The protective effects of selenium-enriched spirulina on the reproductive system of male zebrafish (Danio rerio) exposed to beta-cypermethrin

Abstract

Beta-cypermethrin (beta-CYP), which is widely used for the control of indoor and field pests, is a highly lipophilic insecticide with environmental estrogenic effects. Selenium-enriched Spirulina (Se-SP) is a novel natural antioxidant agent with a high nutritional value. This study was aimed at the investigation of the protective effects of Se-SP on the reproductive system of male zebrafish (Danio rerio) exposed to beta-CYP. We determined the protective effect of Se-SP on male zebrafish exposed to 7 nmol L⁻¹ beta-CYP by measuring the activity of sperm and antioxidants, examining tissue sections, measuring hormone secretion levels, and analyzing the expression of related proteins and genes during spermatogenesis. We found that beta-CYP enhanced VTG synthesis and estrogen (E2) secretion, increased the number of spermatogonia and spermatocytes, and decreased the number of spermatids and Sertoli cells. However, treatment with 50 mg L⁻¹ Se-SP (Se: 25 μmol g⁻¹ Se-SP) almost completely ameliorated the deleterious effects of beta-CYP. The protective mechanism of Se-SP in the testes of beta-CYP-treated fish involved an enhancement of antioxidant enzyme activity and an increase in androgen secretion by the downregulation of the expression of cyp19a, nanos2, piwil1, dazl and sycp3, and the upregulation of the expression of odf3b, igf3, insl3 and dmrt1, which affected testosterone production and spermatogenesis. Our study strongly indicates that treatment with Se-SP can effectively prevent the oxidative damage to the reproductive system during spermatocyte differentiation induced by beta-CYP exposure.