Leydig cell aging and the mechanisms of reduced testosterone synthesis

Sirt1 m6A modification-evoked Leydig cell senescence promotes Cd-induced testosterone decline

Diminished testosterone levels have been documented as a key factor in numerous male health disorders. Both human and animal studies have consistently demonstrated that cadmium (Cd), a pervasive environmental heavy metal, results in decreased testosterone levels. However, the exact mechanism through which Cd interferes with testosterone synthesis remains incompletely elucidated. This research sought to examine the impact of cellular senescence on Cd-suppressed testosterone synthesis. We also investigated the related m6A modification mechanism. The results demonstrated that Cd (100 mg/L) led to a decrease in testosterone levels, along with downregulated expression of testosterone synthase in C57BL/6 N male mice. Furthermore, Cd significantly increased β-galactosidase staining intensity, senescence-related proteins, and senescence-related secretory phenotypes in mouse testicular Leydig cells. Subsequent investigations revealed that Cd decreased the mRNA and protein levels of NAD-dependent deacetylase Sirtuin-1 (SIRT1) in Leydig cells. Mechanistically, mice treated with resveratrol (50 mg/kg), a specific SIRT1 activator, mitigated Leydig cell senescence and reversed Cd-reduced testosterone levels in mouse testes. These effects were also restored by SIRT1 overexpression in Leydig cells. Additionally, we found that Cd increased the level of methyltransferase enzyme METTL3 and Sirt1 m6A modification in Leydig cells. Mettl3 siRNA effectively restored Cd-enhanced Sirt1 m6A level and reversed Cd-downregulated Sirt1 mRNA expression in Leydig cells. Overall, our findings suggest that Cd exposure inhibits testosterone synthesis via Sirt1 m6A modification-mediated senescence in mouse testes. These results offer an experimental basis for investigating the causes and potential treatments of hypotestosteronemia induced by environmental factors.

Clomiphene Citrate Treatment as an Alternative Therapeutic Approach for Male Hypogonadism: Mechanisms and Clinical Implications

Male hypogonadism, which is characterized by low testosterone levels, has a significant impact on male sexual function, overall health, and fertility. Testosterone replacement therapy (TRT) is the conventional treatment for this condition, but it has potential adverse effects and is not suitable for men seeking to conceive. Testosterone plays an essential role in male sexual function, metabolism, mood, and overall well-being. Clomiphene citrate, a drug originally developed for female infertility, has recently gained attention as an off-label treatment for male hypogonadism. By blocking the negative feedback of estrogen on the hypothalamus and pituitary glands, clomiphene stimulates gonadotropin secretion, leading to increased endogenous testosterone production, which, in turn, improves sperm parameters and fertility and alleviates the symptoms of hypogonadism. Regarding the safety profile of clomiphene compared with TRT, clomiphene appears to confer a lower risk than TRT, which is associated with adverse effects such as polycythemia. Furthermore, combination therapy with clomiphene and anastrozole or human chorionic gonadotropin has been investigated as a potential approach to enhancing the effectiveness of treatments for improving hypogonadism symptoms. In conclusion, clomiphene citrate may offer a promising alternative to TRT for men with hypogonadism, particularly those desiring fertility preservations. However, its long-term efficacy and safety remain inadequately understood. Future research should focus on exploring the benefits of combination therapies and personalized treatment strategies based on individual patient characteristics.

Sirtuin 1-mediated autophagy regulates testosterone synthesis in Leydig cells of piglets

Testosterone is secreted by Leydig cells (LCs), which play an important physiological role in preserving male secondary sex characteristics, protecting male reproductive function, and establishing the blood-testis barrier. Studies have shown that autophagy is particularly active in LCs; however, its involvement in testosterone synthesis in porcine LCs has not been fully explored. Therefore, this experiment aimed to investigate the influence of autophagy on testosterone secretion in porcine LCs and its potential regulatory mechanism. Our results demonstrated that both testicular autophagy and serum testosterone levels increased in piglets during postnatal development from 4 to 18 weeks. In addition, autophagy was found to degrade the Na+/H+ exchange regulatory factor 2 (NHERF2), leading to the up-regulation of scavenger receptor class B type 1 (SRB1). This process resulted in increased cholesterol intake and enhanced testosterone production. The observable level of sirtuin 1 (SIRT1) was directly proportional to the level of autophagy. In vitro investigations have shown that SIRT1 can affect the level of autophagy, cholesterol uptake as well as testosterone release. In conclusion, testosterone synthesis during pig development is regulated by SIRT1. SIRT1 mediates the degradation of NHERF2 through autophagy, thereby weakening its negative regulatory effect on the high-density lipoprotein receptor SRB1 in Leydig cells. This process increases cholesterol uptake and enhances testosterone synthesis.

MicroRNA-361-5p Alleviates Leydig Cell Apoptosis and Promotes Cell Growth by Targeting PIAS1 in Late-Onset Hypogonadism

Late-onset hypogonadism (LOH) is an age-related syndrome characterized by deficiency of serum testosterone produced by Leydig cells. Previous evidence suggested that microRNA (miR)-361-3p can serve as a promising biomarker for LOH. Nonetheless, its detailed function and molecular mechanism in LOH remain unclarified. The 24-month-old male mice were selected as an animal LOH model, and mouse Leydig cell line TM3 was stimulated with H2O2. ELISA was employed for testosterone level evaluation. Hematoxylin-eosin staining was implemented for histologic analysis of mouse testicular tissues. Western blotting and RT-qPCR were utilized for evaluating molecular protein and RNA expression, respectively. Functional experiments were conducted to test miR-361-5p roles. Luciferase reporter assay was for verifying the interaction between miR-361-5p and protein inhibitor of activated STAT 1 (PIAS1). miR-361-5p displayed a decreased level in the testes of LOH mice. Overexpressing miR-361-5p attenuated Leydig cell loss in the testis and elevated serum and intratesticular testosterone levels in LOH mice. H2O2 stimulation impaired TM3 cell viability, proliferation and intracellular testosterone production and enhanced cell apoptosis. miR-361-5p targeted PIAS1 in TM3 cell. PIAS1 upregulation counteracted miR-361-5p overexpression-mediated alleviation of cell apoptosis and elevation of testosterone synthesis in H2O2-stimualetd TM3 cells. miR-361-5p ameliorates LOH progression by increasing testosterone production and alleviate Leydig cell apoptosis via downregulation of PIAS1.

Prevention of Male Late-Onset Hypogonadism by Natural Polyphenolic Antioxidants

Androgen production primarily occurs in Leydig cells located in the interstitial compartment of the testis. In aging males, testosterone is crucial for maintaining muscle mass and strength, bone density, sexual function, metabolic health, energy levels, cognitive function, as well as overall well-being. As men age, testosterone production by Leydig cells of the testes begins to decline at a rate of approximately 1% per year starting from their 30s. This review highlights recent findings concerning the use of natural polyphenolics compounds, such as flavonoids, resveratrol, and phenolic acids, to enhance testosterone production, thereby preventing age-related degenerative conditions associated with testosterone insufficiency. Interestingly, most of the natural polyphenolic antioxidants having beneficial effects on testosterone production tend to enhance the expression of the steroidogenic acute regulatory protein (Star) gene in Leydig cells. The STAR protein facilitates the entry of the steroid precursor cholesterol inside mitochondria, a rate-limiting step for androgen biosynthesis. Natural polyphenolic compounds can also improve the activities of steroidogenic enzymes, hypothalamus-pituitary gland axis signaling, and testosterone bioavailability. Thus, many polyphenolic compounds such as luteolin, quercetin, resveratrol, ferulic acid phenethyl ester or gigantol may be promising in delaying the initiation of late-onset hypogonadism accompanying aging in males.

Melatonin alleviates glyphosate-induced testosterone synthesis inhibition via targeting mitochondrial function in roosters

Glyphosate (GLY) is a widely used herbicide that has been revealed to inhibit testosterone synthesis in humans and animals. Melatonin (MET) is an endogenous hormone that has been demonstrated to promote mammalian testosterone synthesis via protecting mitochondrial function. However, it remains unclear whether MET targets mitochondria to alleviate GLY-inhibited testosterone synthesis in avian. In this study, an avian model using 7-day-old rooster upon chronic exposure to GLY with the treatment of MET was designed to clarify this issue. Data first showed that GLY-induced testicular Leydig cell damage, structural damage of the seminiferous tubule, and sperm quality decrease were mitigated by MET. Transcriptomic analyses of the testicular tissues revealed the potentially critical role of mitophagy and steroid hormone biosynthesis in the process of MET counteracting GLY-induced testicular damage. Also, validation data demonstrated that the inhibition of testosterone synthesis due to GLY-induced mitochondrial dynamic imbalance and concomitant Parkin-dependent mitophagy activation is alleviated by MET. Moreover, GLY-induced oxidative stress in serum and testicular tissue were significantly reversed by MET. In summary, these findings demonstrate that MET effectively ameliorates GLY-inhibited testosterone synthesis by inhibiting mitophagy activation, which provides a promising remedy for the application of MET as a potential therapeutic agent to antagonize reproductive toxicity induced by GLY and similar contaminants.

In vitro and in vivo studies on the effect of a mitochondrial fusion promoter on Leydig cell integrity and function

Background: The interstitial testicular Leydig cells are responsible for the production of testosterone, which functionally deteriorate with normal aging. Decreased expression of mitochondrial steroidogenic interactome proteins and diminished mitochondrial function in aging Leydig cells suggest that mitochondrial dynamics play a role in maintaining adequate levels of testosterone. Optic atrophy 1 (OPA1) protein regulates mitochondrial dynamics and cristae formation in many cell types. Previous studies showed that increasing OPA1 expression in dysfunctional Leydig cells restored mitochondrial function and recovered androgen production to levels found in healthy Leydig cells. These findings suggested that mitochondrial dynamics may be a promising target to ameliorate diminished testosterone levels in aging males. Methods: We used twelve-month-old rats to explore the relationship between mitochondrial dynamics and Leydig cell function. Isolated Leydig cells from aged rats were treated ex vivo with the cell-permeable mitochondrial fusion promoter 4-Chloro-2-(1-(2-(2,4,6-trichlorophenyl)hydrazono)ethyl) phenol (mitochondrial fusion promoter M1), which enhances mitochondrial tubular network formation. In parallel, rats were treated with 2 mg/kg/day M1 for 6 weeks before Leydig cells were isolated. Results: Ex vivo M1-treated cells showed enhanced mitochondrial tubular network formation by transmission electron microscopy, enhanced Leydig cell mitochondrial integrity, improved mitochondrial function, and higher testosterone biosynthesis compared to controls. However, in vivo treatment of aged rats with M1 not only failed to re-establish testosterone levels to that of young rats, it also led to further reduction of testosterone levels and increased apoptosis, suggesting M1 toxicity in the testis. The in vivo M1 toxicity seemed to be tissue-specific, however. Conclusion: Promoting mitochondrial fusion may be one approach to enhancing cell health and wellbeing with aging, but more investigations are warranted. Our findings suggest that fusion promoters could potentially enhance the productivity of aged Leydig cells when carefully regulated.

Maternal Fed Zinc-Deficient Diet: Effects on Relaxin Family Peptides and Oxidant System in the Testis and Liver Tissue of Male Offspring

Today, the studies are limited on roles of insulin-like peptide 3 (INSL3), insulin-like peptide 7 (INSL7), and relaxin family peptide receptor 1 (RXFP1) which are synthesized by the testis. It is aimed to investigate the levels of the sex hormone as testosterone and the family of insulin-like proteins (relaxin family peptides), which are important in the puberty transition, in the testicular and liver tissues of male offspring born to female rats fed a zinc-deficient diet during the pregnancy, and in the changes in lipid peroxidation markers. The study was performed on 40 male offspring. In Group I: Control group, both male offspring and mothers were fed with standard rat chow. In Group II: Zinc deficient diet, both male offspring and mothers were fed a zinc-deficient diet (2.8 mg/kg zinc). In Group III: Normal diet, male offspring fed standard rat chow for 45 days (66th day) after being separated from their mothers with a maternal zinc-deficient diet. In Group IV: Zinc-supplemented diet, offspring fed with zinc supplemented (5 mg/kg/day intraperitoneal zinc sulfate, i.p.) in addition to standard rat chow after being separated from their mothers with maternal zinc deficiency until the termination of the study (66th day). Our study suggests that zinc-supplemented diets play an important role in the changes in INSL3, INSL7, RXFP1, and testosterone levels during spermatogenesis. INSL7, INSL3, and RXFP1 levels were higher in zinc-supplemented group than the zinc-deficient diet group. Liver levels of INSL3, INSL7, and MDA were significantly different in zinc-deficiency diet group than zinc-supplemented group.

A narrative review on inflammaging and late-onset hypogonadism

The increasing life expectancy observed in recent years has resulted in a higher prevalence of late-onset hypogonadism (LOH) in older men. LOH is characterized by the decline in testosterone levels and can have significant impacts on physical and mental health. While the underlying causes of LOH are not fully understood, there is a growing interest in exploring the role of inflammaging in its development. Inflammaging is a concept that describes the chronic, low-grade, systemic inflammation that occurs as a result of aging. This inflammatory state has been implicated in the development of various age-related diseases. Several cellular and molecular mechanisms have been identified as contributors to inflammaging, including immune senescence, cellular senescence, autophagy defects, and mitochondrial dysfunction. Despite the extensive research on inflammaging, its relationship with LOH has not yet been thoroughly reviewed in the literature. To address this gap, we aim to review the latest findings related to inflammaging and its impact on the development of LOH. Additionally, we will explore interventions that target inflammaging as potential treatments for LOH.

Dietary supplementation with barley sprouts and d-aspartic acid improves reproductive hormone concentrations, testicular histology, antioxidant status, and mRNA expressions of apoptosis-related genes in aged broiler breeder roosters

The objective was to determine effects of dietary supplementation of barley sprouts (BS) and/or d-aspartic acid (DA) on the reproductive potential of aged broiler roosters. Birds (n = 32, 50 wk old) were randomly allocated to receive dietary supplements of BS powder (2 % of basal diet), and DA (200 mg/kg BW), both, or neither, for 12 wk. Roosters were housed individually, with 14-h light/10-h dark, ad libitum feed and water, and euthanized after 12 wk. Mean (±SEM) total phenolic compounds and IC50 in methanol extract of sprouted barley were 302.8 ± 10.9 mg GAE/g and 600.8 ± 50.5 mg TE per 100 g, respectively. In weekly semen collections, sperm total and progressive motility, plasma membrane integrity, sperm concentration, and sperm production were higher (P < 0.05) in both the DA + BS and BS groups compared to the Control, but sperm abnormalities were unaffected. Feeding DA increased right, left, and combined testicular weights (P < 0.05, P < 0.05, and P < 0.01, respectively) and, the testicular index (P = 0.01). Feeding BS increased seminiferous tubule diameter (P < 0.01), whereas BS + DA increased seminiferous epithelium thickness (P < 0.01). There were more spermatogonia (P < 0.01) and Leydig cells (P < 0.05) in BS-fed roosters but Sertoli cells were highest in BS + DA (P < 0.01). Serum MDA concentrations were lowest in BS (P < 0.01), whereas serum testosterone and LH were highest in DA (P < 0.05) and BS + DA (P < 0.01), respectively. Feeding BS reduced serum total cholesterol (P < 0.05) and increased serum HDL-cholesterol (P < 0.01), with decreases in serum LDL (P < 0.01) and the LDL/HDL ratio (P < 0.01) for BS + DA compared to Control. Relative expression of glutathione peroxidase mRNA was increased by BS (P < 0.01) or DA (P < 0.05), whereas relative mRNA expression of SOD was highest in BA (P < 0.01). Control roosters were highest for both BAX (P < 0.01) and the relative expression of the BAX/BCL-2 ratio (P < 0.01), whereas BS + DA increased BCL-2 (P < 0.05). In conclusion, feeding BS, and/or DA significantly improved reproductive potential in aged broiler roosters.

Traditional Chinese Medicine formula Wubi Shanyao Pills protects against reproductive aging by activating SIRT1/3 to reduce apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

The study of male reproductive aging and its associated concerns holds significant importance within the realm of health issues affecting the elderly population. Wubi Shanyao Pills (WSP), a traditional Chinese patent medicine originating from the Tang Dynasty, has been recognized for its ability to enhance male sexual functions while also tonifying the kidney and spleen. Nevertheless, the precise effects and underlying mechanisms through which WSP ameliorates the decline in reproductive function among aging men remain uncertain.

AIM OF THE STUDY

This study elucidated the distinctive impacts of WSP on ameliorating the decline in reproductive function caused by natural aging, as well as its underlying mechanisms.

MATERIALS AND METHODS

Initially, male mice at the age of 15 months were administered WSP orally at doses of 0.375, 0.75, and 1.50 g/kg per day for a duration of 8 consecutive weeks. The impact of WSP on age-related manifestations in naturally aging mice was assessed based on their behavioral performance. The renal function of the mice was evaluated by measuring serum biochemical indicators, including Creatinine (CR), Uric acid (UA), and Blood urea nitrogen (BUN). Additionally, Superoxide dismutase (SOD) and Malonaldehyde (MDA) levels in renal tissue were determined using applied chemistry methods. Then assessed the levels of Nitric oxide (NO), Total nitric oxide synthase (T-NOS), Guanosine cyclase (GC), and Cyclic guanosine monophosphate (cGMP) in the penile tissue, as well as the expression of Endothelial nitric oxide synthase (eNOS) and Guanylate Cyclase Activator (GUCA) protein, in order to investigate the erectile function of the penis. Additionally, the quality of epididymal sperm was examined using an electron microscope. Furthermore, the serum sex hormone level and related protein expression were determined through the utilization of enzyme-linked immunosorbent assay and immunohistochemistry techniques. Pathological alterations and the ultrastructure of the testis were investigated using hematoxylin-eosin staining and transmission electron microscopy. Subsequently, the apoptosis of spermatogenic cells in the testes was assessed employing TUNEL, immunofluorescence, western blotting, and quantitative real-time polymerase chain reaction.

RESULTS

The administration of WSP has been found to enhance the behavioral performance and sexual behavior in aged mice. It's also could increase in serum levels of CR, UA, and BUN, as well as the elevation of SOD activity in kidney tissue, which subsequently leads to a reduction in MDA levels and an improvement in the structural damage caused by aging in the kidney tissue. Consequently, the renal function is enhanced. Additionally, WSP has been observed to elevate the levels of NO, T-NOS, GC, and cGMP in penile tissue, along with an increase in eNOS and GUCA protein expression, indicating an improvement in penile erectile function. The administration of WSP resulted in a decrease in the occurrence of programmed cell death in testicular germ cells, leading to an enhancement in sperm quality and the overall function of testicular spermatogenesis. This improvement can be attributed to the modulation of hormone levels and the regulation of SIRT1/3, p53, FOXO3, Bax, and Caspase-3 expression.

CONCLUSION

Collectively, our findings indicate that the administration of WSP has the potential to impede the occurrence of programmed cell death in testicular cells by modulating the expression of SIRT1/3 and subsequent genes associated with apoptosis. Consequently, this regulatory mechanism facilitates the proliferation of testicular cells and sustains the spermatogenic function of the testes. Consequently, by modulating the levels of sexual hormones in naturally aging mice, WSP ultimately enhances the quality of sperm and reproductive function. Concurrently, it also ameliorates age-related behavioral changes, renal function, and erectile function.

Knockdown of ZnT4 Induced Apoptosis, Inhibited Proliferation and testosterone synthesis of TM3 cells

Zinc deficiency has a huge impact on male reproduction. The zinc transporter (ZnT) family is involved in the maintenance of zinc homeostasis and testosterone synthesis. However, the underlying mechanisms remain to be investigated. Therefore, in this study, we aimed to determine the effect of zinc transporter 4 (ZnT4) on testosterone synthesis in male Kunming mice and mouse Leydig cells. The results of this study showed that compared with the zinc normal diet group (Con group), the zinc-deficient diet group (ZnD group) had decreased zinc content and increased ZnT4 expression in testicular tissues, and decreased serum testosterone levels, suggesting that ZnT4 may be involved in Leydig cell injury resulting from a zinc-deficient diet. Subsequently, mouse Leydig cell line TM3 cells were used to analyze the effect of ZnT4 downregulation on TM3 cell proliferation and apoptosis, on testosterone synthesis, and its underlying mechanisms. Here, we show that knockdown of ZnT4 can induce the accumulation of zinc, inhibit the viability, and induce apoptosis in TM3 cells. In addition, knockdown of ZnT4 downregulated testosterone concentration and expression of testosterone synthesis-related proteins steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase/D5-D4 isomerase (3β-HSD) in TM3 cells, while hCG could rescue their levels. We show that it is ZnT4 that plays a role in testosterone production through a mediated PI3K/Akt/mTOR autophagy pathway, whereas mTORC1 complex inhibitor (Rapa) blocks the decrease in testosterone levels caused by ZnT4 downregulation. In conclusion, the above results indicate that ZnT4 plays an important role in regulating testosterone synthesis.

A Review on the Impact of Oxidative Stress and Medicinal Plants on Leydig Cells

Leydig cells are essential for steroidogenesis and spermatogenesis. An imbalance in the production of reactive oxygen species (ROS) and the cellular antioxidant level brings about oxidative stress. Oxidative stress (OS) results in the dysfunction of Leydig cells, thereby impairing steroidogenesis, spermatogenesis, and ultimately, male infertility. To prevent Leydig cells from oxidative insults, there needs to be a balance between the ROS production and the cellular protective capacity of antioxidants. Evidence indicates that medicinal plants could improve Leydig cell function at specific concentrations under basal or OS conditions. The increased usage of medicinal plants has been considered a possible alternative treatment for male infertility. This review aims to provide an overview of the impact of oxidative stress on Leydig cells as well as the effects of various medicinal plant extracts on TM3 Leydig cells. The medicinal plants of interest include Aspalathus linearis, Camellia sinensis, Moringa oleifera, Morinda officinale, Taraxacum officinale, Trichilia emetica, Terminalia sambesiaca, Peltophorum africanum, Ximenia caffra, Serenoa repens, Zingiber officinale, Eugenia jambolana, and a combination of dandelion and fermented rooibos (CRS-10). According to the findings obtained from studies conducted on the evaluated medicinal plants, it can, therefore, be concluded that the medicinal plants maintain the antioxidant profile of Leydig cells under basal conditions and have protective or restorative effects following exposure to oxidative stress. The available data suggest that the protective role exhibited by the evaluated plants may be attributed to their antioxidant content. Additionally, the use of the optimal dosage or concentration of the extracts in the management of oxidative stress is of the utmost importance, and the measurement of their oxidation reduction potential is recommended.

Effects of Unripe Black Raspberry Extract Supplementation on Male Climacteric Syndrome and Voiding Dysfunction: A Pilot, Randomized, Double-Blind, Placebo-Controlled Trial

Male climacteric syndrome (MCS) is a medical condition that can affect middle-aged men whose testosterone levels begin to decline considerably. These symptoms may include fatigue, decreased libido, mood swings, and disturbed sleep. MCS can be managed with lifestyle modifications and testosterone replacement. However, testosterone therapy may cause number of side effects, including an increased risk of cardiovascular issues. This study aims to evaluate the efficacy and safety of unripe black raspberry extract (BRE) against MCS and voiding dysfunction in men with andropause symptoms. A total of 30 subjects were enrolled and randomly assigned to the BRE group (n = 15) or the placebo group (n = 15). Participants were supplemented with 4800 mg BRE or placebo twice daily for 12 weeks. The impact of BRE was assessed using the Aging Male's Symptoms (AMS scale), International Prostate Symptom Score (IPSS) and the IPSS quality of life index (IPSS-QoL). Additionally, male sex hormones, lipid profiles, and anthropometric indices were assessed 6 and 12 weeks after treatment. The AMS scores did not differ significantly between the two groups. In the BRE group, the total IPSS and IPSS-QoL scores decreased significantly after 12 weeks compared to baseline (p < 0.05), but there was no significant difference compared to the placebo group. However, a significant difference was observed in the IPSS voiding symptoms sub-score compared to the placebo group. Furthermore, LDL-C and TC levels were also significantly lower in the BRE group than in the placebo group (p < 0.05). Collectively, the study provides strong evidence supporting the safety of BRE as a functional food and its supplementation potentially enhances lipid metabolism and alleviates MCS and dysuria symptoms, limiting the development of BPH.

Primary culture and endocrine functional analysis of Leydig cells in ducks (Anas platyrhynchos)

Testicular Leydig cells (LCs) are the primary known source of testosterone, which is necessary for maintaining spermatogenesis and male fertility. However, the isolation, identification, and functional analysis of testosterone in duck LCs are still ambiguous. The aim of the present study was to establish a feasible method for isolating highly purified primary duck LCs. The highly purified primary duck LCs were isolated from the fresh testes of 2-month-old ducks via the digestion of collagenase IV and Percoll density gradient centrifugation; hematoxylin and eosin (H&E), immunohistochemistry (IHC) staining, ELISA, and radioimmunoassay were performed. Results revealed that the LCs were prominently noticeable in the testicular interstitium of 2-month-old ducks as compared to 6-month-old and 1-year-old ducks. Furthermore, IHC demonstrated that the cultured LCs occupied 90% area of the petri dish and highly expressed 3β-HSD 24 h after culture (hac) as compared to 48 and 72 hac. Additionally, ELISA and radioimmunoassay indicate that the testosterone level in cellular supernatant was highly expressed in 24 and 48 hac, whereas the testosterone level gradually decreased in 72 and 96 hac, indicating the primary duck LCs secrete testosterone at an early stage. Based on the above results, the present study has effectively developed a technique for isolating highly purified primary duck LCs and identified its biological function in synthesizing testosterone.

Role of Macroautophagy in Mammalian Male Reproductive Physiology

Physiologically, autophagy is an evolutionarily conserved and self-degradative process in cells. Autophagy carries out normal physiological roles throughout mammalian life. Accumulating evidence shows autophagy as a mechanism for cellular growth, development, differentiation, survival, and homeostasis. In male reproductive systems, normal spermatogenesis and steroidogenesis need a balance between degradation and energy supply to preserve cellular metabolic homeostasis. The main process of autophagy includes the formation and maturation of the phagophore, autophagosome, and autolysosome. Autophagy is controlled by a group of autophagy-related genes that form the core machinery of autophagy. Three types of autophagy mechanisms have been discovered in mammalian cells: macroautophagy, microautophagy, and chaperone-mediated autophagy. Autophagy is classified as non-selective or selective. Non-selective macroautophagy randomly engulfs the cytoplasmic components in autophagosomes that are degraded by lysosomal enzymes. While selective macroautophagy precisely identifies and degrades a specific element, current findings have shown the novel functional roles of autophagy in male reproduction. It has been recognized that dysfunction in the autophagy process can be associated with male infertility. Overall, this review provides an overview of the cellular and molecular basics of autophagy and summarizes the latest findings on the key role of autophagy in mammalian male reproductive physiology.

The impact of biological clock and sex hormones on the risk of disease

Molecular clocks are responsible for defining 24-h cycles of behaviour and physiology that are called circadian rhythms. Several structures and tissues are responsible for generating these circadian rhythms and are named circadian clocks. The suprachiasmatic nucleus of the hypothalamus is believed to be the master circadian clock receiving light input via the optic nerve and aligning internal rhythms with environmental cues. Studies using both in vivo and in vitro methodologies have reported the relationship between the molecular clock and sex hormones. The circadian system is directly responsible for controlling the synthesis of sex hormones and this synthesis varies according to the time of day and phase of the estrous cycle. Sex hormones also directly interact with the circadian system to regulate circadian gene expression, adjust biological processes, and even adjust their own synthesis. Several diseases have been linked with alterations in either the sex hormone background or the molecular clock. So, in this chapter we aim to summarize the current understanding of the relationship between the circadian system and sex hormones and their combined role in the onset of several related diseases.

Role of ROS/JAK2/STAT3 signaling pathway in di-n-butyl phthalate-induced testosterone synthesis inhibition and antagonism of lycopene

Di-n-butyl phthalate (DBP) causes adverse effects on male reproduction, especially testosterone synthesis inhibition. However, the specific mechanism of DBP-induced testosterone synthesis inhibition and its effective intervention measures of prevention and treatment are scarce presently. Lycopene (LYC) plays beneficial roles in male infertility because of its antioxidant activity. Nevertheless, it is unclear whether LYC could prevent DBP-induced male reproductive toxicity. By in vitro and in vivo investigations, this study demonstrated that DBP activated ROS/JAK2/STAT3 signaling pathway, promoted mitophagy and apoptosis, which in turn inhibited testosterone synthesis. Additionally, another major finding was that LYC supplement could reverse the above change, presenting as the restraint of ROS/JAK2/STAT3 signaling pathway, reduction of mitophagy and apoptosis, and improvement of testosterone synthesis. Our study facilitates deeper understandings of the mechanism in DBP-induced testosterone synthesis inhibition, and identifies LYC as the effective prevention and control strategies for DBP poisoning.

Pituitary-testis axis dysfunction following adjuvant androgen deprivation therapy

Men with high-risk, non-metastatic prostate cancer receive adjuvant androgen deprivation therapy (ADT) for at least 2 years according to Danish guidelines. It remains unclarified if patients regain the function of the pituitary-testis axis after cessation of ADT. Thus, we aimed to investigate the function of the pituitary-testis axis following adjuvant ADT. In this study, we included men who underwent external beam radiation therapy and ADT for high-risk prostate cancer. All patients underwent assessment of testosterone deficiency (TD) symptoms, full biochemical assessment of the pituitary-testis axis, and dynamic stimulatory tests of gonadotropin (gonadotropin-releasing hormone (GnRH) test) and testosterone production (human chorionic gonadotrophin (hCG) test). Patients were diagnosed with TD based on a combination of TD symptoms and testosterone below age-specific reference ranges. TD was characterized as primary, secondary, or mixed based on serum gonadotropins and stimulatory tests. We found that among the 51 patients included in the study, the median time on ADT was 3.2 years and median time since ADT cessation was 3.8 years. Twenty-eight patients were diagnosed with TD; 10 had primary TD (testicular dysfunction), 11 secondary TD (pituitary dysfunction), and 7 mixed TD (combined pituitary and testicular dysfunction). An inadequate testosterone response to hCG stimulation was shown in 42 patients, whereas only 11 patients had a subnormal gonadotropin response to GnRH. We conclude that persistent TD is a common long-term consequence of adjuvant ADT in prostate cancer survivors, equally distributed between pituitary and testicular dysfunction. The study emphasizes the necessity for systematic follow-up of full pituitary-testis axis function in patients receiving adjuvant ADT.

Low-Intensity Pulsed Ultrasound Alleviates Human Testicular Leydig Cell Senescence In Vitro

Aging has a significant negative impact on human testicular function; steroidogenesis is gradually impaired, and testosterone replacement therapy still has many risks. Low-intensity pulsed ultrasound (LIPUS) has been used as a novel non-invasive treatment for male erectile dysfunction and other fields, and has been shown to increase testosterone levels in animal models. Testosterone is synthesized and secreted by Leydig cells (LCs), and the serum testosterone level decreases after aging due to the LCs senescence. However, the effect of LIPUS on human senescent LCs has not been reported. In this study, human senescent LCs were isolated and stimulated with different energy intensities in vitro, and cell morphology, cell apoptosis, cell proliferation, cell senescence levels, lipid droplet number, testosterone and INSL3 secretion levels were tested and analyzed. Quantitative Polymerase Chain Reaction (QPCR) and Western Blot were performed to compare cell senescence characteristics and the expression profile of key pathways of testosterone secretion, and transcriptome analysis was performed to explore the signaling pathways of LCs alteration after LIPUS stimulation. It was safe and effective to stimulate LCs with the 75 mW/cm² energy of LIPUS in vitro, which not only improved the senescence phenotype, but also effectively enhanced the secretory function of LCs in vitro, and increased the expression of key pathways of the testosterone synthesis pathway. These results suggest that LIPUS could be used as a novel treatment to human senescent LCs with decreased testosterone secretion levels in vitro.

Mitochondrial dynamics, Leydig cell function, and age-related testosterone deficiency

The mitochondrial translocator protein (18 kDa; TSPO) is a high-affinity cholesterol-binding protein that is an integral component of the cholesterol trafficking scaffold responsible for determining the rate of cholesterol import into the mitochondria for steroid biosynthesis. Previous studies have shown that TSPO declines in aging Leydig cells (LCs) and that its decline is associated with depressed circulating testosterone levels in aging rats. However, TSPO's role in the mechanistic decline in LC function is not fully understood. To address the role of TSPO depletion in LC function, we first examined mitochondrial quality in Tspo knockout mouse tumor MA-10 nG1 LCs compared to wild-type MA-10 cells. Tspo deletion caused a disruption in mitochondrial function and membrane dynamics. Increasing mitochondrial fusion via treatment with the mitochondrial fusion promoter M1 or by optic atrophy 1 (OPA1) overexpression resulted in the restoration of mitochondrial function and mitochondrial morphology as well as in steroid formation in TSPO-depleted nG1 LCs. LCs isolated from aged rats form less testosterone than LCs isolated from young rats. Treatment of aging LCs with M1 improved mitochondrial function and increased androgen formation, suggesting that aging LC dysfunction may stem from compromised mitochondrial dynamics caused by the age-dependent LC TSPO decline. These results, taken together, suggest that maintaining or enhancing mitochondrial fusion may provide therapeutic strategies to maintain or restore testosterone levels with aging.

Effect of Tetragonia tetragonoides (Pall.) Kuntze Extract on Andropause Symptoms

Testosterone and free testosterone levels decrease in men as they age, consequently inducing andropause symptoms, such as weight gain, fatigue, and depression. Therefore, this study aimed to evaluate the reducing effect of New Zealand spinach (NZS) on these androgenic symptoms by orally administering its extract to 26-week-old rats for four weeks. Biochemical blood testing was conducted, and the andropause symptoms-related indicators and muscular endurance levels were examined. In the NZS extract-treated rats, the decrease in muscle mass was suppressed, and immobility time was reduced in the forced swim test. In addition, the grip force and muscular endurance of the forelimbs were significantly increased compared to the control group; therefore, NZS extract exhibits a positive effect on the maintenance of muscle mass and improves muscular endurance. The representative male hormones, testosterone and progesterone, in the NZS extract-treated group were 1.84 times and 2.48 times higher than those in the control groups, respectively. Moreover, cholesterol and low-density lipoprotein, which affect lipid metabolism, were significantly reduced in the NZS extract-treated group. Overall, NZS extract shows potential for further development as a functional food material for improving muscle strength and relieving andropause symptoms.

The Roles of Androgens in Humans: Biology, Metabolic Regulation and Health

Androgens are an important and diverse group of steroid hormone molecular species. They play varied functional roles, such as the control of metabolic energy fate and partition, the maintenance of skeletal and body protein and integrity and the development of brain capabilities and behavioral setup (including those factors defining maleness). In addition, androgens are the precursors of estrogens, with which they share an extensive control of the reproductive mechanisms (in both sexes). In this review, the types of androgens, their functions and signaling are tabulated and described, including some less-known functions. The close interrelationship between corticosteroids and androgens is also analyzed, centered in the adrenal cortex, together with the main feedback control systems of the hypothalamic-hypophysis-gonads axis, and its modulation by the metabolic environment, sex, age and health. Testosterone (T) is singled out because of its high synthesis rate and turnover, but also because age-related hypogonadism is a key signal for the biologically planned early obsolescence of men, and the delayed onset of a faster rate of functional losses in women after menopause. The close collaboration of T with estradiol (E2) active in the maintenance of body metabolic systems is also presented Their parallel insufficiency has been directly related to the ravages of senescence and the metabolic syndrome constellation of disorders. The clinical use of T to correct hypoandrogenism helps maintain the functionality of core metabolism, limiting excess fat deposition, sarcopenia and cognoscitive frailty (part of these effects are due to the E2 generated from T). The effectiveness of using lipophilic T esters for T replacement treatments is analyzed in depth, and the main problems derived from their application are discussed.

The cost of the circadian desynchrony on the Leydig cell function

The increased frequency of different lifestyles that disrupts circadian rhythms, together with a trend in the accretion of male idiopathic infertility, imposes the necessity to understand the contribution of circadian rhythms disruption to fertility regulation. In this study, the effects of circadian desynchrony (CD) on the steroidogenic capacity of adult Leydig cells were studied. Adult rats were housed under a disturbing light regime (2 days of constant light, 2 days of continual dark, and 3 days of 12:12 h light:dark schedule) designed to mimic shiftwork in humans. CD was characterized by changed and decreased rhythmic locomotor activity and reduced blood testosterone. In the Leydig cells changed transcription of the clock genes (Bmal1, Clock, Cry1 and Reverba/b increased while Per1/2 reversed phase) was detected. This was followed by reduced transcription of genes (Star, Cyp11a1, and Hsd3b1/2) primarily involved in mitosteroidogenesis. In parallel, mitochondrial membrane potential (Δψi) and ATP production declined losing their characteristic oscillatory pattern. Also, the main markers of mitochondrial biogenesis (Ppargc1a, Nrf1, Tfam, Cytc), fusion (Mfn2), and mitophagy (Pink1 and Tfeb) were disturbed. Collectively, CD targets mitochondria in Leydig cells by reducing mitosteroidogenesis, mitoenergetics, and disturbing mitochondrial dynamics. These changes contribute to testosterone decline compromising androgen-dependent functions, including reproduction.

Alginate oligosaccharides increase boar semen quality by affecting gut microbiota and metabolites in blood and sperm

Alginate oligosaccharides (AOS), natural polymers from brown seaweeds (such as Laminaria japonica, Undaria pinnatifida, and Sargassum fusiforme), have been reported to possess many beneficial advantages for health. In the current study, after 9 weeks of dietary supplementation, AOS 10 mg/kg group (AOS 10) group increased boar sperm motility from 87.8% to 93.5%, p < 0.05. Moreover, AOS10 increased the relative abundances of Bifidobacterium, Coprococcus, Butyricicoccus (1.3–2.3-fold; p < 0.05) to increase the beneficial blood and sperm metabolites (1.2–1.6-fold; p < 0.05), and important sperm proteins such as gelsolin, Zn-alpha2 glycoprotein, Cation Channel Sperm-Associated Protein, outer dense fiber of sperm tails, etc. (1.5–2.2-fold; p < 0.05). AOS had a long-term beneficial advantage on boar semen quality by the increase in semen volume (175 vs. 160 ml/ejaculation, p < 0.05). AOS may be used as dietary additives for improving semen quality.

Age-related changes in testicular morphometry and function in Egyptian donkeys

This study aimed to assess the effects of age on testicular morphometry and function in donkeys. Testes and epididymides of 57 donkeys were harvested immediately after slaughtering. The donkeys were grouped: young (1-4 years-old, n=13); adult (5-15 years-old, n=25) and aged (>15 years-old, n=19). Each testis and epididymis were weighted separated. Testicular volume was calculated. Epididymal sperm was harvested by retrograde flushing method, and sperm parameters were evaluated. The testicular parenchyma was immunolabelled for BAX and COX2. Adult and aged donkeys had greater testicular weight and volume than young (P<0.05). Epididymal sperm concentration, motility, and viability were greater (P<0.05) in adults and aged (931.8±39.3 and 858.2±33.2× 10⁶ /mL) than in young animals (316.3±72.8× 10⁶ /mL). Aged donkeys had higher percentage of morphologic sperm defects than the other categories (P<0.05). Histological examination revealed the presence of age-related degenerative changes in testicular tissue of donkeys. Aged donkeys had higher COX2 protein expression than adult and young donkeys. BAX protein was overly expressed in adults than aged or young animals. In conclusion, advancement of age affects the testicular morphometry and function in donkeys.

Low-dose rapamycin prevents Ang-II-induced toxicity in Leydig cells and testicular dysfunction in hypertensive SHR model

Hypertension is a common chronic cardiovascular disease reported among both men and women. Hypertension in males affects the testis and reproduction function; however, the pathogenesis is poorly understood. Rapamycin has been reported to have a variety of beneficial pharmacological effects; however, high-doses rapamycin does have side effects such as immunosuppression. The present study investigates whether low-dose rapamycin can reduce the damage caused by hypertension to the testis of spontaneously hypertensive rats (SHRs) and further examines molecular mechanism of low-dose rapamycin in preventing testicular toxicity induced by angiotensin II (Ang II). Low rapamycin dose restores the testicle size, histological alterations, 3β-hydroxysteroid dehydrogenase (3β-HSD) expression, and prevents apoptosis in SHR rats. Ang II downregulates angiotensin-converting enzyme-2 (ACE2) expression through AT1R, p-ERK, and MAS receptor in LC-540 Leydig cells in a dose-dependent manner. Low doses of rapamycin effectively upregulate steroidogenic enzymes, steroidogenic acute regulatory protein and 3β-HSD expression in Leydig cells. Rapamycin upregulates ACE2 expression through p-PKAc and p-PI3k in Ang II-treated cells. Further, rapamycin curbs mitochondrial superoxide generation and depleted mitochondrial membrane potential induced by Ang II through activation of Nrf2-mediated Gpx4 and superoxide dismutase 2 expression. Our results revealed the involvement of ACE2, AT1R, AT2R, PKAc, and oxidative stress in Ang-II-induced testicular toxicity, suggesting low-dose rapamycin could be a potential therapeutic candidate to attenuate testicular toxicity.

Long-term effects of melatonin and resveratrol on aging rats: A multi-biomarker approach

Aging-related impaired body structure and functions may be, at least partially, caused by elevated oxidative stress. Melatonin (MEL) and resveratrol (RSV) may act as antioxidant and anti-aging compounds, but these actions in experimental animals and humans are controversial. Herein, a rat model of aging was used to study the long-term sex-related effects of MEL and RSV treatment on body mass and blood/plasma parameters of DNA damage, oxidative status (glutathione and malondialdehyde levels), and concentrations of sex hormones. Starting from the age of 3mo, for the next 9mo or 21mo male and female Wistar rats (n = 4-7 per group) were given water to drink (controls) or 0.1 % ethanol in water (vehicle), or MEL or RSV (each 10 mg/L vehicle). DNA damage in whole blood cells was tested by comet assay, whereas in plasma, glutathione, malondialdehyde, and sex hormones were determined by established methods. Using statistical analysis of data by ANOVA/Scheffe post hoc, we observed a similar sex- and aging-dependent rise of body mass in both sexes and drop of plasma testosterone in control and vehicle-treated male rats, whose pattern remained unaffected by MEL and RSV treatment. Compared with controls, all other parameters remained largely unchanged in aging and differently treated male and female rats. We concluded that the sex- and aging-related pattern of growth and various blood parameters in rats were not affected by the long-term treatment with MEL and RSV at the estimated daily doses (300-400 μg/kg b.m.) that exceed usual moderate consumption in humans.

Anatomical Transcriptome Atlas of the Male Mouse Reproductive System During Aging

The elderly males undergo degenerative fertility and testicular endocrine function that jeopardize the reproductive health and well-being. However, the mechanisms underlying reproductive aging are unclear. Here, we tried to address this by investigating the phenotypes and transcriptomes of seven regions of the male mouse reproductive tract: the testis, efferent ductules, initial segment, caput, corpus and cauda epididymidis, and vas deferens, in adult (3 months) and aged (21 months) mice. Quantitative PCR, immunohistochemistry, immunofluorescent staining, and enzyme-linked immunosorbent assay were performed for the analysis of gene expression in mice, human tissues, and semen samples. Aged male mice showed both systematic and reproductive changes, and remarkable histological changes were detected in the testis and proximal epididymis. Transcriptomes of the male reproductive tract were mapped, and a series of region-specific genes were identified and validated in mouse and/or human tissues, including Protamine 1 (Prm2), ADAM metallopeptidase domain 28 (Adam28), Ribonuclease A family member 13 (Rnase13), WAP four-disulfide core domain 13 (Wfdc13), and Wfdc9. Meanwhile, age-related transcriptome changes of different regions of the male reproductive tract were characterized. Notably, increased immune response was functionally related to the male reproductive aging, especially the T cell activation. An immune response-associated factor, phospholipase A2 group IID (Pla2g2d), was identified as a potential biomarker for reproductive aging in mice. And the PLA2G2D level in human seminal plasma surged at approximately 35 years of age. Furthermore, we highlighted Protein tyrosine phosphatase receptor type C (Ptprc), Lymphocyte protein tyrosine kinase (Lck), Microtubule associated protein tau (Mapt), and Interferon induced protein with tetratricopeptide repeats 3 (Ifit3) as critical molecules in the aging of initial segment, caput, caput, and cauda epididymidis, respectively. This study provides an RNA-seq resource for the male reproductive system during aging in mice, and is expected to improve our understanding of male reproductive aging and infertility.

High Throughput scRNA-Seq Provides Insights Into Leydig Cell Senescence Induced by Experimental Autoimmune Orchitis: A Prominent Role of Interstitial Fibrosis and Complement Activation

Leydig cells (Lc), located in the interstitial space of the testis between seminiferous tubules, produce 95% of testosterone in male individuals, which is pivotal for male sexual differentiation, spermatogenesis, and maintenance of the male secondary sex characteristics. Lc are prone to senescence in aging testes, resulting in compromised androgen synthesis capability upon aging. However, little is known about whether Lc undergo senescence in a chronic inflammatory environment. To investigate this question, mouse models of experimental autoimmune orchitis (EAO) were used, and Lc were analyzed by high throughput scRNA-Seq. Data were screened and analyzed by correlating signaling pathways with senescence, apoptosis, androgen synthesis, and cytokine/chemokine signaling pathways. EAO did induce Lc senescence, and Lc senescence in turn antagonized androgen synthesis. Based on the correlation screening of pathways inducing Lc senescence, a plethora of pathways were found to play potential roles in triggering Lc senescence during EAO, among which the Arf6 and angiopoietin receptor pathways were highly correlated with senescence signature. Notably, complement and interstitial fibrosis activated by EAO worsened Lc senescence and strongly antagonized androgen synthesis. Furthermore, most proinflammatory cytokines enhanced both senescence and apoptosis in Lc and spermatogonia (Sg) during EAO, and proinflammatory cytokine antagonism of the glutathione metabolism pathway may be key in inducing cellular senescence during EAO.

Anti-steroidogenic effects of cholesterol hydroperoxide trafficking in MA-10 Leydig cells: Role of mitochondrial lipid peroxidation and inhibition thereof by selenoperoxidase GPx4

Steroid hormone synthesis in steroidogenic cells requires cholesterol (Ch) delivery to/into mitochondria via StAR family trafficking proteins. In previous work, we discovered that 7-OOH, an oxidative stress-induced cholesterol hydroperoxide, can be co-trafficked with Ch, thereby causing mitochondrial redox damage/dysfunction. We now report that exposing MA-10 Leydig cells to Ch/7-OOH-containing liposomes (SUVs) results in (i) a progressive increase in fluorescence probe-detected lipid peroxidation in mitochondrial membranes, (ii) a reciprocal decrease in immunoassay-detected progesterone generation, and ultimately (iii) loss of cell viability with increasing 7-OOH concentration. No significant effects were observed with a phospholipid hydroperoxide over the same concentration range. Glutathione peroxidase GPx4, which can catalyze lipid hydroperoxide detoxification, was detected in mitochondria of MA-10 cells. Mitochondrial lipid peroxidation and progesterone shortfall were exacerbated when MA-10 cells were treated with Ch/7-OOH in the presence of RSL3, a GPx4 inhibitor. However, Ebselen, a selenoperoxidase mimetic, substantially reduced RSL3's negative effects, thereby partially rescuing the cells from peroxidative damage. These findings demonstrate that co-trafficking of oxidative stress-induced 7-OOH can disable steroidogenesis, and that GPx4 can significantly protect against this.

Low-dose bisphenol S exposure induces hypospermatogenesis and mitochondrial dysfunction in rats: A possible implication of StAR protein

A wide variety of environmental chemicals/xenobiotics including bisphenol A (BPA) has been shown to cause male reproductive dysfunctions and infertility. Recently, bisphenol S (BPS) replaces BPA, in several products, including foodstuffs, under the BPA-free label. However, several studies have raised inquietude about the potential adverse effects of BPS. The present study was conducted to evaluate sperm parameters, biochemical parameters, mitochondrial function, and histopathological patterns after post-lactation BPS exposure at a low dose. Male rats (21 days old) were exposed to water containing BPS at 50 μg/L in drinking water for 10 weeks. Results showed no significant alteration in the gonadosomatic index (GSI) and relative reproductive organs weight. However, a significant reduction in epididymal sperm parameters (number, viability, and mobility) with morphological abnormalities were observed in the BPS group compared to control. An increase of malondialdehyde (MDA) level accompanied by antioxidant defense alteration particularly, in glutathione peroxidase activity, as well as a defective mitochondrial function were observed in testicular tissues of BPS treated rats. More importantly, in histopathological diagnosis, BPS treatment induces hypospermatogenesis and alteration in Sertoli cells. In silico docking studies illustrated BPS binds with steroidogenic acute regulatory (StAR) protein thereby affecting the transport of cholesterol into mitochondria resulting in decreased steroidogenesis. These results reflect a reprotoxic effect of BPS vould potentially lead to fertility reduction, in sexually maturity age. We highlighted that post-lactation exposure to BPS, equivalent in humans to the period covering childhood and adolescent stages, disrupt male reproduction function.

Alterations in epididymal sperm maturation caused by ageing

The epididymis is an organ that performs all the biochemical changes responsible for sperm maturation. During ageing, histological alterations in the epididymis and decreased protein synthesis have been found. This might affect the sperm maturation process. The aim of this study was to determine if the changes in the epididymis during ageing might cause alterations in sperm maturation. Wistar rats of 3-4months old (young) and 18-21months old (old) were used. The testosterone concentration was determined and the epididymides were dissected and divided in three regions: caput, corpus, and cauda. The tissues were used for histological processing and sperm extraction. Testosterone concentration decreased 34% in the old animals compared to the young ones. The distribution of mannose, sialic acid, and N-acetylglucosamine in the glycocalyx of the sperm membrane of old animals was different from that of young animals. The same occurred with phosphatidylserine externalisation and protein phosphorylation at tyrosine residues. Epididymis histology in old animals showed tubular and cellular degeneration. Our results suggest that ageing affects maturational markers, likely due to alterations in the epididymis as a result of the testosterone decrease associated with ageing.

The Mechanisms and Management of Age-Related Oxidative Stress in Male Hypogonadism Associated with Non-communicable Chronic Disease

Androgens have diverse functions in muscle physiology, lean body mass, the regulation of adipose tissue, bone density, neurocognitive regulation, and spermatogenesis, the male reproductive and sexual function. Male hypogonadism, characterized by reduced testosterone, is commonly seen in ageing males, and has a complex relationship as a risk factor and a comorbidity in age-related noncommunicable chronic diseases (NCDs), such as obesity, metabolic syndrome, type 2 diabetes, and malignancy. Oxidative stress, as a significant contributor to the ageing process, is a common feature between ageing and NCDs, and the related comorbidities, including hypertension, dyslipidemia, hyperglycemia, hyperinsulinemia, and chronic inflammation. Oxidative stress may also be a mediator of hypogonadism in males. Consequently, the management of oxidative stress may represent a novel therapeutic approach in this context. Therefore, this narrative review aims to discuss the mechanisms of age-related oxidative stress in male hypogonadism associated with NCDs and discusses current and potential approaches for the clinical management of these patients, which may include conventional hormone replacement therapy, nutrition and lifestyle changes, adherence to the optimal body mass index, and dietary antioxidant supplementation and/or phytomedicines.

Venlafaxine-induced adrenergic signaling stimulates Leydig cells steroidogenesis via Nur77 overexpression: a possible role of EGF

Venlafaxine, a norepinephrine and serotonin reuptake inhibitor, impairs rat sperm parameters, spermatogenesis and causes high intratesticular estrogen and testosterone levels, indicating that Leydig cells (LCs) may be a venlafaxine target. We evaluated the effect of venlafaxine treatment on LCs in vivo, focusing on adrenergic signaling, EGF immunoexpression and steroidogenesis. Germ cells mitotic/meiotic activity and UCHL1 levels were also evaluated in the seminiferous epithelium. Adult male rats received venlafaxine (30 mg/kg) or distilled water. In testicular sections, the seminiferous tubules, epithelium and the LCs nuclear areas were measured, and the immunoexpression of Ki-67, UCHL1, StAR, EGF, c-Kit and 17β-HSD was evaluated. UCHL1, StAR and EGF protein levels and Adra1a, Nur77 and Ndrg2 expression were analyzed. MDA and nitrite testicular levels, and serum estrogen and testosterone levels were measured. Venlafaxine induced LCs hypertrophy and Ndrg2 upregulation, in parallel to increased number of Ki-67, c-Kit- and 17β-HSD-positive interstitial cells, indicating that this antidepressant stimulates LCs lineage proliferation and differentiation. Upregulation of Adra1a and Nur77 could explain the high levels of StAR and testosterone levels, as well as aromatization. Enhanced EGF immunoexpresion in LCs suggests that this growth fact is involved in adrenergically-induced steroidogenesis, likely via upregulation of Nur77. Slight tubular atrophy and weak Ki-67 immunoexpression in germ cells, in association with high UCHL1 levels, indicate that spermatogenesis is likely impaired by this enzyme under supraphysiological estrogen levels. These data corroborate the unchanged MDA and nitrite levels. Therefore, venlafaxine stimulates LCs steroidogenesis via adrenergic signaling, and EGF may be involved in this process.

Prolonging photoperiod promotes testosterone synthesis of Leydig cells by directly targeting local melatonin system in rooster testes

The study investigated the effects of prolonging photoperiod on the synthesis of testosterone and melatonin in roosters, and the effect of melatonin on testosterone synthesis in rooster Leydig cells as well as its molecular mechanisms. We randomly divided one hundred and twenty 20-week-old roosters into three groups and provided 6, 12.5 and 16 h light, respectively. The results showed that prolonging photoperiod promoted testosterone synthesis, decreased melatonin production, and inhibited the expression of melatonin membrane receptors MEL1A, MEL1B, MEL1C, and aralkylamine n-acetyltransferase (AANAT) in rooster testes. Subsequently, rooster Leydig cells were isolated and treated with 0, 0.1, 1, 10, and 100 ng/mL melatonin for 36 h. The results suggested that melatonin inhibited testosterone synthesis in rooster Leydig cells, and silencing MEL1A and MEL1B relieved the inhibition of melatonin on testosterone synthesis. Additionally, melatonin reduced the intracellular cyclic adenosine monophosphate (cAMP) level and the phosphorylation level of cAMP-response element binding protein (CREB), and CREB overexpression alleviated the inhibition of melatonin on testosterone synthesis. Furthermore, pretreatment with cAMP activator forskolin or protein kinase A (PKA) activator 8-bromo-cAMP blocked the inhibition of melatonin on CREB phosphorylation and testosterone synthesis. These results indicated that prolonging photoperiod promoted testosterone synthesis associated with the decrease in melatonin production and membrane receptors and biosynthetic enzyme of melatonin in rooster testes, and melatonin inhibited testosterone synthesis of rooster Leydig cells by inhibiting the cAMP/PKA/CREB pathway via MEL1A and MEL1B. This may be evidence that prolonging photoperiod could promote testosterone synthesis through the inhibition of the local melatonin pathway in rooster testes.

Comparative transcriptome analysis reveals potential testosterone function-related regulatory genes/pathways of Leydig cells in immature and mature buffalo (Bubalus bubalis) testes

Leydig cells (LCs) are testosterone-generating endocrine cells that are located outside the seminiferous tubules in the testis, and testosterone is fundamental for retaining spermatogenesis and male fertility. In buffalo, adult Leydig cells (ALCs) are developed by immature Leydig cells (ILCs) in the postnatal testes. However, the genes/pathways associated to the regulation of testosterone secretion function during the development of postnatal LCs remains comprehensively unidentified. The present study comparatively analyzed the transcriptome profiles of ILC and ALC in buffalo with significant differences in testosterone secretion. Differentially expressed genes (DEGs) analysis identified 972 and 1,091 annotated genes that were significantly up- and down-regulated in buffalo ALC. Functional enrichment analysis showed that cAMP signaling being the most significantly enriched pathway, and testosterone synthesis and lipid transport-related genes/pathways were upregulated in ALC. Furthermore, gene set enrichment analysis (GSEA) shows that cAMP signaling and steroid hormone biosynthesis were activated in ALC, demonstrating that cAMP signaling may serve as a positive regulatory pathway in the maintenance of testosterone function during postnatal development of LCs. Protein-protein interaction (PPI) networks analysis highlighted that ADCY8, ADCY2, POMC, CHRM2, SST, PTGER3, SSTR2, SSTR1, NPY1R, and HTR1D as hub genes in the cAMP signaling pathway. In conclusion, this study identified key genes and pathways associated in the regulation of testosterone secretion function during the ILC-ALC transition in buffalo based on bioinformatics analysis, and these key genes might be deeply involved in cAMP generation to influencing testosterone levels in LCs. The results suggest that ALCs might increase testosterone levels by enhancing cAMP production than ILCs. Our data will enhance the understanding of developmental mechanism studies related to testosterone function and provide preliminary evidence for molecular mechanisms of LCs regulating spermatogenesis.

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.

Aging-Related Increase of cGMP Disrupts Mitochondrial Homeostasis in Leydig Cells

Since mitochondria play an essential role in the testosterone biosynthesis, serve as power centers and are a source of oxidative stress, a possible mitochondrial dysfunction could be connected with decreased activity of Leydig cells and lowered testosterone production during aging. Here we chronologically analyzed age-related alterations of mitochondrial function in Leydig cells correlated by the progressive rise of cGMP signaling and with respect to testosterone synthesis. To target cGMP signaling in Leydig cells, acute or long-term in vivo or ex vivo treatments with sildenafil (phosphodiesterase 5 [PDE5] inhibitor) were performed. Aging-related accumulation of cGMP in the Leydig cells is associated with mitochondrial dysfunction illustrated by reduced ATP and steroid production, lowered O2 consumption, increased mitochondrial abundance and mtDNA copies number, decreased expression of genes that regulate mitochondrial biogenesis (Ppargc1a/PGC1a-Tfam-Nrf1/NRF1), mitophagy (Pink1), fusion (Mfn1, Opa1), and increased Nrf2/NRF2. Acute in vivo PDE5 inhibition overaccumulated cGMP and stimulated testosterone but reduced ATP production in Leydig cells from adult, middle-aged, and old rats. The increased ATP/O ratio observed in cells from old compared to adult rats was diminished after stimulation of cGMP signaling. Opposite, long-term PDE5 inhibition decreased cGMP signaling and improved mitochondrial function/dynamics in Leydig cells from old rats. Mitochondrial abundance in Leydig cells decreased while ATP levels increased. Chronic treatment elevated Tfam, Nrf1, Nrf2, Opa1, Mfn1, Drp1, and normalized Pink1 expression. Altogether, long-term PDE5 inhibition prevented age-related NO and cGMP elevation, improved mitochondrial dynamics/function, and testosterone production. The results pointed on cGMP signaling in Leydig cells as a target for pharmacological manipulation of aging-associated changes in mitochondrial function and testosterone production.

Standardized Saw Palmetto Extract Directly and Indirectly Affects Testosterone Biosynthesis and Spermatogenesis

We investigated whether a standardized saw palmetto extract (SP, mixture of supercritical extract and ethanol extract at a ratio of 9.5 to 0.5) can relieve the symptoms of andropause, including metabolic syndrome, and decreases in muscle endurance and spermatogenesis, in old rats. Twenty-four-week-old male Sprague Dawley rats received oral supplementation of SP at 40, 80, and 160 mg/kg body weight (bw) for 4 weeks. We found that SP supplementation reduced body weight gain by decreasing visceral and epididymal fat weights and the levels of serum triglycerides, total cholesterol, and low-density lipoprotein/very low-density lipoprotein cholesterol. In addition, SP supplementation increased muscle endurance, sperm counts, and testosterone biosynthesis through hormonal regulation. In Leydig cells under hydrogen peroxide-induced oxidative stress, SP treatment directly induced testosterone biosynthesis by activating the mRNA expression of the genes encoding 17,20-desmolase and 3β-hydroxysteroid dehydrogenase 4. In conclusion, our results suggest that supplementation of SP may be useful for alleviating the symptoms of andropause via direct and indirect regulation of testosterone biosynthesis.

Rapid Differentiation of Human Embryonic Stem Cells into Testosterone-Producing Leydig Cell-Like Cells In vitro

Background:

Leydig cells (LCs) are testicular somatic cells that are the major producers of testosterone in males. Testosterone is essential for male physiology and reproduction. Reduced testosterone levels lead to hypogonadism and are associated with diverse pathologies, such as neuronal dysfunction, cardiovascular disease, and metabolic syndrome. LC transplantation is a promising therapy for hypogonadism; however, the number of LCs in the testis is very rare and they do not proliferate in vitro. Therefore, there is a need for an alternative source of LCs.

Methods:

To develop a safer, simple, and rapid strategy to generate human LC-like cells (LLCs) from stem cells, we first performed preliminary tests under different conditions for the induction of LLCs from human CD34/CD73 double positive-testis-derived stem cells (HTSCs). Based on the embryological sequence of events, we suggested a 3-step strategy for the differentiation of human ESCs into LLCs. We generated the mesendoderm in the first stage and intermediate mesoderm (IM) in the second stage and optimized the conditions for differentiation of IM into LLCs by comparing the secreted testosterone levels of each group.

Results:

HTSCs and human embryonic stem cells can be directly differentiated into LLCs by defined molecular compounds within a short period. Human ESC-derived LLCs can secrete testosterone and express steroidogenic markers.

Conclusion:

We developed a rapid and efficient protocol for the production of LLCs from stem cells using defined molecular compounds. These findings provide a new therapeutic cell source for male hypogonadism.

Age-related changes in human Leydig cell status

STUDY QUESTION

What are the consequences of ageing on human Leydig cell number and hormonal function?

SUMMARY ANSWER

Leydig cell number significantly decreases in parallel with INSL3 expression and Sertoli cell number in aged men, yet the in vitro Leydig cell androgenic potential does not appear to be compromised by advancing age.

WHAT IS KNOWN ALREADY

There is extensive evidence that ageing is accompanied by decline in serum testosterone levels, a general involution of testis morphology and reduced spermatogenic function. A few studies have previously addressed single features of the human aged testis phenotype one at a time, but mostly in tissue from patients with prostate cancer.

STUDY DESIGN, SIZE, DURATION

This comprehensive study examined testis morphology, Leydig cell and Sertoli cell number, steroidogenic enzyme expression, INSL3 expression and androgen secretion by testicular fragments in vitro. The majority of these endpoints were concomitantly evaluated in the same individuals that all displayed complete spermatogenesis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Testis biopsies were obtained from 15 heart beating organ donors (age range: 19-85 years) and 24 patients (age range: 19-45 years) with complete spermatogenesis. Leydig cells and Sertoli cells were counted following identification by immunohistochemical staining of specific cell markers. Gene expression analysis of INSL3 and steroidogenic enzymes was carried out by qRT-PCR. Secretion of 17-OH-progesterone, dehydroepiandrosterone, androstenedione and testosterone by in vitro cultured testis fragments was measured by LC-MS/MS. All endpoints were analysed in relation to age.

MAIN RESULTS AND THE ROLE OF CHANCE

Increasing age was negatively associated with Leydig cell number (R = -0.49; P < 0.01) and concomitantly with the Sertoli cell population size (R= -0.55; P < 0.001). A positive correlation (R = 0.57; P < 0.001) between Sertoli cell and Leydig cell numbers was detected at all ages, indicating that somatic cell attrition is a relevant cellular manifestation of human testis status during ageing. INSL3 mRNA expression (R= -0.52; P < 0.05) changed in parallel with Leydig cell number and age. Importantly, steroidogenic capacity of Leydig cells in cultured testis tissue fragments from young and old donors did not differ. Consistently, age did not influence the mRNA expression of steroidogenic enzymes. The described changes in Leydig cell phenotype with ageing are strengthened by the fact that the different age-related effects were mostly evaluated in tissue from the same men.

LIMITATIONS, REASONS FOR CAUTION

In vitro androgen production analysis could not be correlated with in vivo hormone values of the organ donors. In addition, the number of samples was relatively small and there was scarce information about the concomitant presence of potential confounding variables.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides a novel insight into the effects of ageing on human Leydig cell status. The correlation between Leydig cell number and Sertoli cell number at any age implies a connection between these two cell types, which may be of particular relevance in understanding male reproductive disorders in the elderly. However aged Leydig cells do not lose their in vitro ability to produce androgens. Our data have implications in the understanding of the physiological role and regulation of intratesticular sex steroid levels during the complex process of ageing in humans.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from Prin 2010 and 2017. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

S-allyl Cysteine Enhances Testosterone Production in Mice and Mouse Testis-Derived I-10 Cells

Hypogonadism, associated with low levels of testosterone synthesis, has been implicated in several diseases. Recently, the quest for natural alternatives to prevent and treat hypogonadism has gained increasing research interest. To this end, the present study explored the effect of S-allyl cysteine (SAC), a characteristic organosulfur compound in aged-garlic extract, on testosterone production. SAC was administered at 50 mg/kg body weight intraperitoneally into 7-week-old BALB/c male mice in a single-dose experiment. Plasma levels of testosterone and luteinizing hormone (LH) and testis levels of proteins involved in steroidogenesis were measured by enzymatic immunoassay and Western blot, respectively. In addition, mouse testis-derived I-10 cells were also used to investigate the effect of SAC on steroidogenesis. In the animal experiment, SAC significantly elevated testosterone levels in both the plasma and the testis without changing the LH level in plasma and increased phosphorylated protein kinase A (p-PKA) levels. Similar results were also observed in I-10 cells. The findings demonstrating the increasing effect of SAC on p-PKA and mRNA levels of Cyp11a suggest that SAC increases the testosterone level by activating the PKA pathway and could be a potential target for hypogonadism therapeutics.

Multiple transcriptomic profiling: p53 signaling pathway is involved in DEHP-induced prepubertal testicular injury via promoting cell apoptosis and inhibiting cell proliferation of Leydig cells

Di(2-ethylhexyl) phthalate (DEHP) is a widely-used plasticizer and has long been recognized as an endocrine-disrupting chemical with male reproductive toxicities. DEHP exposure at the prepubertal stage may lead to extensive testicular injury. However, the underlying mechanisms remain to be elucidated. In the present study, we gavaged male C57BL/6 mice with different concentrations of DEHP (0, 250, and 500 mg/kg-bw·d) from postnatal day 22-35, and exposed TM3 Leydig cells with 0, 100, 200, 300, and 400 μM of MEHP (bioactive metabolite of DEHP) for 12-48 h. RNA sequencing was performed both in testicular tissue and TM3 cells. The results showed that DEHP disrupts testicular development and reduces serum testosterone levels in male prepubertal mice. Bioinformatic analysis and experimental verification have revealed that DEHP/MEHP induces cell cycle arrest in TM3 cells and increases apoptosis both in vivo and in vitro. Furthermore, the p53 signaling pathway was found to be activated upon DEHP/MEHP treatment. The inhibition of p53 by pifithrin-α significantly reduced MEHP-induced injuries in TM3 cells. Cumulatively, these findings revealed the involvement of the p53 signaling pathway in DEHP-induced prepubertal testicular injury by promoting cell apoptosis and inhibiting cell proliferation of Leydig cells.

Hormonal and Metabolic Changes of Aging and the Influence of Lifestyle Modifications

Increased life expectancy combined with the aging baby boomer generation has resulted in an unprecedented global expansion of the elderly population. The growing population of older adults and increased rate of age-related chronic illness has caused a substantial socioeconomic burden. The gradual and progressive age-related decline in hormone production and action has a detrimental impact on human health by increasing risk for chronic disease and reducing life span. This article reviews the age-related decline in hormone production, as well as age-related biochemical and body composition changes that reduce the bioavailability and actions of some hormones. The impact of hormonal changes on various chronic conditions including frailty, diabetes, cardiovascular disease, and dementia are also discussed. Hormone replacement therapy has been attempted in many clinical trials to reverse and/or prevent the hormonal decline in aging to combat the progression of age-related diseases. Unfortunately, hormone replacement therapy is not a panacea, as it often results in various adverse events that outweigh its potential health benefits. Therefore, except in some specific individual cases, hormone replacement is not recommended. Rather, positive lifestyle modifications such as regular aerobic and resistance exercise programs and/or healthy calorically restricted diet can favorably affect endocrine and metabolic functions and act as countermeasures to various age-related diseases. We provide a critical review of the available data and offer recommendations that hopefully will form the groundwork for physicians/scientists to develop and optimize new endocrine-targeted therapies and lifestyle modifications that can better address age-related decline in heath.

Leydig cell aging: Molecular mechanisms and treatments

Late-onset hypogonadism, resulting from deficiency in serum testosterone (T), affects the health and quality of life of millions of aging men. T is synthesized by Leydig cells (LCs) in response to luteinizing hormone (LH). LH binds LC plasma membrane receptors, inducing the formation of a supramolecular complex of cytosolic and mitochondrial proteins, the Steroidogenic InteracTomE (SITE). SITE proteins are involved in targeting cholesterol to CYP11A1 in the mitochondria, the first enzyme of the steroidogenic cascade. Cholesterol translocation is the rate-determining step in T formation. With aging, LC defects occur that include changes in SITE, an increasingly oxidative intracellular environment, and reduced androgen formation and serum T levels. T replacement therapy (TRT) will restore T levels, but reported side effects make it desirable to develop additional strategies for increasing T. One approach is to target LC protein-protein interactions and thus increase T production by the hypofunctional Leydig cells themselves.

m6A mRNA methylation regulates testosterone synthesis through modulating autophagy in Leydig cells

Macroautophagy/autophagy is indispensable for testosterone synthesis in Leydig cells (LCs), and here we report a negative association between m6A modification and autophagy in LCs during testosterone synthesis. A gradual decrease of METTL14 (methyltransferase like 14) and an increase of ALKBH5 (alkB homolog 5, RNA demethylase) were observed in LCs during their differentiation from stem LCs to adult LCs. These events led to reduced mRNA methylation levels of N6-methyladenosine (m6A) and enhanced autophagy in LCs. Similar regulation of METTL14, ALKBH5, and m6A was also observed in LCs upon treatment with human chorionic gonadotropin (HsCG). Mechanistically, m6A modification promoted translation of PPM1A (protein phosphatase 1A, magnesium dependent, alpha isoform), a negative AMP-activated protein kinase (AMPK) regulator, but decreased expression of CAMKK2 (calcium/calmodulin-dependent protein kinase kinase 2, beta), a positive AMPK regulator, by reducing its RNA stability. Thus, m6A modification resulted in reduced AMPK activity and subsequent autophagy inhibition. We further demonstrated that ALKBH5 upregulation by HsCG was dependent on enhanced binding of the transcriptional factor CEBPB (CCAAT/enhancer binding protein [C/EBP], beta) and the TFEB (transcription factor EB) to its gene promoter. Moreover, HsCG treatment decreased METTL14 by reducing its stability. Collectively, this study highlights a vital role of m6A RNA methylation in the modulation of testosterone synthesis in LCs, providing insight into novel therapeutic strategies by exploiting m6A RNA methylation as targets for treating azoospermatism and oligospermatism patients with reduction in serum testosterone.Abbreviations: 3-MA: 3-methyladenine; ACTB: Actin, beta; ALKBH5: alkB homolog 5, RNA demethylase; AMPK: AMP-activated protein kinase; BafA1: bafilomycin A1; CAMKK2: calcium/calmodulin-dependent protein kinase kinase 2, beta; CEBPB: CCAAT/enhancer-binding protein (C/EBP), beta; ChIP: chromatin immunoprecipitation; FTO: fat mass and obesity associated; HsCG: human chorionic gonadotropin; HSD3B: 3β-hydroxysteroid dehydrogenase; LCs: Leydig cells; m6A: N6-methyladenosine; METTL14: methyltransferase like 14; METTL3: methyltransferase like 3; MTOR: mechanistic target of rapamycin kinase; PPM1A: protein phosphatase 1A, magnesium dependent, alpha isoform; PRKAA: 5'-AMP-activated protein kinase catalytic subunit alpha; SQSTM1: sequestosome 1; STK11/LKB1: serine/threonine kinase 11; TFEB: transcription factor EB; ULK1: unc-51-like kinase 1; WTAP: Wilms tumor 1-associating protein; YTHDF: YTH N6-methyladenosine RNA binding protein.

Dependence of Leydig Cell's Mitochondrial Physiology on Luteinizing Hormone Signaling

Knowledge about the relationship between steroidogenesis and the regulation of the mitochondrial bioenergetics and dynamics, in steroidogenic cells, is not completely elucidated. Here we employed in vivo and ex vivo experimental models to analyze mitochondrial physiology in Leydig cells depending on the different LH-cAMP environments. Activation of LH-receptor in rat Leydig cells ex and in vivo triggered cAMP, increased oxygen consumption, mitoenergetic and steroidogenic activities. Increased mitoenergetic activity i.e., ATP production is achieved through augmented glycolytic ATP production and a small part of oxidative phosphorylation (OXPHOS). Transcription of major genes responsible for mitochondrial dynamics was upregulated for Ppargc1a (regulator of mitogenesis and function) and downregulated for Drp1 (main fission marker), Prkn, Pink1 and Tfeb (mitophagy markers). Leydig cells from gonadotropin-treated rats show increased mitogenesis confirmed by increased mitochondrial mass, increased mtDNA, more frequent mitochondria observed by a transmission electron microscope and increased expression of subunits of respiratory proteins Cytc/CYTC and COX4. Opposite, Leydig cells from hypogonadotropic-hypogonadal rats characterized by low LH-cAMP, testosterone, and ATP production, reduced markers of mitogenesis and mitofusion (Mfn1/2, Opa1) associated with reduced mtDNA content. Altogether results underline LH-cAMP signaling as an important regulator of mitochondrial physiology arranging mitochondrial dynamics, bioenergetic and steroidogenic function in Leydig cells.