Combined Toxicity and Toxicity Persistence of Antidepressants Citalopram and Mirtazapine to Zooplankton Daphnia Magna

Abstract

Citalopram (CTP) and mirtazapine (MTP) are two typical psychoactive drugs used for the depression treatment. As emerging pollutants, CTP and MTP has been given widely concern because they are active substances for organisms. Therefore, the ecotoxicological risks of aquatic organisms should be paid more attention to. In this study, the effects of CTP and MTP on the feeding behavior, heartbeat, nutritional enzymes and related gene transcriptions of Daphnia magna were investigated under single and mixed environmental stress. Meanwhile, the recovery of exposed D. magna was studied to analyze the toxic persistence of those pollutants. After 24-hexposure, the ingestion rate decreased by 34.2% and 21.5%, in the group of C-H and Mix-H respectively. After 24-h recovery, the feeding behavior of D. magna was stimulated by compensatory stimulation. In exposure period, the heartbeat rate of D. magna increased by 132.3%, 69%, 111.9%, 139.4%, and 92.4%, in the group of C-L, C-H, M-L, M-H and Mix-L respectively, and was recovered during the recovery period. The activity of α-amylase (AMS) and trypsin were significantly changed in most of the exposed daphnia, both in the exposure period and recovery period. CTP/MTP exposure stimulated transcription of the α-amylase gene. M-H and Mix-H exposure inhibited transcription of the trypsin gene and other stimulated transcriptions. After 24-h recovery, the stimulative or inhibitory effects were alleviated. There were different responses between gene transcription and enzyme activity. In conclusion, our results highlighted the toxic effects of single and mixed pollution of CTP and MTP on feeding, heartbeat, enzymes and genes of D. magna.