Molecular mechanisms regulating spermatogenesis in vertebrates: Environmental, metabolic, and epigenetic factor effects

The renewal of the natural resources is one of the most concerning aspects of modern farming. In animal production, there are many barriers breeders and researchers have to overcome to develop new practices to improve reproductive potential and hasten sexual maturation of the commercially viable species, while maintaining meat quality and sustainability. With the utilization of molecular biology techniques, there have been relevant advances in the knowledge of spermatogenesis, especially in mammals, resulting in new possibilities to control male fertility and the selection of desirable characteristics. Most of these discoveries have not been implemented in animal production. In this review, recent studies are highlighted on the molecular pathways involved in spermatogenesis in the context of animal production. There is also exploration of the interaction between environmental factors and spermatogenesis and how this knowledge may revolutionize animal production techniques. Furthermore, new insights are described about the inheritance of desired characteristics in mammals and there is a review of nefarious actions of pollutants, nutrition, and metabolism on reproductive potential in subsequent generations. Even though there are these advances in knowledge base, results from recent studies indicate there are previously unrecognized environmental effects on spermatogenesis. The molecular mechanisms underlying this interaction are not well understood. Research in spermatogenesis, therefore, remains pivotal as a pillar of animal production sustainability.

Co-treatment of testosterone and estrogen mitigates heat-induced testicular dysfunctions in a rat model

The two gonadal steroid hormones, testosterone and estrogen, regulate spermatogenesis by proliferation, differentiation, and apoptosis of testicular cells. It has been reported that heat stress or increased scrotal temperature impairs spermatogenesis in many mammals. Moreover, testicular heat stress has also been shown to suppress testosterone and estrogen biosynthesis. Furthermore, it is well known that testosterone and estrogen are important for testicular activity. Therefore, we hypothesised that exogenous testosterone and estrogen, alone or in combination, might alleviate the testicular activity in a heat-stressed rat model. To the best of our knowledge, this will be the first report of the exogenous treatment of both testosterone and estrogen in the heat-stressed rat. Our results showed that a combined testosterone and estrogen treatment significantly increased sperm concentration. The histopathological analysis also exhibited a normal histoarchitecture in the combined treatment group along with decreased oxidative stress. The improved spermatogenesis in the combined treatment group was also supported by the increase in PCNA, GCNA, tubule diameter, germinal epithelium height, and Johnsen score in the combined treatment group. Furthermore, the combined treatment also increased the expression of Bcl2, pStat3, and active caspase-3 and decreased expression of Bax. Thus, increased proliferation, apoptotic and anti-apoptotic markers, along with improved histology in the combined treatment group suggest that estrogen and testosterone synergistically act to stimulate spermatogenesis by increasing proliferation and differentiation of germ cells and may also remove the heat-induced damaged germ cells by apoptosis. Overall, the final mechanism of testosterone- and estrogen-mediated improvement of testicular activity could be attributed to amelioration of oxidative stress.

Genistein exhibits therapeutic potential for PCOS mice via the ER-Nrf2-Foxo1-ROS pathway

Polycystic ovarian syndrome (PCOS) is a complex endocrinopathy in women of reproductive age and the main cause of female infertility, but there is no universal drug for PCOS therapy. As a predominant dietary isoflavone present in soybeans, genistein (GEN) possesses estrogenic and antioxidative properties, but limited information is available regarding its therapeutic potential and underlying molecular mechanism in PCOS. In this study, we found that GEN might restore the estrous cycle of PCOS mice and ameliorate the elevation of circulating T, AMH and LH levels as well as LH/FSH ratios along with reduced cystic follicles, indicating the importance of GEN in PCOS therapy. Meanwhile, GEN improved the ovarian secretion function of PCOS mice and attenuated oxidative damage of the ovary through enhancing its antioxidant capability dependent on ER. Supplementation of GEN improved the defect of the ATP level and mitochondrial membrane potential, indicating the significance of GEN in preventing mitochondrial dysfunction. Further analysis demonstrated that GEN via ER heightened the expression of Nrf2 and Foxo1 whose blockage antagonized the defence of GEN on the secretory and mitochondrial functions of ovarian granulosa cells followed by the limited antioxidant capability and increased intracellular ROS level. Moreover, nuclear translocation and transcriptional activity of Nrf2 presented a notable enhancement after exposure to GEN. Addition of the Nrf2 inhibitor ML385 hampered the GEN induction of Foxo1. Nrf2 might directly bind to the antioxidant response element of the Foxo1 promoter region. Collectively, GEN might exhibit therapeutic potential for PCOS mice via the ER-Nrf2-Foxo1-ROS pathway.

The influence of phytoestrogens on different physiological and pathological processes: An overview

Functional foods have nutritional properties and organic functions, which are beneficial to health. Certain types of functional food components are so-called phytoestrogens, non-steroidal compounds derived from the metabolism of precursors contained in plants, which originate secondary metabotypes known to induce biological responses and by mimicry or modulating the action of endogenous estrogen. These molecules are involved in several physiological and pathological processes related to reproduction, bone remodeling, skin, cardiovascular, nervous, immune systems, and metabolism. This review aimed to present an overview of phytoestrogens regarding their chemical structure, actions, and effects in the organism given several pathologies. Several studies have demonstrated beneficial phytoestrogen actions, such as lipid profile improvement, cognitive function, menopause, oxidative stress, among others. Phytoestrogens effects are not completely elucidated, being necessary future research to understand the exact action mechanisms, whether they are via estrogen receptor or whether other hidden mechanisms produce these effects. Thus, this review makes a general approach to the phytoestrogen actions, beneficial effects, risk and limitations. However, the complexities of biological effects after ingestion of phytoestrogens and the differences in their metabolism and bioavailability indicate that interpretation of either risk or benefits needs to be made with caution.

Protective effects of Ceratonia siliqua extract on protamine gene expression, testicular function, and testicular histology in doxorubicin-treated adult rats: An experimental study

BACKGROUND

Spermatogenesis is a complex process that takes place under the influence of many different genes.

OBJECTIVE

The aim of this study was to investigate the possible effects of Ceratonia siliqua hydroalcoholic extract (CSHAE) on protamine gene expression, testicular function, and testicular histology in doxorubicin-treated rats.

MATERIALS AND METHODS

56 adult male rats with a age range of 2.5 to 3 months (210 ± 10 gr) were divided into seven groups (n = 8/each). A) Control group was left untreated; B) Sham group received 0.3 ml distilled water intraperitoneally, C) Negative control group received 3 mg/kg doxorubicin, intraperitoneally once a week for 28 days; and D) Positive control group received 600 mg/kg of CSHAE orally for 48 days; E, F, G) the experimental groups 1, 2, and 3 received 150, 300, and 600 mg/kg of CSHAE respectively orally, for 48 days, as well as 3 mg/kg doxorubicin once a week for 28 days. Hematoxylin-eosin staining was used in the histological study of testes, and enzyme-linked immunosorbent assay method was used in measuring serum levels of testosterone. Protamine gene expression was determined by real-Time PCR method.

RESULTS

The mean body weight, testicular weight, testicular volume, testosterone level (p = 0.022), the count of Leydig, spermatogonia, spermatocyte, and spermatid cells, as well as protamine gene expression (p = 0.008) were significantly increased in the experimental group 2 compared to the negative control group. The regeneration of testicular tissue was observed in the experimental group 2.

CONCLUSION

CSHAE has protective effect on doxorubicin-induced testicular injuries.

Nesfatin-1 ameliorates type-2 diabetes-associated reproductive dysfunction in male mice

PURPOSE

The present study was aimed to demonstrate the recuperative effect of nesfatin-1 on testicular dysfunction in the high-fat diet (HFD)/streptozotocin (STZ)-induced type-2 diabetes mellitus (T2DM) mice.

METHOD AND RESULTS

Three experimental groups were formed: (1) vehicle control (VC), (2) T2DM mice, (3) T2DM + nesf-1. The mice with blood glucose level higher than 300 mg/dL following HFD and a single dose of STZ were used for the experiment. The T2DM mice showed increases in body mass, blood glucose and insulin levels, reductions in spermatogenesis and steroidogenesis, production of antioxidative enzymes, and disturbed lipid profile. These alterations were all ameliorated by administration of nesfatin-1 at 20 μg/Kg BW for 15 days. Nesfatin-1 treatment also increased the production of testosterone (T), improved insulin sensitivity, and effectively ameliorated the testicular aberrations, and increased spermatogenesis and steroidogenesis. In addition, nesfatin-1 treatment upregulated the PCNA and Bcl2 expression and inhibited the caspase-3 and prohibitin expression in T2DM mice. Nesfatin-1 increased insulin receptor (IR) and GLUT8 expressions, and lactate production, the changes that further substantiate the increase of energy influx to the testis.

CONCLUSION

Altogether, the results suggest the ameliorative effect of nesfatin-1 against T2DM-associated testicular dysfunctions and improved insulin sensitivity along with promoting T production and fertility in T2DM mice.