Role of Autophagy in Zinc Oxide Nanoparticles-Induced Apoptosis of Mouse LEYDIG Cells

Abstract

Zinc oxide nanoparticles (ZnO NPs) have shown adverse health impact on the human male reproductive system, with evidence of inducing apoptosis. However, whether or not ZnO NPs could promote autophagy, and the possible role of autophagy in the progress of apoptosis, remain unclear. In the current study, in vitro and in vivo toxicological responses of ZnO NPs were explored by using a mouse model and mouse Leydig cell line. It was found that intragastrical exposure of ZnO NPs to mice for 28 days at the concentrations of 100, 200, and 400 mg/kg/day disrupted the seminiferous epithelium of the testis and decreased the sperm density in the epididymis. Furthermore, serum testosterone levels were markedly reduced. The induction of apoptosis and autophagy in the testis tissues was disclosed by up-regulating the protein levels of cleaved Caspase-8, cleaved Caspase-3, Bax, LC3-II, Atg 5, and Beclin 1, accompanied by down-regulation of Bcl 2. In vitro tests showed that ZnO NPs could induce apoptosis and autophagy with the generation of oxidative stress. Specific inhibition of autophagy pathway significantly decreased the cell viability and up-regulated the apoptosis level in mouse Leydig TM3 cells. In summary, ZnO NPs can induce apoptosis and autophagy via oxidative stress, and autophagy might play a protective role in ZnO NPs-induced apoptosis of mouse Leydig cells.

ZnO Quantum Dots Induced Oxidative Stress and Apoptosis in HeLa and HEK-293T Cell Lines

“…Persaud and Kim et al reported that ZnO NPs induced significantly late apoptosis at the concentrations of 20 µg/ml (Kim et al, 2019;Persaud et al, 2019). Shen et al revealed that ZnO NPs induced early and late apoptosis in low dosage, and mainly increased the late apoptosis in high dosage (Shen et al, 2019). In our…”

“…(Roshini et al, 2017). Moreover they can accumulate in various internal organs (such as liver, spleen, lungs, kidney, and heart) via circulation and then produce adverse consequences (Shen et al, 2019).…”

The Impact of Zinc Oxide Nanoparticles on Male (In)Fertility

“…Most of the in vivo studies reported in Table 2 evaluate changes in testicular and epididymal tissues after exposure of rats or mice to different ZnO NPs concentrations. The histological pattern was similar in both rats or mice, with the formation of multinucleated giant cells [76,77], disorganization of germ cells layers, detachment and sloughing of immature germ cells, and vacuolization of the epithelium of ST after exposure to a high concentrations of ZnO NPs [75][76][77][78]80,86]. These histological alterations are indicative of functional damage in Sertoli cells, which are responsible for the support and protection of germ cells during spermatogenesis [76].…”

“…From all in vitro studies described, only two evaluated apoptosis in Leydig [71,75] and Sertoli cells after exposure to ZnO NPs [71]. These authors found that the apoptosis is associated with ROS formation, and with loss of mitochondrial membrane potential, which leads to the increase of apoptosis in Sertoli and Leydig cells associated with nuclear DNA damage [71,75] (Figure 2). These results clearly indicate a possible negative effect of ZnO NPs on spermatogenesis progression, as the number of Sertoli and Leydig apoptotic cells increases after exposure to these nanoparticles.…”

“…These results clearly indicate a possible negative effect of ZnO NPs on spermatogenesis progression, as the number of Sertoli and Leydig apoptotic cells increases after exposure to these nanoparticles. In mouse Leydig cells, autophagy stimulated by oxidative stress might protect cells from ZnO NPs-induced apoptosis [75].…”