Protective effects of melatonin on testicular torsion/detorsion-induced ischemia–reperfusion injury in rats

Proanthocyanidin alleviates testicular torsion/detorsion-induced ischemia/reperfusion injury in rats

Testicular torsion is an urological emergency and can lead to ischemia damage and testicular loss if not diagnosed in time. Proanthocyanidin is reported to have anti-inflammatory and antioxidant properties. The current study aimed to examine the possible effects of proanthocyanidin (P) on the testis in torsion/detorsion (T/D)-induced testicular ischemia/reperfusion (I/R) injury in rats. Forty rats were divided into four groups (n=10 for each): sham-operated (sham), I/R, I/R + P100 (100 mg/kg, 30 min before torsion), and I/R + P200 (200 mg/kg, 30 min before torsion). Testicular T/D was performed on the left testicle by 3 hours of torsion at 720° clockwise, followed by 3 hours of detorsion. In the I/R group, an increase in malondialdehyde (MDA) levels and a decrease in glutathione (GSH), vitamin C (Vit C), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD) values were determined compared to the sham group (p<0.001). Moreover, an increase in the expression of cleaved caspase-3 and Bcl2-associated X protein (Bax), a decrease in the expression of B-cell lymphoma 2 (Bcl-2) and proliferating cell nuclear antigen (PCNA) were detected in the I/R group (p<0.001). Histopathologically, it was determined that the Johnsen and Cosentino scores of the testicles were irregular in the I/R group (p<0.001). Proanthocyanidin treatment caused a decrease in MDA, cleaved caspase-3 and Bax levels and an increase in GSH, Vit C, GPx, G6PD, Bcl-2 and PCNA values. Additionally, Johnsen and Cosentino rearranged the scores. The present findings revealed the protective and curative effects of proanthocyanidin in organ damage due to testicular torsion/detorsion-induced ischemia/reperfusion with their antioxidative and antiapoptotic properties.

Pathophysiology and management of testicular ischemia/reperfusion injury: Lessons from animal models

Testicular torsion is a urological emergency that involves the twisting of the spermatic cord along its course. Compelling pieces of evidence have implicated oxidative stress-sensitive signaling in pathogenesis of testicular I/R injury. Although, surgical detorsion is the mainstay management; blockade of the pathways involved in the pathogenesis may improve the surgical outcome. Experimental studies using various testicular I/R models have been reported in a bid to explore the mechanisms associated with testicular I/R and evaluate the benefits of potential therapeutic measures; however, most are limited by their shortcomings. Thus, this review was intended to describe the details of the available testicular I/R models as well as their merits and drawbacks, the pathophysiological basis and consequences of testicular I/R, and the pharmacological agents that have being proposed to confer testicular benefits against testicular I/R. This provides an understanding of the pathophysiological events and available models used in studying testicular I/R. In addition, this research provides evidence-based molecules with therapeutic potentials as well as their mechanisms of action in testicular I/R.

The navel nanoethosomal formulation of gamma-oryzanol attenuates testicular ischemia/reperfusion damages

Testicular torsion reduces blood flow to testes and induces tissue ischemia. Antioxidant can have pivotal roles in alleviation of the effects of torsion/reperfusion. Gamma-oryzanol (γ-Oryzanol) has several pharmacological properties such as antioxidant and anti-apoptosis that can be used in this way. This study was conducted to evaluate the effects of nanoethosomal formulation of gamma-oryzanol (γ-Oryzanol-NEs) on testicular damages in a mouse model of ischemia/reperfusion damage. Following induction of ischemia/reperfusion, the mice were treated with γ-Oryzanol and γ-Oryzanol-NEs (6 mg/kg) in times of 3 h and 6 h. The expression of positive cells of TUNEL, superoxide dismutase (SOD), glutathione peroxidase (GPx), heat shock protein-70 (HSP70) and caspase 3 and histopathological parameters were assessed. The results showed higher expression of positive cells of TUNEL, HSP70 and caspase 3 and lower expressions of SOD and GPx in control mice compared with those treated with γ-Oryzanol-NEs (P = 0.001). The treatment with γ-Oryzanol-NEs could decrease pathological damages and the expression of positive cells of TUNEL, HSP70 and caspase 3 and increase the expressions of SOD and GPx. In conclusion, γ-Oryzanol-NEs could have the protective effects on torsion/reperfusion by decreasing apoptosis and increasing antioxidant status in a mouse model.

Protective effects of empagliflozin on testicular injury induced by torsion/detorsion in adult male rats

INTRODUCTION

Testicular torsion is a known urologic emergency condition and one of the common causes of infertility in males. Hence, prompt diagnosis and treatment play a crucial role in prevention of testicular injury. It has been observed that empagliflozin, a drug for management of hyperglycemia, has anti-oxidative properties against different pathologies, the most important of which are ischemia reperfusion related injuries.

OBJECTIVE

This study aims to evaluate the protective effects of empagliflozin on a testicular torsion injury in adolescent rats followed by ischemia/reperfusion (I/R) phenomena.

STUDY DESIGN

Thirty-six rats were randomly assigned into three groups including sham-operated group received all surgical procedures except testicular torsion-detorsion, torsion/detorsion + dimethyl sulfoxide (DMSO) as vehicle, and torsion/detorsion + empagliflozin (10 mg/kg). Testicular torsion was performed for 2 h through rotating right testis 720° in the clockwise direction. Thirty minutes before detorsion, a single intraperitoneal dose of empagliflozin was injected to treatment group. Four hours later, orchiectomy was conducted for histopathological and biochemical examinations of testicular tissue specimens.

RESULTS

The malondialdehyde (MDA) content in the torsion/detorsion animals was markedly greater than in the animals under sham operated procedure. Moreover, the testicular MDA levels in the torsion/detorsion + empagliflozin group were significantly lower than in the torsion/detorsion group. Also, significant decreases observed in catalase, superoxide dismutase, and glutathione peroxidase activities in the torsion/detorsion group in comparison with sham operated group. These values were significantly improved in the empagliflozin group. Furthermore, histopathological examinations also revealed severe testicular injury which were improved by empagliflozin administration.

DISCUSSION

Empagliflozin prevented increases in oxidative stress markers and subsequently reduced the tissue injury induced by torsion/detorsion in the current study.

CONCLUSION

It can be concluded that administration of empagliflozin before prevents I/R related cellular damage in testicular torsion, possibly via oxidative stress inhibition.

[Conservative therapy after self-mutilation of the scrotum resulting in bilateral testicular underperfusion]

We report the case of a patient with massive penile and scrotal swelling due to use of a compression ring with auto-erotic intent and under the influence of addictive substances. Based on the patient history, the mechanical pressure on the scrotum was about 30 hours (h). The Doppler sonogram showed no central perfusion in either testicle. Conservative treatment with antibiotics and analgesics was initiated with a slight increase in inflammatory parameters and local edema and necrosis formation. Follow-up showed regression of swelling, healing of necrosis and improvement of laboratory parameters. Testosterone substitution therapy was necessary due to the bilateral testicular atrophy that developed.

Protective effects of melatonin against physical injuries to testicular tissue: A systematic review and meta-analysis of animal models

BACKGROUND

Modern societies face infertility as a global challenge. There are certain environmental conditions and disorders that damage testicular tissue and may cause male infertility. Melatonin, as a potential antioxidant, may protect testicular tissue. Therefore, we conducted this systematic review and meta-analysis to evaluate the effects of melatonin in animal models against physical, heat, and ischemic damage to the testicular tissue.

METHODS

PubMed, Scopus, and Web of Science were systematically searched to identify animal trials evaluating the protective effect of melatonin therapy on rodent testicular tissue when it is exposed to physical, thermal, ischemic, or hypobaric oxygen stress. Random-effect modeling was used to estimate the standardized mean difference and 95% confidence intervals based on the pooled data. Additionally, the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool was used to assess the risk of bias. The study protocol was prospectively registered in PROSPERO (CRD42022354599).

RESULTS

A total of 41 studies were eligible for review out of 10039 records. Studies employed direct heat, cryptorchidism, varicocele, torsion-detorsion, testicular vascular occlusion, hypobaric hypoxia, ischemia-reperfusion, stress by excessive or restraint activity, spinal cord injury, and trauma to induce stress in the subjects. The histopathological characteristics of testicular tissue were generally improved in rodents by melatonin therapy. Based on the pooled data, sperm count, morphology, forward motility, viability, Johnsen's biopsy score, testicular tissue glutathione peroxidase, and superoxide dismutase levels were higher in the melatonin treatment rodent arms. In contrast, the malondialdehyde level in testicular tissue was lower in the treatment rodent arms. The included studies suffered from a high risk of bias in most of the SYRCLE domains.

CONCLUSION

This study concludes that melatonin therapy was associated with improved testicular histopathological characteristics, reproductive hormonal panel, and tissue markers of oxidative stress in male rodents with physical, ischemic, and thermal testicular injuries. In this regard, melatonin deserves scientific investigations as a potential protective drug against rodent male infertility.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022354599.

Melatonin Increases Proliferation and Decreases Apoptosis of GC-1 spg Cells by Upregulating the Expression of circTec

Melatonin has been shown to be beneficial for the motility of human sperm, although its mechanism remains to be uncovered. Circular RNAs (circRNAs) have been shown to regulate cellular function in many diseases. However, there has been no relevant research on the effect of melatonin on sperm circRNAs. In this study, we aimed to explore the changes in circRNAs after melatonin treatment of GC-1 spg cells and identify key functional circRNAs. The results showed that melatonin enhanced the proliferation and reduced the apoptosis of GC-1 spg cells. A total of 1423 circRNAs were found to be significantly differentially expressed between groups with and without melatonin treatment. Of these circRNAs, 702 were upregulated and 721 were downregulated. circTec was one of the upregulated circRNAs. Suppressing the expression of circTec significantly reduced cell proliferation and mammalian target of rapamycin (mTOR) signaling pathway activation but promoted melatonin-treated GC-1 spg cell apoptosis. In conclusion, melatonin increased the expression of circTec to exert its physiological effects on GC-1 spg cells, possibly by activating the mTOR signaling pathway. These results enhance our understanding of the biological function of circTec and its regulation by melatonin in spermatogenesis and infertility.

Coenzyme Q10 and Melatonin for the Treatment of Male Infertility: A Narrative Review

BACKGROUND

Lifestyle and environmental factors can negatively impact fertility by means of oxidative stress. In this context, antioxidant supplementation therapy has gained much interest in recent years, and different molecules, alone or in combination, have been studied.

OBJECTIVE

The purpose of the present review is to investigate the evidence regarding the efficacy of coenzyme Q10 (CoQ10) and melatonin on male infertility.

METHODS

A literature search using PUBMED database from 2000 to October 2022 was performed to explore the role of CoQ10 and melatonin on male reproductive function.

CONCLUSIONS

The analysis involved a narrative synthesis. CoQ10, alone or in combination, appears to reduce testicular oxidative stress and sperm DNA fragmentation and to improve sperm parameters; particularly sperm motility. Moreover, CoQ10 treatment is associated with higher pregnancy rates, both naturally and through assisted reproductive technology (ART). Larger studies are needed to precisely determine its clinical efficacy. Melatonin is a known antioxidant and preclinical studies have shown its ability to modulate reproductive function through hormonal and immune system regulation and sperm cell proliferation. Regardless, clinical studies are necessary to assess its potential in male infertility.

Overview of biological effects of melatonin on testis: A review

Infertility is a major global health issue and male factors account for half of all infertility cases. One of the causes of male infertility is the loss of spermatogonial stem cells, which may occur because of chemotherapy, radiotherapy or genetic defects. In numerous animal species, the evidence suggests the pineal gland and melatonin secretion in their reproductive activities are involved. Recently, considerable attention has pointed to the usage of melatonin in the treatment of diseases. Melatonin is associated with the regulation of circadian and seasonal rhythmic functions, immune system functions, retinal physiology, spermatogenesis and inhibition of tumour growth in different species. Several studies demonstrated that melatonin acts as an anti-apoptotic, anti-inflammatory, anticancer and antioxidant agent. Melatonin can also protect testicles and spermatogonia against oxidative damage, chemotherapy drugs, environmental radiation, toxic substances, hyperthermia, ischemia/reperfusion, diabetes-induced testicular damage, metal-induced testicular toxicity, improve sperm quality and it affects the testosterone secretion pathway by affecting Leydig cells. Therefore, the objective of this study is to investigate the biological effects of melatonin as a natural antioxidant on testicles and their disorders.

Attenuation Effect of Salvianolic Acid B on Testicular Ischemia-Reperfusion Injury in Rats

During testicular ischemia-reperfusion, overproduction of reactive oxygen species is associated with testicular injury. We injected hydrogen peroxide (a representative of reactive oxygen species) into normal testis via the testicular artery. The experiment demonstrates that reactive oxygen species can cause spermatogenic injury. Salvianolic acid B, the most abundant bioactive component in Salvia miltiorrhiza Bunge, has been reported to possess a potent antioxidant activity. This study was conducted to evaluate the effect of salvianolic acid B on testicular ischemia-reperfusion injury in a rat testicular torsion-detorsion model. Rats were randomly separated into three groups, including 20 rats in each group: control group with sham operation, testicular ischemia-reperfusion group, and testicular ischemia-reperfusion + salvianolic acid B-treated group. In the testicular ischemia-reperfusion group, left testicular torsion of 720° for 2 hours was induced, and then testicular detorsion was carried out. Rats in the salvianolic acid B-treated group additionally had salvianolic acid B administered intravenously at detorsion. At 4 hours after detorsion, testes of 10 rats from each group were collected to analyze the protein expression of xanthine oxidase which catalyzes generation of reactive oxygen species and malondialdehyde concentration (an indirect indicator of reactive oxygen species). At 3 months after detorsion, testes of the remaining 10 rats from each group were collected to analyze spermatogenesis. Compared with the control group, xanthine oxidase protein expression and malondialdehyde concentration in ipsilateral testes of testicular ischemia-reperfusion group increased significantly, while spermatogenesis decreased significantly. In the salvianolic acid B-treated group, xanthine oxidase protein expression and malondialdehyde concentration in ipsilateral testes decreased significantly, while spermatogenesis increased significantly, compared with the testicular ischemia-reperfusion group. These results suggest that salvianolic acid B can attenuate testicular torsion/detorsion-induced ischemia/reperfusion injury by downregulating the xanthine oxidase protein expression to inhibit reactive oxygen species formation.

May Argyrophilic Nucleolar Organizer Regions Be Used as a Biomarker for the Detection of the Degree of Ischemic Damage Instead of Tunel in Testicular Torsion?

Background and Objectives: It is of great importance to obtain information about the severity of ischemic damage and duration of testicular torsion for an effective treatment strategy. Nucleolar-organizing regions (NORs) are sites of the ribosomal genes composed of ribosomal DNA and proteins. Post-silver staining NORs are termed “AgNOR”. Since AgNORs clearly reveals the self-renewal potential of cells damaged in ischemic events, we performed the current study. Materials and Methods: The study was carried out in four groups as control, sham, early, and late T/D. In the surgical groups, testes were corrected after a 4-h ischemia period. Testicular tissue samples were taken on the third day after detorsion in group 1, 2, 3, and on the tenth day after detorsion in group 4. TUNEL and silver stainings were applied to all samples. Results: The differences were significant among the groups for both mean AgNOR number and total AgNOR area/total nuclear area (TAA/TNA). Moreover, the differences between control and early torsion-detorsion (T/D), between control and late T/D, between sham and early T/D, between sham and late T/D, and between early T/D and late were statistically significant for AgNOR amount. Furthermore, statistically significant differences among the groups for an average number of apoptotic cells per tubule and the percentage of apoptotic tubule values were detected. Discussion: The apoptotic index gives the ratio of cells that are damaged and will die in a programmed way and cells that remain intact, rather than show the viability of the returning testicle. However, by measuring cells that regenerate with AgNOR, we can show not only those that survive but also cells that can repair themselves. Conclusion: AgNOR proteins are usable for the early observation of ischemic injury levels. The amount of AgNOR protein can enlighten us about the extent of testicular damage after T/D treatment. It may also help the physician in the development of effective treatment strategies for cases.

Beneficial effects of memantine on ischemia/reperfusion injury following torsion/detorsion induced testicular damage in rats: Improvement in histological and biochemical parameters

INTRODUCTION

Testicular torsion is a common urologic emergency and one of the causes of infertility in males. Hence, prompt diagnosis and treatment are important to prevent testicular damages. It has been reported that memantine, a drug for Alzheimer's disease has anti-oxidative role against cerebral ischemic stroke and cardiac ischemia reperfusion.

OBJECTIVE

In this experimental study, the effects of memantine on a testicular torsion injury in adolescent rat testis after ischemia/reperfusion (I/R) were evaluated.

STUDY DESIGN

Thirty-six adolescent rats were divided into three groups with 12 rats per group including sham-operated, T/D (torsion/detorsion) + vehicle, and T/D + memantine (10 mg/kg). Testicular torsion was induced for 2 h by rotating right testis 720⁰ in the clockwise direction. In treated group 30 min before detorsion, a single intraperitoneal dose of memantine was administered. After 4 h of reperfusion, orchiectomy was conducted and Histopathological and biochemical evaluations of testicular tissue samples were performed.

RESULTS

The malondialdehyde level in the T/D group was significantly greater than in the sham operated group. Moreover, the testicular malondialdehyde values in the T/D + memantine group were significantly lower than in the T/D group. Also, significant decreases occurred in catalase and superoxide dismutase activities in the T/D group compared with sham operated group. These values were significantly greater in the memantine group than in the T/D group. Furthermore, after induction of T/D, histopathological evaluations also revealed severe testicular damages which were improved by memantine administration.

DISCUSSION

Memantine prevented increases in oxidative stress markers and reductions of antioxidants during I/R injury in the current study. Subsequently the histologic injury was reduced in rats treated with memantine. The antioxidant characteristics of memantine and its protective effects have been shown in our study.

CONCLUSION

These results suggest that administration of memantine before detorsion prevents I/R cellular damage in testicular torsion. This drug probably acts through reduction of reactive oxygen species and support antioxidant enzyme systems.

Impact of platelet-rich plasma versus selenium in ameliorating induced toxicity in rat testis: histological, immunohistochemical, and molecular study

This study was conducted on forty adult rats divided into four groups: Group I (control) that is divided into subgroups A, B, and C and Group II (methotrexate (MTX)-treated); the rats were injected intraperitoneally with MTX at a dose of 1 mg/kg/week, for 8 weeks. Group III (MTX-Se co-treated) was injected with MTX like Group II plus an oral administration of selenium at a dose of 10 μg/kg b.w/day, for 8 weeks. Group IV (MTX-PRP co-treated), rats were injected intraperitoneally with MTX like Group II plus platelet-rich plasma (PRP) injection under the scrotum, three times with 2-week intervals (volume-0.1 ml per injection) and euthanized after 8 weeks. Histological, immunohistochemical, and genetic expression using qPCR and western blotting technique were conducted. There was improvement in histological structure of testes in most specimens of Group IV. The latter group revealed a significant decrease in Bax and an increase in Bcl-2. The regeneration of testicular tissue was more observed in Group IV as measured by an increase in mean number of PCNA. Moreover, Group IV revealed an increased genetic level of FSCN3, GCNF, UBQLN3, and DAZL. Both MTX-Se and MTX-PRP have an anti-inflammatory effect as measured by a reduction in NF-κb. The anti-oxidative effect of selenium and PRP was noticed by a decrease in the level of the iNos and an increase in eNos protein and the autophagy marker LC3. PRP has ameliorative effects on induced rat testicular toxicity as evaluated by morphological changes and confirmed by immunohistochemical reactions, genetic expression, and western blotting analyses including oxidative and anti- oxidative markers.

Short- and long-term effects of rapamycin on ischemic damage and apoptotic changes in torsion of rat testes

Rapamycin has antioxidant defense mechanisms and immune suppressive effects. To detect the short- and long-term effects of rapamycin on ischemic damage and apoptotic changes in torsion of rat testes, mature male albino Wistar rats (n = 48) were included in the study as control, sham, early torsion-detorsion (T/D), early rapamycin treatment, early rapamycin control, late T/D, late rapamycin treatment, and late rapamycin control. The right testis was rotated 720° in a clockwise direction during 4 h in operation groups. Rapamycin was administered orally three times: 30 min before detorsion and 24 and 48 h after detorsion. The animals were killed on the third day in early groups and on the tenth day in late groups after detorsion. Statistically significant differences among all groups were detected for SOD and TBARS, mean seminiferous tubule diameter (MSTD) and Cosentino's histologic score (CHS), caspase 3, bax, average number of apoptotic cells per tubule (ANPCT), and percentage of apoptotic tubule (PAT) values. ANPCT values ​​were 10% lower in the rapamycin treatment groups compared with the untreated T/D groups, and the PAT values ​​were also approximately 1.3 times lower. Although short-term usage of rapamycin may reduce to the tubular injury caused by I/R conversely to apoptosis in the testicular tissue after testicular torsion, rapamycin may have the potential to increase the long-term apoptosis with/without testicular torsion and a subsequent regression in fertility.

The potential protective and therapeutic effects of platelet-rich plasma on ischemia/reperfusion injury following experimental torsion/detorsion of testis in the Albino rat model

AIMS

This study was designed to evaluate the protective and therapeutic efficacy of platelet-rich plasma (PRP) against testicular degeneration and germ cell apoptosis after induced spermatic cord torsion/detorsion (TD) in rats.

MATERIALS

Forty rats were allocated into 5 groups: 1) control, 2) short torsion/detorsion (STD), 3) long torsion detorsion (LTD), 4) protective (PRP/P) and 5) treatment (PRP/T). Testicular ischemia was induced by twisting the right testis 1080° clockwise for 2.5 h. PRP (10 μl) was injected intra-testicular 5 min before (PRP/P) and 3 h after (PRP/T) detorsion. At the end of the experiment, rats were euthanized at 2, 30, 2, and 30 days for groups 2-5 respectively. Nitric oxide, malondialdehyde, catalase, total antioxidant capacity, reduced glutathione, glutathione-S-transferase, interleukin1 beta, tumor necrosis factor, caspase-3, and B-cell lymphoma 2 expressions were assessed in the testes. Moreover, histological examination was performed.

KEY FINDINGS

PRP treatment significantly mitigated the torsion-detorsion induced testicular degeneration. Particularly, by improving the state of oxidative stress (NO, P = 0.0001) and antioxidant markers (TAC, GSH, GST, P = 0.0001-0.01) and decreasing the expression of IL-1β, TNF-α and cas 3 and increase the BCL2 fold changes (P = 0.0001). The protective use of PRP is superior to the therapeutic use of PRP in the restoration of the testicular histoarchitecture following TD.

SIGNIFICANCE

This study illustrates the cyto-protective role of PRP against TD induced testicular cell injury that highlight possible application of PRP as a complementary therapy in different testicular degenerative diseases which might attribute to its ability to ameliorate the oxidative stress and inhibit induced apoptosis.

Effects of Magnesium Sulfate Administration on Testicular Ischemia/Reperfusion Injury in Rats

This study aimed at investigating the effects of intraperitoneal (IP) administration of magnesium sulfate (MgSO4) on testicular ischemia-reperfusion (IR) injury in rats. In total, 50 adult Wistar rats were randomly divided into 5 groups. Group 1 received no injection (control); however, group 2 was subjected to 2 h of I and 24 h of R. Subsequently, group 3 was subjected to 2 h of 1, and after 1 h of I, 125 mg/kg MgSO4 was injected intraperitoneally followed by 24 h of R. Groups 4 and 5 were subjected to the same process as group 3, whereas the rats were injected with 250 and 500 mg/kg of MgSO4, respectively. After 24 h, the left testes of all rats were removed for histological analysis and antioxidant activities. According to the results, there was a significant increase in tissue malondialdehyde (MDA) among I/R rats (P&amp;lt;0.05), whereas MgSO4 decreased I/R-induced MDA (P&amp;lt;0.05). Furthermore, experimental I/R diminished glutathione peroxidase (GPx) and superoxide dismutase (SOD) levels significantly (P&amp;lt;0.05). Moreover, MgSO4 (250 and 500 mg/kg) increased GPx and SOD activity significantly in I/R rats (P&amp;lt;0.05). Furthermore, seminiferous tubules degenerated, and few spermatocytes were observed in the testis tubules of the I/R rats. Regarding pathological parameters, seminiferous tubules and spermatocyte were normal in the testes of MgSO4 (250 and 500 mg/kg)-treated experimental I/R-induced rats. In conclusion, this study demonstrated the beneficial effects of MgSO4 on testicular IR injury in rats.

Melatonin protects the mouse testis against heat-induced damage

Spermatogenesis, an intricate process occurring in the testis, is responsible for ongoing production of spermatozoa and thus the cornerstone of lifelong male fertility. In the testis, spermatogenesis occurs optimally at a temperature 2–4°C lower than that of the core body. Increased scrotal temperature generates testicular heat stress and later causes testicular atrophy and spermatogenic arrest, resulting in a lower sperm yield and therefore impaired male fertility. Melatonin (N-acetyl-5-methoxytryptamine), a small neuro-hormone synthesized and secreted by the pineal gland and the testis, is widely known as a potent free-radical scavenger; it has been reported that melatonin protects the testis against inflammation and reactive oxygen species generation thereby playing anti-inflammatory, -oxidative and -apoptotic roles in the testis. Nevertheless, the role of melatonin in the testicular response to heat stress has not been studied. Here, by employing a mouse model of testicular hyperthermia, we systematically investigated the testicular response to heat stress as well as the occurrence of autophagy, apoptosis and oxidative stress in the testis. Importantly, we found that pre-treatment with melatonin attenuated heat-induced apoptosis and oxidative stress in the testis. Also, post-treatment with melatonin promoted recovery of the testes from heat-induced damage, probably by maintaining the integrity of the Sertoli cell tight-junction. Thus, we for the first time provide the proof of concept that melatonin can protect the testis against heat-induced damage, supporting the potential future use of melatonin as a therapeutic drug in men for sub/infertility incurred by various testicular hyperthermia factors.

Picroside II attenuates ischemia/reperfusion testicular injury by alleviating oxidative stress and apoptosis through reducing nitric oxide synthesis

Purpose:

To investigate the effect of Picroside II on testicular ischemia and reperfusion (l/R) injury and the underlying mechanism.

Methods:

Sprague-Dawley rats were randomly divided into 4 groups: sham operated group (Sham), Sham with Picroside II treatment group (Sham+ Pic II), l/R group (l/R) and l/R with Picroside II treatment group (I/R+ Pic II). l/R model was established by rotating the left testis 720° in a clock-wise direction for 4 hours. The histopathologic and spermatogenetic evaluation was performed. The apoptosis changes and the levels of HO-1 (heme oxygenase-1), MPO (myeloperoxidase), NOX (NADPH oxidase), SOD (superoxide dismutase), XO (xanthine oxidase) and NOS (nitric oxide synthase) were measured.

Results:

The seminiferous tubules were damaged in l/R rats, but Picroside II alleviated the changes induced by l/R. The increased level of apoptosis was decreased by Picroside II (P=0.01, 9.05±0.35 vs. 4.85±0.25). The activities of HO-1, MPO, NOX, XO and MDA content were increased and the SOD activity was decreased in l/R (P<0.05) and could be reversed by Picroside II (P=0.03, 405.5±7.5 vs. 304±17U/mgprot; P=0.02, 0.99±0.05 vs. 0.52±0.04 mgprot; P=0.01, 260+7 vs. 189±2 mgprot; P=0.04, 10.95+0.55 vs. 8.75+0.35 U/mgprot; P=0.045, 6.8+0.7 vs. 3.75+0.35 mgprot; P=0.04, 44.5+3.5 vs. 57.5+3.5 mgprot). Western blot showed that the expression of iNOS, nNOS and eNOS were increased in l/R (P<0.05); however, they were decreased after Picroside II treatment (P<0.05).

Conclusion:

Picroside II attenuated testicular I/R injury in rats mainly through suppressing apoptosis and oxidative stress through reduction of nitric oxide synthesis.

Protective effect of dipeptidyl peptidase-4 inhibitors in testicular torsion/detorsion in rats: a possible role of HIF-1α and nitric oxide

Spermatic cord torsion is a serious and common urologic emergency. It requires early diagnosis for prevention of subfertility and testicular necrosis. Vildagliptin and sitagliptin are anti-diabetic drugs of the dipeptidyl peptidase-4 (DPP-4) inhibitors that have a protective role against cerebral ischemic stroke and cardiac ischemia reperfusion. This study aimed to investigate the role and mechanism of action of vildagliptin and sitagliptin in a model of testicular ischemia/reperfusion injury by testicular torsion/detorsion (T/D). Testicular T/D was done and vildagliptin and sitagliptin were administered either alone or in combination with nitric oxide synthase (NOS) inhibitor. Serum total cholesterol and testosterone were measured, while in testicular tissue testosterone, malondialdehyde (MDA) level, total antioxidant capacity (TAC), nitric oxide level, caspase-3, superoxide dismutase (SOD), hypoxia-inducible factor-1α (HIF-1α), tumor necrosis factor-α (TNF-α) and endothelial NOS (eNOS), and inducible NOS (iNOS) and neuronal NOS (nNOS) were measured. Histopathology of testicular tissue was done. Vildagliptin and sitagliptin increased serum testosterone, expression, and activity of SOD and testicular TAC. It also reduced total serum cholesterol, testicular MDA, caspase-3, HIF-1α, TNF-α, and expression of eNOS, iNOS, and nNOS. Vildagliptin and sitagliptin also improved histopathological picture of testicular tissue. NOS inhibitor produced similar result to DDP-4 inhibitors; however, its co-administration augmented the effect of vildagliptin and sitagliptin on these parameters. DPP-4 inhibitors, vildagliptin, and sitagliptin were protective against testicular T/D-induced injury mostly by anti-oxidative stress, and anti-apoptotic and anti-inflammatory actions that was augmented by NOS inhibition with a possible role for HIF-1α expression.

Effects of L-carnitine and betamethasone on ischemia-reperfusion injuries and sperm parameters following testicular torsion in a rat model

Testicular torsion is a consequence of spermatic cord twisting which causes progressive damage to the structure of the testis and reduces sperm quality and usually results in infertility. In the present study, with the assumption of the protective effects of L-carnitine and betamethasone against ischemia-reperfusion (IR) injuries, their effects on twisted testicles were evaluated and compared. Twenty Wistar rats were randomly divided into four groups and used in this study. Except for the Sham (S) group, testicular IR was induced surgically in three other groups, including Control (C), Betamethasone (BM), and L-carnitine (LC) groups. Betamethasone and L-carnitine were injected before detorsion in the BM and LC groups, respectively. After twelve hours of reperfusion, the testicles were detached, and prepared for sperm parameters evaluation such as sperm count, motility, viability, morphology, and chromatin quality, and histopathologic evaluations, including mean seminiferous tubular diameter (MSTD), germinal epithelial cell thickness (GECT), and Johnsen's mean testicular biopsy scoring (MTBS). The MSTD, GECT, and healthy sperms in the C group were significantly lower than the other groups, while the BM and LC groups were significantly different from others in MTBS. The number of sperms and sperm motility in the BM group was significantly higher than the C group. Sperm viability in the BM and LC groups were significantly higher than the C group. The results of this study showed that both L-carnitine and betamethasone similarly can be effective in treating testicular IR injuries.

Effects of pomegranate peel extract on histopathology, testosterone levels and sperm of testicular torsion–detorsion induced in adult Wistar rats

Background

In the present study, effects of pomegranate peel extract have been evaluated on decreasing the damage induced by testis torsion.

Methods

In this study, 30 adult Wistar rats were randomly divided into three groups of control, experimental (1) and experimental (2). Control: no ischemia, received vehicle alone, exposed to sham operation. Experimental (1): Received the vehicle alone during ischemia followed by 60 days’ reperfusion. Experimental (2): After performing ischemia reperfusion, 500 mg/kg of pomegranate peel extract has been used for 60 days. Blood samples and sperm samples were collected. Testes were harvested and stained with haematoxylin and eosin to study the structure of seminiferous tubules.

Results

The statistical comparison between sperm count and their viability and testosterone hormone amount showed a significant difference between control and experimental (1) groups and control and experimental (2) groups. The results showed an improvement of morphological condition of seminiferous tubules.

Conclusions

Pomegranate peel extract has revealed desirable changes on the effective parameters in infertility.

The role of melatonin on chemotherapy-induced reproductive toxicity

Objectives

Reproductive malfunctions after chemotherapy still are a reason of reducing fertility and need specialized intensive care. The aim of this review was to investigate the effect of melatonin on the reproductive system under threatening with chemotherapeutic drugs.

Methods

To find the role of melatonin in the reproductive system during chemotherapy, a full systematic literature search was carried out based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in the electronic databases up to 17 April 2017 using search terms in the titles and abstracts. A total of 380 articles are screened according to our inclusion and exclusion criteria. Finally, 18 articles were included in this study.

Key findings

It has been cleared that melatonin has bilateral effects on reproductive cells. Melatonin protects normal cells via mechanisms, including decrease in oxidative stress, apoptosis, inflammation and modulating mitochondrial function, and sexual hormones. Furthermore, melatonin with antiproliferative properties and direct effects on its receptors improves reproductive injury and function during chemotherapy. On the other hand, melatonin sensitizes the effects of chemotherapeutic drugs and enhances chemotherapy-induced toxicity in cancerous cells through increasing apoptosis, oxidative stress and mitochondrial malfunction.

Conclusions

The study provides evidence of the bilateral role of melatonin in the reproductive system during chemotherapy.

Melatonin and mitochondrial function during ischemia/reperfusion injury

Ischemia/reperfusion (IR) injury occurs in many organs and tissues, and contributes to morbidity and mortality worldwide. Melatonin, an endogenously produced indolamine, provides a strong defense against IR injury. Mitochondrion, an organelle for ATP production and a decider for cell fate, has been validated to be a crucial target for melatonin to exert its protection against IR injury. In this review, we first clarify the mechanisms underlying mitochondrial dysfunction during IR and melatonin's protection of mitochondria under this condition. Thereafter, special focus is placed on the protective actions of melatonin against IR injury in brain, heart, liver, and others. Finally, we explore several potential future directions of research in this area. Collectively, the information compiled here will serve as a comprehensive reference for the actions of melatonin in IR injury identified to date and will hopefully aid in the design of future research and increase the potential of melatonin as a therapeutic agent.

Pathological effect of arterial ischaemia and venous congestion on rat testes

Many studies on various organs have concluded that venous congestion (VC) causes severe organ dysfunction with elevation of oxidative stress relative to that of arterial ischaemia (AI). However, a comparison of the pathological effects of AI and VC on the testes has not been conducted. In this study, models of AI and VC and their reperfusion in rat testes, respectively, were developed and analysed. Testicular arteries or veins were interrupted for 6 h, re-perfused and kept for 4 weeks; the effects on the testes were then evaluated. Severe spermatogenic disturbances were observed at 4 weeks after reperfusion in AI but not in VC. At 6 h after blood flow interruption, oxidative stress was significantly increased and germ cells were severely damaged in AI compared with those in VC. RT-PCR analyses revealed that haem oxygenase-1, which exhibits anti-oxidative effects, and vascular endothelial growth factor-A, which exhibits vasculogenic effects, were significantly increased in VC but not in AI. Surprisingly, the results of our experiment in rat testes differed from those of experiments in previous studies performed in other organs. Oxidative stress in testes was more easily elevated by AI than it was by VC, explainable by the different experimental conditions.

Local Actions of Melatonin in Somatic Cells of the Testis

The pineal hormone melatonin regulates testicular function through the hypothalamic-adenohypophyseal axis. In addition, direct actions of melatonin in somatic cells of the testis have been described. Melatonin acts as a local modulator of the endocrine activity in Leydig cells. In Sertoli cells, melatonin influences cellular growth, proliferation, energy metabolism and the oxidation state, and consequently may regulate spermatogenesis. These data pinpoint melatonin as a key player in the regulation of testicular physiology (i.e., steroidogenesis, spermatogenesis) mostly in seasonal breeders. In patients with idiopathic infertility, melatonin exerts anti-proliferative and anti-inflammatory effects on testicular macrophages, and provides protective effects against oxidative stress in testicular mast cells. Consequently, melatonin is also involved in the modulation of inflammatory and oxidant/anti-oxidant states in testicular pathology. Overall, the literature data indicate that melatonin has important effects on testicular function and male reproduction.

Protective effects of polydatin on experimental testicular torsion and detorsion injury in rats

Oxidative stress plays a critical role in the process of testicular torsion and detorsion (T/D). The purpose of the present study was to investigate the protective effect of polydatin (PD) on testicular T/D injury. Rats were randomly divided into three groups, a sham group, a group subjected to 2 h torsion followed by 24 h detorsion and a group subjected to T/D and injected i.p. with 20 mg kg−1 PD 30 min before detorsion. Unilateral orchiectomy was performed after 24 h of reperfusion. Half the testes were prepared for histological examination by haematoxylin–eosin staining and the terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labelling (TUNEL) technique. In the remaining tissues, levels of malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) were determined, as was the expression of several apoptosis-related proteins. Compared with the T/D group, PD pretreatment significantly ameliorated the morphological damage, lowered the Cosentino histological score and increased the mean number of germ cell layers and Johnsen’s testicular biopsy score. In addition, PD treatment markedly decreased MDA levels and upregulated CAT, GPx and SOD activity. Furthermore, PD decreased T/D-induced germ cell-specific apoptosis, attenuated the activation of caspase-3, caspase-8, caspase-9 and poly(ADP-ribose) polymerase and increased the Bcl-2/Bax ratio. The findings indicate that PD has a protective effect against testicular T/D injuries, especially at the histological, antioxidative stress and antiapoptotic levels.

Protection from ischemia by preconditioning, postconditioning, and combined treatment in rabbit testicular ischemia reperfusion injury

This study aimed to investigate the protection of ischemic preconditioning (IPreC), ischemic postconditioning (IPostC) and combined treatment on ischemia reperfusion injury (IRI) of testis. A rabbit testicular ischemia reperfusion (IR) model was established with determining of rabbit serum testosterone, nitric oxide (NO), malondialdehyde (MDA), protein carbonyl (PC), superoxide dismutase (SOD), myeloperoxidase (MPO), glutathione peroxidase (GSH-Px), and tissues pathology. After IR, the NO, MDA, PC, SOD, MPO, and GSH-Px expression significantly increased in torsive testis, and significantly decreased after IPreC, IPostC, and combined treatment in torsive testis when compared to contralateral testis. In torsive testis, testicular tissues was severely damaged with spermatogenic cells disappearing, and were filled with light eosin edema liquid. Cell apoptosis index significantly increased, and the ratio of Bcl-2/Bax significantly decreased. After IPreC, IPostC, and combined treatment, testicular tissues were restored to normal, cell apoptosis index significantly decreased, and the ratio of Bcl-2/Bax significantly increased. It indicates that IPreC, IPostC, and combined treatment has an obvious protective effect on testicular IRI, by decreasing the oxidative stress index and cell apoptosis, provides a significant reference for the treatment of testicular torsion induced infertility, and exhibits a great value in clinical applications.

Effectiveness of lycopene on experimental testicular torsion

AIM

We aimed to demonstrate the long term effectiveness of lycopene, a precursor of vitamin A, on the testes for ischemia-reperfusion injury.

MATERIALS AND METHODS

Seventy male Wistar albino rats were used for this experiment. The rats were divided into seven groups. Group 1 served as the control group; group 2 was sham-operated; group 3 received 20mg/kg/day lycopene (intraperitoneally); in group 4, the right testes of rats were kept torted for 2hours and then were detorted and the animals lived for three days; in group 5, the right testes of rats were kept torted for 2hours and then were detorted and the animals lived for ten days; in group 6, the right testes of the rats were kept torted for 2hours and then detorted and the animals received 20mg/kg/day lycopene (intraperitoneally) for three days; in group 7, the right testes of the rats were kept torted for 2hours and then were detorted and the animals received 20mg/kg/day lycopene (intraperitoneally) for ten days. Lycopene was used intraperitoneally. Some of the testes tissues were used for biochemical analyses and the other tissues were used for histological procedures. The Johnsen's score was used for seminiferous tubule deterioration. The TUNEL method was utilized to show apoptosis of testicular tissue. Testosterone levels were measured from blood samples and SOD, MDA, TNF-α, IL-1β and IL-6 measurements were recorded from tissue samples. The results were analyzed statistically.

RESULTS

In groups 1, 2 and 3 there was normal testicular structure. Rats in groups 4 and 5 had damaged testicular tissues. In groups 6 and 7, in which we used lycopene, the testes were not better than those in groups 4 and 5. The MSTD and JTBS values were better in group 6, but not in group 7 among the torsion groups. As a result, MDA, SOD, TNF-α and IL-1β were increased and serum testosterone and IL-6 levels were decreased in groups 4 and 5 compared to group 1. There was no improvement in the groups treated with lycopene for therapeutic purposes.

CONCLUSION

It was shown that lycopene, as an antioxidant agent, is not effective for testicular torsion in the long term. This study can be considered as a preliminary study showing the need for further researches using different antioxidant agents to determine their long term effects in ischemia-reperfusion injuries in an appropriate experimental design.

Mannitol has a protective effect on testicular torsion: An experimental rat model

OBJECTIVE

Testicular torsion is an emergency condition that causes testicular injury. Any treatment opportunity reducing the destructive effect of testicular torsion is important for the future life of patients. In this experimental study we investigated the protective effect of mannitol on ischemia-reperfusion (I/R) injury in a rat testes torsion model.

METHOD

In total, 32 male Sprague Dawley rats were included. Four experimental groups included eight rats each. Group A was a sham group in which the right testis was brought out through a scrotal incision and then replaced in the scrotum without torsion. In Group B, the right testis was torsioned, by rotating 720° clockwise and fixed to the scrotum with no treatment. In Group C, the same testicular torsion process was performed with saline infusion just after testicular torsion. In group D, mannitol infusion was used just after testicular torsion. Testicles were detorsioned after 3 h and left inside for more than 2 h before orchiectomy. Histopathological, immunohistochemical, and biochemical analyses were performed.

RESULTS

Testicular architecture was disturbed significantly in the torsion groups without mannitol infusion. However, testicular tissue structure was significantly better in the mannitol-treated group, demonstrating a protective effect. Similar findings were also shown for the proliferating cell nuclear antigen (PCNA) index and antioxidant activity; both were higher in the mannitol group than in the no-treatment and saline groups (p < 0.01). The apoptotic index was also significantly lower in the mannitol-treated group compared with the no treatment and saline groups (p < 0.01).

CONCLUSIONS

The seminiferous tubule structure in testicular torsion without mannitol treatment was significantly disturbed, whereas the structural disruption was considerably less in the mannitol group. Mannitol treatment also decreased reactive oxygen radical levels significantly and was able to decrease apoptosis. These results were consistent with other organ model studies that evaluated the protective effects of mannitol treatment in I/R injury. Mannitol infusion had a protective effect against I/R injury in testicular torsion in rats. This experimental study may guide clinicians to evaluate the effectiveness of mannitol in human testicular torsion.

Melatonin and male reproduction

Melatonin is a neurohormone secreted by the pineal gland whose concentrations in the body are regulated by both the dark-light and seasonal cycles. The reproductive function of seasonal breeding animals is clearly influenced by the circadian variation in melatonin levels. Moreover, a growing body of evidence indicates that melatonin has important effects in the reproduction of some non-seasonal breeding animals. In males, melatonin affects reproductive regulation in three main ways. First, it regulates the secretion of two key neurohormones, GnRH and LH. Second, it regulates testosterone synthesis and testicular maturation. Third, as a potent free radical scavenger that is both lipophilic and hydrophilic, it prevents testicular damage caused by environmental toxins or inflammation. This review summarizes the existing data on the possible biological roles of melatonin in male reproduction. Overall, the literature data indicate that melatonin affects the secretion of both gonadotropins and testosterone while also improving sperm quality. This implies that it has important effects on the regulation of testicular development and male reproduction.

Protective effects of melatonin against arsenic-induced apoptosis and oxidative stress in rat testes

This study aimed to investigate the protective effects of melatonin against arsenic-induced apoptosis and oxidative stress in rat testes. A total of 27 male rats were divided into 3 groups: control (saline: 5 ml kg−1 day−1, intragastrically), arsenic (sodium arsenite (NaAsO2): 5 mg kg−1 day−1, intragastrically), and arsenic + melatonin (sodium arsenite (NaAsO2): 5 mg kg−1 day−1, intragastrically and melatonin: 25 mg kg−1 day−1, intraperitoneally) group. At the end of 30 days, the rats were killed under anesthesia. Histopathological examination showed that testicular injury mediated by arsenic was ameliorated by the administration of melatonin. The number of apoptotic germ cell was increased, and the number of proliferating cell nuclear antigen (PCNA)-positive germ cell was decreased in testis after arsenic administration. Our data indicate a significant reduction in the activity of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, and there was a rise in the expression of PCNA in testis of arsenic + melatonin group. The decreased superoxide dismutase, catalase, and glutathione peroxidase activities as well as increased malondialdehyde levels in testis due to arsenic administration were also counteracted by melatonin. These data suggested that melatonin has beneficial effects against arsenic-induced testicular damage by decreasing morphological damage, germ cell apoptosis, lipid peroxidation, and oxidative stress. Our results suggest that melatonin plays a protective role against arsenic-induced testicular apoptosis and oxidative stress.

Contemporary review of testicular torsion: new concepts, emerging technologies and potential therapeutics

Testicular torsion is one of the few emergencies in pediatric urology which requires an accurate and timely diagnosis in order to avoid testis loss. It is not an uncommon event affecting a young male population. In fact, testicular torsion is more common than testicular tumors for this same age group, yet testicular torsion has not been given the public attention it deserves as a male health risk. In this review we highlight the new information published over the past four years regarding testicular torsion. We will discuss a variety of topics associated with torsion including: medical legal issues, etiology and genetics, imaging diagnostics, innovative surgical techniques, management controversies, fertility, and new drug therapies.

The protective effects of grape seed extract on MDA, AOPP, apoptosis and eNOS expression in testicular torsion: an experimental study

OBJECTIVES

Grape seed proanthocyanidin extract (GSPE) is a potent antioxidant and a free radical scavenger. This study was designed to determine whether GSPE could protect against dysfunction and oxidative stress induced by torsion-detorsion injury in rat testis.

METHODS

A total of 45 male Wistar albino rats were divided into five groups: control group, sham group, torsion-detorsion (T/D) group, T/D + GSPE group, GSPE group. GSPE was administrated 100 mg/kg/day with oral gavage over seven days before torsion. Testicular torsion was performed for 2 h, and afterward, detorsion was performed for 2 h. The rats were decapitated under ketamine anesthesia, and their testes tissues were removed. Tissue malondialdehyde, advanced oxidation protein products levels, eNOS expression, apoptosis and histopathological damage scores were then compared.

RESULTS

Testicular torsion-detorsion caused significant increases in malondialdehyde level, apoptosis and eNOS expression level and caused a significant decrease in advanced oxidation protein product levels and testicular spermatogenesis in ipsilateral testes. GSPE prevented the rise in malondialdehyde, apoptosis and eNOS expression and improved testicular morphology and Johnsen's score.

CONCLUSIONS

As a result, testicular torsion gives rise to serious damage in testes and GSPE is a potent antioxidant agent in preventing testicular injury.

The effects of α-lipoic acid against testicular ischemia-reperfusion injury in Rats

Testicular torsion is one of the urologic emergencies occurring frequently in neonatal and adolescent period. Testis is sensitive to ischemia-reperfusion injury, and, therefore, ischemia and consecutive reperfusion cause an enhanced formation of reactive oxygen species that result in testicular cell damage and apoptosis. α-lipoic acid is a free radical scavenger and a biological antioxidant. It is widely used in the prevention of oxidative stress and cellular damage. We aimed to investigate the protective effect of α-lipoic acid on testicular damage in rats subjected to testicular ischemia-reperfusion injury. 35 rats were randomly divided into 5 groups: control, sham operated, ischemia, ischemia-reperfusion, and ischemia-reperfusion +lipoic acid groups, 2 h torsion and 2 h detorsion of the testis were performed. Testicular cell damage was examined by H-E staining. TUNEL and active caspase-3 immunostaining were used to detect germ cell apoptosis. GPx , SOD activity, and MDA levels were evaluated. Histological evaluation showed that α-lipoic acid pretreatment reduced testicular cell damage and decreased TUNEL and caspase-3-positive cells. Additionally, α-lipoic acid administration decreased the GPx and SOD activity and increased the MDA levels. The present results suggest that LA is a potentially beneficial agent in protecting testicular I/R in rats.

Downregulation of cold-inducible RNA-binding protein activates mitogen-activated protein kinases and impairs spermatogenic function in mouse testes

Cold-inducible RNA-binding protein (CIRP) is an RNA-binding protein that is expressed in normal testes and downregulated after heat stress caused by cryptorchidism, varicocele or environmental temperatures. The purpose of this study was to investigate the functions of CIRP in the testes. We employed RNAi technique to knock down the expression of CIRP in the testes, and performed haematoxylin and eosin staining to evaluate morphological changes following knockdown. Germ cell apoptosis was examined by terminal deoxynucleotidal transferase-mediated dUTP nick end labelling (TUNEL) assay, and mitogen-activated protein kinase (MAPK) signalling pathways were investigated by Western blotting to determine the possible mechanism of apoptosis. We found that using siRNA is a feasible and reliable method for knocking down gene expression in the testes. Compared to controls, the mean seminiferous tubule diameter (MSTD) and the thickness of the germ cell layers decreased following siRNA treatment, whereas the percentage of apoptotic seminiferous tubules increased. The p44/p42, p38 and SAPK/JNK MAPK pathways were activated after downregulation of CIRP. In conclusion, we discovered that downregulation of CIRP resulted in increased germ cell apoptosis, possibly via the activation of the p44/p42, p38 and SAPK/JNK MAPK pathways.