Search

Ageing is the time-dependent gradual decline of the functional characteristics in an organism. It has been shown that it results in the loss of reproductive health and fertility. The age-dependent decline of fertility is a potential issue as the parenthood age is increasing in Western countries, mostly due to socioeconomic factors. In comparison to women, for whom the consequences of ageing are well documented and general awareness of the population is extensively raised, the effects of ageing for male fertility and the consequences of advanced paternal age for the offspring have not been widely studied. Studies with humans are welcome but it is hard to implement relevant experimental approaches to unveil the molecular mechanisms by which ageing affects male reproductive potential. Animal models have thus been extensively used. These models are advantageous due to their reduced costs, general easy maintenance in laboratory facilities, rigorous manipulation tools, short lifespan, known genetic backgrounds, and reduced ethical constraints. Herein, we discuss animal models for the study of male reproductive ageing. The most well-known and studied reproductive ageing models are rodents and non-human primates. The data collected from these models, particularly studies on testicular ageing, steroidogenesis, and genetic and epigenetic changes in spermatogenesis are detailed. Notably, some species challenge the currently accepted ageing theories and the concept of senescence itself, which renders them interesting animal models for the study of male reproductive ageing., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel that is crucial for fluid homeodynamics throughout the male reproductive tract. Previous evidence shed light on a potential molecular partnership between this channel and aquaporins (AQPs). Herein, we explore the role of CFTR on AQPs-mediated glycerol permeability in mouse Sertoli cells (mSCs). We were able to identify the expression of CFTR, AQP3, AQP7, and AQP9 in mSCs by RT-PCR, Western blot, and immunofluorescence techniques. Cells were then treated with CFTRinh-172, a specific CFTR inhibitor, and its glycerol permeability was evaluated by stopped-flow light scattering. We observed that CFTR inhibition decreased glycerol permeability in mSCs by 30.6% when compared to the control group. A DUOLINK proximity ligation assay was used to evaluate the endogenous protein-protein interactions between CFTR and the various aquaglyceroporins we identified. We positively detected that CFTR is in close proximity with AQP3, AQP7, and AQP9 and that, through a possible physical interaction, CFTR can modulate AQP-mediated glycerol permeability in mSCs. As glycerol is essential for the control of the blood-testis barrier and elevated concentration in testis results in the disruption of spermatogenesis, we suggest that the malfunction of CFTR and the consequent alteration in glycerol permeability is a potential link between male infertility and cystic fibrosis., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Leptin is an adipose tissue hormone that acts as energy sensor and reproductive function regulator. Recent reports suggest that leptin is involved in mitochondrial biogenesis in different tissue cells. Herein, we hypothesized that leptin could also affect Sertoli cells mitochondrial dynamics and biogenesis. Human Sertoli cells (hSCs) were cultured in the presence of different leptin concentrations (5, 25 and 50 ng/mL) or vehicle for 24 h. The three different leptin concentrations were selected to mimic the circulating levels found either in normal weight, obese, and morbidly obese individuals, respectively. Leptin receptor (LEPR) expression was evaluated as well as mitochondrial membrane potential, complexes levels, complex II activity and basal respiration. Moreover, mitochondrial DNA copy number and expression of mitochondrial biogenesis markers were assessed. In hSCs, leptin concentrations similar to those found both in lean men decreased mitochondrial complex II protein levels, but no changes in its activity were observed. This is in agreement with basal respiration and mitochondrial membrane potential assessments, which indicate no alterations in mitochondrial fitness. Furthermore, no changes in mitochondrial biogenesis markers were observed upon leptin exposure, although SIRT1/3 levels were increased after exposure to the highest leptin concentration. Overall, the increase in SIRT1/3 levels suggests a role for leptin in glycolysis, which given the relevance of SCs glycolytic flux for germ cells nutritional support further reinforces that this mechanism can be linked to obesity-related subfertility/infertility.

Background: Strong evidence has suggested an important role of telomeres in meiosis, fertilization, and embryo development., Purpose: To determine if sperm telomere length (STL) in sperm purified by differential gradient centrifugation followed by swim-up (selected STL) is correlated with sperm quality and clinical outcomes., Methods: Relative selected STL was assessed by quantitative polymerase chain reaction (Q-PCR) in 78 consecutive assisted reproductive technology (ART) treatments during 2017. Statistical analyses were performed in the totality of patients, and in normozoospermic and non-normozoospermic patients. These included correlations between selected STL and sperm quality parameters, embryological parameters (multivariable linear regression), and clinical parameters (multivariable logistic regression)., Results: No significant correlations were found between selected STL and sperm quality in the total population. However, selected STL was significantly correlated with total sperm count (r = 0.361; P = 0.039) and sperm DNA fragmentation-post-acrosomal region pattern (r = - 0.464; P = 0.030) in normozoospermic patients. No relation was observed between selected STL and clinical outcomes in any clinical group., Conclusions: As the correlations observed in normozoospermic patients were not representative of the whole heterogeneous population, differences in the sperm characteristics of the study population may lead to discrepant results when evaluating the association of STL with sperm quality. Since the total population selected STL was not related with sperm quality and with clinical outcomes, results do not support the use of selected STL measurement to evaluate the reproductive potential of the male patient or to predict the success rates of ART treatments.

In the last decade, several reports highlight the importance of the low molecular weight protein tyrosine phosphatase (LMWPTP) in cancer aggressiveness and resistance. Specifically, in chronic myeloid leukemia, we have reported that high expression of the LMWPTP maintains Src and Bcr-Abl kinases in an activated status and the glucose metabolism is directed to lactate production and, in turn, favor the pentoses pathway (one of the key process for antioxidant and protective responses). In this present study, we investigated the possible correlation between the LMWPTP and autophagy. In resistant chronic myeloid leukemia cells, the antioxidant response is supported by the glycolytic metabolism and antioxidant enzymes such as SOD and catalase, both favored by the LMWPTP. Therefore, when the cells were challenged by hydrogen peroxide treatment, the LMWPTP level goes down as well as SOD, and in turn, autophagy process was stimulated. The findings presented here reveal a novel aspect by which LMWPTP cooperates for the resistance of CML towards stressor stimuli.

In the male reproductive tract, ionic equilibrium is essential to maintain normal spermatozoa production and, hence, the reproductive potential. Among the several ions, HCO 3 - and H + have a central role, mainly due to their role on pH homeostasis. In the male reproductive tract, the major players in pH regulation and homeodynamics are carbonic anhydrases (CAs), HCO 3 - membrane transporters (solute carrier 4-SLC4 and solute carrier 26-SLC26 family transporters), Na + -H + exchangers (NHEs), monocarboxylate transporters (MCTs) and voltage-gated proton channels (Hv1). CAs and these membrane transporters are widely distributed throughout the male reproductive tract, where they play essential roles in the ionic balance of tubular fluids. CAs are the enzymes responsible for the production of HCO 3 - which is then transported by membrane transporters to ensure the maturation, storage, and capacitation of the spermatozoa. The transport of H + is carried out by NHEs, Hv1, and MCTs and is essential for the electrochemical balance and for the maintenance of the pH within the physiological limits along the male reproductive tract. Alterations in HCO 3 - production and transport of ions have been associated with some male reproductive dysfunctions. Herein, we present an up-to-date review on the distribution and role of the main intervenient on pH homeodynamics in the fluids throughout the male reproductive tract. In addition, we discuss their relevance for the establishment of the male reproductive potential.

Life expectancy of most human populations has greatly increased as a result of factors including better hygiene, medical practice, and nutrition. Unfortunately, as humans age, they become more prone to suffer from neurodegenerative diseases and neurotoxicity. Polyphenols can be cheaply and easily obtained as part of a healthy diet. They present a wide range of biological activities, many of which have relevance for human health. Compelling evidence has shown that dietary phytochemicals, particularly polyphenols, have properties that may suppress neuroinflammation and prevent toxic and degenerative effects in the brain. The mechanisms by which polyphenols exert their action are not fully understood, but it is clear that they have a direct effect through their antioxidant activities. They have also been shown to modulate intracellular signaling cascades, including the PI3K-Akt, MAPK, Nrf2, and MEK pathways. Polyphenols also interact with a range of neurotransmitters, illustrating that these compounds can promote their health benefits in the brain through a direct, indirect, or complex action. We discuss whether polyphenols obtained from diet or food supplements are an effective strategy to prevent or treat neurodegeneration. We also discuss the safety, mechanisms of action, and the current and future relevance of polyphenols in clinical treatment of neurodegenerative diseases. As populations age, it is important to discuss the dietary strategies to avoid or counteract the effects of incurable neurodegenerative disorders, which already represent an enormous financial and emotional burden for health care systems, patients, and their families.

The formation of competent spermatozoa is a complex event that depends on the establishment of adequate environments throughout the male reproductive tract. Bicarbonate is essential not only to ionic homeostasis but also to pH maintenance along the male reproductive tract. Previous studies support an association of high 17β-estradiol (E2) levels with modulation of specific ion transporters expression. Herein we determined the effect of E2 on the expression/functionality of SLC4 family bicarbonate transporters in rat Sertoli cells (SCs). All studied transporters [anion exchanger 2 (AE2), Na(+)-driven Cl(-)/HCO3 (-) exchanger (NDCBE), electrogenic Na(+)/HCO3 (-) co-transporters (NBCe1), and electroneutral Na(+)/HCO3 (-) co-transporters (NBCn1)] were identified in SCs, being AE2 and NBCn1 the most abundant. In E2-treated cells (100 nM), increases in AE2 and NBCn1 protein levels were observed, as well as altered transcellular transport. E2-treated SCs presented a significant perturbation of ATP-induced short-circuit current. This alteration was concurrent with augmented AE2 and NBCn1 levels. Overall, we report a relation between increased E2 levels and the expression/function of AE2 and NBCn1 in rat SCs, providing new evidence on the mechanisms by which E2 can regulate SCs physiology and consequently spermatogenesis, with direct influence on male reproductive potential.

Mitochondria have a crucial role in the supply of energy to the brain. Mitochondrial alterations can lead to detrimental consequences on the function of brain cells and are thought to have a pivotal role in the pathogenesis of several neurologic disorders. This study was aimed to evaluate mitochondrial function, fusion-fission and biogenesis and autophagy in brain cortex of 6-month-old Goto-Kakizaki (GK) rats, an animal model of nonobese type 2 diabetes (T2D). No statistically significant alterations were observed in mitochondrial respiratory chain and oxidative phosphorylation system. A significant decrease in the protein levels of OPA1, a protein that facilitates mitochondrial fusion, was observed in brain cortex of GK rats. Furthermore, a significant decrease in the protein levels of LC3-II and a significant increase in protein levels of mTOR phosphorylated at serine residue 2448 were observed in GK rats suggesting a suppression of autophagy in diabetic brain cortex. No significant alterations were observed in the parameters related to mitochondrial biogenesis. Altogether, these results demonstrate that during the early stages of T2D, brain mitochondrial function is maintained in part due to a delicate balance between mitochondrial fusion-fission and biogenesis and autophagy. However, future studies are warranted to evaluate the role of mitochondrial quality control pathways in late stages of T2D.

Natural products are some of the important sources of new anticancer drugs. The Brazilian flora is considered one of the most diverse in the word, although not many large-scale pharmacological and phytochemical studies have been conducted to date. With this in mind, in the present study we evaluated the antiproliferative activity of Solanum lycocarpum fruit glycoalkaloid extract (SL) and its major compounds, solamargine (SM) and solasonine (SS), against different tumor cell lines: murine melanoma (B16F10), human colon carcinoma (HT29), human breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (HeLa), human hepatocellular liver carcinoma (HepG2) and human glioblastoma (MO59J, U343 and U251). The antiproliferative activity was evaluated using XTT assay and results were expressed as IC50. The most pronounced antiproliferative activity was observed for SM, with IC50 values ranging from 4.58 to 18.23 μg/mL. The lowest IC50 values were observed against HepG2, being 9.60 μg/mL for SL, 4.58 μg/mL for SM and 6.01 μg/mL for SS. Thus, SL, SM and SS demonstrated antiproliferative activity against the tumor cell lines tested, and were most effective against the HepG2 cell line.

The formation of competent spermatozoa is a complex event that depends on the establishment of adequate environments throughout the male reproductive tract. This includes the control of bicarbonate (HCO₃⁻) concentration, which plays an essential role in the maintenance of extracellular and intracellular pH (pH(i)) values. Diabetes mellitus alters pHi regulation in mammalian cells, mainly by altering the activity of ion transporters, particularly HCO₃⁻-dependent mechanisms. Yet, little is known about the effects of this pathology and its prodromal stage, prediabetes, on the membrane transport mechanisms of male reproductive tract cells. Herein, we analyzed protein and mRNA levels of the most relevant HCO₃⁻ transporters of the SLC4 family [anion exchanger 2 (AE2), Na⁺-driven Cl⁻/HCO₃⁻ exchanger (NDCBE), electrogenic Na⁺/HCO₃⁻ cotransporter 1 (NBCe1), electroneutral Na⁺/HCO₃⁻ cotransporter 1 (NBCn1)] in the testis and epididymis of a prediabetic animal model. Firstly, we identified the HCO₃⁻ transporters of the SLC4 family, in both testicular and epididymal tissue. Secondly, although no alterations were detected in protein expression, mRNA levels of NBCe1, NBCn1 and NDCBE were significantly increased in the testis of prediabetic rats. On the other hand, in the epididymis, prediabetes caused an increase of AE2 and a decrease of NDCBE protein levels. These alterations may be translated into changes of HCO₃⁻ transepithelial epididymal fluxes in vivo, which may represent a threat for sperm survival. Moreover, these results provide evidence of the molecular mechanism that may be responsible for the significant increase in abnormal sperm morphology already reported in prediabetic rats.

Hormonal regulation is essential to spermatogenesis. Sertoli cells (SCs) have functions that reach far beyond the physical support of germ cells, as they are responsible for creating the adequate ionic and metabolic environment for germ cell development. Thus, much attention has been given to the metabolic functioning of SCs. During spermatogenesis, germ cells are provided with suitable metabolic substrates, in a set of events mediated by SCs. Multiple signaling cascades regulate SC function and several of these signaling pathways are hormone-dependent and cell-specific. Within the seminiferous tubules, only SCs possess receptors for some hormones rendering them major targets for the hormonal signaling that regulates spermatogenesis. Although the mechanisms by which SCs fulfill their own and germ cells metabolic needs are mostly studied in vitro, SC metabolism is unquestionably a regulation point for germ cell development and the hormonal control of these processes is required for a normal spermatogenesis.

Sertoli cells play a key role in the establishment of an adequate luminal environment in the seminiferous tubules of the male reproductive tract. Secretion of the seminiferous tubular fluid (STF) is vital for the normal occurrence of spermatogenesis and for providing a means of transport to the developing spermatozoa. However, several studies on this subject have not completely clarified the origin and composition of this fluid. Electrolyte and water are central components of STF. Sertoli cells secrete an iso-osmotic fluid with a higher content of K(+) than the blood and express various membrane and water transporters (Na(+)/K(+)-ATPase; Ca(2+)-ATPase; V-type ATPase; Cl(-) channels; CFTR Cl(-) channels; K(+) channels; L-, T- and N-type Ca(2+) channels; Na(+)/H(+) exchangers; Na(+)-driven HCO(3) (-)/Cl(-) exchangers (NDCBEs); Na(+)/HCO(3) (-) cotransporters (NBCes); Na(+)-K(+)-2Cl(-) cotransporter; Na(+)/Ca(2+) exchanger; and aquaporins 0 and 8) involved in cellular and secretory functions. Studies with knockout mice for some of these transporters showed tubular fluid accumulation and associated infertility, revealing the relevance of these processes for the normal occurrence of spermatogenesis. Nevertheless, the role of the several membrane transporters in the establishment of STF electrolyte composition needs to be further elucidated. This review summarizes the available data on the ionic composition of STF and on the Sertoli cell membrane mechanisms responsible for ion and water movement. Deepening the knowledge on the mechanisms involved in the secretion, composition and regulation of SFT is essential and will be a major step in understanding the infertility associated with some pathological conditions.

Sertoli cells are responsible for regulating a wide range of processes that lead to the differentiation of male germ cells into spermatozoa. Cytoplasmic pH (pHi) has been shown to be an important parameter in cell physiology, regulating namely cell metabolism and differentiation. However, membrane transport mechanisms involved in pHi regulation mechanisms of Sertoli cells have not yet been elucidated. In this work, pHi was determined using the pH-sensitive fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). Addition of weak acids resulted in rapid acidification of the intracellular milieu. Sertoli cells then recovered pHi by a mechanism that was shown to be sensitive to external Na+. pHi recovery was also greatly reduced in the presence of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and amiloride. These results point toward the action of an Na+-driven HCO3-/Cl- exchanger and/or an Na+/HCO3- cotransporter and the action of the Na+/H+ exchanger on pHi regulation in the experimental conditions used. pHi recovery was only slightly affected by ouabain, suggesting that the inhibition of Na+/K+-ATPase affects recovery indirectly, possibly via the shift on the Na+ gradient. On the other hand, recovery from the acid load was independent of the presence of concanamycin A, a specific inhibitor of the V-type ATPases, suggesting that these pumps do not have a relevant action on pHi regulation in bovine Sertoli cells.

In the freshwater mollusc Anodonta cygnea and other unionids, the mantle plays an important role in the regulation of the movements of ions between the shell and the extrapaleal fluid. In this report, a mathematical model that attempts to describe the cell metabolic mechanisms underlying the operation of the outer mantle epithelium as a source of protons is presented. We encoded the information gathered by studying the epithelium in vitro, which includes the electrophysiology of the preparation, measurements of basic rates of transport of protons and base, the effect of metabolic and transport inhibitors on its electrical behavior and the dynamic measurements of pHi. The model was conceived so that the short-circuit current (Isc) and fluxes of Na+, K+ and Cl(-); intracellular volume; electrical potential; and ionic concentrations can be computed as a function of time. Furthermore, the analytical descriptions of all ionic fluxes involved are such that the effect of transport inhibitors can be simulated. In all the simulations performed, it was possible to reproduce the experimental results obtained with specific inhibitors of transport systems on the Isc and on pHi. In some cases, it was necessary to make alterations to one or more parameters of the reference condition. For each simulation carried out, the analysis of the results was consistent. The model is an analytical tool that can be used to show the internal coherence of the qualitative model previously proposed and to plan further experiments.