Abstract

The aim of this study is to elucidate the toxicity induced by PbCl₂, administered in graded doses (1; 2.5; 5 mg/L), in the redox state, in the fatty acid composition and in the histological structure of Mactra corallina digestive glands. Our findings showed a progressive accumulation of Pb in the M. corallina digestive glands in all treated groups. After 5 days of treatment with PbCl₂, an increase in H₂O₂, MDA, PCO, GSH, NPSH and MT levels was observed in the digestive glands of treated groups. Moreover, activities of antioxidant enzymes, such as GPx and CAT, increased while SOD activity decreased in all treated groups, indicating a failure of the antioxidant defense system. Furthermore, the cholinergic function was evaluated by assessing the acetylcholinesterase activity, which was inhibited in all the treated digestive glands compared to the control group. In our experiment, the levels of n-3 (Omega-3) and n-6 (Omega-6) polyunsaturated fatty acids were greatly altered in the groups treated with 5 mg/L of PbCl₂ (p < 0.001). Indeed, DHA and EPA decreased significantly in the digestive glands treated with 2.5 and 5 mg/L of PbCl₂, respectively. On the other hand, under exposure to the medium and high doses (2.5 and 5 mg/L), arachidonic acid (ARA) and linoleic acid (LA) significantly increased (p < 0.001). These changes in PUFA were confirmed by significant modifications in the polyene and peroxidation indices. The histological findings confirmed the biochemical results.

• Highlights

• Integrated parameters were used to explore the toxic effect of PbCl₂ graded doses in Mactra corallina digestive gland.

• Metals accumulation in digestive glands of M. corallina was greatly dependent to dose of PbCl₂.

• Metabolic and macromolecules damaging of clams digestive glands were more sensitive at higher PbCl₂ doses.

• Fatty acids composition especially polyunsaturated fatty acids (PUFA) and essentials fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in clams digestive glands were intensively altered at higher PbCl₂ doses.

• Inflammation responses revealed in studied tissue.

摘要

本研究的目的是阐明 PbCl ₂诱导的毒性，在分级剂量 (1; 2.5; 5 mg/L)、氧化还原状态、脂肪酸组成和Mactra 珊瑚消化腺的组织学结构中给药. 我们的研究结果显示，在所有治疗组中， M.corallina消化腺中的铅逐渐积累。_{用 PbCl 2}处理 5 天后，H ₂ O _2增加、MDA、PCO、GSH、NPSH和MT水平在治疗组的消化腺中观察到。此外，在所有治疗组中，抗氧化酶（如 GPx 和 CAT）的活性增加，而 SOD 活性降低，表明抗氧化防御系统失效。此外，通过评估乙酰胆碱酯酶活性来评估胆碱能功能，与对照组相比，乙酰胆碱酯酶活性在所有处理过的消化腺中均受到抑制。在我们的实验中，在用 5 mg/L PbCl _{2处理的组中，} n -3 (Omega-3) 和n -6 (Omega-6) 多不饱和脂肪酸的水平发生了很大变化( p  < 0.001)。实际上，用 2.5 和 5 mg/L PbCl 处理的消化腺中的 DHA 和 EPA 显着下降₂，分别。另一方面，在中高剂量（2.5 和 5 mg/L）下，花生四烯酸（ARA）和亚油酸（LA）显着增加（p  < 0.001）。多烯和过氧化指数的显着变化证实了 PUFA 的这些变化。组织学发现证实了生化结果。

• 强调

• 综合参数用于探索PbCl ₂分级剂量对Mactra珊瑚消化腺的毒性作用。

• M.corallina消化腺中的金属积累很大程度上取决于PbCl ₂的剂量。

• 对蛤蜊消化腺的代谢和大分子损伤在较高的PbCl ₂剂量下更为敏感。

• _{在较高的 PbCl 2}剂量下，蛤蜊消化腺中的脂肪酸组成，尤其是多不饱和脂肪酸 (PUFA) 和二十二碳六烯酸 (DHA) 和二十碳五烯酸 (EPA) 等必需脂肪酸发生了强烈变化。

• 在研究的组织中发现了炎症反应。