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Background and Objective: Copper oxide nanoparticles with unique properties have numerous biological applications with probably toxicity. This study was conducted to determine the toxicity of copper oxide nanoparticles on the pituitary-gonadal axis and spermatogenesis in male rats.
Methods: In this experimental study, 40 male Wistar rats were randomly allocated into 4 groups including control group and three intervention  groups which receiving the cancentration of 10, 20 and 30 mg/kg of copper oxide nanoparticles 5 times intra-peritoneally, respectively. Blood sampling was collected first day and 15 days after the last injection. Level of testosterone, FSH and LH were measured by ELISA method. After anesthesia and dissection of mice in each group, tissue sections of testis were prepared and stained with hematoxylin-eosin. Morphological status of spermatogenesis process and counting of types of cells (spermatogonium, spermatocyte and spermatid) were studied by optical microscope.
Results: In the first day of blood collection, a significant increase in LH and FSH level was observed at concentrations of 10 and 30 mg/kg, respectively. Also, Testosterone and FSH level decreased significantly reduced at 10 mg/kg/bw concentration compared to control (P<0.05). In 15 days after of the last injection, level of testosterone (P<0.05) and LH (P<0. 05) significantly increased in concentrations of 10 and 30 mg/kg/bw respectively. Also, there was a significant reduction in level of FSH in the concentration of 10 mg/kg/bw (P<0.05). The examination of testis tissue sections showed a significant decrease (P<0.05) in density and number of cell types (spermatogonium, spermatocyte and spermatid) and anomalies in the spermatogenesis process, in a dose-dependent manner. The most disturbances was seen at a concentration of 30 mg/kg/bw of copper oxide nanoparticles.
Conclusion: Copper oxide nanoparticles may interfere with the secretion of gonadotropins and testosterone and ultimately lead to a disruption of the spermatogenesis process.

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Background and Objective: Copper oxide nanoparticles, in addition to useful applications, may have adverse effects on the organisms.This study was done to determine the effect of copper oxide nanoparticles on liver toxicity, enzymes changes and liver histological structure of rats.
Methods: In this experimental study, 40 Wistar male rats were randomly allocated into 4 groups. During 10 days, five times (one day interval), 3 groups of rats were received 10, 20 and 30 mg/kg of copper oxide nanoparticles with a diameter of less than 50 nm and purity of 99% and a surface of 80 m²/g intraperitoneally, respectively. One group was considered as the control group. Activity of Lactate dehydrogenase (LDH), Alkaline phosphatase (ALP), Aspartate transaminase (AST) and Alanine aminotransferase (ALT) enzymes were tested in two stages (one day and 15 days after treatment). Also, liver tissue sections were prepared and stained with hematoxylin-eosin.
Results: No significant alterations of AST enzyme activity were not seen between different groups in two stages. The activity of ALT, ALP, and LDH enzymes in the first stage showed a significant increase in all treatment groups compared to control and returned to normal after 15 days. Rat's weight changes were not statistically significant between different groups. Histological studies revealed multiple tissue injuries in dose-dependent in treatment groups which included mild and severe hyperemia, hepatocytes degeneration, hyperplasia and inflammation.
Conclusion: Injection of low doses of copper oxide nanoparticles, after 15 days, although changes in enzyme activity return to normal, but significant disturbances observes in the structure of the liver tissue.