Alleviation of specific responses in the combined exposure of freshwater mussel Unio tumidus to psychoactive substances and microplastics

The environmentally relevant aquatic pollution is associated with the mixtures of xenobiotics, each in the low, picomolar to micromolar concentrations. Among these substances, the combinations of pharmaceuticals and microplastics (MP) have become an increasingly serious threat. The objective of this study was to track the specific and multi-stress responses of swollen river mussels (Unio tumidus) to the psychoactive substances caffeine (Caff) and chlorpromazine (Cpz) in the combined exposure with MP. The MP (1 mg•L-1, size 35–50 μm), Caff (20 µg•L-1), Cpz (12 ng•L-1) or their mixture (Mix) were administered to mussels for 14 days. The redox state, enzymes of biotransformation and apoptosis were analysed in the digestive gland. All exposures except Mix caused oxidative injury to lipids and proteins, accompanied by increased GSH and metallothionein levels, suppressed NAD+ and activation of GST (except Mix), and GTPase. MP had the lower particular impact. Specific responses to Caff were activation of Cyp450 (EROD) and cathepsin D, decreased GSH/GSSG ratio and prominent demetallation of metallothionein. The Cpz caused an increase in NADH/NAD+ ratio and caspase-3 inhibition. In the combined exposure, the specific responses to single xenobiotics were alleviated which was confirmed by discriminant analysis. The Mix-group was distinguished by the highest NADH/NAD+ and GSH/GSSG ratios, markedly increased caspase-3 activity accompanied by the decrease of protein carbonyl level and the highest IBR index, attesting to the negative cumulative effect of multi-stress exposure. The vulnerability of mussels to pM concentration of neuroleptic Cpz needs particular attention.

与环境相关的水生污染与外源性物质（如药物和微塑料）的混合物有关，这些物质在低至皮摩尔至微摩尔浓度范围内。在这些物质中，药物与微塑料（MP）的混合物已成为日益严重的威胁。本研究的目的是追踪膨胀河蚌（Unio tumidus）对微塑料（MP）（浓度为1 mg•L-1，尺寸为35–50 μm）、咖啡因（Caff）（20 µg•L-1）和氯丙嗪（Cpz）（12 ng•L-1）联合暴露中精神活性物质的特定和多应激反应。MP、Caff、Cpz或其混合物（Mix）被给予河蚌连续14天。在消化腺中分析了氧化还原状态、生物转化酶和细胞凋亡。除混合物外，所有暴露均导致了脂质和蛋白质的氧化损伤，伴随GSH和金属硫蛋白水平的升高，NAD+的抑制和GST（除混合物外）的激活，以及GTPase的激活。MP具有较低的特殊影响。对Caff的特定反应包括Cyp450（EROD）和半胱天冬酶D的激活，GSH/GSSG比值的降低和金属硫蛋白的显著去甲基化。Cpz导致NADH/NAD+比值的增加和半胱天冬酶-3抑制。在联合暴露中，对单一外源性物质的特定反应得到缓解，这通过判别分析得到证实。混合物组表现出最高的NADH/NAD+和GSH/GSSG比值，伴随蛋白质羰基水平的降低和最高的IBR指数，这证明了多应激暴露的负性累积效应。对神经安定剂Cpz的pM浓度敏感的河蚌易损性需要特别关注。