Involvement of the bax and bcl-2 system in the induction of germ cell apoptosis is correlated with the time of reperfusion after testicular ischemia in a rat model

Apoptotic balance during testicular detorsion after one hour induced torsion in rats

Testicular torsion (TT) is an emergency complication that leads to oxidative stress and adversely affects spermatogenesis. Although immediate treatment consists of testicular detorsion (TD) to reverse TT-induced ischemia, mechanisms underlying recovery have yet to be fully understood. The current study aimed to investigate TD effects after a one-hour experimental TT by evaluating testicular antioxidant status and apoptosis-related proteins. Forty male Wistar rats were submitted to TT by testicular rotation, for one hour. Following TT, 32 rats were submitted to TD for 1, 2, 4, and 8 h (N = 8/group), the other 8 rats euthanized as TT-only. For controls, 8 rats were sham-operated. Testicular tissues were aseptically dissected for biochemical, histopathological, and immunohistochemistry analyses. The TD groups, especially after 4 h of TD, exhibited diminished MDA and increased TAC and GPX levels in testicular tissue. Levels of p53 and Caspase-3 were down-regulated in T1D4 and T1D8 groups versus torsion group. Bcl-2 was increased in T1D4 and T1D8 groups compared to the TT group. Moreover, spermatogenesis was recovered in T1D4 and T1D8 groups compared to the TT group. It can be concluded that after 1 h TT in rats, at least 4 h post-TD is needed for testicular tissue to initiate recovery.

Protective Effects of Topical Application of Nitrite on Testicular Ischemia-Reperfusion Injury in Rats

Testicular torsion is a urologic emergency induced by torsion of the spermatic cord, interrupting blood circulation to the testis. Therapeutic options for testicular torsion, except surgical restoration of testis, are rarely applied in clinical practice. This study, therefore, investigated whether topical application of nitrite (NO₂⁻) is beneficial in tissue damage due to testicular ischemia-reperfusion (I/R) injury in rats. Pubertal Sprague-Dawley rats were assigned to seven groups: group A, sham-operated control group; group B, I/R with no treatment; groups C, D, and E, I/R followed by treatment with three different doses of nitrite; group F, I/R followed by administration of nitrite and a NO scavenger, C-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt); and group G, I/R followed by administration of nitrate (NO₃⁻). Unilateral testicular ischemia was maintained for 5 h, followed by reperfusion for 24 h. Nitrite and nitrate were topically administered before reperfusion. Compared to group A, germ cell apoptosis, oxidative stress, antioxidant enzymatic function, and lipid peroxidation were significantly increased, along with abnormal morphology and impaired spermatogenesis in group B (P < 0.05). In contrast, testicular damage was generally attenuated in the nitrite treatment groups due to a reduction in superoxide and peroxynitrite levels and the inhibition of caspase-3-dependent apoptosis (P < 0.05 vs. group B). These therapeutic effects of nitrite-derived NO were suppressed after injection of C-PTIO, which showed in group F. Taken together, our results demonstrate that topical application of nitrite may be one of the therapeutic strategies for testicular ischemia-reperfusion injury.

Cross-link between mitochondrial-dependent apoptosis and cell cycle checkpoint proteins after experimental torsion and detorsion in rats

The current study assessed the cross-link between mitochondria-related apoptosis and cell cycle machinery systems during ischemia and reperfusion in a rat model of testicular torsion and detorsion. The Wistar male rats were divided into control, 1 h, 2 h, 4 h and 8 h testicular torsion-induced, and 1 h, 2 h, 4 h and 8 h testicular detorsion-induced groups. The Johnson's score was analyzed. The mRNA and protein contents of Bcl-2, Bax, Caspase-3, Cyclin D1, Cdk4, P21 and P53 were investigated by sqRT-PCR and immunohistochemical staining, respectively. The apoptosis index was analyzed by TUNEL staining. The mRNA levels of bax, p53, p21 and cyclin D1 were increased, and the mRNA levels of bcl-2 and cdk4 were decreased in torsion and reperfusion-induced groups, time-dependently. The caspase-3 mRNA was increased in torsion-induced and diminished in detorsion-induced groups. A time-dependent reduction in Bcl-2⁺, Caspase-3⁺, Cyclin D1⁺, Cdk4⁺ and P53⁺ and increment in P21⁺ cells distribution per mm² of tissue were revealed after torsion and detorsion. The apoptosis index was increased after torsion and decreased after detorsion. In conclusion, torsion-induced severe DNA damage stimulates the cyclin D1, p53 and p21 mRNA expression while more than 8 h is needed to reveal them as protein content in testicular tissue. About detorsion, decreased Cyclin D1 and Cdk4 proteins and the P53-induced transcriptional effect on p21 expression, stimulates the p21 bind to cdk4 and consequent failure in Cyclin D1/Cdk4 complex formation. This situation in association with apoptotic genes results in spermatogenesis failure.

Antioxidant treatment ameliorates germ cell apoptosis induced by a high-dose ionizing irradiation in rats

BACKGROUND

Exposure to ionizing radiation results in cytotoxic and genotoxic effects caused mainly by the oxidative damage. In the present study, we investigated the radioprotective effect of novel antioxidant cocktail on germ cell apoptosis and spermatogenesis in rats subjected to whole body radiation (WBIR).

METHODS

Adult male rats weighing 250-270 g were divided into four groups, eight rats each. Group 1 served as untreated control, group 2 received an IP single dose of antioxidant cocktail (1 ml). Group 3 was exposed to a WBIR (6 Gy). Group 4 received antioxidant cocktail before WBIR. Rats from each group were killed after 48 h. MDA levels were measured in serum (TBARS assay). Johnsen's criteria and the number of germinal cell layers were used to categorize spermatogenesis. TUNEL assay was used to determine germ cell apoptosis. Statistical analysis was performed using one-way ANOVA test.

RESULTS

WBIR resulted in histological testicular damage (decrease in Johnsen's criteria, p < 0.05) that was accompanied by a significant increase in germ cell apoptosis, expressed as the number of apoptotic cells per 100 tubules (AI-1 apoptotic index) and the number of positive tubules per 100 tubules (AI-2 apoptotic index). Treatment with antioxidant cocktail resulted in a significant decrease in germ cell apoptosis (33% decrease in AI-1, p < 0.05 and 34% decrease in AI-2, p < 0.05) that was accompanied by an improved spermatogenesis (increase in Johnsen's criteria, p < 0.05).

CONCLUSIONS

In a rat model of WBIR, antioxidant treatment ameliorates oxidative stress-induced testicular damage, decreases germ cell apoptosis and improves spermatogenesis.

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.

Methotrexate induces germ cell apoptosis and impairs spermatogenesis in a rat

PURPOSE

The primary toxic effects of methotrexate (MTX) are myelosuppression and/or intestinal mucositis. The objective of the present study is to investigate the effect of MTX on germ cell apoptosis and spermatogenesis in a rat.

METHODS

Male Sprague-Dawley rats were divided into three experimental groups: control rats treated with vehicle; MTX-2 rats treated with one dose (20 μg/kg) of MTX given IP and killed on the second day; and MTX rats treated with IP MTX (20 μg/kg) and killed on day 4. Johnsen's criteria and the number of germinal cell layers in the testes were used to categorize the spermatogenesis. TUNEL assay was used to determine germ cell apoptosis. Western blotting was used to determine Bax and Bcl-2 protein levels. Statistical analysis was performed using the non-parametric Kruskal-Wallis ANOVA test, with p less than 0.05 considered statistically significant.

RESULTS

On day 2, MTX-treated animals demonstrated minimal changes in the histological parameters of spermatogenesis, but germ cell apoptosis increased significantly (threefold increase, p = 0.002) compared to control rats. On day 4, MTX-treated rats demonstrated a trend toward a decrease in germ cell apoptosis, compared to day 2, and showed histological signs of impaired spermatogenesis (decreased number of germ cell layers and Johnsen's criteria). A significant increase in cell apoptosis in MTX-treated rats was correlated with higher Bax/Bcl-2 protein levels.

CONCLUSIONS

MTX induced germ cell apoptosis and impaired spermatogenesis in rat testes.

The hypoxic testicle: physiology and pathophysiology

Mammalian spermatogenesis is a complex biological process occurring in the seminiferous tubules in the testis. This process represents a delicate balance between cell proliferation, differentiation, and apoptosis. In most mammals, the testicles are kept in the scrotum 2 to 7°C below body core temperature, and the spermatogenic process proceeds with a blood and oxygen supply that is fairly independent of changes in other vascular beds in the body. Despite this apparently well-controlled local environment, pathologies such as varicocele or testicular torsion and environmental exposure to low oxygen (hypoxia) can result in changes in blood flow, nutrients, and oxygen supply along with an increased local temperature that may induce adverse effects on Leydig cell function and spermatogenesis. These conditions may lead to male subfertility or infertility. Our literature analyses and our own results suggest that conditions such as germ cell apoptosis and DNA damage are common features in hypoxia and varicocele and testicular torsion. Furthermore, oxidative damage seems to be present in these conditions during the initiation stages of germ cell damage and apoptosis. Other mechanisms like membrane-bound metalloproteinases and phospholipase A2 activation could also be part of the pathophysiological consequences of testicular hypoxia.

Inhaled hydrogen gas therapy for prevention of testicular ischemia/reperfusion injury in rats

PURPOSE

This study evaluated whether 2% hydrogen (H(2)) gas therapy protects against testicular ischemia/reperfusion injury which results in increased formation of reactive oxygen species and/or reactive nitrogen species, leading to testicular apoptosis and impaired spermatogenesis.

METHODS

Pubertal six-week-old Spraque-Dawley rats were assigned to 5 groups (10 animals/group) as follows: group A was a sham operated group; groups B, C, D, and E underwent 5 hours of left testicular ischemia followed by 0, 30, 60, and 120 minutes of 2% H(2) gas therapy, respectively. Histological analysis was performed to verify structure and morphology of the testes and to investigate Johnsen scores, mean seminiferous tubule diameter, and the number of germ cell layers to classify spermatogenesis. Germ cell apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay and Bax/Bcl-2 ratio real-time polymerase chain reaction. We also investigated malondialdehyde levels as an indicator of lipid peroxidation.

RESULTS

Compared to the sham group (A), germ cell apoptosis and lipid peroxidation in the ischemia group (B) were significantly increased with abnormal morphology and impaired spermatogenesis. In contrast, amelioration of testicular damages was evident in the H(2) therapy groups (C, D, and E).

CONCLUSIONS

Our results showed that inhalation of 2% H(2) gas may be a promising therapy with anti-apoptotic and anti-oxidant properties in cases of testicular ischemia/reperfusion injury.

Long term testicular ischemia-reperfusion injury-induced apoptosis: involvement of survivin down-regulation

Testicular torsion is associated with damage to the testicular tissue as a result of ischemia-reperfusion injury (IRI) and induction of apoptosis leading to progressive damage to spermatogenesis. Survivin is suggested to be an important regulator in the control of the mitochondrial apoptotic pathway, although its role in torsion-induced IRI is unknown. Therefore, we sought to evaluate testicular survivin expression after long term IRI induced by testicular torsion. Survivin expression was measured by real-time PCR in 6-12 month old New Zealand white rabbits divided into three groups (4 animals/group): group (A) sham control, group (B) ischemia alone for 60 min and group (C) ischemia for 60 min followed by reperfusion for 6 months. Germ cell apoptosis was evaluated by TUNEL assay, Bax/Bcl-2 ratio and DNA fragmentation. The Johnsen score was used to assess testicular morphological damage, while lipid peroxidation was used as an indicator for oxidative stress. Survivin expression was detected in all testicular tissue samples. The rate of survivin expression after IRI was significantly higher (p<0.05) compared with ischemic only and sham control testes. Its expression in IRI samples was inversely correlated with the significant increase (p<0.05) in apoptosis, oxidative levels and spermatogenic damage. In conclusion, down-regulation of testicular survivin expression after long term IRI to the testis and its association with apoptosis induction suggests its involvement in the regulation of this apoptotic pathway. These findings also identify survivin as a potential new target for the prevention of germ cell death during testicular torsion.