The role of autosomal cell apoptosis regulator genes in human spermatogenesis

The effect of micronized purified flavonoid fraction on the prevention of testicular pathologies in adolescent rats with experimentally induced varicocele

PURPOSE

We investigated the effect of micronized purified flavonoid fraction on the prevention of testicular pathologies following varicocele induction.

MATERIALS AND METHODS

A total of 66 adolescent (6-week-old) male Wistar rats were included in study. Rats were divided into 7 groups, including group 1--control, group 2--sham operation, group 3--left varicocele induced, group 4--varicocele induced, varicocelectomy done 4 weeks later and micronized purified flavonoid fraction administered for 4 weeks, group 5--varicocele induced and micronized purified flavonoid fraction administered for 8 weeks, group 6--varicocele induced and beginning 4 weeks later micronized purified flavonoid fraction administered for 4 weeks, and group 7--varicocele induced and varicocelectomy done 4 weeks later. Before sacrifice bilateral real-time testicular microvascular perfusion of all rats was measured using the PeriFlux System 5000 PF 5010 LDPM Unit (Perimed, Järfälla, Sweden). All testes were graded according to the Johnsen scoring system. To assess apoptosis caspase-3 levels were measured.

RESULTS

Testicular weight in group 3 was markedly decreased and the extent of seminiferous tubular damage was significantly increased compared with the other groups. Bilateral testicular blood flow and the number of apoptotic germ cells were greater in group 3. Significantly higher Johnsen scores and a meaningful decrease in the apoptotic index were detected in groups 4 to 7 compared with group 3.

CONCLUSIONS

We observed favorable effects of micronized purified flavonoid fraction on the regression of testicular damage secondary to varicocele.

Increased sperm DNA damage in patients with varicocele: relationship with seminal oxidative stress

BACKGROUND

The pathophysiology of the testicular damage in varicocele has not been completely understood. Oxidative stress and related sperm DNA damage have been identified as significant causes of male infertility. The current study was designed to determine the extent of sperm nuclear DNA damage in patients with varicocele and to examine its relationship with oxidative stress.

METHODS

Semen samples from 55 patients with clinical varicocele and 25 normozoospermic donors were examined. Varicocele sperm samples were classified as normal or abnormal according to World Health Organization guidelines. Sperm DNA damage was evaluated by the sperm chromatin structure assay/flow cytometry and by the terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay. Levels of reactive oxygen species (ROS) and total antioxidant capacity were assessed by a chemiluminescence assay.

RESULTS

DNA fragmentation index (DFI) (percentage of sperm with denatured DNA) values and the percentage of TUNEL-positive cells were significantly greater in patients with varicocele, either with normal (DFI, 20.7 +/- 4.0; TUNEL positive, 26.1 +/- 3.2) or with abnormal (DFI, 35.5 +/- 9.0; TUNEL positive, 32.2 +/- 4.1) semen profile, compared with controls (DFI, 7.1 +/- 0.9; TUNEL positive, 14.2 +/- 1.2). Similarly, ROS levels were significantly higher (P < 0.01) in both groups of patients with varicocele.

CONCLUSIONS

The presence of a varicocele is associated with high levels of DNA-damage spermatozoa even in the presence of normal semen profile. The results also indicate that oxidative damage is associated with sperm DNA damage in these patients.

Apoptosis-related proteins in the testes of infertile men with varicocele

OBJECTIVES

To assess immunohistochemically the expression of apoptosis-related proteins in the testes of infertile men, to determine which of these proteins were related to hypospermatogenesis, as a previous report suggested that apoptosis was suppressed in infertile men with varicocele.

MATERIALS AND METHODS

The expression of Bcl-2, Bax, caspase-1 (ICE) and caspase-3 (CPP32) were examined in bilateral testicular specimens from 26 infertile men with varicocele and six normal testicular specimens, using the avidin-biotin-peroxidase complex method. Clinical variables were also assessed.

RESULTS

Bax, ICE, and CPP32 were expressed in germ cells, while Bcl-2 was not. Differences in staining in left or right testes were not significant. In both testes of infertile patients with varicocele, significantly fewer germ cells stained for CPP32 than in controls (P < 0.001). For Bax and ICE, total germ cell staining was similar between these groups. Staining was less frequent in infertile patients for both CPP32 and ICE when the analysis was restricted to spermatogonia. Serum luteinizing hormone levels correlated positively with CPP32 staining (P = 0.0457).

CONCLUSIONS

The reduced expression of CPP32 participates in regulating apoptosis in the testes of infertile men with varicocele.

The CREM system in human spermatogenesis

Spermatogenesis is a multi-step process, regulated by endocrine, paracrine and autocrine signals, through which immature germ cells differentiate into spermatozoa. The cAMP-dependent transcription factor CREM directs in the testis the expression of genes related to the structuring of mature spermatozoa. CREM gene expression originates different isoforms, which in turn can be divided into activators or repressors of gene expression. Whereas only CREM repressors are expressed in pre-meiotic germ cells in mice, a switch to the expression of the CREM activator tau occurs in post-meiotic germ cells. In addition, mice lacking CREM gene are infertile and present an arrest of germ cell maturation at the stage of round spermatid. We have demonstrated that CREM gene is expressed also in human germ cells and that a switch from the expression of repressors to activators is present in normospermic men. In particular, CREM tau mRNA is located in the cytoplasm of round spermatids. Conversely, in patients showing a testicular pattern of round spermatid maturation arrest only CREM repressors are expressed. Other reports have confirmed our data, supporting the hypothesis that CREM plays a role also in human spermatogenesis and that the absence of "the CREM switch" can be associated to spermatogenic arrest.