Effect of tertiary-butyl hydroperoxide (TBHP)-induced oxidative stress on mice sperm quality and testis histopathology

Oocyte Vitrification Reduces its Capability to Repair Sperm DNA Fragmentation and Impairs Embryonic Development

Oocytes play a crucial role in repairing sperm DNA damage, which can affect the next generation; however, certain factors can impair this ability. This study examined whether oocyte vitrification, a widely used method for fertility preservation, negatively affects repair ability. Male DBA/2 mice (n = 28) were injected with 101.60 µmol/100 g body weight of tert-Butyl hydroperoxide (tBHP) for 14 days to induce sperm DNA damage. Histological changes, sperm functions, and DNA fragmentation were assessed using the TUNEL assay. Cumulus-oocyte-complexes (COCs) of superovulated female DBA/2 mice (n = 28) were vitrified using the Cryotop method. Fresh and vitrified oocytes were then fertilized by tBHP-treated and untreated sperms, and subsequent embryonic development was monitored. Additionally, the expression of Mre11a, Rad51, Brca1, and Xrcc4 was assessed in resulting zygotes and blastocysts using real-time PCR. The sperm tBHP treatment reduced differentiated spermatogenic cells in the testicular tissue, sperm concentration, and motility, while increasing DNA fragmentation (P < 0.05). The fertilization rate was decreased in the tBHP-treated sperm-vitrified oocyte group (P < 0.05), and the two-cell rate diminished in tBHP-treated sperm-fresh and vitrified oocyte groups (P < 0.05). The four-cell to blastocyst rate decreased in the untreated sperm-vitrified oocyte and the tBHP-treated sperm-fresh and vitrified oocyte groups (P < 0.05), and the tBHP-treated sperm-vitrified oocyte groups had the lowest blastocyst rate. In zygotes, Brca1 was upregulated in the tBHP-treated sperm-vitrified oocyte group (P < 0.05). Also, in blastocysts, Rad51, Brca1, and Xrcc4 were significantly upregulated in the untreated sperm-vitrified oocytes group (P < 0.05). Damages to the oocyte due to vitrification can disrupt the repair of sperm DNA fragmentation and consequently impair the embryo development.

Propolis Protects GC-1spg Spermatogonial Cells against Tert-Butyl Hydroperoxide-Induced Oxidative Damage

Propolis is a natural resin produced by honeybees with plenty of pharmacologic properties, including antioxidant activity. Oxidative stress disrupts germ cell development and sperm function, with demonstrated harmful effects on male reproduction. Several natural antioxidants have been shown to reduce oxidative damage and increase sperm fertility potential; however, little is known about the effects of propolis. This work evaluated the role of propolis in protecting spermatogonial cells from oxidative damage. Propolis' phytochemical composition and antioxidant potential were determined, and mouse GC-1spg spermatogonial cells were treated with 0.1-500 µg/mL propolis (12-48 h) in the presence or absence of an oxidant stimulus (tert-butyl hydroperoxide, TBHP, 0.005-3.6 µg/mL, 12 h). Cytotoxicity was assessed by MTT assays and proliferation by Ki-67 immunocytochemistry. Apoptosis, reactive oxygen species (ROS), and antioxidant defenses were evaluated colorimetrically. Propolis presented high phenolic and flavonoid content and moderate antioxidant activity, increasing the viability of GC-1spg cells and counteracting TBHP's effects on viability and proliferation. Additionally, propolis reduced ROS levels in GC-1spg, regardless of the presence of TBHP. Propolis decreased caspase-3 and increased glutathione peroxidase activity in TBHP-treated GC-1spg cells. The present study shows the protective action of propolis against oxidative damage in spermatogonia, opening the possibility of exploiting its benefits to male fertility.

Crosstalk between AML and stromal cells triggers acetate secretion through the metabolic rewiring of stromal cells

Acute myeloid leukaemia (AML) cells interact and modulate components of their surrounding microenvironment into their own benefit. Stromal cells have been shown to support AML survival and progression through various mechanisms. Nonetheless, whether AML cells could establish beneficial metabolic interactions with stromal cells is underexplored. By using a combination of human AML cell lines and AML patient samples together with mouse stromal cells and a MLL-AF9 mouse model, here we identify a novel metabolic crosstalk between AML and stromal cells where AML cells prompt stromal cells to secrete acetate for their own consumption to feed the tricarboxylic acid cycle (TCA) and lipid biosynthesis. By performing transcriptome analysis and tracer-based metabolic NMR analysis, we observe that stromal cells present a higher rate of glycolysis when co-cultured with AML cells. We also find that acetate in stromal cells is derived from pyruvate via chemical conversion under the influence of reactive oxygen species (ROS) following ROS transfer from AML to stromal cells via gap junctions. Overall, we present a unique metabolic communication between AML and stromal cells and propose two different molecular targets, ACSS2 and gap junctions, that could potentially be exploited for adjuvant therapy.

Respiratory exposure to carbon black nanoparticles may induce testicular structure damage and lead to decreased sperm quality in mice

Environmental carbon black nanoparticles (CBNPs) can enter into various organs including testes through the respiratory tract. However, there are few studies describing reproductive toxicity of CBNPs after respiratory exposure. In this study, male KM mice were exposed to CBNPs in their natural breathing state. Four-, 8-, and 12-week-old mice were exposed to 0, 9, 18 and 27 mg/m³ of CBNPs for 4 weeks in order to examine the relationship between CBNP exposure and age. Eight-week-old mice were exposed to CBNPs at the same four concentrations for 1-4 weeks in order to examine the effects of CBNP exposure time. After CBNP exposure, testicular oxidative stress and inflammation increased significantly, and these effects varied with exposure time. Seminiferous tubule diameter (STD), seminiferous epithelium height (SEH), the number of spermatogenic and Leydig cells, sperm motility, and sperm speed decreased significantly, and these effects varied with exposure dose. Data analyses suggested that increased oxidative stress and inflammation in testes damaged testicular morphology, spermatogenesis, and testosterone secretion, and decreased sperm quality. Morphological damage to the testes was also closely related to decreased the sperm quantity. These findings are of significance for evaluating the reproductive toxicity of CBNPs.

Effect of prenatal exposure to Benzo[a]pyrene on ovarian toxicity and reproductive dysfunction: Protective effect of atorvastatin in the embryonic period

As an environmental contaminant, Benzo[a]pyrene (B[a]P; BaP) disrupts the antioxidant signaling and thus leads to the induction of oxidative stress and the damage of DNA in the ovary. low-dose atorvastatin (ATV) has antioxidant and anti-apoptotic properties. The present study aimed to survey the effects of prenatal exposure to BaP on ovarian toxicity and also to investigate the protective role of ATV in reducing ovarian toxicity. In this study, rats were divided into seven groups: control, ATV (10 mg/kg), oil, BaP (10 and 20 mg/kg), and ATV + BaP (10 and 20 mg/kg). BaP and ATV were administrated from gestation day 7-16 (GD7 to GD16), orally. 10 weeks after the birth, female offsprings were examined for oxidative stress markers, sex hormones, ovarian and tubular tissue structure, and the apoptosis markers. Data showed that BaP significantly reduced glutathione, increased malondialdehyde level, and disrupted the tissue structure of the ovary. Moreover, estrogen and progesterone levels significantly decreased in the offsprings rats. Also, BaP increased caspase-3 immunoreactivity. Atorvastatin treatment along with BaP in the embryonic period were able to bring the antioxidant status and sex hormones levels relatively close to normal. Besides, histological findings showed that atorvastatin was able to improve ovarian and oviduct abnormalities caused by BaP. Based on the above studies be concluded that atorvastatin in the embryonic during was able to reduce ovarian damage caused by BaP with antioxidant and anti-apoptotic properties.

Modulation of amyloid fibrillation of bovine β-lactoglobulin by selective methionine oxidation

Deposition of oxidation-modified proteins during normal aging and oxidative stress are directly associated with systemic amyloidoses. Methionine (Met) is believed to be one of the most readily oxidisable amino acid residues of protein. Bovine beta-lactoglobulin (β-lg), a model globular whey protein, has been presented as a subsequent paradigm for studies on protein aggregation and amyloid formation. Herein, we investigated the effect of t-butyl hydroperoxide (tBHP)-induced oxidation on structure, compactness and fibrillation propensity of β-lg at physiological pH. Notably, whey protein modification, specifically Met residues, plays an important role in the dairy industry during milk processing and lowering nutritional value and ultimately affecting their technological properties. Several bio-physical studies revealed enhanced structural flexibility and aggregation propensity of oxidised β-lg in a temperature dependent manner. A molecular docking study is used to predict possible interactions with tBHP and infers selective oxidation of methionine residues at 7, 24 and 107 positions. From our studies, it can be corroborated that specific orientations of Met residues directs the formation of a partially unfolded state susceptible to fibrillation with possible different cytotoxic effects. Our studies have greater implications in deciphering the underlying mechanism of different whey proteins encountering oxidative stress. Our findings are also important to elucidate the understanding of oxidation induced amyloid fibrillation of protein which may constitute a new route to pave the way for a modulatory role of oxidatively stressed proteins in neurological disorders.

Neuroprotective effect of cajaninstilbene acid against cerebral ischemia and reperfusion damages by activating AMPK/Nrf2 pathway

Introduction

Ischemic stroke is one of the leading causes of death worldwide. Recently, neuroprotection is regarded as an important preventative and therapeutic strategy for ischemic stroke. Cajaninstilbene acid (CSA), a unique stilbenoid with a styryl group, is a potential neuroprotective agent.

Objectives

Hence, this study aimed to evaluate the neuroprotective effect and molecular mechanism of CSA against cerebral ischemia/reperfusion (I/R) damages.

Methods

Cerebral ischemia was modeled by oxygen and glucose deprivation (OGD) in SH-SY5Y cells or transient intraluminal suture middle cerebral artery occlusion (MCAO) in rats, and tert-butyl hydroperoxide (t-BHP) was used to induce oxidative stress in SH-SY5Y cells. CSA (2.5, 5 mg/kg) was intraperitoneally given upon reperfusion after 2 h of MCAO. The signaling pathways were analyzed by Western blotting and inhibitor blocking.

Results

CSA possessed significant neuroprotective activity, as evidenced by the reduced cell death in OGD/R or t-BHP injured SH-SY5Y cells, and decreased infarct volume and neurological deficits in MCAO/R rats. Further studies indicated that the protective effect was achieved via the antioxidant activity of CSA, which decreased the oxidative stress and its related mitochondrial dysfunction in SH-SY5Y cells. Notably, Nrf2 was activated in SH-SY5Y cells and MCAO/R rats by CSA, and the inhibition of Nrf2 by brusatol weakened CSA-mediated neuroprotection. Furthermore, after applying a series of kinase inhibitors, CSA-induced Nrf2 activation was markedly inhibited by BML-275 (an AMPK inhibitor), implying that AMPK was the dominant kinase to regulate the Nrf2 pathway for CSA’s neuroprotective effects with enhanced AMPK phosphorylation observed both in vivo and in vitro.

Conclusion

CSA exerted neuroprotection via activating the AMPK/Nrf2 pathway to reduce I/R-induced cellular oxidative stress and mitochondrial disfunction. CSA could be a potential neuroprotective drug candidate for the treatment of ischemic stroke.

Dietary trans and saturated fatty acids effects on semen quality, hormonal levels and expression of genes related to steroid metabolism in mouse adipose tissue

Our objectives were to assess sperm alteration and adipose tissue (AT) genes expression related to steroid metabolism subsequent to fatty acids consumption. Twenty-nine mature male mice were divided into: fat diet (FD; n = 15) and the control group (n = 14). FD group was fed with low level of trans and saturated fatty acids source for 60 days. Sperm parameters, levels of hormones and the mRNA abundance of the target genes in AT were assessed. The sperm concentration, total and progressive motilities were lower in FD group compared to that of control (p < 0.01). Blood estradiol levels increased in FD (p < 0.001), whereas no significant difference was observed in testosterone. The mRNA levels of StAR, CYP11A1, CYP17A1, 17βHSD7 and 17βHSD12 in AT of FD were higher than those of the control (p < 0.05). In contrast, mRNA level of Cyp19a1 in FD was significantly (p < 0.05) lower than that of control. 17βHSD12 and 17βHSD7 (as oestrogenic genes) increased, while 17βHSD5 and 17βHSD3 (as androgenic genes) remained unchanged, indicating that dietary trans/saturated fatty acids affect AT genes expression. Probably, sperm parameters were altered by increment of expression level of genes involved in oestrogenic metabolism rather than those engaged in androgenic metabolism after fatty acids consumption.

Effects of benzo[a]pyrene as an environmental pollutant and two natural antioxidants on biomarkers of reproductive dysfunction in male rats

Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-β hydroxysteroid dehydrogenase (17β-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.

Paternal obesity induces metabolic and sperm disturbances in male offspring that are exacerbated by their exposure to an "obesogenic" diet

Obesity and related comorbidities are becoming increasingly prevalent globally. In mice preconception paternal exposure to a high fat diet (HFD) impairs the metabolic and reproductive health of male offspring, despite their control diet (CD) consumption. However, offspring share lifestyle, including diet, with parents. We assessed if male offspring from HFD fathers have a heightened susceptibility to HFD-induced metabolic and reproductive derangements. This 2 × 2 design saw founder males (F0) and their offspring (F1) fed either a HFD or a nutritionally matched CD. Regardless of paternal diet, HFD fed male offspring had greater total body weight and adiposity. Offspring sired by a HFD male and fed a HFD were the heaviest, had the greatest adiposity and had the greatest concentration of serum cholesterol, triglyceride, HDL, and NEFA compared with CD sired/fed littermates. A synergistic increase in serum insulin was unmasked by both father/son HFD consumption, concomitant with increased sera glucose. Either a paternal or offspring HFD was associated with similar reductions to offspring sperm motility. Whereas sperm ROS concentrations and sperm-oocyte binding saw detrimental effects of both F0 HFD and F1 HFD with an interaction evident between both, culminating in the most impaired sperm parameters in this group. This indicates that metabolic and fertility disturbances in male offspring sired by HFD fathers are exacerbated by a "second-hit" of exposure to the same obesogenic environment postnatally. If translatable to human health, this suggests that adverse reproductive and metabolic outcomes may be amplified across generations through a shared calorie dense diet, relevant to the current worldwide obesity epidemic.

TBHP-induced oxidative stress alters microRNAs expression in mouse testis

PURPOSE

Reactive oxygen species (ROS) and oxidative stress is one of the main reasons of male infertility. MicroRNAs (miRNAs) regulate multiple intracellular processes. Alterations in miRNAs expression may occur in different conditions and diseases. In this study, the effect of oxidative stress induced by tertiary-butyl hydroperoxide (TBHP) on the expression of candidate miRNAs in mouse testis was investigated.

METHODS

After determining median lethal dose (LD50), TBHP was intraperitoneally (ip) injected at the dilution of 1:10 LD50 into the adult male mice for 2 weeks, and then testis tissues were removed in order to assay the ROS level. Total RNA was extracted and the expression of five miRNAs was quantified by reverse transcription-real time polymerase chain reaction (RT-qPCR).

RESULTS

The flow cytometry analysis showed a significant increase in ROS level in testis. The expression of three out of five selected miRNAs, including miR-34a, miR-181b and miR-122a, showed some degrees of changes following exposure to oxidative stress. These miRNAs are involved in antioxidant responses, inflammation pathway and spermatogenesis arrest.

CONCLUSIONS

In conclusion, TBHP alters the miRNA expression profile of testis which might play a potential role in oxidative and antioxidative responses and spermatogenesis.

Persistence and intergenerational transmission of differentially expressed genes in the testes of intracytoplasmic sperm injection conceived mice

Intracytoplasmic sperm injection (ICSI) is commonly used to solve male infertility problems. Previous studies showed that early environmental exposure of an embryo may influence postnatal development. To detect whether ICSI operations affect the reproductive health of a male or his offspring, we established assisted reproductive technologies (ART) conceived mouse models, and analyzed gene expression profiles in the testes of both ICSI and naturally conceived (NC) newborn F1 mice using micro-array analysis. Among the differentially expressed genes, we focused on the expression of eight male reproduction-related genes. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was used to analyze the expression of these genes in the testes of both adult and old F1 generation mice and adult F2 generation mice. Our results showed that down-regulated and somatic cell-expressed genes in newborn mice retained their differential expression patterns in adult and old F1 generation individuals, implying the persistence and fetal origin of the alteration in the expression of these genes. The intergenerational transmission of differential gene expression was observed, but most changes tended to be reduced in adult F2 generations. Controlled ovarian hyperstimulation (COH) and in vitro fertilization (IVF) mice models were added to explore the precise factors contributing to the differences in ICSI offspring. The data demonstrated that superovulation, in vitro culture, and mechanical stimulation involved in ICSI had a cumulative effect on the differential expression of these male reproductive genes.