Involvement of calpain for apoptosis in dysfunction of the unaffected testis in rats with experimental testicular torsion

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.

Heat-Induced Apoptosis of Mouse Meiotic Cells Is Suppressed by Ectopic Expression of Testis-Specific Calpastatin

Calpastatin is a naturally occurring inhibitor of calpain, a protease involved in apoptotic cell death. A testis-specific isoform of calpastatin (tCAST) has been identified that is transcribed in haploid germ cells but not in spermatocytes. To investigate the possible function(s) of tCAST, we tested the hypothesis that the ectopic expression of calpastatin in spermatocytes would suppress the death of these cells in response to an apoptosis-inducing stimulus in vivo. To this end, the 5'-flanking region of the mouse ldhc gene was linked to tCAST, and transgenic mice were generated. Immunohistochemical analysis revealed that, in contrast to control sections in which the signal for tCAST was seen in round spermatids, intense staining was visualized in pachytene spermatocytes in the transgenic animals, indicating that the strategy we used to generate the transgenic animals resulted in the ectopic expression of tCAST in spermatocytes. We then tested the effect of a short period of heating on germ cell apoptosis in the testes of wild-type and transgenic mice. Pachytene spermatocytes were the major germ cell type seen to undergo apoptosis after heat treatment. There were no differences in the number of apoptotic germ cells per seminiferous tubule between wild-type and tCAST transgenic control mice; thus, there was no apparent effect of the transgene on normal apoptosis. Heating resulted in increased numbers of TUNEL-positive germ cells in both wild-type and tCAST transgenic mice, as well as increased testicular DNA fragmentation. Heating the tCAST transgenic mouse testes resulted in significantly fewer apoptotic cells per seminiferous tubule than in wild-type mice at both 8 and 24 hours after treatment. Thus, as hypothesized, the ectopic expression of tCAST in pachytene spermatocytes suppressed germ cell apoptosis.

Immunohistopathology of the contralateral testis of rats undergoing experimental torsion of the spermatic cord

AIM

To evaluate the immunohistopathological changes in the contralateral testis of rats after an experimental spermatic cord torsion.

METHODS

Male Sprague-Dawley rats of 45-50 days old were subjected to a 720 degree unilateral spermatic cord torsion for 10, 30 and 80 days (experimental group, E), respectively or sham operation (control group, C). Histopathology of the contralateral testis as well as germ cell apoptosis were studied using the Terminal Deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) technique. The number of testicular lymphocytes, mast cells and macrophages, and the expression of tumor necrosis factor-alpha (TNF-alpha) and its receptor (TNFR1) in testicular cells of the contralateral testis were quantified by histochemistry and immunohistochemistry. TNF-alpha concentration in testicular fluid was determined by ELISA.

RESULTS

In the contralateral testis of rats from the E group, the maximal degree of damage of the germinal epithelium was seen 30 days after torsion. At this time we observed in the E group vs. the C group increases: (i) the number of testicular T-lymphocytes; (ii) the number of testicular mast cells and macrophages; (iii) the percentage of macrophages expressing TNF-alpha; (iv) TNF-a concentration in testicular fluid; (v) the number of apoptotic germ cells; and (vi) the number of TNFR1+ germ cells.

CONCLUSION

Experimental spermatic cord torsion induces, in the contralateral testis, a focal damage of seminiferous tubules characterized by apoptosis and sloughing of germ cells. Results suggest humoral and cellular immune mediated testicular cell damage in which macrophages and mast cells seem to be involved in the induction of germ cell apoptosis through the TNF-alpha/TNFR1 system and in the modulation of the inflammatory process.

Gene transfer to mouse testes by electroporation and its influence on spermatogenesis

We transferred the adventitious gene pCAGGS-lacZ to mouse testes with the use of a square-wave electroporator and investigated the efficiency of gene transfer (GT) and the influence of the procedure on testicular damage and spermatogenesis. Mice were divided into 5 groups: (1-2) injection of gene/phosphate-buffered saline (PBS) into the interstitial space followed by electroporation (EP), (3) EP alone, (4-5) injection of gene/PBS without EP. The presence of the lacZ gene was determined by X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside) staining and the polymerase chain reaction (PCR). The influence of transfer on spermatogenesis was assessed by evaluating the seminiferous tubules according to the Johnsen score (JS). TdT-mediated dUTP-biotin nick end-labeling (TUNEL) staining was performed for the detection of apoptosis in the testes to evaluate the testicular damage caused by GT, and fertilization ability was assessed by mating male mice from each group with normal female mice at 1, 2, 4, 6, and 8 weeks after the procedure. LacZ expression was detected by X-gal staining and PCR for 4 weeks after GT in group 1. But in group 4, LacZ expression was not detected for all times. In groups 1 through 3, the JSs decreased gradually until 4 weeks and recovered at 6 and 8 weeks after GT. The JSs were significantly decreased at 4 weeks for groups 1 through 3 compared with groups 4 and 5. In groups 1 through 3, apoptotic cells were significantly more numerous at 1, 2, and 4 weeks after the procedure, and there were significant differences in their numbers between groups 1 through 3 and groups 4 and 5 until 4 weeks after the procedure. The number of offspring did not differ significantly between all groups. These results suggest that although spermatogenic damage caused by EP could present problems, GT by EP might be effective for transfecting germ cells or somatic cells and could be applicable for in vivo gene therapy for male infertility in the future.

Comparison of two methods of in vivo gene transfer by electroporation

OBJECTIVE

To evaluate two contrasting methods of in vivo gene transfer into testicular cells using electroporation, with regard to efficiency of transfer and damage to the testes.

DESIGN

Controlled animal study.

SETTING

Research laboratory at a university medical school.

ANIMAL(S)

8-10-week-old male mice.

INTERVENTION(S)

The reporter construct pCAGGS-LacZ consisting of a cytomegalovirus enhancer/chicken beta-actin promoter attached to the LacZ gene was introduced into the testes in vivo using electroporation. For eight weeks, the efficiency and extent of LacZ gene expression, and the extent to which the testis was damaged by the technique, were investigated.

MAIN OUTCOME MEASURE(S)

Beta-galactosidase activity resulting from expression of the LacZ transgene was verified by X-gal staining, and LacZ mRNA expression was determined by RT-PCR analysis. Potential disorders associated with seminiferous tubular sperm formation were evaluated using the Johnsen score.

RESULT(S)

Long-lasting beta-galactosidase activity was detected in spermatogenic cells up to eight weeks postelectroporation. Apparent damage to spermatogenesis was evident but was transient in nature and recovered with time; this plasticity was particularly evident following rete testes injection.

CONCLUSION(S)

Injection into the rete testis appears to be more suitable for in vivo gene transfer by electroporation than direct intratesticular injection.

Unilateral spermatic cord torsion without ipsilateral spermatogenetic material: effects on testicular blood flow and fertility potential

This experiment was planned to answer the question of how the elimination of ipsilateral spermatogenetic material, which is necessary for contralateral testicular damage caused by an autoimmune response, affects contralateral testicular blood flow and fertility potential in unilateral spermatic cord torsion (USCT). Thirty-four male and 68 female adult albino rats were divided into three groups. Group 1 rats underwent a control operation, group 2 rats underwent subepididymal orchiectomy to eliminate spermatogenetic material, and group 3 rats underwent USCT after subepididymal orchiectomy. Testicular blood flows of the rats were measured by (133)Xe clearance technique. Additionally, to determine fertility potential, each male rat was housed with two female rats. Numbers of impregnated and delivered rats were recorded. Both mean testicular blood flow and fecundity of group 3 were significantly lower than those of groups 1 and 2. When compared with groups 1 and 2, fertility and mean number of the impregnated rats of group 3 were lower but the differences were not significant. These findings suggest that absence of spermatogenetic material in USCT reduces contralateral blood flow and fertility potential. Therefore, contralateral testicular damage originating from blood flow alterations rather than autoimmune mechanism should be considered to explain fertility problems encountered following USCT.