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Evaluation of Resmethrin Toxicity to Neonatal Testes in Organ Culture
Hyun-Jung Park1, Won-Young Lee2, Mingtian Zhang1
1Department of Stem Cell and Regenerative Biology, Konkuk University, Gwangjin-gu, Seoul 05029, Republic of Korea.
Abstract:
Resmethrin is a widely used pyrethroid insecticide, which causes low toxicity in mammals. However, its toxicity in testes has not been fully investigated. Therefore, we evaluated the toxicity of resmethrin in mouse testes using an in vitro organ culture. Mouse testicular fragments (MTFs) derived from neonates were cultured in medium containing resmethrin for 30 days. Effects on spermatogenesis in the cultured testes were investigated as functions of both time and dose. Resmethrin significantly downregulated the transcription levels of marker genes for spermatogonia and the number of spermatogenic germ cells relative to those of the controls, according to quantitative PCR and immunostaining. In addition, spermatocyte was observed in the control, but not in 50 μM resmethrin-exposed cultures. Levels of the SYCP3 meiotic marker and phosphorylated H2AX decreased by resmethrin treatment, as observed by Western blotting. Toxic or apoptotic effects of resmethrin in Sertoli and Leydig cells from MTFs were not observed by immunostaining and Tunnel assay. No changes in the expression of steroidogenic enzymes were noted. Apoptosis was only detected in the germ cells of resmethrin-treated MTFs. Thus, the highest dose of resmethrin tested (50 μM) completely inhibited spermatogenesis, because of apoptosis of germ cells and spermatocytes. Although the in vivo toxicity of resmethrin has not yet been studied in detail, significant evidence for cytotoxicity was observed in our organ cultures. This methodological approach is useful for the study of reproductive toxicity before proceeding to animal models, as it greatly reduces the use of laboratory animals.
Insights
Resmethrin insecticide exposure significantly harms mouse testes, inhibiting spermatogenesis by inducing germ cell apoptosis. This study highlights potential reproductive toxicity using an in vitro organ culture model.
Area of Science:
- Reproductive Toxicology
- Environmental Health
- In Vitro Toxicology
Background:
- Resmethrin, a common pyrethroid insecticide, exhibits low mammalian toxicity.
- However, its specific effects on testicular toxicity and spermatogenesis remain incompletely understood.
- Investigating insecticide reproductive toxicity is crucial for public health and environmental safety.
Purpose of the Study:
- To evaluate the in vitro toxicity of resmethrin on mouse testicular function.
- To assess the impact of resmethrin on spermatogenesis and germ cell viability.
- To establish an in vitro organ culture method for reproductive toxicity screening.
Main Methods:
- Primary mouse testicular fragments (MTFs) were cultured for 30 days with varying resmethrin concentrations.
- Quantitative PCR and immunostaining were used to analyze gene expression and cell populations.
- Western blotting and TUNEL assays assessed meiotic markers and apoptosis.
Main Results:
- Resmethrin significantly downregulated spermatogonial marker genes and reduced germ cell numbers.
- Spermatogenesis was completely inhibited at 50 μM resmethrin, with observed apoptosis in germ cells and spermatocytes.
- Sertoli and Leydig cell toxicity or apoptosis was not detected; steroidogenic enzyme expression remained unchanged.
Conclusions:
- Resmethrin induces significant reproductive toxicity in mouse testes by disrupting spermatogenesis via germ cell apoptosis.
- The in vitro organ culture model effectively demonstrates resmethrin's cytotoxicity, reducing the need for animal testing.
- This approach provides a valuable screening tool for assessing the reproductive hazards of environmental chemicals.
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