Tri-ortho-cresyl phosphate induces autophagy of rat spermatogonial stem cells

Abstract

Tri-ortho-cresyl phosphate (TOCP) has been widely used as plasticizers, plastic softeners, and flame retardants in industry and reported to have a deleterious effect on the male reproductive system in animals besides delayed neurotoxicity. Our preliminary results found that TOCP could disrupt the seminiferous epithelium in the testis and inhibit spermatogenesis, but the precise mechanism is yet to be elucidated. This study shows that TOCP inhibited viability of rat spermatogonial stem cells in a dose-dependent manner. TOCP could not lead to cell cycle arrest in the cells; the mRNA levels of p21, p27, p53, and cyclin D1 in the cells were also not affected by TOCP. Meanwhile, TOCP did not induce apoptosis of rat spermatogonial stem cells. After treatment with TOCP, however, both LC3-II and the ratio of LC3-II/LC3-I were markedly increased; autophagy proteins ATG5 and beclin 1 were also increased after treatment with TOCP, indicating that TOCP could induce autophagy in the cells. Ultrastructural observation under the transmission electron microscopy indicated that autophagic vesicles in the cytoplasm containing extensively degraded organelles such as mitochondria and endoplasmic reticulum increased significantly after the cells were treated with TOCP. In summary, we have shown that TOCP can inhibit viability of rat spermatogonial stem cells and induce autophagy of the cells, without affecting cell cycle and apoptosis.

Tea polyphenols alleviate tri‐ortho‐cresyl phosphate‐induced autophagy of mouse ovarian granulosa cells

“…TOCP has been shown to induce autophagy of human neuroblastoma SH‐SY5Y cells . We also found that TOCP could induce autophagy of mouse spermatogonial stem cells and mouse Leydig TM3 cells . In the present study, we found that TOCP exposure induced autophagic cell death of mouse ovarian granulosa cells, which was in accordance with our previous results .…”

Tri‐ortho‐cresyl phosphate (TOCP)‐induced reproductive toxicity involved in placental apoptosis, autophagy and oxidative stress in pregnant mice

“…In this study we found that TOCP treatment significantly upregulated the levels of Beclin‐1, Atg5 proteins and the ratio of LC3 II/LC3 I in almost all doses of TOCP‐treated groups on GD 13 and 400 mg/kg/day TOCP‐treated group on GD 8. Our results above were in accordance with Liu's findings that exposed to 0 to 0.5 mM TOCP, mice Leydig TM3 cells had elevated expression levels of LC3 II/LC3 I, Atg5, and Beclin1 . Moreover, previous studies also demonstrated that the autophagy‐related proteins Atg5, Beclin‐1, and LC3 II/LC3I expression were markedly increased in rat spermatogonial stem cells after exposure to 0 to 1.0 mM TOCP for 48 hours .…”

“…Furthermore, male mice orally administered different concentrations of TOCP for 28 days showed hepatocellular injury, accompanied by the increase of MDA and decrease of SOD and glutathione . It suggested that the cell damage caused by TOCP was partly mediated by the increase of oxidative stress . On the other hand, our study also showed that the levels of CAT and SOD in placental tissues were increased significantly in the high dose group on GD 8, which may be a compensatory mechanism beneficial to recover the body damage when exposed to TOCP during early pregnant process.…”

“…Studies have demonstrated that TOCP treatment for 5 or 63 days decreased the motility and density of cauda epididymal sperm and inhibited testicular enzymes activity in a dose‐dependent manner and changed sperm morphology in male rats. Chen et al found that TOCP suppressed the viability and proliferation of rat spermatogonial stem cells by inducing cell autophagy or inhibiting the neuropathy target esterase. Incubations with TOCP for 48 hours significantly decreased the viability and testosterone secretion of mouse Leydig TM3 cells via the oxidative stress‐induced cell autophagy .…”

VEGFA splicing: divergent isoforms regulate spermatogonial stem cell maintenance

“…In the rat, approximately half of all germ cells die at parturition (Roosen-Runge and Leik 1968), and apoptosis of male germ cells has been detected even while these cells are mitotically arrested (Coucouvanis et al 1993). Autophagy has also been recently demonstrated in SSCs following the addition of a plasticizer in vitro (Liu et al 2015). Treatment with angiogenic VEGFA164 has been demonstrated to promote germ cell survival, whereas inhibition of VEGFA signal transduction results in germ cell loss in cultured bovine testis explants (Caires et al 2009).…”