Effect of copper nanoparticles on rainbow trout olfaction and recovery

Abstract

Fish depend on olfaction for reproduction and survival. Here, using molecular to behavioural endpoints, we compared the effect of two neurotoxic contaminants, Cu ions (Cu2+) and copper nanoparticles (CuNPs) on rainbow trout olfaction. Exposure to equitoxic concentrations of Cu2+ and CuNPs resulted in distinct toxicity patterns over time in rainbow trout olfactory mucosa. During continuous exposure to Cu2+, fish olfactory function was partially recovered. However, the olfactory function of CuNP-exposed fish showed a steady decline over time. Gene-transcript profiles of Cu2+-exposed olfactory mucosa showed neural repair mechanisms were upregulated to recover the olfactory dysfunction. In the CuNP treatment, dysregulation of transcripts that regulate function and reestablishment of damaged olfactory mucosa represented key mechanisms of CuNP-induced olfactory toxicity. Moreover, our findings revealed the CuNP-induced olfactory dysfunction was irreversible after the 7-day recovery period. Collectively, CuNPs and Cu2+ exert their effects via separate mechanisms in rainbow trout olfactory mucosa.