 days after its treatment. We gavaged 0, 10, 100, and 200 mg/kg BPAF to rats on post-EDS day 7-28. BPAF significantly reduced serum testosterone and progesterone levels at ≧10 mg/kg. It markedly reduced serum levels of estradiol, luteinizing hormone, and follicle-stimulating hormone at 100 and 200 mg/kg. BPAF significantly reduced Leydig cell number at 200 mg/kg. BPAF significantly down-regulated the expression of Cyp17a1 at doses of 10 mg/kg and higher and the expression of Insl3, Star, Hsd17b3, Hsd11b1 in Leydig cells at 100 and 200 mg/kg, while it induced a significant up-regulation of Fshr, Dhh, and Sox9 in Sertoli cells at 200 mg/kg. BPAF induced oxidative stress and reduced the level of SOD2 at 200 mg/kg. It induced apoptosis and autophagy by increasing the levels of BAX, LC3B, and BECLIN1 and lowering the levels of BCL2 and p62 at 100 and 200 mg/kg. It induced autophagy possibly via decreasing the phosphorylation of AKT1 and mTOR. BPAF also significantly induced ROS production and apoptosis at a concentration of 10 μM, and reduced testosterone synthesis in rat R2C Leydig cells at a concentration of 10 μM in vitro, but did not affect cell viability after 24 h of treatment. In conclusion, BPAF is a novel endocrine disruptor, inhibiting the regeneration of Leydig cells.

Insights into the Regulation on Proliferation and Differentiation of Stem Leydig Cells

Male hypogonadism is a clinical syndrome caused by testosterone deficiency. Hypogonadism can be caused by testicular disease (primary hypogonadism) or hypothalamic-pituitary dysfunction (secondary hypogonadism). The present strategy for treating hypogonadism is the administration of exogenous testosterone. But exogenous testosterone is reported to have negative side effects including adverse cardiovascular events and disruption of physiological spermatogenesis probably due to its inability to mimic the physiological circadian rhythm of testosterone secretion in vivo. In recent years, a growing number of articles demonstrated that stem Leydig cells (SLCs) can not only differentiate into functional Leydig cells (LCs) in vivo to replace chemically disrupted LCs, but also secrete testosterone in a physiological pattern. The proliferation and differentiation of SLCs are regulated by various factors. However, the mechanisms involved in regulating the development of SLCs remain to be summarized. Factors involved in the regulation of SLCs can be divided into environmental pollutants, growth factors, cytokine and hormones. Environmental pollutants such as Perfluorooctanoic acid (PFOA) and Triphenyltin (TPT) could suppress SLCs proliferation or differentiation. Growth factors including FGF1, FGF16, NGF and activin A are essential for the maintenance of SLCs self-renewal and differentiation. Interleukin 6 family could inhibit differentiation of SLCs. Among hormones, dexamethasone suppresses SLCs differentiation, while aldosterone suppresses their proliferation. The present review focuses on new progress about factors regulating SLC's proliferation and differentiation which will undoubtedly deepen our insights into SLCs and help make better clinical use of them. Different factors affect on the proliferation and differentiation of stem Leydig cells. Firstly, each rat was intraperitoneally injected EDS so as to deplete Leydig cells from the adult testis. Secondly, the CD51+ or CD90+ cells from the testis of rats are SLCs, and the p75+ cells from human adult testes are human SLCs. These SLCs in the testis start to proliferate and some of them differentiate into LCs. Thirdly, during the SLCs regeneration period, researchers could explore different function of those factors (pollutants, growth factors, cytokines and hormones) towards SLCs.

Advances in stem cell research for the treatment of primary hypogonadism

In Leydig cell dysfunction, cells respond weakly to stimulation by pituitary luteinizing hormone, and, therefore, produce less testosterone, leading to primary hypogonadism. The most widely used treatment for primary hypogonadism is testosterone replacement therapy (TRT). However, TRT causes infertility and has been associated with other adverse effects, such as causing erythrocytosis and gynaecomastia, worsening obstructive sleep apnoea and increasing cardiovascular morbidity and mortality risks. Stem-cell-based therapy that re-establishes testosterone-producing cell lineages in the body has, therefore, become a promising prospect for treating primary hypogonadism. Over the past two decades, substantial advances have been made in the identification of Leydig cell sources for use in transplantation surgery, including the artificial induction of Leydig-like cells from different types of stem cells, for example, stem Leydig cells, mesenchymal stem cells, and pluripotent stem cells (PSCs). PSC-derived Leydig-like cells have already provided a powerful in vitro model to study the molecular mechanisms underlying Leydig cell differentiation and could be used to treat men with primary hypogonadism in a more specific and personalized approach.

Low dose of fire retardant, 2,2',4,4'-tetrabromodiphenyl ether (BDE47), stimulates the proliferation and differentiation of progenitor Leydig cells of male rats during prepuberty

2,2',4,4'-Tetrabromodiphenyl ether (BDE47), a flame retardant, is extensively distributed in the food chain. However, whether BDE47 affects Leydig cell development during prepuberty remains unclear. BDE47 was daily gavaged to 21-day-old Sprague-Dawley male rats with 0 (corn oil), 0.1, 0.2, and 0.4 mg/kg for 14 days. BDE47 did not affect the body weight or testis weight of rats. It significantly increased serum testosterone level at 0.4 mg/kg, but decreased luteinizing hormone (LH) level without affecting estradiol level. BDE47 induced Leydig cell hyperplasia (the number of CYP11A1-positive Leydig cells increased), and up-regulated the expression of Scarb1, Star, Hsd11b1, Pcna, and Ccnd1 in the testis. BDE47 significantly reduced p53 and p21 levels but increased CCND1 level. It also markedly increased the phosphorylation of AKT1, AKT2, ERK1/2, and CREB. BDE47 significantly up-regulated the expression of Scarb1, Star, and Hsd11b1 and stimulated androgen production by immature Leydig cells from rats under basal, LH, and 8Br-cAMP stimulated conditions at 100 nM in vitro. In conclusion, BDE47 increased Leydig cell number and up-regulated the expression of Scarb1 and Star, thereby leading to increased testosterone synthesis.

Effects of Midazolam on the Development of Adult Leydig Cells From Stem Cells In Vitro

BACKGROUND

Midazolam is a neurological drug with diverse functions, including sedation, hypnosis, decreased anxiety, anterograde amnesia, brain-mediated muscle relaxation, and anticonvulsant activity. Since it is frequently used in children and adolescents for extended periods of time, there is a risk that it may affect their pubertal development. Here, we report a potential effect of the drug on the development of Leydig cells (LCs), the testosterone (T)-producing cells in the testis.

METHODS

Stem LCs (SLCs), isolated from adult rat testes by a magnetic-activated cell sorting technique, were induced to differentiate into LCs in vitro for 3 weeks. Midazolam (0.1-30 μM) was added to the culture medium, and the effects on LC development were assayed.

RESULTS

Midazolam has dose-dependent effects on SLC differentiation. At low concentrations (0.1-5 μM), the drug can mildly increase SLC differentiation (increased T production), while at higher concentrations (15-30 μM), it inhibits LC development (decreased T production). T increases at lower levels may be due to upregulations of scavenger receptor class b Member 1 (SCARB1) and cytochrome P450 17A1 (CYP17A1), while T reductions at higher levels of midazolam could be due to changes in multiple steroidogenic proteins. The uneven changes in steroidogenic pathway proteins, especially reductions in CYP17A1 at high midazolam levels, also result in an accumulation of progesterone. In addition to changes in T, increases in progesterone could have additional impacts on male reproduction. The loss in steroidogenic proteins at high midazolam levels may be mediated in part by the inactivation of protein kinase B/cAMP response element-binding protein (AKT/CREB) signaling pathway.

CONCLUSION

Midazolam has the potential to affect adult Leydig cell (ALC) development at concentrations comparable with the blood serum levels in human patients. Further studies are needed to test the effects on human cells.

Leydig Cell and Spermatogenesis

Leydig cells of the testis have the capacity to synthesize androgen (mainly testosterone) from cholesterol. Adult Leydig cells are the cell type for the synthesis of testosterone, which is critical for spermatogenesis. At least four steroidogenic enzymes take part in testosterone synthesis: cytochrome P450 cholesterol side chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase, cytochrome P450 17α-hydroxylase/17,20-lyase and 17β-hydroxysteroid dehydrogenase isoform 3. Testosterone metabolic enzyme steroid 5α-reductase 1 and 3α-hydroxysteroid dehydrogenase are expressed in some precursor Leydig cells. Androgen is transported by androgen-binding protein to Sertoli cells, where it binds to androgen receptor to regulate spermatogenesis.

Gestational vinclozolin exposure suppresses fetal testis development in rats

Vinclozolin is a common dicarboximide fungicide used to protect crops from diseases. It is also an endocrine disruptor and is thought to be related to abnormalities of the reproductive tract. However, its mechanism of inducing abnormalities of the male reproductive tract is still unclear. The purpose of this study was to study the effect of gestational vinclozolin exposure on the development of rat fetal Leydig cells. Female pregnant Sprague-Dawley rats were exposed to vinclozolin (0, 25, 50, and 100 mg/kg body weight/day) by gavage from gestational day 14-21. Vinclozolin dose-dependently reduced serum testosterone levels at doses of 50 and 100 mg/kg and the anogenital distance at 100 mg/kg. RNA-seq, qPCR, and Western blotting showed that vinclozolin down-regulated the expression of Nr5a1, Sox9, Lhcgr, Cyp11a1, Hsd3b1, Hsd17b3, Amh, Pdgfa, and Dhh and their encoded proteins. Vinclozolin reduced the number of NR2F2-positive stem Leydig cells at a dose of 100 mg/kg and enhanced autophagy in the testes. In conclusion, vinclozolin disrupts reproductive tract development and testis development in male fetal rats via several pathways.

Monocyte Chemoattractant Protein-1 stimulates the differentiation of rat stem and progenitor Leydig cells during regeneration

Background

Monocyte chemoattractant protein-1(MCP-1) is a chemokine secreted by Leydig cells and peritubular myoid cells in the rat testis. Its role in regulating the development of Leydig cells via autocrine and paracrine is still unclear. The objective of the current study was to investigate the effects of MCP-1 on Leydig cell regeneration from stem cells in vivo and on Leydig cell development in vitro.

Results

Intratesticular injection of MCP-1(10 ng/testis) into Leydig cell-depleted rat testis from post-EDS day 14 to 28 significantly increased serum testosterone and luteinizing hormone levels, up-regulated the expression of Leydig cell proteins, LHCGR, SCARB1, CYP11A1, HSD3B1, CYP17A1, and HSD17B3 without affecting progenitor Leydig cell proliferation, as well as increased ERK1/2 phosphorylation. MCP-1 (100 ng/ml) significantly increased medium testosterone levels and up-regulated LHCGR, CYP11A1, and HSD3B1 expression without affecting EdU incorporation into stem cells after in vitro culture for 7 days. RS102895, a CCR2 inhibitor, reversed MCP-1-mediated increase of testosterone level after culture in combination with MCP-1.

Conclusion

MCP-1 stimulates the differentiation of stem and progenitor Leydig cells without affecting their proliferation.

Fibroblast growth factor 16 stimulates proliferation but blocks differentiation of rat stem Leydig cells during regeneration

OBJECTIVES

We aim to investigate the effects of fibroblast growth factor 16 (FGF16) on Leydig cell regeneration in ethane dimethane sulphonate (EDS)-treated rat testis.

METHODS

We intraperitoneally inject 75 mg/kg EDS to adult male Sprague Dawley rats and then intratesticularly inject FGF16 (0, 10 and 100 ng/testis/day) from post-EDS day 14 for 14 days. We investigate serum hormone levels, Leydig cell number, gene and protein expression in vivo. We also explore the effects of FGF16 treatment on stem Leydig cell proliferation in vitro.

RESULTS

FGF16 lowers serum testosterone levels (21.6% of the control at a dose of 100 ng/testis) without affecting the levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) on post-EDS day 28 in vivo. FGF16 increases Leydig cell number at doses of 10 and 100 ng/mg without affecting Sertoli cell number, increases the percentage of PCNA-positive Leydig cells, and down-regulates the expression of Leydig cell genes (Lhcgr, Scarb1, Star, Cyp11a1, Cyp17a1 and Hsd17b3) and Sertoli cell genes (Fshr, Dhh and Sox9) and their proteins in vivo. FGF16 increases phosphorylation of AKT1 and AKT2 as well as EKR1/2 in vivo, indicating that it possibly acts via AKT1/ATK2 and ERK1/2 pathways. FGF16 also lowers medium testosterone levels and down-regulates the expression of Leydig cell genes (Lhcgr, Scarb1, Star, Cyp11a1, Cyp17a1 and Hsd17b3) but increases EdU incorporation into stem Leydig cells in vitro.

CONCLUSIONS

These data suggest that FGF16 stimulates stem and progenitor Leydig cell proliferation but blocks their differentiation, thus lowering testosterone biosynthesis.

Fibroblast Growth Factor 1 Promotes Rat Stem Leydig Cell Development

Fibroblast growth factor 1 (FGF1) is reported to be expressed in the testis. How FGF1 affects stem Leydig cell development remains unclear. Here, we report the effects of FGF1 on rat stem Leydig cell development in an ethane dimethane sulfonate (EDS)-treated model. FGF1 (100 ng/testis) significantly increased serum testosterone level, increased PCNA-positive Leydig cell percentage and Leydig cell number, but down-regulated the expression of Lhcgr, Star, Cyp11a1, Hsd3b1, Cyp17a1, and Hsd11b1 in Leydig cells per se, after its daily intratesticular injection from post-EDS day 14 for 14 days. Primary culture of the seminiferous tubules showed that FGF1 stimulated EdU incorporation to stem Leydig cells but blocked the differentiation into the Leydig cell lineage, possibly via FGFR1-mediated mechanism. In conclusion, FGF1 promotes stem Leydig cell proliferation but blocks its differentiation.