Department of Forensic Medicine and Toxicology, Faculty of Veterinary Medicine, Alexandria University, Edfina, Beheira, 22758, Egypt.
Department of Pathology, Faculty of Veterinary Medicine, Alexandria University, Edfina, Beheira, 22758, Egypt.
Environ Sci Pollut Res Int. 2020 Jun;27(18):23108-23128. doi: 10.1007/s11356-020-08588-5. Epub 2020 Apr 24.
Thiamethoxam (TMX) is a widely used neonicotinoid insecticide for its effective potential for controlling insects from the agricultural field, which might induce toxicity to the aquatic biota. In this study, the role of the probiotic Bacillus subtilis (BS) and a phytogenic oil extract of Thymus vulgaris essential oil (TVEO) in the modulation of thiamethoxam (TMX)-induced hepatorenal damage, oxidative stress, and immunotoxicity in African catfish (Clarias garipenus) has been evaluated. Fish were subjected to TMX (5 mg L) and fed with a diet either supplemented with BS (1000 ppm) or TVEO (500 ppm). The experiment lasted for 1 month. By the end of the experiment, blood was sampled for biochemical analysis and fish organs and tissues were collected for histopathological and immunohistochemical examinations. Results showed a substantial increase of serum markers of hepatorenal damage such as the activities of aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) and levels of blood urea nitrogen (BUN) and creatinine with an obvious decrease of serum protein levels in the TMX-intoxicated group. Also, there was a considerable increase in malondialdehyde (MDA) levels and glutathione-S-transferase (GST) activity. TMX remarkably suppressed serum lysozyme activity, respiratory burst activity, and phagocytosis with a conspicuous elevation of the levels of interleukins (interleukin-1 beta (IL-1β) and interleukin-6 IL-6). The histopathological findings showed that TMX induced degenerative changes and necrosis in the gills, liver, head kidneys, and spleen of the intoxicated fish. Significant alterations of frequency, size, and area percentage of melanomacrophage centers (MMCs), decreased splenocyte proliferation, and increased number of caspase-3 immunopositive cells were also observed. Contrariwise, the concurrent supplementation of either BS or TVEO in the diets of catfish partially mitigated both the histopathological and histomorphometric lesions of the examined tissues. Correspondingly, they improved the counts of proliferating cell nuclear antigen (PCNA) and caspase-3 immunopositive splenocytes. In conclusion, the co-administration of either BS or TVEO in catfish diets partially diminished the toxic impacts of TMX. Nonetheless, the inclusion of TVEO in the diets of catfish elicited better protection than BS against TMX-induced toxicity in response to its potential anti-inflammatory, antioxidant, anti-apoptotic, and immune-stimulant effects.
噻虫嗪（TMX）是一种广泛使用的新烟碱类杀虫剂，因其对控制农业领域昆虫具有有效潜力而被广泛应用，但可能会对水生生物群产生毒性。在这项研究中，评价了益生菌枯草芽孢杆菌（BS）和牛至精油（Thymus vulgaris essential oil，TVEO）植物源提取物对噻虫嗪（TMX）诱导的非洲鲶鱼（Clarias garipenus）肝肾功能损伤、氧化应激和免疫毒性的调节作用。将鱼暴露于 TMX（5mg/L）中，并喂食添加 BS（1000ppm）或 TVEO（500ppm）的饮食。实验持续了 1 个月。在实验结束时，采集血液进行生化分析，并采集鱼的器官和组织进行组织病理学和免疫组织化学检查。结果表明，与对照组相比，TMX 处理组的血清肝肾功能损伤标志物如天冬氨酸转氨酶（AST）、丙氨酸转氨酶（ALT）和碱性磷酸酶（ALP）的活性以及血尿素氮（BUN）和肌酐的水平显著升高，而血清蛋白水平显著降低。同时，丙二醛（MDA）水平和谷胱甘肽-S-转移酶（GST）活性也显著升高。TMX 显著抑制了血清溶菌酶活性、呼吸爆发活性和吞噬作用，同时白细胞介素（白细胞介素-1β（IL-1β）和白细胞介素-6（IL-6））水平显著升高。组织病理学检查结果表明，TMX 导致中毒鱼的鳃、肝、头肾和脾发生退行性变化和坏死。还观察到黑素巨噬细胞中心（MMC）的频率、大小和面积百分比的显著改变，脾细胞增殖减少，以及 caspase-3 免疫阳性细胞数量增加。相反，在鱼的饮食中同时添加 BS 或 TVEO 可部分减轻检查组织的组织病理学和组织形态学病变。相应地，它们增加了增殖细胞核抗原（PCNA）和 caspase-3 免疫阳性脾细胞的计数。总之，在鱼的饮食中同时添加 BS 或 TVEO 可部分减轻 TMX 的毒性影响。然而，与 BS 相比，在鱼的饮食中添加 TVEO 对 TMX 诱导的毒性具有更好的保护作用，这可能与其潜在的抗炎、抗氧化、抗凋亡和免疫刺激作用有关。
