Testosterone, an important sex hormone, regulates sexual maturation, testicular development, spermatogenesis and the maintenance of secondary sexual characteristics in males. Testicular Leydig cells are the primary source of testosterone production in the body. Hezuo pigs, native to the southern part of Gansu, China, are characterized by early sexual maturity, strong disease resistance and roughage tolerance. This study employed type IV collagenase digestion combined with cell sieve filtration to isolate and purify Leydig cells from the testicular tissue of 1-month-old Hezuo pigs. We also preliminarily investigated the functions of these cells. The results indicated that the purity of the isolated and purified Leydig cells was as high as 95%. Immunofluorescence analysis demonstrated that the isolated cells specifically expressed the 3β-hydroxysteroid dehydrogenase antibody. Enzyme-linked immunosorbent assay results showed that the testosterone secretion of the Leydig cells cultured in vitro (generations 5-9) ranged between 1.29-1.67 ng/mL. Additionally, the content of the cellular autophagy signature protein microtubule-associated protein 1 light chain 3 was measured at 230-280 pg/mL. Through this study, we established an in vitro system for the isolation, purification and characterization of testicular Leydig cells from 1-month-old Hezuo pigs, providing a reference for exploring the molecular mechanism behind precocious puberty in Hezuo pigs.

Klinefelter\'s syndrome (KS) was once considered infertile due to congenital chromosomal abnormalities, but the presence of focal spermatozoa changed this. The key to predict and promote spermatogenesis is to find targets that regulate focal spermatogenesis.
To explore the trend of fertility changes in KS patients at different ages and identify potential therapeutic targets.
Bibliometric analysis was used to collect clinical research data on KS from the Web of Science Core Collection (WoSCC) from 1992 to 2022. A cross-sectional study was conducted on 75 KS patients who underwent microscopic testicular sperm extraction (mTESE) from 2017 to 2022 in the real world. The reproductive hormones, testicular histopathology, androgen receptors, insulin-like factor 3 (INSL3) receptors and sperm recovery rate (SRR) were analyzed.
Male infertility, dysplasia, Sertoli cells, Leydig cells, testosterone and spermatogenesis were the research focuses related to KS. Luteinizing hormone (LH), testosterone, and INSL3 were evaluation indicators of Leydig cell function that fluctuate with age. Testosterone and LH peaked at ages 13-19 and 30-45, while INSL3 only peaked at ages 13-19. 27 patients (27/75) recovered sperm through mTESE and experienced SRR peaks at the ages of 20, 28, 34, and 37. The SRR of fibrosis patients was 46.15%, fatty degeneration was 7.14%, and melanosis was 40.00%. The INSL3 and androgen receptors were highly expressed and roughly balanced in focal spermatogenesis.
Abnormal metabolism of Leydig cells led to imbalanced expression of INSL3 and androgen receptors, which might be a potential target for spermatogenesis in KS.

The process of testis development in mammals is accompanied by the proliferation and maturation of Sertoli, Leydig and germ cells. Spermatogenesis depends on hormone regulation, which must bind to a receptor to exert its biological effects. The changes in Hu sheep testis cell composition and FSHR, LHR and AR expression during different developmental stages are unclear (newborn, puberty and adulthood). To address this, using single-cell RNA sequencing, we analyzed testis cell composition and hormone receptor expression changes during three important developmental stages of Hu sheep. We observed significant changes in the composition of somatic and germ cells in different Hu sheep testis developmental stages. Furthermore, we analyzed the FSHR, LHR and AR distribution and expression changes at three important periods and verified them by qRT-PCR and immunofluorescence. Our results suggest that after birth, the proportion of germ cells increased gradually, peaking in adulthood; the proportion of Sertoli cells decreased gradually, reaching the lowest in adulthood; and the proportion of Leydig cells increased and then decreased, reaching the lowest in adulthood. In addition, FSHR, LHR and AR are mainly located in Sertoli, Leydig and germ cells. LHR and FSHR expression decreased with increasing age, while AR expression increased and then decreased with increasing age.

Insulin-like peptide 3 (INSL3) is a peptide biomarker secreted specifically by the mature Leydig cells of the testes. It is constitutive, has low within-individual variance, and effectively measures the functional capacity of Leydig cells to make testosterone. In young adult men there is a large 10-fold range of serum INSL3 concentration, persisting into old age, and implying that later hypogonadal status might be programmed in early life. To determine whether maternal exposure to environmental endocrine disrupting compounds (EDCs) influences adult serum INSL3 concentration, using a retrospective paradigm, INSL3 was measured in young adult male rats (80-90 days) from the F1 generation of females maternally exposed to varied doses of bisphenol A (BPA), butylparaben, epoxiconazole, and fludioxonil as single compounds, as well as estrogenic and anti-androgenic mixtures of BPA and butylparaben, and di(2-ethylhexyl) phthalate and procymidone respectively. A mixture of BPA and butylparaben significantly reduced circulating INSL3 concentration in adult male progeny. The remaining compounds or mixtures tested, though sufficient to induce other effects in the F1 generation were without significant effect. Maternal exposure to low concentrations of some EDCs may be a contributing factor to the variation in the Leydig cell biomarker INSL3 in young adulthood, though caution is warranted translating results from rats to humans.

Aging in men is accompanied by a broad range of symptoms, including sexual dysfunction, cognitive and musculoskeletal decline, obesity, type 2 diabetes, cardiovascular disease and hypertension, organ degeneration/failure, and increasing neoplasia, some of which are associated with declining levels of Leydig cell-produced testosterone. High natural biological variance, together with multiple factors that can modulate circulating testosterone concentration, may influence its interpretation and clinical implications. Insulin-like peptide 3 is a biomarker of Leydig cell function that might provide complementary information on testicular health and its downstream outcomes.
To characterize insulin-like peptide 3 as a biomarker to assess gonadal status in aging men.
A large European multicenter (European Male Aging Study) cohort of community-dwelling men was analyzed to determine how insulin-like peptide 3 relates to a range of hormonal, anthropometric, and lifestyle parameters.
Insulin-like peptide 3 declines cross-sectionally and longitudinally within individuals at approximately 15% per decade from age 40 years, unlike testosterone (1.9% per decade), which is partly compensated by increasing pituitary luteinizing hormone production. Importantly, lower insulin-like peptide 3 in younger men appears to persist with aging. Multiple regression analysis shows that, unlike testosterone, insulin-like peptide 3 is negatively dependent on luteinizing hormone and sex hormone-binding globulin and positively dependent on follicle-stimulating hormone, suggesting a different mechanism of gonadotropic regulation. Circulating insulin-like peptide 3 is negatively associated with increased body mass index or waist circumference and with smoking, and unlike testosterone, it is not affected by weight loss in obese individuals. Geographic variation in mean insulin-like peptide 3 within Europe appears to be largely explained by differences in these parameters. The results allowed the establishment of a European-wide reference range for insulin-like peptide 3 (95% confidence interval) adjusted for increasing age.
Insulin-like peptide 3 is a constitutive biomarker of Leydig cell functional capacity and is a robust, reliably measurable peptide not subject to gonadotropin-dependent short-term regulation and within-individual variation in testosterone.

Elevated luteinizing hormone (LH) in combination with low-normal testosterone (mild Leydig cell insufficiency) is common in testicular cancer (TC) survivors and is associated with impaired insulin sensitivity and metabolic syndrome. The aim was to evaluate if testosterone replacement therapy (TRT) improves metabolic health in this subgroup of TC survivors.
This was a single-center, double-blind, randomized, controlled trial. The main eligibility criterion was LH above the age-adjusted upper limit of normal in combination with free testosterone in the lower half of the age-adjusted normal range (mild Leydig cell insufficiency) >1 year after TC treatment. Eligible patients were randomly assigned (1:1) to 12 months transdermal TRT (Tostran, gel, 2%) or placebo with a maximum daily dose of 40 mg. The primary outcome was difference in Δ2 hour glucose measured with oral glucose tolerance test between groups assessed at 12 months. Outcomes were assessed after 6-, 12- and 3 months post-treatment. The study was registered at www.
gov (NCT02991209) and ended June 2019.
Between October 2016 and February 2018, 140 patients were screened for eligibility and 69 were randomized to testosterone (n = 35, 51%) or placebo (n = 34, 49%). TRT was not associated with a statistically significant difference in Δ2 hour glucose compared to placebo after 12 months of treatment (0.04 mmol/L (95% CI: -0.53, 0.60)). There was no statistically significant difference in Δ2 hour insulin between the groups after 12 months of treatment (28.23 pmol/L (95% CI: -34.40, 90.86)). Similarly, TRT was not associated with significant improvement in components of metabolic syndrome. TRT was associated with a decrease in fat mass after 12 months compared to placebo (-1.35 kg, (95% CI: -2.53, -0.18)).
In TC survivors with mild Leydig cell insufficiency, TRT was not associated with improvement of metabolic health. These findings do no not support routine use of TRT in these patients.

Non-obstructive azoospermia (NOA) is one of the most important causes of male infertility. Although many congenital factors have been identified, the aetiology in the majority of idiopathic NOA (iNOA) cases remains unknown. Herein, using single-cell RNA-Seq data sets (GSE149512) from the Gene Expression Omnibus (GEO) database, we constructed transcriptional regulatory networks (TRNs) to explain the mutual regulatory relationship and the causal relationship between transcription factors (TFs). We defined 10 testicular cell types by their marker genes and found that the proportion of Leydig cells (LCs) and macrophages (tMΦ) was significantly increased in iNOA testis. We identified specific TFs including LHX9, KLF8, KLF4, ARID5B and RXRG in iNOA LCs. In addition, we found specific TFs in iNOA tMΦ such as POU2F2, SPIB IRF5, CEBPA, ELK4 and KLF6. All these identified TFs are strongly engaged in cellular fate, function and homeostasis of the microenvironment. Changes in the activity of the above-mentioned TFs might affect the function of LCs and tMΦ and ultimately cause spermatogenesis failure. This study illustrate that these TFs play important regulatory roles in the occurrence and development of NOA.

Testicular cancer (TC) treatment leaves many patients with low levels of testosterone. While most TC patients with low testosterone (< - 2 SD) and hypogonadal symptoms will initiate testosterone replacement therapy (TRT), the role of TRT in patients with mild Leydig cell insufficiency, defined as elevated luteinizing hormone in combination with borderline low testosterone, is unknown. To clarify if TRT improves symptoms of depression and anxiety, sexual function, fatigue, and quality of life in TC survivors with mild Leydig cell insufficiency.
In total, 69 men aged between 18 and 65 years with mild Leydig cell insufficiency after TC treatment were randomized 1:1 to 12 months daily transdermal testosterone (maximum dose 40 mg/daily) vs. placebo. Patient reported anxiety, depression, sexual function, fatigue, and overall quality of life were assessed at baseline, after 6- and 12 months treatment, and 3 months post-treatment using validated questionnaires.
After 12 months of treatment, median luteinizing hormone and median free testosterone were normalized in the testosterone group. Compared to placebo, TRT was not associated with statistically significant improvement of symptoms of anxiety and depression, sexual function, fatigue, and overall quality of life. Testosterone replacement therapy did not improve anxiety, depression, sexual function, fatigue, or overall quality of life in patients with mild Leydig cell insufficiency compared to placebo.
Routine TRT in TC survivors with mild Leydig cell insufficiency to improve sexual function and quality of life cannot be generally recommended. The findings should preferably be validated in a larger cohort.

Anastomosing hemangioma is a recently described vascular neoplasm, initially identified in the male genitourinary tract. Since its first description, it has been reported at multiple anatomic sites, including rare cases in the female genital tract, most in the ovary. Herein we report the largest series to date of 12 ovarian anastomosing hemangiomas identified at our institution over a 15-yr period. The patients\' age at the time of resection ranged from 50 to 76 yr (median: 62 yr), 3 patients presented with symptomatic pelvic masses, 3 tumors were identified by imaging studies, and the remaining 6 were incidentally discovered in ovaries removed for other indications. All tumors were unilateral, occurred at the ovarian hilum, and contained a vaguely lobulated architecture with sinusoidal-like vessels lined by hobnail endothelial cells with minimal to no cytologic atypia. A rim of luteinized/Leydig cells with abundant, eosinophilic cytoplasm and round, centrally placed nuclei surrounding the hemangioma was present in 9/12 tumors. Reinke crystals were observed in 3 of these 9 tumors. The volume of luteinized cells relative to the vascular proliferation ranged from 2% to 30%. All tumors with luteinized/Leydig cells also displayed numerous small eosinophilic, globular intracytoplasmic inclusions within the endothelial cells. The 3 tumors without luteinized/Leydig cells were exclusively intravascular lesions. Despite the frequent presence of luteinization/Leydig cells none of the patients experienced hormonal manifestations. Awareness of this rare benign ovarian entity is important, as its association with luteinized cells/Leydig cell hyperplasia (often exuberant) may be misinterpreted as a steroid cell tumor, Leydig-cell tumor, or as a mixed stromal-vascular tumor.

BACKGROUND: The discovery of kisspeptin signaling as a key regulator of gonadotropin- releasing hormone (GnRH) secretion from the hypothalamus enhanced our understanding of the neuroendocrine regulation of mammalian reproduction. Effects of central and peripheral administration of kisspeptin on plasma gonadotropins, testosterone, and spermatogenesis are studied in detail.
OBJECTIVE: The present study was conducted to check the ultrastructure of Leydig cells in prepubertal male rats in response to the administration of a range of kisspeptin doses.
METHODS: We administered a range of kisspeptin-10 doses (1 μg, 1 ηg, and 10 ρg) intraperitoneally to prepubertal male Sprague-Dawley rats (PND 35) twice daily after every 12 hours. Control rats were injected with physiological saline in parallel.
RESULTS: At the end of the treatment, plasma concentrations of testosterone were measured by competitive binding radioimmunoassay, and small pieces of rat testicular tissue were processed for electron microscopy to examine the ultrastructure of Leydig cells. Plasma testosterone concentration was reduced significantly at 1ηg (P<0.05) and 1μg (P<0.01) doses as compared to control. Distinct ultrastructural changes categorized as dilatation of cytoplasmic organelles, irregularly shaped nuclei with nuclear membrane invaginations, reduced nuclear sizes, degeneration, and vacuolation were observed in the kisspeptin-10 treated Leydig cells as compared to control. Quantification of the data showed reduced Leydig cell indices and hyperplasia of the interstitial cells.
CONCLUSIONS: It is concluded that chronic intermittent administration of kisspeptin-10 has a dose-dependent degenerative effect on the plasma testosterone levels and Leydig cells ultrastructure in prepubertal male rats.