As a widely used plasticizer, di-(2-ethylhexyl) phthalate (DEHP) is known to induce significant testicular injury. However, the potential mechanism and effects of pubertal exposure to DEHP on testis development remain unclear. In vivo, postnatal day (PND) 21 male rats were gavaged with 0, 250, and 500 mg/kg DEHP for ten days. Damage to the seminiferous epithelium and disturbed spermatogenesis were observed after DEHP exposure. Meanwhile, oxidative stress-induced injury and pyroptosis were activated. Both endoplasmic reticulum (ER) stress and mitophagy were involved in this process. Monoethylhexyl phthalate (MEHP) was used as the biometabolite of DEHP in vitro. The GC-1 and GC-2 cell lines were exposed to 0, 100 μM, 200 μM, and 400 μM MEHP for 24 h. Reactive oxygen species (ROS) generation, oxidative stress damage, ER stress, mitophagy, and pyroptosis were significantly increased after MEHP exposure. The ultrastructure of the ER and mitochondria was destroyed. X-box binding protein 1 (XBP1) was observed to be activated and translocated into the nucleus. ROS generation was inhibited by acetylcysteine. The levels of antioxidative stress, ER stress, mitophagy, and pyroptosis were decreased as well. After the administration of the ER stress inhibitor 4-phenyl-butyric acid, both mitophagy and pyroptosis were inhibited. Toyocamycin-induced XBP1 down-regulation decreased the levels of mitophagy and pyroptosis. The equilibrium between pyroptosis and mitophagy was disturbed by XBP1 accumulation. In summary, our findings confirmed that DEHP induced a ROS-mediated imbalance in pyroptosis and mitophagy in immature rat testes via XBP1. Moreover, XBP1 might be the key target in DEHP-related testis dysfunction.

Cryptorchidism-caused adult infertility is a common component of idiopathic reasons for male infertility. Retinoic acid (RA) has a vital effect on the spermatogenesis process. Here, we found that the expression of c-Kit, Stra8, and Sycp3 could be up-regulated via the activation of retinoic acid receptor α (RARα) after RA supplementation in neonatal cryptorchid infertile rats. We also demonstrated that the protein expression of PI3K, p-Akt/pan-Akt, and p-mTOR/mTOR was higher in cryptorchid than in normal testes, and could be suppressed with RA in vivo. After RA treatment in infertile cryptorchid testis in vivo, the levels of the autophagy proteins LC3 and Beclin1 increased and those of P62 decreased. Biotin tracer indicated that the permeability of blood-testis barrier (BTB) in cryptorchid rats decreased after RA administration. Additionally, after blocking the RARα with AR7 (an RARα antagonist) in testicle culture in vitro, we observed that compared with normal testes, the PI3K-Akt-mTOR signaling pathway and the autophagy pathway was increased and decreased, respectively, which were coincident with cryptorchisd testes in vivo. Additionally, the appropriate concentrations of RA treatment could depress the PI3K-Akt-mTOR signaling pathway and improve the autophagy pathway. The results confirmed that RA can rehabilitate BTB function and drive key protein levels in spermatogonial differentiation through depressing the PI3K-Akt-mTOR signaling pathway via RARα.

This study aims to determine key genes and pathways that could play important roles in the spermatogenic process of patients with cryptorchidism. The gene expression profile data of GSE25518 was obtained from the Gene Expression Omnibus (GEO) database. Microarray data were analyzed using BRB-Array Tools to identify differentially expressed genes (DEGs) between high azoospermia risk (HAZR) patients and controls. In addition, other analytical methods were deployed, including hierarchical clustering analysis, class comparison between patients with HAZR and the normal control group, gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and the construction of a protein–protein interaction (PPI) network. In total, 1015 upregulated genes and 1650 downregulated genes were identified. GO and KEGG analysis revealed enrichment in terms of changes in the endoplasmic reticulum cellular component and the endoplasmic reticulum protein synthetic process in the HAZR group. Furthermore, the arachidonic acid pathway and mTOR pathway were also identified as important pathways, while RICTOR and GPX8 were indentified as key genes involved in the spermatogenic process of patients with cryptorchidism. In present study, we found that changes in the synthesis of endoplasmic reticulum proteins, arachidonic acid and the mTOR pathway are important in the incidence and spermatogenic process of cryptorchidism. GPX8 and RICTOR were also identified as key genes associated with cryptorchidism. Collectively, these data may provide novel clues with which to explore the precise etiology and mechanism underlying cryptorchidism and cryptorchidism-induced human infertility.