The Role of G3BP1 Gene Mediates P38 MAPK/JNK Pathway in Testicular Spermatogenic Dysfunction Caused by Cyfluthrin

Abstract

In recent years, male infertility has received global attention and seriously affected the quality of human fertility, and pyrethroids (type II pyrethroids), as recognized environmental endocrine disruptors, may threaten male reproductive health. Therefore, in this study, we established an in vivo model for the development of testicular and germ cell toxicity induced by cyfluthrin and explored the role and mechanism of the G3BP1 gene-mediated P38 MAPK/JNK pathway in testicular and germ cell damage caused by cyfluthrin to find early and sensitive indicators and new therapeutic targets for the development of testicular damage. Firstly, 40 male Wistar rats (about 260 g) were divided into a control group (corn oil), low dose group (6.25 mg/kg), middle dose group (12.5 mg/kg) and high dose group (25 mg/kg). The rats were anesthetized and executed after 28 days of poisoning on alternate days. Then, HE staining, transmission electron microscopy, ELISA, q-PCR, Western blot, immunohistochemistry, double-immunofluorescence and TUNEL were used to observe the pathology, androgen levels, oxidative damage and altered expression of the key factors of the G3BP1 and MAPK pathways in rat testes. The results showed that, compared with the control group, the testicular tissue and spermatocytes were superficially damaged with an increasing dose of cyfluthrin; furthermore, it could interfere with the normal secretion of the hypothalamic–pituitary–gonadal axis (serum GnRH, FSH, T and LH levels) and cause hypergonadal dysfunction. A dose-dependent increase in MDA and a dose-dependent decrease in T-AOC indicated that the oxidative–antioxidative homeostatic balance was disrupted. The Western blot and qPCR analysis revealed that G3BP1, p-JNK1/2/3, P38 MAPK, p-ERK, COX1 and COX4 proteins and mRNA expression were decreased, and p-JNK1/2/3, p-P38MAPK, caspase 3/8/9 proteins and mRNA expression were significantly increased. The double-immunofluorescence and immunohistochemistry results showed that the protein expression of G3BP1 decreased with an increasing dose of staining, while the expression of JNK1/2/3 and P38 MAPK were increased significantly. The positive expressions of G3BP1 were mainly located in the testicular germinal epithelium and germ cell layer, and the positive expressions of JNK1/2/3 were mainly located in the testicular germinal epithelium and sperm cells, while the positive expressions of P38 MAPK were located in all levels of the germ cells and spermatozoa. Our results demonstrated that exposure to cyfluthrin caused testicular and spermatocyte damage in rats, which could cause pathomorphology, altered androgen levels and a decreased antioxidant capacity. When the intracellular antioxidant capacity was impaired, G3BP1 expression and activity were inhibited, causing activation of the P38 MAPK/JNK pathway and activation of the intracellular apoptotic pathway, which, in turn, led to germ cell apoptosis.