Acute reproductive toxicology after intratesticular injection of silver nanoparticles (AgNPs) in Wistar rats

Abstract

This study aimed to evaluate the effects of an intratesticular injection of silver nanoparticles (AgNPs) on reproductive parameters and health of rats, and to evaluate the AgNPs biodistribution in order to develop a nanotechnological contraceptive agent for male animals. Treated animals received 220 μL of AgNPs solution (0.46 µg-Ag/ml) in each testicle and were euthanized: seven, 14, 28, and 56 days after injection. A significant decrease (p < 0.05) in the percentage of motile sperm in D7 (8.8%) was observed, comparing to the control (73.3%), D14 (86.0%), D28 (68.2%), and D56 (90.0%) groups. D7 group also presented a decrease (p < 0.05) in the percentage of normal spermatozoa. Additionally, D7 group showed an increase (p < 0.05) in abnormal midpiece and sperm head morphology compared to the Control group. Seminiferous tubules presented all germline cell types and spermatozoa for all groups. However, D7 group did not present spermatozoa in the epididymis, whereas some spermatozoa and cellular debris were visible in D14 and D28 groups. All animals presented hematological parameters, creatinine, and alanine aminotransferase values within the normal limits for Wistar rats. The percentage of silver found in the liver was always higher than in the other organs analyzed. A pioneering mathematical model is proposed, from which the half-life time of silver in the liver (17 days), spleen (23 days), lungs (30 days), and kidneys (35 days) was extracted. In conclusion, some acute and severe toxic effects were observed in sperm cells following intratesticular injection of AgNPs, although these effects were reversible. No adverse effects to general animal health were observed.

Keywords:

• Reproductive toxicity
• sperm morphology
• sperm motility
• seminiferous tubules
• nanosilver
• rats

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This work was supported in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES #1) under Grant (Finance Code 001); National Institute of Science and Technology-Nanobiotechnology (INCT-Nanobiotecnologia) of the Ministry of Science, Technology and Innovation (MCT/CNPq #2) under Grant (#573.880/2008-5); Ministry of Science and Innovation Spain (MICINN #3) under Grant (#MAT2017-88752-R); and J.L.M. Brito received scholarships from CAPES and CNPq.