Copper nanoparticle-induced ovarian injury, follicular atresia, apoptosis, and gene expression alterations in female rats

Abstract

Numerous studies have reported the accumulation of copper nanoparticles (Cu NPs) in organs and the corresponding damage, although whether Cu NPs can be translocated to the ovaries and their ovarian toxicity are still unknown. In this study, three groups of female rats were injected with 3.12, 6.25, or 12.5 mg/kg Cu NPs for 14 consecutive days. The pathological changes, hormone levels, apoptosis and apoptotic proteins, oxidative stress, and gene expression characteristics in the ovaries were then investigated. The results demonstrated that the Cu NPs exhibited obvious accumulation in the rat ovaries, leading to ovarian injury, an imbalance of sex hormones, and ovarian cell apoptosis. Cu NP exposure activated caspase 3, caspase 8, caspase 9, and tBid, decreased the protein levels of Bcl-2, increased the expression levels of the proteins Bax and cytochrome c , and promoted malondialdehyde (MDA) accumulation and superoxide dismutase (SOD) reduction. Furthermore, gene microarray analysis showed that Cu NPs (12.5 mg/kg/d) caused 321 differentially expressed genes. Of these, 180 and 141 genes were upregulated and downregulated, respectively. Hsd17b1 , Hsd3b1 , Hsd3b6 , and Hsd3b were involved in steroid and hormone metabolism, whereas Mt3 and Cebpb were associated with apoptosis. Overall, these findings provide strong evidence that Cu NPs trigger both intrinsic and extrinsic apoptotic pathways and regulate key ovarian genes in oxidative stress-mediated ovarian dysfunction.

Copper nanoparticle‐induced uterine injury in female rats

“…Additionally, Sizoval et al indicated that exposure to Cu‐NPs could induce apoptosis or necrosis in different types of cells or organs, such as the liver and kidney. Recently, our research team showed that the intraperitoneal injection of Cu‐NPs at 12.5 mg/kg/d could induce ovarian atresia and apoptosis in rats . The findings of the present study were consistent with those of earlier studies, and further indicate that Cu‐NPs induce oxidative stress and activate apoptosis‐related proteins, leading to uterine injury.…”

“…Sarkar et al reported that copper nanomaterial induces oxidative stress and apoptosis in the kidney via both the extrinsic and intrinsic pathways. Similarly, we recently found that ovarian apoptosis induced by exposure to Cu‐NPs (12.5 mg/kg/d) occurred through both the extrinsic and intrinsic pathways . Taken together, these findings strongly indicate that exposure to Cu‐NPs (12.5 mg/kg/d) induces uterine tissue apoptosis via both the extrinsic (mitochondria‐independent) and intrinsic (mitochondria‐induced) apoptotic pathways.…”

“…Cu‐NPs were obtained from Da Yu Medical Instrument Co. Ltd. (Wuhan, Hubei, China) and were characterized in our previous report . Briefly, the Cu‐NPs were mainly composed of elemental copper and had an average size of approximately 100 nm.…”

“…For the experiment, 80 rats were randomly divided into four groups ( n = 20), including a control group (treated with 1% HPMC, w/v) and three experimental groups: Nano‐Cu High (12.5 mg/kg BW/d Cu‐NPs), Nano‐Cu Med (6.25 mg/kg BW/d Cu‐NPs), and Nano‐Cu Low (3.12 mg/kg BW/d Cu‐NPs). The dosages used in this study were selected based on previous studies and correspond to human exposures of approximately 0.03‐0.14 g of Cu‐NPs, based on a BW of 70 kg . After weighing the rats, the Cu‐NPs suspensions were administered via intraperitoneal administration for 14 consecutive days.…”

“…For instance, Liu et al reported that exposure to Cu‐NPs (40 mg/kg body weight [BW] thrice weekly) results in accumulation and injury in the liver, kidneys, and olfactory bulbs of mice Liao et al found that repeated oral administration of Cu‐NPs (50, 100, and 200 mg/kg) for 5 days resulted in widespread renal proximal tubule necrosis in the rat kidneys, which was accompanied by increases in blood urea nitrogen and creatinine levels Another study evaluated two different modes of Cu‐NPs exposure, sub‐acute inhalation (4 h/day, 5 days/week for 2 weeks, 3.5 mg/m (3)) and intratracheal instillation (24 h post‐exposure, 3, 35, and 100 μg/mouse), and observed increased inflammatory responses in mice . Our previous in vivo studies demonstrated that exposure to 12.5 mg/kg/d Cu‐NPs for 14 days led to an obvious accumulation in the ovaries, resulting in ovarian injury, an imbalance in sex hormone levels, and ovarian cell apoptosis . In previous studies, our research team successfully applied Cu‐NPs to develop a novel copper/low‐density polyethylene nanocomposite material for intrauterine devices (IUDs) .…”