The implementation of anesthetic procedure in aquatic crustaceans remains mostly limited to studies dealing with sedation and survival from anesthesia, possibly owing to the debated question of pain in invertebrates. However, two important issues are generally overlooked: actual analgesic-like effect, and possible physiological post-anesthesial effects. Here we report on the anesthetic properties and possible after-effects of MS-222 (Tricaine Methanesulfonate or Ethyl 3-aminobenzoate methanesulfonate) and Eugenol in the freshwater amphipod Gammarus pulex. We first optimized the concentration of MS-222, and the induction and recovery time, based on preliminary tests and published studies. We then relied on the nociceptive modulation of sheltering behavior to assess the analgesic-like effect of the two drugs, using a new semi-automated electric shock device. In addition, we monitored the impact of anesthesia with MS-222 on locomotor activity and oxygen consumption and addressed potential adverse effects upon recovery using biomarkers related to metabolism and neurotoxicity. We provide evidence for the sedative and analgesic-like effects of MS-222 at 600 mg.L⁻¹ and, to a lesser extent, of Eugenol at 100 µL.L⁻¹, with no decrease in survival rate at 6 days post anesthesia. Oxygen consumption was reduced -but not eliminated- under full anesthesia with 600 mg.L⁻¹ MS-222. No significant physiological effect of anesthesia was evidenced on the activity of the mitochondrial electron transfer system, or that of acetylcholine esterase, nor on total antioxidant capacity. We therefore conclude to the efficiency of MS-222 as an anesthetic drug in G. pulex. Eugenol should be tested at a higher concentration to reach the same efficiency, providing that increased concentration would not incur side-effects. Furthermore, the new and original semi-automated electric chock device used to induce nociception can be easily adapted to any species of aquatic invertebrates and small-sized fish and tadpoles, offering a standardized and flexible protocol to study nociceptive response and anesthesia in aquatic organisms.

在水生甲壳类动物中实施麻醉程序仍然主要限于处理镇静和麻醉存活的研究，这可能是由于无脊椎动物疼痛的争论问题。然而，两个重要问题通常被忽视：实际的镇痛样作用和可能的麻醉后生理作用。在这里，我们报告了淡水片脚类动物Gammarus pulex中 MS-222（三卡因甲磺酸盐或 3-氨基苯甲酸乙酯甲磺酸盐）和丁香酚的麻醉特性和可能的​​后遗症. 我们首先根据初步测试和已发表的研究优化了 MS-222 的浓度以及诱导和恢复时间。然后，我们使用一种新的半自动电击装置，依靠对避难行为的伤害性调节来评估这两种药物的镇痛样作用。此外，我们监测了 MS-222 麻醉对运动活动和耗氧量的影响，并使用与代谢和神经毒性相关的生物标志物解决了恢复后的潜在不利影响。^{我们为 600 mg.L -1}的 MS-222和 100 µL.L ^-1丁香酚的镇静和镇痛样作用提供了证据。，麻醉后 6 天的存活率没有降低。^{在用 600 mg.L -1} MS-222完全麻醉的情况下，氧气消耗减少了，但并未消除。麻醉对线粒体电子传递系统或乙酰胆碱酯酶的活性以及总抗氧化能力没有明显的生理影响。因此，我们得出结论，MS-222 作为G. pulex中的麻醉药的有效性. 丁香酚应在更高浓度下进行测试以达到相同的效率，前提是增加浓度不会产生副作用。此外，用于诱发伤害感受的新的和原创的半自动电塞装置可以很容易地适应任何种类的水生无脊椎动物和小型鱼类和蝌蚪，为研究水生生物的伤害感受和麻醉提供了一个标准化和灵活的协议。