J Vet Sci.  2010 Jun;11(2):115-119. 10.4142/jvs.2010.11.2.115.

Involvement of the Fas and Fas ligand in testicular germ cell apoptosis by zearalenone in rat

• Jee Y
• Noh EM
• Cho ES
• Son HY

• KMID: 1110857
• DOI: http://doi.org/10.4142/jvs.2010.11.2.115

Abstract

Zearalenone (ZEA), a nonsteroidal estrogenic mycotoxin, is known to cause testicular toxicity in animals. In the present study, the effects of ZEA on spermatogenesis and possible mechanisms involved in germ cell injury were examined in rats. Ten-week-old Sprague-Dawley rats were treated with 5 mg/kg i.p. of ZEA and euthanized 3, 6, 12, 24 or 48 h after treatment. Histopathologically, spermatogonia and spermatocytes were found to be affected selectively. They were TUNEL-positive and found to be primarily in spermatogenic stages I-VI tubules from 6 h after dosing, increasing gradually until 12 h and then gradually decreasing. Western blot analysis revealed an increase in Fas and Fas ligand (Fas-L) protein levels in the ZEA-treated rats. However, the estrogen receptor (ER)alpha expression was not changed during the study. Collectively, our data suggest that acute exposure of ZEA induces apoptosis in germ cells of male rats and that this toxicity of ZEA is partially mediated through modulation of Fas and Fas-L systems, though ERalpha may not play a significant role.

Keyword

apoptosis; estrogen receptor; Fas ligand; testis; zearalenone

MeSH Terms

Animals
Antigens, CD95/*immunology
Apoptosis/*drug effects/immunology
Estrogens, Non-Steroidal/*toxicity
Fas Ligand Protein/*immunology
Histocytochemistry
Immunoblotting
In Situ Nick-End Labeling
Male
Random Allocation
Rats
Rats, Sprague-Dawley
Spermatocytes/cytology/*drug effects/immunology
Spermatogenesis/drug effects/immunology
Spermatogonia/drug effects/immunology
Testis/cytology/*drug effects/immunology
Zearalenone/*toxicity

Figure

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  Fig. 1 Seminiferous tubules from control rats. Seminiferous tubules in stages I-VI have degenerating germ cells with pyknotic nuclei and eosinophilic cytoplasm (arrowhead) and TUNEL-labeled germ cells (arrow). A: H&E stain, ×400, B: TUNEL, ×400.

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  Fig. 2 Seminiferous tubules from zearalenone treated rats (12 h after dosing). Seminiferous tubules in stages I-VI show increased degenerating (arrowhead) and TUNEL-labeled germ cells (arrows). A: H&E stain, ×400, B: TUNEL, ×400.

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  Fig. 3 Stage-specific quantification of TUNEL-labeled germ cells per 20 seminiferous tubules in each time point. TUNEL-labeled germ cells were observed mainly in stages I-VI seminiferous tubules. Values are mean ± SD. Statistical significance was denoted at p < 0.05 (*) and p < 0.01 (**) as compared to control group values.

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  Fig. 4 Total quantification of TUNEL-labeled germ cells per 100 seminiferous tubules in each time point. The number of TUNEL-labeled germ cells increased progressively, peaked at 12 h at about four times the control levels, and then gradually decreased. Statistical significance was denoted at p < 0.05 (*) and p < 0.01 (**) as compared to control group values.

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  Fig. 5 Immunoblot analysis of Fas, Fas ligand (Fas-L), and estrogen receptor (ER)α protein levels. Note the Fas-L protein levels increased compared with the control group values in a time-dependent manner. Fas protein levels were increased from 3 h, peaked at 12 h and then recovered at 48 h after treatment as compared to control samples. However, ERα protein expression levels were not affected by zearalenone treatment.

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