Effects of Silver Citrate Prolonged Exposure on Behavioral and Cognitive Functions of Mice

Pure silver as well as silver compounds have been used as antiseptics for centuries. Nowadays, the most frequently applied silver compounds are silver nanoparticles. Several studies demonstrate the ability of silver nanoparticles and silver salts to accumulate in the brain of laboratory animals as well as the ability of silver nanoparticles to influence behavioral and cognitive functions of laboratory mammals. For the first time, the influence of silver citrate on the change dynamics of behavioral and cognitive functions of laboratory mice at the daily oral exposure during 30, 60, 120, and 180 days were investigated in the present research. We observed the anxiety increase after 30 days of the exposure as well as the ability of mice to adapt to the prolonged oral exposure of silver citrate manifested in the anxiety decrease, increase of locomotor activity and the tendency of long-term contextual memory improvement at the further stages of the experiment. Increase of locomotor activity and memory improvement might be associated with the sensitivity increase and regarded as compensatory mechanism to anxiety increase. The observed phenomenon is classified as a hormetic effect. A comparison with the analogous study, which implemented polyvinylpyrrolidone coated silver nanoparticles, is carried out. It was concluded that the nanoscale impacts into the toxicity of silver compound.