Alterations in oxidative, inflammatory and apoptotic events in short-lived and long-lived mice testes

Impact of COVID-19 on sperm quality and the prostaglandin and polyamine systems in the seminal fluid

BACKGROUND

The implications of SARS-CoV-2 infection on male fertility remain largely unknown. Besides their well-known pro- and anti-inflammatory actions, prostaglandins and polyamines are present in semen, where they play key roles in sperm quality.

OBJECTIVES

To analyze semen parameters, oxidative profile and the seminal fluid prostaglandin and polyamine systems in samples collected from individuals without coronavirus disease 2019 diagnosis and men who recovered from coronavirus disease 2019.

MATERIALS AND METHODS

This study compared semen collected from men without positive coronavirus disease 2019 diagnosis with samples obtained from individuals 1-6 months and 7-30 months post SARS-CoV-2 infection. Semen parameters, thiobarbituric acid reactive substances, cyclooxygenase 2 expression by fluorescence immunocytochemistry and immunoblotting, prostaglandin levels by enzyme immunoassay, ornithine decarboxylase activity by a radioactive assay, and polyamine and acetylated polyamine levels by thin-layer chromatography were assessed.

RESULTS

In both groups of semen samples from coronavirus disease 2019 recovered men, sperm vitality, total and progressive sperm motility, and putrescine levels were significantly decreased when compared with samples from the uninfected group. In contrast, lipid peroxidation, leukocyte-associated cyclooxygenase 2 expression, and prostaglandin D2 levels were higher in semen from coronavirus disease 2019 recovered men than in samples from uninfected individuals. While sperm concentration and morphology, ornithine decarboxylase activity, and N-acetylputrescine levels were statistically diminished in semen obtained up to 6 months after coronavirus disease 2019 recovery, these parameters remained unchanged when samples were collected 7-30 months after coronavirus disease 2019 recovery. Coronavirus disease 2019 vaccination did not show negative effects on any of the parameters evaluated.

DISCUSSION AND CONCLUSION

Our work provides insights into the detrimental impact of coronavirus disease 2019 on several sperm parameters, in some cases, even more than a year after SARS-CoV-2 infection, which would be accompanied by alterations in the seminal fluid prostaglandin and polyamine profiles. Therefore, future treatments targeting the prostaglandin and polyamine pathways in coronavirus disease 2019 recovered men could lead to a successful reinstatement of semen parameters.

Biogenic amines in the testis: sources, receptors and actions

Biogenic amines are signaling molecules with multiple roles in the central nervous system and in peripheral organs, including the gonads. A series of studies indicated that these molecules, their biosynthetic enzymes and their receptors are present in the testis and that they are involved in the regulation of male reproductive physiology and/or pathology. This mini-review aims to summarize the current knowledge in this field and to pinpoint existing research gaps. We suggest that the widespread clinical use of pharmacological agonists/antagonists of these signaling molecules, calls for new investigations in this area. They are necessary to evaluate the relevance of biogenic amines for human male fertility and infertility, as well as the potential value of at least one of them as an anti-aging compound in the testis.

Effects of Reactive Oxygen and Nitrogen Species on Male Fertility

Significance: In recent decades, male fertility has been severely reduced worldwide. The causes underlying this decline are multifactorial, and include, among others, genetic alterations, changes in the microbiome, and the impact of environmental pollutants. Such factors can dysregulate the physiological levels of reactive species of oxygen (ROS) and nitrogen (RNS) in the patient, generating oxidative and nitrosative stress that impairs fertility. Recent Advances: Recent studies have delved into other factors involved in the dysregulation of ROS and RNS levels, such as diet, obesity, persistent infections, environmental pollutants, and gut microbiota, thus leading to new strategies to solve male fertility problems, such as consuming prebiotics to regulate gut flora or treating psychological conditions. Critical Issues: The pathways where ROS or RNS may be involved as modulators are still under investigation. Moreover, the extent to which treatments can rescue male infertility as well as whether they may have side effects remains, in most cases, to be elucidated. For example, it is known that prescription of antioxidants to treat nitrosative stress can alter sperm chromatin condensation, which makes DNA more exposed to ROS and RNS, and may thus affect fertilization and early embryo development. Future Directions: The involvement of extracellular vesicles, which might play a crucial role in cell communication during spermatogenesis and epididymal maturation, and the relevance of other factors such as sperm epigenetic signatures should be envisaged in the future.

Effects of metformin on behavioral alterations produced by chronic sucrose consumption in male rats

Excessive consumption of sugary drinks negatively impacts the developing brain, producing long-lasting behavioral and metabolic disorders. Here, we study whether treatment with the antihyperglycemic agent metformin prevents some of the anxiety and memory alterations produced by chronic sucrose consumption. Male Sprague-Dawley rats had unrestricted access to water (control group) and a bottle containing a 10% sucrose solution (sucrose group, SUC) for 35 days. In parallel, a group of animals from SUC received metformin (25 mg/kg or 50 mg/kg, orally; MET 25 and MET 50 groups, respectively). After 2 weeks of metformin treatment, the animals weighed less than controls. SUC and MET 50 groups compensated for the caloric intake from the sugary solution by consuming less chow. In contrast, total energy intake in MET 25 was higher than the rest of the groups, but they still weighed less than control and SUC groups, suggesting that at this concentration, metformin delays body growth. The animals were then tested for the open field (OF), elevated plus maze (EPM) and novel object location (NOL) tests. In the OF, SUC animals spent more time in the central zone of the arena, evidenced by an increased number of entries and the distance traveled there. In the EPM, SUC animals spent more time in the open arms and less time in the central square. Metformin treatment prevented the decreased anxiety observed in SUC animals in the OF and EPM. In the NOL test, SUC animals showed less interest in novelty and metformin treatment did not improve this alteration. The preference for open spaces in the OF and EPM were associated with increased serum triglycerides (TG) and malondialdehyde levels in the medial prefrontal cortex (mPFC) and the hippocampus (HIP), while poor memory performance was associated with high basal blood glucose levels. In conclusion, the decreased anxiety-like behavior produced by chronic sucrose consumption was prevented by metformin treatment, through a mechanism that probably involves normalization of TG levels and decreased oxidative stress in mPFC and HIP.

A single-cell transcriptomic landscape of mouse testicular aging

INTRODUCTION

Advanced paternal age of reproduction is an increasing trend, especially in developed countries and areas. This trend results in elevated risks of adverse reproductive outcomes such as reduced fertility rates, increased pregnancy loss, and poor childhood health. Yet, a systematic profiling of aging-associated molecular and cellular alterations in testicular tissue is still missing.

OBJECTIVES

We aimed to dissect aging-associated molecular characteristics in testes of mice.

METHODS

Single-cell transcriptomic sequencing and analysis were conducted in testes of young (2 months old) and old mice (24 months old). Immunofluorescences and immunochemistry were used to characterize aging-associated phenotypes and verify single cell sequence results.

RESULTS

Here, we constructed the first single-cell transcriptomic atlases of testes of young and old mice. In-depth dissection of aging-dependent transcriptional alterations in specific cell types revealed multiple dysregulated biological processes such as increased 'senescence-associated secretory phenotype' and 'inflammation', which were major aging-associated characteristics. Further analysis of aging-related differentially expressed genes uncovered a disrupted balance of undifferentiated and differentiated spermatogonia stem cells in spermatogonia, indicative of a potential role of spermatogonia stem cells in aging-associated subfertility. Importantly, for the first time, our results identified an increased subtype of aging-specific macrophages, which may contribute to a hostile proinflammatory microenvironment during testicular aging.

CONCLUSION

Taken together, our findings depict the distinct single-cell transcriptional features of the aged mouse testes and provide enormous resources for a comprehensive understanding of the cell-type-specific molecular mechanisms underlying mouse testicular aging, which may shed light on developing novel potential diagnostic biomarkers and therapeutic targets for age-associated male subfertility.

Melatonin improves oxidative state and lactate metabolism in rodent Sertoli cells

Antioxidant actions of melatonin and its impact on testicular function and fertility have already been described. Considering that Sertoli cells contribute to provide structural support and nutrition to germ cells, we evaluated the effect of melatonin on oxidative state and lactate metabolism in the immature murine TM4 cell line and in immature hamster Sertoli cells. A prooxidant stimulus applied to rodent Sertoli cells expressing MT1/MT2 receptors, increased lipid peroxidation whereas decreased antioxidant enzymes (superoxide dismutase 1, catalase, peroxiredoxin 1) expression and catalase activity. These changes were prevented by melatonin. Furthermore, melatonin stimulated lactate dehydrogenase (LDH) expression/activity via melatonin receptors, and increased intracellular lactate production in rodent Sertoli cells. Interestingly, oral melatonin supplementation in infertile men positively regulated LDHA testicular mRNA expression. Overall, our work provides insights into the potential benefits of melatonin on Sertoli cells contributing to testicular development and the future establishment of a sustainable spermatogenesis.

Aging induced testicular damage: analyzing the ameliorative potential of Mucuna pruriens seed extract

Mucuna pruriens Linn. (M. pruriens), a leguminous plant, was used extensively in Ayurveda, to treat male-related infertility. Previous studies have demonstrated antioxidant, androgenic, aphrodisiac, and spermatogenic properties of M. pruriens seed extract. Surprisingly, the biological activities of M. pruriens on aging-induced pathological changes in the testis microenvironment have never been explored and the present study was focused on the testing therapeutic efficacy of M. pruriens on aged rat testis. Male Wistar albino rats were grouped as; adult (3 months), aged (24 months), aged + M. pruriens and adult + M. pruriens (N = 6/group). The extract was administrated at a dose of 200 mg/kg body weight (dosage determined in our previous study) daily by gavage for 60 days. The total and free testosterone, FSH and LH levels were considerably increased in aged + M. pruriens. The diameter & volume of the seminiferous tubules, the height & volume of the epithelium, and the number of Leydig cells number were significantly decreased in aged rat testis, concomitantly connective tissue proportion was increased compared to adult rats. The seminiferous epithelium indicates significant rejuvenation or restoration of spermatogenic cells in aged + M. pruriens rat testis. The highlighting observations in aged + M. pruriens was increased in the following parameters i.e., tubular diameter (25%), number of tubules (35%), epithelial height (25%) & volume (20%), and number of Leydig cells (35%) when compared to untreated aged rat testis. The TNFα, NF-κB, cytochrome c, Caspase-9, Caspase-3, Bcl-2, Bax, PARP iNOS, and inflammatory and apoptotic factors were downregulated in aged + M. pruriens. M. pruriens was able to restore spermatogenesis and enhance the activity of Sertoli cells and Leydig cells and improve the pituitary-gonadal axis in aged rat testis and observations indicate the therapeutic activity of M. pruriens in aged rat testis.

Cordycepin mitigates spermatogenic and redox related expression in H2O2-exposed Leydig cells and regulates testicular oxidative apoptotic signalling in aged rats

CONTEXT

Cordycepin (COR), from Cordyceps militaris L., (Cordycipitaceae), is a valuable agent with immense health benefits.

OBJECTIVE

The protective effects of COR in ageing-associated oxidative and apoptosis events in vivo and hydrogen peroxide (H₂O₂)-exposed spermatogenesis gene alterations in TM3 Leydig cells was investigated.

MATERIALS AND METHODS

Male Sprague-Dawley rats were divided into young control (YC), aged control (AC) and COR treated (COR-20) aged groups. COR-20 group received daily doses of COR (20 mg/kg) for 6 months. Cell viability and hormone levels were analysed by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and enzyme immunoassay kits with COR treated at 1, 5, and 10 μg/mL. Oxidative enzymes, spermatogenic, and apoptotic expression in testis tissues were evaluated by Western blotting and real-time RT-PCR.

RESULTS

COR treatment (1, 5, and 10 μg/mL) significantly (p < 0.05 ∼ p < 0.001) inhibited the H₂O₂-induced decrease in the percentage of viable cells (from 63.27% to 71.25%, 85.67% and 93.97%, respectively), and reduced the malondialdehyde (MDA) content (from 4.28 to 3.98, 3.14 and 1.78 nM MDA/mg protein, respectively). Further, the decreased antioxidant enzymes (glutathione-S-transferase mu5, glutathione peroxidase 4 and peroxiredoxin 3), spermatogenesis-related factors (nectin-2 and inhibin-α) and testosterone levels in H₂O₂-exposed TM3 cells were significantly (p < 0.05 ∼ p < 0.001) ameliorated by COR. In aged rats, COR (20 mg/kg) restored the altered enzymatic and non-enzymatic antioxidative status and attenuated the apoptotic p53 and Bax/Bcl-2 expression significantly (p < 0.05).

CONCLUSION

COR might be developed as a potential agent against ageing-associated and oxidative stress-induced male infertility.

Age-related histopathological and biochemical testicular damages were ameliorated by vitamin C administration

INTRODUCTION AND OBJECTIVES

Aging is an irreversible process associated with decreased biological functions that can lead to the reduction of reproductive organs capacities in males and females. Paternal age is a significant predictor of offspring health and development. So, the aim of this study was to evaluate the effects of vitamin C on histopathological and biochemical testicular changes following aging process with a focus on stereological methods.

MATERIAL AND METHODS

For this study, 48 adult male NMRI mice were divided into two control and experimental groups. Mice in experimental group were supplemented with vitamin C (150mg/kg) including 24-h interval by oral gavage for 33 weeks. Same regime was performed for animals in control group except that vitamin C was replaced by water. Then, right testes were extracted for stereological and left testes were used for molecular analyses on weeks 8, 12, and 33.

RESULTS

Our findings showed low semen quality, decreased level of serum Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), and testosterone along with increased reactive oxygen species (ROS) production and higher apoptotic gene expression following aging. Stereological studies showed that the volume of testes, the length of seminiferous tubules, and the number of spermatogenic and none-spermatogenic cells decreased significantly during aging. Also, vitamin C consumption for 33 weeks significantly improved biochemical and histological indices. The impact of aging on male reproduction seems to be inevitable worldwide. Therefore, the use of protective and preventive remedies conserving male fecundity is very important and based on our results, vitamin C is a beneficial candidate for improving age-related testicular changes due to aging process.

The Modulatory Role of Growth Hormone in Inflammation and Macrophage Activation

Inflammation is a body's response to remove harmful stimuli and heal tissue damage, which is involved in various physiology and pathophysiology conditions. If dysregulated, inflammation may lead to significant negative impacts. Growth hormone (GH) has been shown responsible for not only body growth but also critical in the modulation of inflammation. In this review, we summarize the current clinical and animal studies about the complex and critical role of GH in inflammation. Briefly, GH excess or deficiency may lead to pathological inflammatory status. In inflammatory diseases, GH may serve as an inflammatory modulator to control the disease progression and promote disease resolution. The detailed mechanisms and signaling pathways of GH on inflammation, with a focus on the modulation of macrophage polarization, are carefully discussed with potential direction for future investigations.

Single-cell analysis of human testis aging and correlation with elevated body mass index

Aging men display reduced reproductive health; however, testis aging is poorly understood at the molecular and genomic levels. Here, we utilized single-cell RNA-seq to profile over 44,000 cells from both young and older men and examined age-related changes in germline development and in the testicular somatic cells. Age-related changes in spermatogonial stem cells appeared modest, whereas age-related dysregulation of spermatogenesis and somatic cells ranged from moderate to severe. Altered pathways included signaling and inflammation in multiple cell types, metabolic signaling in Sertoli cells, hedgehog signaling and testosterone production in Leydig cells, cell death and growth in testicular peritubular cells, and possible developmental regression in both Leydig and peritubular cells. Remarkably, the extent of dysregulation correlated with body mass index in older but not in younger men. Collectively, we reveal candidate molecular mechanisms underlying the complex testicular changes conferred by aging and their possible exacerbation by concurrent chronic conditions such as obesity.

Mice with gene alterations in the GH and IGF family

Much of our understanding of GH's action stems from animal models and the generation and characterization of genetically altered or modified mice. Manipulation of genes in the GH/IGF1 family in animals started in 1982 when the first GH transgenic mice were produced. Since then, multiple laboratories have altered mouse DNA to globally disrupt Gh, Ghr, and other genes upstream or downstream of GH or its receptor. The ability to stay current with the various genetically manipulated mouse lines within the realm of GH/IGF1 research has been daunting. As such, this review attempts to consolidate and summarize the literature related to the initial characterization of many of the known gene-manipulated mice relating to the actions of GH, PRL and IGF1. We have organized the mouse lines by modifications made to constituents of the GH/IGF1 family either upstream or downstream of GHR or to the GHR itself. Available data on the effect of altered gene expression on growth, GH/IGF1 levels, body composition, reproduction, diabetes, metabolism, cancer, and aging are summarized. For the ease of finding this information, key words are highlighted in bold throughout the main text for each mouse line and this information is summarized in Tables 1, 2, 3 and 4. Most importantly, the collective data derived from and reported for these mice have enhanced our understanding of GH action.

Hallmarks of Testicular Aging: The Challenge of Anti-Inflammatory and Antioxidant Therapies Using Natural and/or Pharmacological Compounds to Improve the Physiopathological Status of the Aged Male Gonad

The evolutionary theory of aging supports a trade-off relationship between reproduction and aging. Aging of the male reproductive system primarily affects the testes, leading to a decrease in the levels of sexual hormones, alterations in sperm quality and production, and a decline in fertility that does not necessarily involve a complete cessation of spermatogenesis. Inflammation, oxidation, and apoptosis are events considered as predictors of pathogenesis and the development of age-related diseases that are frequently observed in aged testes. Although the molecular mechanisms are still poorly understood, accumulating evidence points toward pro-inflammatory molecules and reactive oxygen species as primary contributing factors for testicular aging. However, the real impact of aging-related testicular alterations on fertility, reproductive health, and life span is far from being fully revealed. This work discusses the current knowledge on the impact of aging in the testis, particularly of aging-related dysregulated inflammation and oxidative damage on the functioning of its different cell populations. More interestingly, this review covers the potential benefits of anti-aging interventions and therapies using either pharmacological compounds (such as non-selective non-steroidal anti-inflammatory medication) or more natural alternatives (such as various nutraceuticals or even probiotics) that exhibit anti-inflammatory, antioxidant, and anti-apoptotic properties. Some of these are currently being investigated or are already in clinical use to delay or prevent testicular aging.

Cyclooxygenases of ovoviviparous black rockfish (Sebastes schlegelii): Cloning, tissue distribution and potential role in mating and parturition

Prostaglandins are a series of unsaturated fatty acids that play critical roles in regulating reproductive events. The prostaglandins endoperoxide H synthases-1/2 (PGHS-1/2; also named cyclooxygenases-1/2, COX-1/2) catalyse the commitment step in prostaglandin synthesis. However, the of the cox genes in teleosts, especially ovoviviparous teleosts, is still unclear. The aim of the present study was to determine the potential role of cox genes in mating and parturition behaviour using black rockfish (Sebastes schlegelii) as a model species. Two transcripts, cox1 and cox2, were cloned. The phylogenetic analysis results revealed that both cox genes were closely related to mammalian coxs. qPCR analyses of their tissue distribution showed that cox1 was mainly expressed in the heart in both sexes, while cox2 was mainly expressed in the testis and ovary. Detection of cox expression in samples from reproductive-related stages further showed that both cox genes may play important roles in mating and parturition processes. In situ hybridization further detected positive cox mRNA signals in the testis and ovary, where they are known to be involved in mating and parturition behaviour. These data suggest that cox1 and cox2 are crucial in inducing mating, gonad regeneration and parturition behaviour.

The dynamic changes of Nrf2 mediated oxidative stress, DNA damage and base excision repair in testis of rats during aging

Accumulation of oxidative stress, DNA damage and impaired DNA repair appear to play critical roles in the decline of testicular function with aging. However, when those factors begin to lose control in testis during aging has not yet been well understood. This study was designed to assess the changes of oxidative stress and DNA damage status, and DNA repair capacity in testis during aging. Thus, male Sprague-Dawley rats at 3, 9, 15 and 24 months of age were used to delineate the dynamic changes in testicular weight and index, testosterone concentration, testicular histology, Nrf2-mediated oxidative stress, DNA damage, DNA repair and apoptosis. Results showed that testicular weight and index, testosterone concentration and spermatid number progressively declined from 9 to 24 months of age. Similarly, seminiferous tubule diameters and seminiferous epithelium heights gradually diminished with aging. Nrf2-mediated antioxidant defense ability was significantly impaired in testis with increasing age including decreased the activity of SOD and the expression levels of Nrf2, HO-1 and NQO-1, and increased the contents of MDA. In addition, DNA damage including DNA single-strand breaks (SSBs) and DNA double-strand breaks (DSBs) also progressively increased accompanied by increased levels of 8-hydroxydeoxyguanosine (8-OHdG) and γ-H2AX, and activated ATM/Chk2 and ATR/Chk1 pathway. Consistent with the results of Nrf2 pathway, the expression levels of APE1, OGG1 and XRCC1 involved in base excision DNA repair (BER) pathway increased from 3 to 9 months of age, and then gradually decreased after 9 months of age. Finally, TUNEL and Western blot results further confirmed germ cell apoptosis progressively increased from 3 to 24 months of age as evidenced by decreased ratio of Bcl-2/Bax and levels of Bcl-2 expression, and increased Bax expression levels. Taken together, our results suggest that downregulation of antioxidant ability mediated by Nrf2 pathway and impairment of BER capacity might correlate with increased DNA damage, and then induce declining testicular function during aging after adult.

Male and female gonadal ageing: its impact on health span and life span

Ageing is linked to changes in the hypothalamic-pituitary-gonadal axis and a progressive decline in gonadal function. While women become infertile when they enter menopause, fertility decline in ageing men does not necessarily involve a complete cessation of spermatogenesis. Gonadal dysfunction in elderly people is characterized by morphological, endocrine and metabolic alterations affecting the reproductive function and quality of life. With advancing age, sexuality turns into a critical emotional and physical factor actually defining the number of years that ageing people live a healthy life. Gonadal ageing correlates with comorbidities and an increased risk of age-related diseases including diabetes, kidney problems, cardiovascular failures and cancer. This article briefly summarizes the current state of knowledge on ovarian and testicular senescence, explores the experimental models used in the study of gonadal ageing, and describes the local pro-inflammatory, oxidative and apoptotic events and the associated signalling pathways that take place in the gonads while people get older. Overall, literature reports that ageing exacerbates a mutual crosstalk among oxidative stress, apoptosis and the inflammatory response in the gonads leading to detrimental effects on fertility. Data also highlight the clinical implications of novel therapeutic interventions using antioxidant, anti-apoptotic and anti-inflammatory drugs on health span and life span.

BaZiBuShen alleviates altered testicular morphology and spermatogenesis and modulates Sirt6/P53 and Sirt6/NF-κB pathways in aging mice induced by D-galactose and NaNO2

ETHNOPHARMACOLOGICAL RELEVANCE

Sperm infertility and testicular atrophy are symptoms associated with aging. BaZiBuShen formula (BZBS), a patented Chinese herbal prescription composed of Semen Cuscutae, Fructus Lycii, Epimedii Folium, Fructus Schisandrae Sphenantherae, Fructus Cnidii, Fructus Rosae Laevigatae, Semen Allii Tuberosi., Radix Morindae Officinalis, Herba Cistanches, Fructus Rubi, Radix Rehmanniae Recens, Radix Cyathulae, Radix Ginseng, Cervi Cornu Pantotrichum, Hippocampus, and Fuctus Toosendan, has been used as a kidney-tonifying and anti-aging drug as well as for the treatment of impotence and male infertility in traditional Chinese medicine.

AIM OF THE STUDY

We aimed at investigating whether BZBS preserves sperm and testes morphology in aging mice, and to explore the underlying mechanisms.

MATERIALS AND METHODS

BZBS was orally administered to aging mice induced by D-galactose (D-gal) and NaNO2 for 65 days. Sperm quality and testes pathophysiological alterations were examined by a Semen Analysis System, hematoxylin-eosin staining, transmission electron microscopy, and mitochondrial complex IV activity. In addition, serum levels of total antioxidant capacity (TAC), malondialdehyde (MDA), 8-hydroxy-desoxyguanosine (8-OH-dG), reduced glutathione (GSH), oxidized glutathione disulfide (GSSG), testosterone (T), follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2) and tumor necrosis factor-α (TNF-α) were determined by ELISA. The expressions of P450 aromatase (CYP19), sirtuin 6 (Sirt6), P53, inducible nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-κB)-p65, and phospho-NF-κB-p65 (NF-κB-pp65) in the testes were examined by western blot and/or immunohistochemical staining.

RESULTS

Sustained exposure to D-gal/NaNO2 caused a deterioration of sperm quality and testes morphology in this rapid aging mouse model. BZBS treatment curtailed these alterations. These beneficial effects were associated with increased serum levels of TAC, GSH/GSSG, T, E2, and FSH, and decreased levels of MDA, TNF-α, and 8-OH-dG. BZBS treatment also downregulated the expressions of P53, iNOS, and NF-κB-pp65, as well as upregulated the expressions of Sirt6 and CYP19 in aging testes.

CONCLUSIONS

BZBS preserves testicular morphology and spermatogenesis possibly via inhibition of oxidative stress and the modulation of the Sirt6/P53 and Sirt6/NF-κB signaling pathways. The results shed light on the beneficial effect of BZBS on sperm quality and fertility in aging males.

Anti-aging effects of a functional food via the action of gut microbiota and metabolites in aging mice

Wushen (WS) is a mixed food containing 55 natural products that is beneficial to human health. This study aimed to reveal the preventive effect of WS on aging via a combined analysis of gut microbiome and metabolome. Senescence-accelerated mouse prone 8 (SAMP8) mice were used as aging model and senescence-accelerated mouse resistant 1 (SAMR1) mice as control. The mice were fed four diet types; control diet (for SAMR1 mice), standard diet (for SAMP8 mice, as SD group), WS diet, and fecal microbiota transplantation (FMT; transplanted from aging-WS mice). Our results showed that the weight, food intake, neurological function, and general physical conditions significantly improved in WS-fed mice compared to those fed with SD. The CA1 hippocampal region in WS-fed aged mice showed fewer shriveled neurons and increased neuronal layers compared to that of the SD group. WS-fed mice showed a decrease in malondialdehyde and an increase in superoxide dismutase levels in the brain; additionally, IL-6 and TNF-α levels significantly decreased, whereas IL-2 levels and the proportion of lymphocytes, CD3+CD8+ T, and CD4+IFNγ+T cells increased in WS-fed mice. After fed with WS, the abundance of Ruminococcus and Butyrivibrio markedly increased, whereas Lachnoclostridium and Ruminiclostridium significantly decreased in the aging mice. In addition, 887 differentially expressed metabolites were identified in fecal samples, among these, Butyrivibrio was positively correlated with D-glucuronic acid and Ruminococcus was positively associated with 5-acetamidovalerate. These findings provide mechanistic insight into the impact of WS on aging, and WS may be a valuable diet for preventing aging.

Mouse models of growth hormone deficiency

Nearly one century of research using growth hormone deficient (GHD) mouse lines has contributed greatly toward our knowledge of growth hormone (GH), a pituitary-derived hormone that binds and signals through the GH receptor and affects many metabolic processes throughout life. Although delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, small body size, and glucose intolerance appear to be among the negative characteristics of these GHD mouse lines, these mice still consistently outlive their normal sized littermates. Furthermore, the absence of GH action in these mouse lines leads to enhanced insulin sensitivity (likely due to the lack of GH's diabetogenic actions), delayed onset for a number of age-associated physiological declines (including cognition, cancer, and neuromusculoskeletal frailty), reduced cellular senescence, and ultimately, extended lifespan. In this review, we provide details about history, availability, growth, physiology, and aging of five commonly used GHD mouse lines.

Melatonin daily oral supplementation attenuates inflammation and oxidative stress in testes of men with altered spermatogenesis of unknown aetiology

We have previously shown an inverse correlation between testicular melatonin concentration and inflammation/oxidative stress-related markers levels in infertile men showing unexplained azoospermia. Here, we evaluated the impact of melatonin oral supplementation (daily 3 mg dose used to treat sleep disorders) in the incidence of local inflammation, oxidative stress, and tubular wall fibrosis development in young and middle-aged infertile adult men. Compared with testes without histological alterations, gonads with morphological abnormalities showed lower melatonin concentration along with increased macrophage numbers, TBARS generation, and expression levels of inflammation-related markers and antioxidant enzymes, as well as tubular wall collagen fibers disorganization and thickening. Melatonin oral supplementation not only increased its own testicular levels but also decreased inflammation- and oxidative stress-related markers levels, and improved the tubular wall aspect. Overall, our work provides insights into the potential benefits of melatonin on the inflammatory and oxidative status in testes of patients suffering from unexplained infertility.

Testicular Aging: An Overview of Ultrastructural, Cellular, and Molecular Alterations

The trend in parenthood at an older age is increasing for both men and women in developed countries, raising concerns about the reproductive ability, and the consequences for the offspring's health. While reproductive activity in women stops with menopause, a complete cessation of the reproductive potential does not occur in men. Although several studies have been published on the effects of aging on semen parameters and spermatozoa DNA integrity, literature on impact of aging on the testis, particularly cellular, and molecular alterations, has been, so far, limited and controversial. This work discusses the current knowledge on testicular aging in humans and other mammals, covering topics from tissue ultrastructure, to cellular and molecular alterations. Aging affects male reproductive function at multiple levels, from sperm production and quality, to the morphology and histology of the male reproductive system. The morphological and functional changes that occur in the testes result in variations in the levels of many hormones, changes in molecules involved in mitochondrial function, receptors, and signaling proteins. Despite knowing that these age-related alterations occur, their real impact on male fertility and reproductive health are still far from being fully understood, highlighting that research in the field is crucial.

Growth hormone-mediated reprogramming of macrophage transcriptome and effector functions

Macrophages are an important component of the innate immune response. Priming and activation of macrophages is stimulated by cytokines (i.e IFNγ). However, growth hormone (GH) can also stimulate macrophage activation. Based on these observations, the goal of this work was to 1) to compare the transcriptome profile of macrophages activated in vitro with GH and IFNγ, and 2) to assess the impact of GH on key macrophage functional properties like reactive oxygen species (ROS) production and phagosomal proteolysis. To assess the global transcriptional and functional impact of GH on macrophage programming, bone marrow derived macrophages were treated with GH or IFNγ. Our data strongly support a potential link between GH, which wanes with age, and impaired macrophage function. The notable overlap of GH with IFNγ-induced pathways involved in innate immune sensing of pathogens and antimicrobial responses argue for an important role for GH in macrophage priming and maturation. By using functional assays that report on biochemical activities within the lumen of phagosomes, we have also shown that GH alters physiologically relevant processes such as ROS production and proteolysis. These changes could have far reaching impacts on antimicrobial capacity, signaling, and antigen presentation.

β-adrenergic receptors in the up-regulation of COX2 expression and prostaglandin production in testicular macrophages: Possible relevance to male idiopathic infertility

Catecholaminergic neuronal elements (CNE) and macrophages (MACs) are increased in testes of patients with idiopathic infertility. Now, we describe an anatomical proximity between CNE and MACs, expression of specific α- and β-adrenergic receptors (ADRs) subtypes in MACs, and a positive correlation between the number of MACs and cyclooxygenase (COX2) expression - key enzyme in prostaglandin (PG) synthesis and an inflammatory marker - in testes of infertile men. To examine a potential effect of adrenergic input on COX2 expression, we used two additional experimental models: non-testicular human MACs (THP1 cell line) and non-human testicular MACs purified from adult Syrian hamsters. We found that epinephrine and norepinephrine up-regulate COX2 expression and PGD2 production through β1-and β2-ADRs. Our results demonstrate the existence of a yet unknown link between CNE and MACs in the human testis that could trigger inflammation and tissue homeostatic dysregulation associated with pathogenesis or maintenance of infertility states.

Association Between Nonalcoholic Fatty Liver Disease and Severe Male Reproductive Organ Impairment (Germinal Epithelial Loss): Study on a Mouse Model and on Human Patients

Metabolic syndrome (MS) has been associated with testicular damage. Nonalcoholic fatty liver disease (NAFLD) is a multisystemic disease that affects different organs, but its effect on the testes is unknown. A study analyzing germ cell involvement on BALB/c mice was carried out. A parallel comparative study was conducted that investigated alterations in the germinal epithelium of male humans that died from an unrelated acute event. The complete medical histories and histologic samples of the thoracic aorta, liver tissue, and testicular tissue from the deceased subjects were collected. The degree of germinal epithelial loss (DGEL) was evaluated and the clinical and histologic data were compared between individuals with and without NAFLD. The only metabolic or morphologic variable that caused a significant difference in the DGEL, in both the animal model and humans, was the presence of liver steatosis. The percentage of steatosis was also correlated with the percentage of the DGEL. In humans, steatosis (greater than 20%) increased the risk 12-fold for presenting with a severe DGEL (OR: 12.5; 95% CI [1.2, 128.9]; p = .03). There was no association with age above 50 years or MS components. Steatosis grade was also correlated with atherosclerosis grade. NAFLD was a strongly associated factor implicated in severe DGEL, as well as the testis was identified as a probable target organ for damage caused by the disease. This finding could result in the search for new approach strategies in the management of men with fertility problems. Further studies are required to confirm these results.

Aging: Molecular Pathways and Implications on the Cardiovascular System

The world's population over 60 years is growing rapidly, reaching 22% of the global population in the next decades. Despite the increase in global longevity, individual healthspan needs to follow this growth. Several diseases have their prevalence increased by age, such as cardiovascular diseases, the leading cause of morbidity and mortality worldwide. Understanding the aging biology mechanisms is fundamental to the pursuit of cardiovascular health. In this way, aging is characterized by a gradual decline in physiological functions, involving the increased number in senescent cells into the body. Several pathways lead to senescence, including oxidative stress and persistent inflammation, as well as energy failure such as mitochondrial dysfunction and deregulated autophagy, being ROS, AMPK, SIRTs, mTOR, IGF-1, and p53 key regulators of the metabolic control, connecting aging to the pathways which drive towards diseases. In addition, senescence can be induced by cellular replication, which resulted from telomere shortening. Taken together, it is possible to draw a common pathway unifying aging to cardiovascular diseases, and the central point of this process, senescence, can be the target for new therapies, which may result in the healthspan matching the lifespan.

GH and ageing: Pitfalls and new insights

The interrelationships of growth hormone (GH) actions and aging are complex and incompletely understood. The very pronounced age-related decline in GH secretion together with benefits of GH therapy in individuals with congenital or adult GH deficiency (GHD) prompted interest in GH as an anti-aging agent. However, the benefits of treatment of normal elderly subjects with GH appear to be marginal and counterbalanced by worrisome side effects. In laboratory mice, genetic GH deficiency or resistance leads to a remarkable extension of longevity accompanied by signs of delayed and/or slower aging. Mechanisms believed to contribute to extended longevity of GH-related mutants include improved anti-oxidant defenses, enhanced insulin sensitivity and reduced insulin levels, reduced inflammation and cell senescence, major shifts in mitochondrial function and energy metabolism, and greater stress resistance. Negative association of the somatotropic signaling and GH/insulin-like growth factor 1 (IGF-1)-dependent traits with longevity has also been shown in other mammalian species. In humans, syndromes of GH resistance or deficiency have no consistent effect on longevity, but can provide striking protection from cancer, diabetes and atherosclerosis. More subtle alterations in various steps of GH and IGF-1 signaling are associated with reduced old-age mortality, particularly in women and with improved chances of attaining extremes of lifespan. Epidemiological studies raise a possibility that the relationship of IGF-1 and perhaps also GH levels with human healthy aging and longevity may be biphasic. However, the impact of somatotropic signaling on neoplastic disease is difficult to separate from its impact on aging, and IGF-1 levels exhibit opposite associations with different chronic, age-related diseases.

Stem cell therapy for the treatment of Leydig cell dysfunction in primary hypogonadism

The production of testosterone occurs within the Leydig cells of the testes. When production fails at this level from either congenital, acquired, or systemic disorders, the result is primary hypogonadism. While numerous testosterone formulations have been developed, none are yet fully capable of replicating the physiological patterns of testosterone secretion. Multiple stem cell therapies to restore androgenic function of the testes are under investigation. Leydig cells derived from bone marrow, adipose tissue, umbilical cord, and the testes have shown promise for future therapy for primary hypogonadism. In particular, the discovery and utilization of a group of progenitor stem cells within the testes, known as stem Leydig cells (SLCs), has led not only to a better understanding of testicular development, but of treatment as well. When combining this with an understanding of the mechanisms that lead to Leydig cell dysfunction, researchers and physicians will be able to develop stem cell therapies that target the specific step in the steroidogenic process that is deficient. The current preclinical studies highlight the complex nature of regenerating this steroidogenic process and the problems remain unresolved. In summary, there appears to be two current directions for stem cell therapy in male primary hypogonadism. The first method involves differentiating adult Leydig cells from stem cells of various origins from bone marrow, adipose, or embryonic sources. The second method involves isolating, identifying, and transplanting stem Leydig cells into testicular tissue. Theoretically, in-vivo re-activation of SLCs in men with primary hypogonadism due to age would be another alternative method to treat hypogonadism while eliminating the need for transplantation.

Reactive oxygen species (ROS) production triggered by prostaglandin D2 (PGD2) regulates lactate dehydrogenase (LDH) expression/activity in TM4 Sertoli cells

Reactive oxygen species (ROS) regulate testicular function in health and disease. We previously described a prostaglandin D2 (PGD2) system in Sertoli cells. Now, we found that PGD2 increases ROS and hydrogen peroxide (H2O2) generation in murine TM4 Sertoli cells, and also induces antioxidant enzymes expression suggesting that defense systems are triggered as an adaptive stress mechanism that guarantees cell survival. ROS and specially H2O2 may act as second messengers regulating signal transduction pathways and gene expression. We describe a stimulatory effect of PGD2 on lactate dehydrogenase (LDH) expression via DP1/DP2 receptors, which is prevented by the antioxidant N-acetyl-L-cysteine and the PI3K/Akt pathway inhibitor LY 294002. PGD2 also enhances Akt and CREB/ATF-1 phosphorylation. Our results provide evidence for a role of PGD2 in the regulation of the oxidant/antioxidant status in Sertoli cells and, more importantly, in the modulation of LDH expression which takes place through ROS generation and the Akt-CREB/ATF-1 pathway.