Leydig Cell and Spermatogenesis

Triptolide induced spermatogenesis dysfunction via ferroptosis activation by promoting K63-linked GPX4 polyubiquitination in spermatocytes

Triptolide (TP) is a major bioactive compound derived from Tripterygium wilfordii Hook. F. (TwHF) known for its medicinal properties, but it also exhibits potential toxic effects. It has been demonstrated to induce severe male reproductive toxicity, yet the precise mechanism behind this remains unclear, which limits its broad clinical application. This study aimed to investigate the mechanisms underlying testicular damage and spermatogenesis dysfunction induced by TP in mice, using both mouse models and the spermatocyte-derived cell line GC-2spd. In the present study, it was found that TP displayed significant testicular microstructure damaged and spermatogenesis defects including lower concentration and abnormal morphology by promoting ROS formation, MDA production and restraining GSH level, glutathione peroxidase 4 (GPX4) expression in vivo. Furthermore, Ferrostatin-1 (FER-1), a ferroptosis inhibitor, was found to significantly reduce the accumulation of lipid peroxidation, alleviate testicular microstructural damage, and enhance spermatogenic function in mice. Besides, notably decreased cell viability, collapsed mitochondrial membrane potential, and elevated DNA damage were observed in vitro. The above-mentioned phenomenon could be reversed by pre-treatment of FER-1, indicating that ferroptosis participated in the TP-mediated spermatogenesis dysfunction. Mechanistically, TP could enhance GPX4 ubiquitin degradation via triggering K63-linked polyubiquitination of GPX4, thereby stimulating ferroptosis in spermatocytes. Functionally, GPX4 deletion intensified ferroptosis and exacerbated DNA damage in GC-2 cells, while GPX4 overexpression mitigated ferroptosis induced by TP. Overall, these findings for the first time indicated a vital role of ferroptosis in TP induced-testicular injury and spermatogenic dysfunction through promoting GPX4 K63-linked polyubiquitination, which hopefully offers a potential therapeutic avenue for TP-related male reproductive damage. In addition, this study also provides a theoretical foundation for the improved clinical application of TP or TwHF in the future.

Androgens and erectile dysfunction: from androgen deficiency to treatment

INTRODUCTION

Androgens play important roles in regulating the growth and development of the male reproductive system and maintaining libido and erectile function. The specific mechanisms by which androgen deficiency leads to erectile dysfunction (ED) are not yet fully understood.

OBJECTIVES

To understand the mechanisms and treatment of androgen deficiency-related ED.

METHODS

A literature search in the past 10 years was conducted in PubMed and Google Scholar to determine the effects of androgen deficiency on erectile function and the treatment of androgen deficiency.

RESULTS

Androgen deficiency can be caused by hypothalamic-pituitary lesions and injuries, testicular-related diseases and injuries, endocrine and metabolic disorders, the side effects of medication, and age. Androgen deficiency can lead to ED by inhibiting the NOS/NO/cGMP pathway (nitric oxide synthase/nitric oxide/cyclic guanosine monophosphate) and altering the expression of ion channel proteins, as well as by inducing oxidative stress, death, and fibrosis in penile corpus cavernosum cells. Testosterone replacement therapy is effective at improving the serum testosterone levels and erectile function in patients with androgen deficiency. For patients who need to maintain a low androgenic state, erectile function can be improved by lifestyle changes, treatment with phosphodiesterase type 5 inhibitors, low-intensity extracorporeal shock wave therapy, and stem cell therapy.

CONCLUSIONS

Androgen deficiency can affect the structure and function of the penile corpus cavernosum, leading to ED. Areas of further study include how androgen replacement therapy can improve erectile function and how to improve the maintenance of erectile function in patients with hypoandrogenic status.

Aflatoxin B1-Induced Testosterone Biosynthesis Disorder via the ROS/AMPK Signaling Pathway in Male Mice

The worldwide prevalence of Aflatoxin B1 (AFB1), which contaminates feedstock and food, is on the rise. AFB1 inhibits testosterone (T) biosynthesis, but the mechanism is not yet clear. By establishing in vivo and in vitro models, this study found the number of Leydig cells (LCs), T content, and the expression of T biosynthesis key enzymes were suppressed after AFB1 treatment. AFB1 exposure also increased reactive oxygen species (ROS) and promoted mitochondrial injury and mitochondrial pathway apoptosis. Moreover, the AMPK signaling pathway was activated, and using an AMPK inhibitor relieved apoptosis and the suppressed T biosynthesis key enzymes of LCs caused by AFB1 through regulating downstream p53 and Nur77. Additionally, adding ROS intervention could inhibit AMPK activation and alleviate the decreased T content caused by AFB1. In summary, AFB1 promotes the apoptosis of LCs and inhibits T biosynthesis key enzyme expression via activating the ROS/AMPK signaling pathway, which eventually leads to T synthesis disorder.

Betaine ameliorates heat stress-induced apoptosis by affecting oxidative and endoplasmic reticulum stress in mouse Leydig cells

In order to explore the potential protective role of betaine in heat stress (HS)-elicited apoptosis in mouse Leydig cells (mLCs). Betaine at 16 mm exerted a greater inhibitory effect on HS-induced viability attenuation of cells, which also significantly suppressed the heat shock protein 70 level in HS-treated cells. Furthermore, betaine ameliorated certain negative effects, including increased cell apoptotic ratio, enhancement of apoptosis-related modulator caspase-3 activity, reduced activity levels of such antioxidant enzymes as SOD, CAT, GSH-Px, and MDA upregulation, and inhibited the protein levels of critical endoplasmic reticulum (ER) stress indices like CHOP and GRP78 in mLCs exposed to HS. Besides, treatment of cells with betaine significantly restored diminished testosterone production in response to HS. Correspondingly, betaine effectively rescued the reduced serum testosterone concentration in vivo. In summary, betaine ameliorated HS-induced apoptosis by affecting oxidative and ER stress, thereby providing benefits for the treatment of hyperthermia-related impairment in mLCs.

Alginate oligosaccharide extends the service lifespan by improving the sperm metabolome and gut microbiota in an aging Duroc boars model

Introduction

Alginate oligosaccharide (AOS), as a natural non-toxic plant extract, has been paid more attention in recent years due to its strong antioxidant, anti-inflammatory, and even anti-cancer properties. However, the mechanism by which AOS affects animal reproductive performance is still unclear.

Methods

The purpose of this study is to use multi-omics technology to analyze the effects of AOS in extending the service lifespan of aging boars.

Results

The results showed that AOS can significantly improve the sperm motility (p < 0.05) and sperm validity rate (p < 0.001) of aging boars and significantly reduce the abnormal sperm rate (p < 0.01) by increasing the protein levels such as CatSper 8 and protein kinase A (PKA) for semen quality. At the same time, AOS significantly improved the testosterone content in the blood of boars (p < 0.01). AOS significantly improved fatty acids such as adrenic acid (p < 0.05) and antioxidants such as succinic acid (p < 0.05) in sperm metabolites, significantly reducing harmful substances such as dibutyl phthalate (p < 0.05), which has a negative effect on spermatogenesis. AOS can improve the composition of intestinal microbes, mainly increasing beneficial bacteria Enterobacter (p = 0.1262) and reducing harmful bacteria such as Streptococcus (p < 0.05), Prevotellaceae_UCG-001 (p < 0.05), and Prevotellaceae_NK3B31_group (p < 0.05). Meanwhile, short-chain fatty acids in feces such as acetic acid (p < 0.05) and butyric acid (p < 0.05) were significantly increased. Spearman correlation analysis showed that there was a close correlation among microorganisms, sperm metabolites, and sperm parameters.

Discussion

Therefore, the data indicated that AOS improved the semen quality of older boars by improving the intestinal microbiota and sperm metabolome. AOS can be used as a feed additive to solve the problem of high elimination rate in large-scale boar studs.

The constructive and destructive impact of autophagy on both genders' reproducibility, a comprehensive review

Reproduction is characterized by a series of massive renovations at molecular, cellular, and tissue levels. Recent studies have strongly tended to reveal the involvement of basic molecular pathways such as autophagy, a highly conserved eukaryotic cellular recycling, during reproductive processes. This review comprehensively describes the current knowledge, updated to September 2022, of autophagy contribution during reproductive processes in males including spermatogenesis, sperm motility and viability, and male sex hormones and females including germ cells and oocytes viability, ovulation, implantation, fertilization, and female sex hormones. Furthermore, the consequences of disruption in autophagic flux on the reproductive disorders including oligospermia, azoospermia, asthenozoospermia, teratozoospermia, globozoospermia, premature ovarian insufficiency, polycystic ovarian syndrome, endometriosis, and other disorders related to infertility are discussed as well.Abbreviations: AKT/protein kinase B: AKT serine/threonine kinase; AMPK: AMP-activated protein kinase; ATG: autophagy related; E2: estrogen; EDs: endocrine disruptors; ER: endoplasmic reticulum; FSH: follicle stimulating hormone; FOX: forkhead box; GCs: granulosa cells; HIF: hypoxia inducible factor; IVF: in vitro fertilization; IVM: in vitro maturation; LCs: Leydig cells; LDs: lipid droplets; LH: luteinizing hormone; LRWD1: leucine rich repeats and WD repeat domain containing 1; MAP1LC3: microtubule associated protein 1 light chain 3; MAPK: mitogen-activated protein kinase; MTOR: mechanistic target of rapamycin kinase; NFKB/NF-kB: nuclear factor kappa B; P4: progesterone; PCOS: polycystic ovarian syndrome; PDLIM1: PDZ and LIM domain 1; PI3K: phosphoinositide 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PtdIns3K: class III phosphatidylinositol 3-kinase; POI: premature ovarian insufficiency; ROS: reactive oxygen species; SCs: Sertoli cells; SQSTM1/p62: sequestosome 1; TSGA10: testis specific 10; TST: testosterone; VCP: vasolin containing protein.

Melatonin or vitamin C attenuates lead acetate-induced testicular oxidative and inflammatory damage in mice by inhibiting oxidative stress mediated NF-κB signaling

Lead (Pb) acts as an environmental endocrine disruptor and has negative effects in animals; excessive accumulation of lead causes reproductive dysfunction in male animals. Oxidative stress plays a vital role in Pb-induced injury. However, the mechanisms underlying chronic testicular toxicity of Pb remain unclear. In this study, we aimed to determine the effects of lead acetate on reproductive function in male mice, identify the underlying mechanisms, and test counter measures to alleviate the toxic effects. Male mice were dosed with lead acetate (500 mg/L) in free drinking water for 12 weeks, and administered melatonin (5 mg/kg) or vitamin C (500 mg/kg) by intraperitoneal injection. Blood from the eyeball, testicles, and sperm from the caudal epididymis were collected after 12 weeks and analyzed. Pb exposure reduced sperm count and motility, increased sperm malformation (P < 0.01), disrupted testicular morphology and structure, and decreased the expression of steroid hormone synthesis-related enzymes and serum testosterone concentration (P < 0.01). Pb also increased the number of inflammatory cells and the levels of the pro-inflammatory cytokines TNF-α and IL-6 (P < 0.01), and activated NF-κB signaling. Furthermore, the ROS yield and oxidation indicators LPO and MDA were significantly increased (P < 0.01), and the antioxidant indicators T-AOC, SOD, and GSH were significantly reduced (P < 0.01). Treatment with melatonin or vitamin C reversed the effects of lead acetate; vitamin C was more effective in restoring SOD activity (P < 0.01) and enhancing ZO-1 protein levels (P < 0.01). Thus, long-term exposure to lead acetate at low concentrations could adversely affect sperm quality and induce inflammatory damage by oxidative stress mediated NF-κB signaling. Vitamin C could act as a protective agent and improve reproductive dysfunction in male animals after lead accumulation.

Prenatal DEHP Exposure Induces Premature Testicular Aging by Promoting Leydig Cell Senescence through the MAPK Signaling Pathways

Previous studies show that prenatal di-(2-ethylhexyl) phthalate (DEHP) exposure induces premature testicular aging. However, the evidence is weak, and the underlying mechanisms remain unclear. p38/extracellular signal-regulated kinase (ERK)/c-Jun NH(2)-terminal kinase (JNK) MAPK pathways participate in aging. Leydig cell (LC) senescence results in testicular aging. Whether prenatal DEHP exposure induces premature testicular aging by promoting LC senescence warrants further study. Here, male mice undergo prenatal exposure to 500 mg per kg per day DEHP, and TM3 LCs are treated with 200 µm mono (2-ethylhexyl) phthalate (MEHP). MAPK pathways, testicular toxicity, and senescent phenotypes (β-gal activity, p21, p16, and cell cycle) of male mice and LCs are explored. Prenatal DEHP exposure induces premature testicular aging in middle-aged mice (poor genital development, reduced testosterone synthesis, poor semen quality, increased β-gal activity, and upregulated expression of p21 and p16). MEHP induces LCs senescence (cell cycle arrest, increased β-gal activity, and upregulated expression of p21). p38 and JNK pathways are activated, and the ERK pathway is inactivated. In conclusion, prenatal DEHP exposure induces premature testicular aging by promoting LC senescence through MAPK signaling pathways.

Wnt10a downregulation contributes to MEHP-induced disruption of self-renewal and differentiation balance and proliferation inhibition in GC-1 cells: Insights from multiple transcriptomic profiling

Di (2-ethylhexyl) phthalate (DEHP), one of phthalic acid esters, has been widely used in daily products. Its main metabolite, mono (2-ethylhexyl) phthalate (MEHP) was reported to possess higher testicular toxicity than DEHP. To explore the precise mechanism in MEHP-induced testis damage, multiple transcriptomic sequencing was employed in spermatogonia cell line GC-1 cells treated with MEHP (0, 100, and 200 μM) for 24 h. Integrative omics analysis and empirical validation revealed that Wnt signaling pathway was downregulated and wnt10a, one of hub genes, may be the key player in this process. Similar results were observed in DEHP-exposed rats. MEHP-induced disturbance of self-renewal and differentiation was dose-dependent. Moreover, self-renewal proteins were downregulated; the differentiation level was stimulated. Meanwhile, GC-1 proliferation was decreased. Stable transformation strain of wnt10a overexpression GC-1 cell line constructed from lentivirus was utilized in this study. The upregulation of Wnt10a significantly reversed the dysfunction of self-renewal and differentiation and promoted the cell proliferation. Finally, retinol, predicted to be useful in CONNECTIVITY MAP (cMAP), failed to rescue the damage caused by MEHP. Cumulatively, our findings revealed that the downregulation of Wnt10a induced the imbalance of self-renew and differentiation, and inhibition of cell proliferation in GC-1 cells after MEHP exposure.

The long noncoding RNA CIRBIL is a regulator of steroidogenesis in mice

Infertility affects roughly 8-12 % of couples worldwide, and in above 50 % of couples, male factors are the primary or contributing cause. Many long noncoding RNAs (lncRNAs) are detected in the testis, but their functions are not well understood. CIRBIL was 862 nucleotides in length and was found to be localized mostly in the cytosol of Leydig cell, a small portion was positioned inside the seminiferous tubules. Loss of CIRBIL in mice resulted in male subfertility, characterized by smaller testis and increased germ cell apoptosis. Deletion of CIRBIL significant decreased the number of sperm and impaired the integrity of sperm head and tail. In CIRBIL KO mice, testosterone levels in serum and expression of testosterone biosynthesis genes (STAR and 3β-HSD) were both reduced. Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were primarily enriched in steroid synthesis process in CIRBIL-binding proteins. Protein-protein (PPI) interaction networks revealed that both cis- and trans-regulated target genes of CIRBIL were associated with testosterone synthesis. Collectively, our results strongly suggest that CIRBIL is a regulator of steroid hormone synthesis.

Triphenyl phosphate induced apoptosis of mice testicular Leydig cells and TM3 cells through ROS-mediated mitochondrial fusion inhibition

Triphenyl phosphate (TPHP) is a widely used organophosphate flame retardant and has biological toxicity. Previous studies showed TPHP can restrain testosterone biosynthesis in Leydig cells, while the underlying mechanisms remain unclear. In this study, C57BL/6J male mice were exposed to 0, 5, 50, and 200 mg/kg B.W. of TPHP for 30 d by oral, as well as TM3 cells were treated with 0, 50, 100, and 200 μM of TPHP for 24 h. Results showed that TPHP induced testes damage, including spermatogenesis disorders and testosterone synthesis inhibition. Meanwhile, TPHP can cause apoptosis in testicular Leydig cells and TM3 cells, as evidenced by the increased apoptosis rate and decreased Bcl-2/Bax ratio. Moreover, TPHP disrupted mitochondrial ultrastructure of testicular Leydig cells and TM3 cells, reduced healthy mitochondria content and depressed mitochondrial membrane potential of TM3 cells, as well as inhibited mitochondrial fusion proteins mitofusin 1 (Mfn1), mitofusin 2 (Mfn2), and optic atrophy 1 (Opa1) expression, without effect on mitochondrial fission proteins dynamin-related protein 1 (Drp1) and fission 1 (Fis1) in testicular tissue and/or TM3 cells. Then, the mitochondrial fusion promoter M1 was used to pre-treat TPHP-exposed TM3 cells to determine the roles of mitochondrial fusion inhibition in TPHP-induced Leydig cells apoptosis. The results showed M1 pretreatment alleviated the above changes and further mitigated TM3 cells apoptosis and testosterone levels decreased, indicating TPHP induced TM3 cells apoptosis by inhibited mitochondrial fusion. Intriguingly, the intervention experiment of N-acetylcysteine (NAC) showed that TPHP-induced mitochondrial fusion inhibition is ROS dependent, because inhibition of ROS overproduction alleviated mitochondrial fusion inhibition, and subsequently relieved TPHP-induced apoptosis in TM3 cells. In summary, above data revealed that apoptosis is a specific mechanism for TPHP-induced male reproductive toxicity, and that ROS-mediated mitochondrial fusion inhibition is responsible for Leydig cells apoptosis caused by TPHP.

Local adrenomedullin gene delivery inhibits Leydig cell dysfunction by rescuing steroidogenic enzymes in vivo

Adrenomedullin (ADM) has beneficial effects on Leydig cells under pathological conditions, including lipopolysaccharide (LPS)-induced orchitis. Our previous studies demonstrated that ADM exerts a restorative effect on steroidogenesis in LPS-treated primary rat Leydig cells by attenuating oxidative stress, inflammation and apoptosis. In this study, we aim to investigate whether ADM inhibits Leydig cell dysfunction by rescuing steroidogenic enzymes in vivo. Rats were administered with LPS and injected with Ad-ADM, an adeno-associated virus vector that expressed ADM. Then, rat testes were collected for 3β-hydroxysteroid dehydrogenase (3β-HSD) immunofluorescence staining. Steroidogenic enzymes or steroidogenic regulatory factors or protein, including steroidogenic factor-1 (SF-1), liver receptor homologue-1 (LRH1), Nur77, steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side chain cleavage enzyme (P450scc), 3β-HSD, cytochrome P450 17α-hydroxylase/17, 20 lyase (CYP17) and 17β-hydroxysteroid dehydrogenase (17β-HSD), were detected via gene expression profiling and western blot analysis. Plasma testosterone concentrations were measured. Results showed that ADM may inhibit Leydig cell dysfunction by rescuing steroidogenic enzymes and steroidogenic regulatory factors in vivo. The reduction in the number of Leydig cells after LPS exposure was reversed by ADM. ADM rescued the gene or protein levels of SF-1, LRH1, Nur77, StAR, P450scc, 3β-HSD, CYP17 and 17β-HSD and plasma testosterone concentrations. To summarize ADM could rescue some important steroidogenic enzymes, steroidogenic regulatory factors and testosterone production in Leydig cells in vivo.

Serum Nerve Growth Factor Levels as a Predictor of Bull Candidate Semen Quality of Madura Cattle

Madura cattle are the germplasm of native cattle on the verge of extinction because of crossbreeding. Therefore, the present study was aimed to determine the serum nerve growth factor (NGF) concentration as a predictor of fresh ejaculate fertility parameters in Madura bull candidates. Eleven Madura bull candidates used for frozen semen production were selected for the study. Blood samples were collected using a vacutainer from the jugular vein for analyzing serum NGF and testosterone levels. Meanwhile, semen collection was conducted using an artificial vagina for sperm motility, viability, and concentration assessment. Data were analyzed to determine the correlation among variables and the linear regression of NGF concentration to other significant variables. The result showed that NGF had a significant correlation (p < 0.05) with testosterone levels, sperm motility, viability, and concentration. A significant correlation was observed between testosterone levels, sperm concentration, and sperm viability. The regression equation among significantly correlated variables was determined. For artificial insemination, suitable bull ejaculates for obtaining frozen semen should reach at least 2.12 ng/mL of NGF levels, with sperm viability, sperm concentration, and testosterone levels of more than 78.63%, 1,462.177 million/mL ejaculate, and 25.67 ng/mL, respectively. This is the first study to identify NGF as a predictor of male fertility in bull candidates of Madura cattle. Therefore, NGF levels could be used as a marker of male fertility in Madura bull cattle candidates. Thus, based on the minimum NGF levels, the ejaculate of Madura bull candidate that meets the requirements for frozen semen production could predict fertility.