Global changes in epigenomes during mouse spermatogenesis: possible relation to germ cell apoptosis

Sperm DNA Fragmentation in Male Infertility: Tests, Mechanisms, Meaning and Sperm Population to Be Tested

Sperm DNA fragmentation (sDF) is a DNA damage able to predict natural conception. Thus, many laboratories added tests for the detection of sDF as an adjunct to routine semen analysis with specific indications. However, some points related to sDF are still open. The available tests are very different each from other, and a direct comparison, in terms of the prediction of reproductive outcomes, is mandatory. The proposed mechanisms responsible for sDF generation have not yielded treatments for men with high levels of sDF that have gained the general consent in clinical practice, thus requiring further research. Another relevant point is the biological meaning to attribute to sDF and, thus, what we can expect from tests detecting sDF for the diagnosis of male infertility. SDF can represent the "tip of iceberg" of a more extended and undetected sperm abnormality somehow impacting upon reproduction. Investigating the nature of such a sperm abnormality might provide novel insights into the link between sDF and reproduction. Finally, several studies reported an impact of native sDF on assisted reproduction technique outcomes. However, to fertilise the oocyte, selected spermatozoa are used where sDF, if present, associates with highly motile spermatozoa, which is the opposite situation to native semen, where most sDF associates with non-viable spermatozoa. Studies comparing the impact of sDF, as assessed in both native and selected spermatozoa, are needed.

Differential Impairment Mechanism of Sperm Production via Induction of miR-34c-Activated Apoptosis and Spermatogenesis Pathway in Diet-Induced Obesity and Resistant Mice and GC-1 Spg Cells

Male reproductive dysfunction is a clinical disease, with a large number of cases being idiopathic. Reproductive disorders have been found in obese (diet-induced obesity and diet-induced obesity-resistant) mice, but the mechanism behind the male reproductive dysfunction between them may be different. The purpose of this study was to explore the possible role and mechanism of miR-34c on sperm production in high-fat-diet-induced obesity-resistant (DIO-R) mice and GC-1 spg cells, which may differ from those in high-fat-diet-induced obesity (DIO) mice. In vivo and in vitro experiments were performed. C57BL/6J mice were fed a high-fat diet for 10 weeks to establish the DIO and DIO-R mouse model. GC-1 spg cells were used to verify the mechanism of miR-34c on sperm production. During in vivo experiments, sperm production damage was found in both DIO and DIO-R male mice. Compared to the control mice, significantly decreased levels of testosterone, LH, activities of acrosome enzyme (ACE), HAse, and activating transcription factor 1 (ATF1) were found in both DIO and DIO-R male mice (p < 0.05). Compared with the control group, the ratio of B-cell lymphoma-2 (Bcl-2)/bcl-2-associated X protein (Bax) in the DIO group was significantly decreased, and the expression level of cleaved caspase-3 was significantly increased (p < 0.05). Compared with the control group, the Bcl-2 protein expression level in the testes of the DIO-R group significantly decreased (p < 0.05). However, the Bax expression level increased. Thus, the Bcl-2/Bax ratio significantly decreased (p < 0.01); however, the factor-related apoptosis (Fas), Fas ligand (FasLG), cleaved caspase-8, caspase-8, cleaved caspase-3, and caspase-3 protein expression levels significantly increased (p < 0.05). Compared with the DIO group, in DIO-R mice, the activities of ACE, ATF1, Bcl-2, and Bcl-2/Bax's spermatogenesis protein expression decreased, while the apoptosis-promoting protein expression significantly increased (p < 0.05). During the in vitro experiment, the late and early apoptotic ratio in the miR-34c over-expression group increased. MiR-34c over-expression enhanced the expression of apoptosis-related proteins Fas/FasLG and Bax/Bcl-2 while inhibiting the expression of ATF1 and the sperm-associated protein in GC-1 spg cells. DIO and DIO-R could harm sperm production. DIO-R could impair sperm production by inducing the miR-34c-activated apoptosis and spermatogenesis pathway, which may be different from that of DIO.

Shilajit mitigates chemotherapeutic drug-induced testicular toxicity: Study on testicular germ cell dynamics, steroidogenesis modulation, and Nrf-2/Keap-1 signaling

BACKGROUND

Medications, including chemotherapeutic drugs, contribute to male infertility as external factors by inducing oxidative stress in testicular cells. Shilajit is a naturally occurring bioactive antioxidant used in Ayurvedic medicine to treat a variety of ailments.

OBJECTIVE

This study examines the potential of Shilajit to counteract the negative effects of the chemotherapeutic drug cyclophosphamide (CPA) on testicular germ cell dynamics.

MATERIAL AND METHODS

Male Parkes mice received single intraperitoneal CPA injection (200 mg/kg BW) on day one, followed by daily supplementation of Shilajit (100 and 200 mg/kg BW) for one spermatogenic cycle.

RESULTS

CPA adversely affected testicular germ cell dynamics by inhibiting the conversion of spermatogonia-to-spermatids, altering testicular histoarchitecture, impairing Sertoli cell function and testicular steroidogenesis, and disturbing the testicular oxido-apoptotic balance. Shilajit supplementation restores testicular germ cell dynamics in CPA-exposed mice, as evidenced by improved histoarchitecture of the testis. Shilajit improves testicular daily production and sperm quality by promoting the conversion of spermatogonia (2C) into spermatids (1C), stimulating germ cell proliferation (PCNA), improving Sertoli cell function (N-Cadherin and β-Catenin), and maintaining the Bax/Bcl2 ratio. Additionally, Shilajit enhances testosterone biosynthesis by activating enzymes like 3β-HSD, and 17β-HSD. Shilajit also reduces testicular oxidative stress by increasing antioxidant enzyme activity (SOD) and decreasing lipid peroxidation (LPO). These effects are mediated by upregulation of the antioxidant protein Nrf-2 and downregulation of Keap-1.

CONCLUSION

The findings underscore the potent androgenic and antioxidant characteristics of Shilajit, as well as its ability to enhance fertility in cases of testicular damage caused by chemotherapeutic drugs.

Microenvironment for spermatogenesis and sperm maturation

The male reproductive system consists of testes, a series of ducts connecting the testes to the external urethral orifice, accessory sex glands, and the penis. Spermatogonial stem cells differentiate and mature in testes and epididymides, and spermatozoa are ejaculated with exocrine fluids secreted by accessory sex glands. Many studies have clarified the detailed structure and function of the male reproductive system, and have shown that various biologic controls, including genomics, epigenetics, and the neuroendocrine-immune system regulate proliferation, differentiation, and maturation of germ cells. In other words (1) genetic deletion or abnormalities, (2) aberration of DNA methylation and histone modifications, as well as small RNA dysfunction, and (3) neuroendocrine-immune disorders are involved in functional failure of the male reproductive system. In this article, we review these three factors for germ cell microcircumstance, especially focused on the immunoendocrine environment. In particular, the relation between factors protecting germ cells with strong auto-immunogenicity and opposite factors compromising this protection are discussed. Reductions in sperm count, concentration, and semen quality are serious problems in developed countries, although the causes are complex and remain unclear. The accumulation of basic knowledge regarding the structure, function, and regulation of the male reproductive system under various experimental conditions will be important to resolve these problems.

Quantitative evaluation of spermatogenesis by fluorescent histochemistry

Identifying the types of spermatogenic cells that compose seminiferous tubules, as well as qualitative confirmation of the presence or absence of disorders, has been regarded as crucial in spermatogenesis. Sperm count and fertilizing capacity, both of which depend on the quality as well as quantity of spermatogenesis, are factors critical to fertilization. However, the quantitative assessment of spermatogenesis is not commonly practiced. Spermatogenesis has species-specific stages; when the specific stage in the seminiferous tubules is precisely determined, the types of spermatogenic cells in each stage can be spontaneously identified. Thereafter, a unique marker is used to classify the cells observed in each stage. Quantitative assessment of spermatogenesis has the potential to detect inapparent spermatogenesis disorders or numerically indicate the degree of the disorder. To this end, a histochemical approach using unique markers is indispensable for the quantitative assessment of spermatogenesis. Future developments in techniques to measure cell populations using computer software will further facilitate the establishment of quantitative assessment of spermatogenesis as a standard analysis method that can contribute significantly to advance our understanding of spermatogenesis.

Runjing Decoction alleviated cyclophosphamide-induced oligoasthenospermia rats by inhibiting cell apoptosis via RXFP1/AKT/FOXO1 pathway

Runjing Decoction (RJD) is a prescription of traditional Chinese medicine for the treatment of oligoasthenospermia. However, the molecular mechanism of RJD on oligoasthenospermia still remains unknown. A model of oligoasthenospermia was induced in 30 Sprague Dawley rats by intraperitoneal injection of cyclophosphamide at 35 mg/kg per day for 5 days and treated by intragastric RJD (13.5 g/kg) or L-carnitine (100 mg/kg) for 14 days. The body weight, testis and epididymis weight, grade A spermatozoa, grade B spermatozoa, the percentage of sperm forward motility (PR%), the sperm activity rate and the sperm density of rats were evaluated before and after RJD treatment. The testis apoptosis was determined by TUNEL staining. The expressions of RXFP1, FoxO1, PI3K, Akt, Bax and Bcl-2 were determined by qRT-PCR and Western blot, respectively. After RJD treatment, the grade A spermatozoa, sperm PR%, sperm activity and sperm density were significantly increased relative to those in model rats. Cell apoptosis of testis tissue was reversed by RJD. RJD suppressed cell apoptosis, inhibited the expression of RXFP1, FOXO1, PI3K, AKT and Bax, and promoted the expression levels of Bcl-2 in testicular tissue of oligoasthenospermia rats. RJD could alleviate sperm quality and testis damage in oligoasthenospermia rats by inhibiting RXFP1/AKT/FOXO1 pathway.

Exposure effects of inhaled nickel nanoparticles on the male reproductive system via mitochondria damage

Nickel nanoparticles (Ni NPs) have a wide range of application prospects, however there is still a lack of their safety evaluation for the reproductive system. Nowadays, male reproductive health has been widely concerned for the increasing incidence of male infertility. To investigate the male reproductive toxicity induced by Ni NPs and its relation with the mitochondrial fission and mitophagy, male mice were administered with or without 5, 15, and 45 mg/kg of Ni NPs by intratracheal instillation. At the end of intervention, sex hormone level, sperm abnormality rate, pathological morphology of testis, cell apoptosis and the expression levels of Drp1, Pink1 and Parkin proteins in testis tissues were detected. The results indicated that the rate of sperm deformity and serum levels of reproductive hormones increased obviously with the increasing concentrations of Ni NPs. Testicular spermatogenic cells were damaged and the number of apoptotic cells increased significantly. Furthermore, the expressions of key proteins (Drp1, Pink1 and Parkin) related to mitochondrial fission/autophagy in testis tissues also increased after exposure to Ni NPs. Collectively, mitochondria damage may play an important role in male mice reproductive toxicity induced by the intratracheal instillation of Ni NPs.