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Cylindrospermopsin directly disrupts spermatogenesis in isolated male zebrafish testis
A C N Moraes1, H P Fallah2, V F Magalhães3
1Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; Department of Biological Science, University of Calgary, Calgary, Alberta, Canada.
Abstract:
Cylindrospermopsin (CYN) is a cytotoxin, and its documented effects in mammals include damage to several organs. CYN also has hormone-disrupting properties, including estrogenic activity, progesterone production inhibition, and apoptosis induction. While CYN has been reported to exert reproductive toxicity in mice, little is known about its effect on fish reproductive function. Using ex vivo organ culture, we investigated the direct action of CYN on the male reproductive system. Isolated zebrafish testis was exposed to 250, 500, and 1000 µg/L CYN for 24 h and 7 d, followed by histo-morphological analysis. The results demonstrate that exposure to CYN led to a decrease in cell types from all three phases of spermatogenesis in zebrafish testis. There were also significant changes in fshr, lhr, and igf3 transcript levels, as well as testosterone secretion following exposure to CYN. In summary, this study provides novel information on the adverse effects of CYN on testicular spermatogenesis and male reproduction in zebrafish. These results provide a framework for a better understanding of CYN toxicity and the mechanism underlying the adverse action of CYN on male reproduction in fish.
Insights
Cylindrospermopsin (CYN) harms zebrafish male reproduction by disrupting spermatogenesis and altering hormone levels. This study reveals CYN
Area of Science:
- Environmental Toxicology
- Reproductive Biology
- Aquatic Toxicology
Background:
- Cylindrospermopsin (CYN) is a potent cyanobacterial cytotoxin with known mammalian organ toxicity and endocrine-disrupting effects.
- Previous research indicates CYN causes reproductive toxicity in mice, but its impact on fish reproductive function remains largely uncharacterized.
- Understanding CYN's effects on fish is crucial given its prevalence in aquatic ecosystems and potential for bioaccumulation.
Purpose of the Study:
- To investigate the direct effects of CYN exposure on the male reproductive system of zebrafish using an ex vivo organ culture model.
- To assess the impact of CYN on spermatogenesis, gene expression related to reproduction, and hormone secretion in zebrafish testes.
Main Methods:
- Isolated zebrafish testes were cultured ex vivo and exposed to varying concentrations of CYN (250, 500, 1000 µg/L) for 24 hours and 7 days.
- Histo-morphological analysis was performed to evaluate changes in testicular tissue.
- Quantitative analysis of gene transcript levels (fshr, lhr, igf3) and testosterone secretion was conducted.
Main Results:
- CYN exposure significantly reduced the abundance of germ cells across all three phases of spermatogenesis in zebrafish testes.
- Significant alterations were observed in the transcript levels of follicle-stimulating hormone receptor (fshr), luteinizing hormone receptor (lhr), and insulin-like growth factor 3 (igf3).
- Testosterone secretion was significantly impacted following CYN exposure.
Conclusions:
- This study demonstrates the direct adverse effects of CYN on testicular spermatogenesis and male reproductive function in zebrafish.
- CYN exposure disrupts key reproductive gene expression and hormone secretion, contributing to its reproductive toxicity in fish.
- The findings provide a foundation for understanding the mechanisms of CYN toxicity in male fish reproduction.
