MitoQ ameliorates testis injury from oxidative attack by repairing mitochondria and promoting the Keap1-Nrf2 pathway

Mitochondrial damage are involved in Aflatoxin B1-induced testicular damage and spermatogenesis disorder in mice

Aflatoxin B₁ (AFB₁) is an unavoidable environmental pollutants, which seriously endangers human and animal health. AFB₁ has male reproductive toxicity, yet the underlying mechanisms remain inconclusive. Mitochondra are a kind of crucial organelle for maintaining spermatogenesis in testis. Thus, we hypothesized that AFB₁ can impair mitochondria to aggravate testicular damage and spermatogenesis disorder. To verify this hypothesis, 48 male mice were intragastrically administered with 0, 0.375, 0.75 or 1.5 mg/kg body weight AFB₁ for 30 days, respectively. In this study, we found AFB₁ caused testicular histopathological lesions and spermatogenesis abnormalities, with the elevation of oxidative stress (increased H₂O₂, whereas decreased SOD and GSH). Significant mitochondria structure damage of germ cells and Leydig cells, MMP loss, ATP contents reduction, and inhibited activities of mitochondrial complexes I-IV in mice testis were found in AFB₁ treatment groups. Besides, AFB₁ inhibited mitochondrial biogenesis and mitochondrial dynamics, presenting as the decreased mRNA and protein expressions of PGC-1α, Nrf1, Tfam, Drp1, Fis1, Mfn1 and Opa1. The results revealed that the mitochondrial damage were involved in AFB₁-induced testicular damage and spermatogenesis disorder, providing a considerable direction to clarify potential mechanisms of AFB₁ reproductive toxicity.

Protective effect of Dioscorea zingiberensis ethanol extract on the disruption of blood-testes barrier in high-fat diet/streptozotocin-induced diabetic mice by upregulating ZO-1 and Nrf2

Testicular injury is the primary pathogenesis of diabetes-induced male infertility. Dioscorea zingiberensis (DZ), a traditional Chinese medicine (TCM) including saponins, flavonoids and cellulose, is used to treat diseases in the reproductive system. But the protective effects of DZ on diabetes-induced testicular injury remain poorly understood. In this study, the therapeutic effects of chronic oral DZ treatment on testis impairment in a diabetic mouse model were explored by assessing sperm morphology, blood-testes barrier (BTB) integrity and testicular histological examination. Our results showed that DZ significantly reversed BTB disruption, testicular tissue injury and abnormal sperm morphology in diabetic mice. Interestingly, diabetes-induced disruption of the BTB was associated with a decrease in the tight junction (TJ) protein zonula occludens-1 (ZO-1). Dioscorea zingiberensis effectively increased ZO-1 expression in testis tissue to restore the integrity of the BTB. Moreover, DZ treatment significantly reduced hyperglycaemia-induced increases in malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. Further mechanistic studies revealed that DZ substantially enhanced the expression of Nrf2, NOQ1 and HO-1, which indicated that DZ exerts potential antioxidant effects against testicular tissue damage via the activation of Nrf2. In conclusion, the protective effects of DZ rely on repairing the integrity of the BTB and on reducing oxidative stress damage by mediating ZO-1 and Nrf2. The study contributes to discovering the DZ possible mechanism of action.

Epigallocatechin-3-gallate modulates germ cell apoptosis through the SAFE/Nrf2 signaling pathway

To examine the role of the transcription factor nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2) and the SAFE pathway (JAK/STAT) in the induction of germ cell apoptosis (GCA) and the protective role of epigallocatechin-3-gallate (EGCG) during testicular ischemia reperfusion injury (tIRI). Male Sprague-Dawley rats (n = 18) were divided into three groups: sham, unilateral tIRI, tIRI + epigallocatechin-3-gallate (EGCG, 50 mg/Kg). Unilateral tIRI was induced by 1-h ischemia followed by 4-h reperfusion, and EGCG was injected i.p. 30-min post ischemia. Immuno-histological analyses were used to detect spermatogenesis, oxidative DNA damage, and the immuno-expression of the JAK2, STAT3, and STAT1. Biochemical assays were used to investigate the oxidative, apoptosis proteins and enzymes, while Western blot was used to detect the expression of NOX and Nrf2. Expression of apoptosis-related genes was measured by real-time PCR. During tIRI, there was a clear damage to spermatogenesis associated with decreased activities of SOD, CAT, and GPx and increased levels of lipid peroxidation and oxidative DNA damage. In addition, GCA was indicated by the activation of caspase1, PARP, decreased gene expression of survivin and increased Bax to Bcl2 ratio. In contrast to lowered Nrf2 levels, NOX levels were augmented and phosphorylation of JAK2, STAT3, and STAT1 was increased. Pre-perfusion treatment with EGCG prevented the above modulations. The coordinated activation of the SAFE pathway and suppression of Nrf2 contribute to the tIRI-induced oxidative damages and GCA, which were modulated by EGCG.

Aucubin, a natural iridoid glucoside, attenuates oxidative stress-induced testis injury by inhibiting JNK and CHOP activation via Nrf2 up-regulation

BACKGROUND

Eucommia ulmoides has been used for many years as a successful strategy to treat male infertility. Aucubin (AU) is the active ingredient extracted from Eucommia ulmoides. However, its protective action and exact mechanism on testicular injury is not yet known.

PURPOSE

Here, the protective effect and the mechanism of action of AU on testis damage under oxidative stress was investigated in vivo and in vitro.

METHODS

As regard the in vivo experiment, male mice were divided into five groups and testicular injury model was established by Triptolide (TP) (120 μg/kg) intraperitoneal injection for two weeks. Animals in the treatment group were pretreated with an intraperitoneal injection of AU at different doses (5, 10 and 20 mg/kg) for 1 h and subsequently treated with TP (120 μg/kg). At the end of the experimental period, the testis was collected for biochemical and histological examination. As regard the in vitro experiment, Sertoli cells (SCs) were used to investigate the protective effect and mechanism of action of AU against disruption of the blood-testis-barrier (BTB) and apoptosis induced by TP via apoptosis detection, western blot, immunofluorescence analysis, and siRNA transient transfection.

RESULTS

TP-treated animals showed testicular atrophy, BTB disruption, increased ROS levels and spermatogenic dysfunction. Pre-administration of AU resulted in a significant protection on keeping a normal testicular weight, sperm morphology, BTB integrity, and a normal level of oxidative stress markers and antioxidants. Furthermore, AU prevented apoptosis through an effective inhibition of PERK/CHOP and JNK dependent apoptosis pathway, as well as protected the integrity of BTB by up-regulating the expression of tight junction proteins (ZO-1, Occludin, Claudin-11) and gap junction protein (Cx43). The mechanistic study revealed that AU significantly triggered Nrf2 translocation, thus increasing nuclear Nrf2 accumulation and then induced antioxidant enzymes expression in the testis and SCs. Furthermore, Nrf2 silencing unsuccessfully reversed the increased CHOP and p-JNK expression induced by TP, abolishing the protective effect of AU.

CONCLUSION

These results indicate that AU might be considered as a potential protective agent against testicular injury.

Strategies to target bioactive molecules to subcellular compartments. Focus on natural compounds

Many potential pharmacological targets are present in multiple subcellular compartments and have different pathophysiological roles depending on location. In these cases, selective targeting of a drug to the relevant subcellular domain(s) may help to sharpen its impact by providing topological specificity, thus limiting side effects, and to concentrate the compound where needed, thus increasing its effectiveness. We review here the state of the art in precision subcellular delivery. The major approaches confer "homing" properties to the active principle via permanent or reversible (in pro-drug fashion) modifications, or through the use of special-design nanoparticles or liposomes to ferry a drug(s) cargo to its desired destination. An assortment of peptides, substituents with delocalized positive charges, custom-blended lipid mixtures, pH- or enzyme-sensitive groups provide the main tools of the trade. Mitochondria, lysosomes and the cell membrane may be mentioned as the fronts on which the most significant advances have been made. Most of the examples presented here have to do with targeting natural compounds - in particular polyphenols, known as pleiotropic agents - to one or the other subcellular compartment.