Involvement of mitogen-activated protein kinases (MAPKs) during testicular ischemia-reperfusion injury in nuclear factor-kappaB knock-out mice

Testicular torsion in vivo models: Mechanisms and treatments

BACKGROUND

Testicular torsion is a condition in which a testis rotates around its longitudinal axis and twists the spermatic cord. This in turn results in a significant decrease in blood flow and perfusion of testicular tissue. During Testicular torsion, the testicular tissue is affected by ischemia, heat stress, hypoxia, and oxidative and nitrosative stress. The testicular torsion should be considered an emergency condition and surgical intervention (testicular detorsion ) as the sole treatment option in viable cases involves counter-rotation on twisted testes associated, when possible, to orchipexy, in order to avoid recurrence. Possible testicular detorsion side-effects occur due to reperfusion and endothelial cells injury, microcirculation disturbances, and intense germ cells loss.

OBJECTIVES

To discuss testicular torsion surgery-based methods, different time frames for testicular torsion induction, and the associated pathophysiology by emphasizing cellular and molecular events as well as different therapeutic agent applications for testicular torsion.

MATERIALS AND METHODS

We reviewed all original research and epidemiological papers related to testicular torsion condition.

RESULTS

Testicular torsion causes germ cell necrosis, arrested spermatogenesis, and diminished testosterone levels, with consequent infertility. Among different involved pathophysiological impacts, testicular torsion/detorsion-induced ischemia seems to play the key role by leading the tissue toward other series of events in testis. Numerous studies have used adjuvant antioxidants, calcium channel blockers, anti-inflammatory agents, or vasodilating agents in order to decrease these effects.

DISCUSSION AND CONCLUSION

To the best of our knowledge, no previously conducted study examined therapeutical agents' beneficial effects post clinical I/R condition in humans. Different agents targeting different pathophysiological conditions were used to ameliorate the ischemia/reperfusion-induced condition in animal models, however, none of the administrated agents were tested in human cases. Although considering testicular detorsion surgery is still the golden method to reverse the testicular torsion condition and the surgical approach is undeniable, the evaluated agents with beneficial effects, need to be investigated furthermore in clinical conditions. Thus, furthermore clinical studies and case reports are required to approve the animal models proposed agents' beneficial impacts.

Protective effect of cerium oxide on testicular function and oxidative stress after torsion/detorsion in adult male rats

Testicular torsion (T)/detorsion (D) can cause testicular injury due to the rotation of the spermatic cord and its vessels, therefore it represents an urological emergency that is surgically treated. Oxidative damage occurs in the testis and distant organs because of the overproduction of free radicals and overexpression of proinflammatory cytokines by reperfusion after surgery. Cerium oxide (CeO₂) nanoparticles, a material also known as nanoceria, have regenerative antioxidant properties on oxidative stress. The present study aimed to investigate the effects of nanoceria on testis tissues in testicular T/D in rats. A total of 24 rats were equally and randomly divided into four groups: Control, CeO₂, T/D and CeO2-T/D groups. Left inguinoscrotal incision was performed in the control group. In the CeO₂ group, 0.5 mg/kg CeO₂ was given intraperitoneally 30 min before inguinoscrotal incision. In the T/D group, unilateral testicular T/D was performed through an inguinoscrotal incision and rotating the left testis 720˚ clockwise, which was then left ischemic for 120 min, followed by 120 min of reperfusion. In the CeO₂-T/D group, 0.5 mg/kg CeO₂ was given intraperitoneally 30 min before testicular T/D. At the end of the experiment, testis tissues were removed for histopathological and biochemical examinations. The samples were histologically examined, Glutathione-s transferase (GST), catalase (CAT), paraoxonase (PON) activities and malondialdehyde (MDA) levels were measured via biochemical analysis methods, while the expression levels of p53, Bax and Bcl-2 were detected using immunohistochemistry. The present results revealed statistically significant inter-group differences in PON, CAT and GST activities and MDA levels. GST, CAT and PON activities were significantly higher, whereas MDA levels in the CeO₂-T/D group were significantly lower compared with those in the T/D group. The T/D group had increased Bax and decreased Bcl-2 expression levels in their seminiferous tubules compared with the control and CeO₂ groups. CeO₂ treatment led to downregulation of Bax and upregulation of Bcl-2. The expression of p53 was high in the T/D group compared with that in the control and CeO2 groups, and was upregulated in all germinal cells. However, compared with that in the T/D group, p53 expression was significantly decreased in the CeO₂-T/D group. The testicular injury score significantly increased in the CeO₂-T/D group compared with the control and CeO₂ groups. Rats in the CeO₂-T/D group demonstrated significantly milder tissue lesions compared with those in T/D group. The present findings indicated that nanoceria may protect testis in rats against the harmful effects of T/D. Further studies are required to evaluate how CeO₂ reduces oxidative stress and cell death in testis tissue that underwent T/D-related injury.

Role of p38 MAPK Signalling in Testis Development and Male Fertility

The testis is an important male reproductive organ, which ensures reproductive function via the secretion of testosterone and the generation of spermatozoa. Testis development begins in the embryonic period, continues after birth, and generally reaches functional maturation at puberty. The stress-activated kinase, p38 mitogen-activated protein kinase (MAPK), regulates multiple cell processes including proliferation, differentiation, apoptosis, and cellular stress responses. p38 MAPK signalling plays a crucial role in testis development by regulating spermatogenesis, the fate determination of pre-Sertoli, and primordial germ cells during embryogenesis, the proliferation of testicular cells in the postnatal period, and the functions of mature Sertoli and Leydig cells. In addition, p38 MAPK signalling is involved in decreased male fertility when exposed to various harmful stimuli. This review will describe in detail the biological functions of p38 MAPK signalling in testis development and male reproduction, together with its pathological role in male infertility.

Acetyl-11-keto-β-boswellic acid prevents testicular torsion/detorsion injury in rats by modulating 5-LOX/LTB4 and p38-MAPK/JNK/Bax/Caspase-3 pathways

AIMS

Testicular torsion/detorsion (T/D) is a critical medical condition that necessitates prompt surgical intervention to avoid testicular atrophy and infertility. The use of natural compounds may protect against the associated detrimental oxidative stress and inflammatory responses. Interestingly, acetyl-11-keto-β-boswellic acid (AKBA), the main active constituent of Boswellia resin, has shown potent inhibitory effect on 5-lipoxygenase enzyme which converts arachidonic acid into inflammatory mediators. Therefore, this study was conducted to assess the protective mechanisms by which AKBA may protect against testicular T/D injury in rats.

MAIN METHODS

Male rats were randomly distributed into five groups: Sham, AKBA (50 mg/kg, p.o.), unilateral testicular T/D, AKBA at two dose levels (25 or 50 mg/kg for 15 successive days) followed by T/D. Histological examination and Johnsen's score were performed to assess testicular injury and perturbations in spermatogenesis. Biochemical parameters included markers of testicular function (serum testosterone), oxidant/antioxidant status (malondialdehyde, glutathione), inflammation (5-lipoxygenase, leukotriene-B4, myeloperoxidase, interleukin-1β, interleukin-6), apoptosis (Bax, Bcl2, caspase-3), DNA integrity (quantitative DNA fragmentation, DNA laddering, PARP-1), energy production (ATP), in addition to p38 MAPK and JNK protein expression.

KEY FINDINGS

In a dose dependent manner, AKBA significantly inhibited testicular T/D-induced upregulation of 5-LOX/LTB4 and p38-MAPK/JNK/Bax pathways and their associated downstream inflammatory and apoptotic cascades. These effects were accompanied with ATP replenishment and DNA preservation, resulting ultimately in salvage of the testis.

SIGNIFICANCE

Unprecedentedly, the present mechanistic study revealed the pathways by which AKBA may inhibit testicular T/D injury and offered a novel protective approach that may attenuate the severity of this condition.

Ferroptosis is associated with oxygen-glucose deprivation/reoxygenation-induced Sertoli cell death

Sertoli cell death contributes to spermatogenesis impairment, which is associated with male infertility. Testicular ischemia‑reperfusion (I/R) injury induces the cell death of germ cells and Sertoli cells, whereas inhibition of cell death ameliorates acute testicular I/R damage. The aim of the present study was to investigate the mechanism of I/R stress-induced cell death in TM4 cells. Oxygen‑glucose deprivation and reoxygenation (OGD/R) was demonstrated to induce I/R injury and cell death in TM4 cells. Cell death was blocked by the reactive oxygen species (ROS) inhibitor N‑acetylcysteine, as well as lipid peroxidation inhibitors Liproxstatin‑1 and iron chelator deferoxamine; however, inhibitors of apoptosis, necrosis or autophagy had no effect. It was also demonstrated that iron and lipid ROS levels were elevated in I/R injury and that mitochondria decreased in size and increased in membrane density, which is indicative of ferroptosis. Furthermore, the generation of lipid ROS suggests iron accumulation and glutathione (GSH) depletion. The expression of ferroportin (Fpn) protein and mRNA was decreased in TM4 cells. Notably, overexpression of Fpn inhibited ferroptosis, lipid ROS generation and iron accumulation. In addition, GSH‑dependent peroxidase 4 (GPX4) was inactivated via GSH depletion following I/R injury, whereas GPX4 activation blocked I/R‑induced ferroptosis by reducing lipid ROS levels. The mitogen‑activated protein kinase (MAPK) pathway was also investigated in the present study; it was observed that I/R‑induced ferroptosis was blocked by inhibiting p38 MAPK activation. The results of the present study demonstrate that ferroptosis is a pervasive and dynamic type of cell death induced by OGD/R injury in Sertoli cells. This may provide a novel insight into the application of cytoprotection in testicular I/R damage‑induced cell loss.

Medical perspective in testicular ischemia-reperfusion injury

Testicular torsion or torsion of the spermatic cord is one of the most serious urological conditions. It causes testicular injury, which potentially leads to male subfertility. The turning of the spermatic cord and spermatic structures around themselves results in biochemical and histological changes; however, following testicular detorsion, tissues undergo reperfusion that causes more severe damage than that induced by ischemia. Since the primary causes of testicular damage are reactive oxygen species production, an increase in intra-mitochondrial calcium concentration and an increased rate of cellular apoptosis, different medications may potentially be effective. It seems that several medications, experimentally and sometimes clinically, serve an adjuvant role in the cellular damage that occurs following ischemia-reperfusion. Antioxidants, calcium channel blockers, phytotherapeutical medicinals, anaesthetics, hormones and platelet inhibitors may potentially create a solid basis for an adjuvant restoring therapy and ameliorate testicular function following torsion. The current study aimed to review the relevant literature and discuss the actions of a number of molecules that may protect the testes during ischemia/reperfusion injury.

Hyperbaric oxygen therapy in rats attenuates ischemia-reperfusion testicular injury through blockade of oxidative stress, suppression of inflammation, and reduction of nitric oxide formation

OBJECTIVE

To evaluate the therapeutic utility of hyperbaric oxygen (HBO) therapy on testicular ischemia/reperfusion (I/R) injury and elucidate the underlying molecular mechanism, we tested whether HBO therapy provided rescue of the testes after torsion in rats.

METHODS

Sprague-Dawley rats were randomly divided into 4 groups: control group, control plus HBO therapy, I/R group, and I/R plus HBO therapy. The I/R model was induced by torsion of the right testis.

RESULTS

I/R in the testis resulted in disrupted seminiferous tubules, germ cell-specific apoptosis, followed by a marked reduction in testis weight and daily sperm production. HBO therapy preserved seminiferous tubules, suppressed apoptosis, and prevented testicular atrophy in I/R testes. HBO therapy abated oxidative stress in I/R testes, marked by reduced malondialdehyde formation, enhanced activities of superoxide dismutase and heme oxygenase 1 (HO-1), and decreased activities of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and xanthine oxidase. HBO therapy resulted in a reduction of myeloperoxidase (MPO) activity in I/R testes, a marker of neutrophil recruitment. HBO therapy suppressed inflammation in I/R testes, marked by reduced messenger RNA (mRNA) levels of tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), and CD44. Furthermore, HBO therapy suppressed the activation of nuclear factor kappa B (NFκB), p38, and c-JUN-N-terminal kinase (JNK) signaling pathways in I/R testes. In addition, HBO therapy reduced nitric oxide formation in I/R testes through suppression of inducible nitric oxide synthase and dimethylarginine dimethylaminohydrolase.

CONCLUSION

HBO therapy in rats attenuated I/R-induced testicular injury, possibly through abating oxidative stress, suppressing inflammation, and reducing nitric oxide formation.

Effects of polydeoxyribonucleotide on the histological damage and the altered spermatogenesis induced by testicular ischaemia and reperfusion in rats

The effects of polydeoxyribonucleotide (PDRN), an agonist of the A2A adenosine receptors which when activated positively influences sperm activity, were tested in an experimental testicular ischaemia/reperfusion injury model. Anaesthetized male Sprague-Dawley rats were subjected to testicular torsion-induced ischaemia, followed by reperfusion (TI/R). Immediately after detorsion, randomized animals, including SHAM, received intraperitoneal injections of: (i) vehicle (1 mL/kg 0.9% NaCl solution); (ii) PDRN (8 mg/kg); (iii) DMPX (3,7-dimethyl-1-propargilxanthine, 0.1 mg/kg); or (iv) PDRN (8 mg/kg) + DMPX (0.1 mg/kg). Animals were euthanized at 1, 7 and 30 days following reperfusion. Vascular endothelial growth factor (VEGF) expression is normally associated with adenosine A2A receptor stimulation. After treatment, VEGF mRNA/protein expression quantified by qPCR and Western blot, vascular endothelial growth factor receptor-1 (VEGFR1) and endothelial nitric oxide synthase (eNOS) mRNA measured by qPCR, VEGF and VEGFR1 assessed using immunohistochemical methods, histological staining and spermatogenic activity were all analysed. Testis ischaemia-reperfusion (TI/R) injury caused increases in VEGF mRNA and protein, VEGFR1 and eNOS mRNA, histological damage and reduced spermatogenic activity. Immunostaining showed a lower expression of VEGF in germinal epithelial cells and a strong expression of VEGFR1 in Leydig cells after TI/R. PDRN administration increased significantly VEGF message/protein, VEGFR1 and eNOS message, decreased histological damage and ameliorated spermatogenic activity. PDRN might be useful in the management of testicular torsion.

Time courses of subcellular signal transduction and cellular apoptosis in remote viable myocardium of rat left ventricles following acute myocardial infarction: role of pharmacomodulation

We tested hypothesis that acute myocardial infarction (AMI) induces cellular apoptosis and serial changes of protein kinase C epsilon (PKC-epsilon) and p38 mitogen-activated protein kinase (p38 MAPK), and tested cardio-protective effect of losartan in this condition. The rats were assigned to group A (sacrificed on day 2), group B (sacrificed on day 5), and group C (sacrificed on day 14). Rats in each group were further randomized into the following groups: AMI (ligation of left coronary artery) without losartan (AMI-L0); AMI with losartan 20 mg/ kg/d (AMI-L1); and sham groups (L0 and L1). The PKC-epsilon expression in membrane compartment was increased in AMI-L1 group than in other groups on day 5 and in AMI groups than in sham groups on day 14 (P < .01). Phosphorylated form of cytosolic p38 MAPK level was increased in AMI-L1 than in other groups on day 14 (P < .05). Furthermore, 14-day left ventricular ejection fraction was higher and cellular apoptosis was lower in AMI-L1 group than in AMI-L0 group (P < .0001).

JNK pathway is involved in the inhibition of inflammatory target gene expression and NF-kappaB activation by melittin

Background

Bee venom therapy has been used to treat inflammatory diseases including rheumatoid arthritis in humans and in experimental animals. We previously found that bee venom and melittin (a major component of bee venom) have anti-inflammatory effect by reacting with the sulfhydryl group of p50 of nuclear factor-kappa B (NF-κB) and IκB kinases (IKKs). Since mitogen activated protein (MAP) kinase family is implicated in the NF-κB activation and inflammatory reaction, we further investigated whether activation of MAP kinase may be also involved in the anti-inflammatory effect of melittin and bee venom.

Methods

The anti-inflammatory effects of melittin and bee venom were investigated in cultured Raw 264.7 cells, THP-1 human monocytic cells and Synoviocytes. The activation of NF-κB was investigated by electrophoretic mobility shift assay. Nitric oxide (NO) and prostaglandin E₂ (PGE₂) were determined either by Enzyme Linked Immuno Sorbent Assay or by biochemical assay. Expression of IκB, p50, p65, inducible nitric oxide synthetase (iNOS), cyclooxygenase-2 (COX-2) as well as phosphorylation of MAP kinase family was determined by Western blot.

Results

Melittin (0.5–5 μg/ml) and bee venom (5 and 10 μg/ml) inhibited lipopolysaccharide (LPS, 1 μg/ml) and sodium nitroprusside (SNP, 200 μM)-induced activation of c-Jun NH2-terminal kinase (JNK) in RAW 264.7 cells in a dose dependent manner. However, JNK inhibitor, anthra [1,9-cd]pyrazole-6 (2H)-one (SP600215, 10–50 μM) dose dependently suppressed the inhibitory effects of melittin and bee venom on NF-κB dependent luciferase and DNA binding activity via suppression of the inhibitory effect of melittin and bee venom on the LPS and SNP-induced translocation of p65 and p50 into nucleus as well as cytosolic release of IκB. Moreover, JNK inhibitor suppressed the inhibitory effects of melittin and bee venom on iNOS and COX-2 expression, and on NO and PGE₂ generation.

Conclusion

These data show that melittin and bee venom prevent LPS and SNP-induced NO and PGE₂ production via JNK pathway dependent inactivation of NF-κB, and suggest that inactivation of JNK pathways may also contribute to the anti-inflammatory and anti-arthritis effects of melittin and bee venom.