Mitra Nilesh K, Nadarajah Vishna D, Siong How Hee
Human Biology Department, International Medical University, No. 126, Jalan 19/155B, Bukit Jalil, 57000 Kuala Lumpur, Malaysia.
Folia Neuropathol. 2009;47(1):60-8.
Dermal absorption of chlorpyrifos (CPF), an organophosphate (OP) pesticide, is important because of its popular use. Stress has been reported to exacerbate neurotoxic effects of certain OP pesticides; however, quantitative studies to corroborate this are not reported. This study correlates the changes in acetylcholinesterase (AChE) levels and neuronal counts in areas of the hippocampus to consecutive exposure of stress, heat and CPF. Male mice (60 days) were segregated into six groups: one control, one stress control, and four treated groups (n=10). CPF was applied in doses of 1/2 and 1/5 of dermal LD50 (E1 and E2) over the tail of mice under occlusive bandages for 3 weeks. Stress control [(s) C] mice were subjected to swim stress at 38 degrees C (6 mins/day, 3 weeks). (s) E1 and (s) E2 were subjected to swim stress before CPF application. Blood and brain AChE levels were estimated using a spectrofluorometric method (Amplex Red). Pyramidal neurons of the cornu ammonis of the hippocampus under Nissl stain from histological sections were counted per unit area of section and analyzed statistically using one way ANOVA. Swim stress at 38 degrees C aggravated reduction of serum AChE by dermal exposure to CPF by 19.7%. Neurons of CA3 and CA1 regions of the hippocampus showed significant reduction in neuronal counts in (s) E1 and (s) E2 groups compared to E1 and E2 groups. Whereas application of CPF 1/2 dermal LD50 (E1) showed significant reduction of neuronal counts only in the CA3 area.
毒死蜱（CPF）是一种有机磷（OP）农药，由于其广泛使用，其经皮吸收具有重要意义。据报道，应激会加剧某些OP农药的神经毒性作用；然而，尚未有定量研究来证实这一点。本研究将海马体区域乙酰胆碱酯酶（AChE）水平的变化和神经元计数与应激、热和CPF的连续暴露相关联。将60日龄雄性小鼠分为六组：一组为对照组，一组为应激对照组，四组为处理组（n = 10）。在封闭绷带下，以皮肤半数致死剂量（LD50）的1/2和1/5剂量（E1和E2）将CPF涂抹于小鼠尾部，持续3周。应激对照组[（s）C]小鼠在38摄氏度下接受游泳应激（每天6分钟，持续3周）。（s）E1和（s）E2在涂抹CPF之前接受游泳应激。使用分光荧光法（Amplex Red）估计血液和大脑中的AChE水平。对组织学切片经尼氏染色的海马体角锥体细胞，在切片的单位面积内进行计数，并使用单因素方差分析进行统计学分析。38摄氏度的游泳应激使经皮暴露于CPF导致的血清AChE降低加剧了19.7%。与E1和E2组相比，（s）E1和（s）E2组海马体CA3和CA1区域的神经元计数显著减少。而涂抹CPF皮肤LD50的1/2（E1）仅在CA3区域显示出神经元计数的显著减少。
