Kamata R, Saito S, Suzuki T, Takewaki T, Kobayashi H
Department of Veterinary Pharmacology, Faculty of Agriculture, Iwate University, Morioka, Japan.
Neurotoxicology. 2001 Apr;22(2):203-14. doi: 10.1016/s0161-813x(00)00012-7.
To find new putative target(s) for organophosphorus induced delayed neurotoxicity (OPIDN), we investigated the biochemical and pharmacological characteristics of [3H] diisopropyl phosphorofluoridate (DFP) binding to membrane and cytosol preparations from the brain and spinal cord of hens. Specific [3H]DFP binding was determined by subtracting non-specific binding from total binding. The binding sites of [3H]DFP, an organophosphate that induces OPIDN, were found not only on membrane but also in cytosol. Reduction of subsequent ex vivo specific [3H]DFP binding by in vivo pretreatment with unlabeled DFP was found in cytosol, not membrane. The reduced binding lasted to the onset of OPIDN, especially in spinal cord. These results suggest that the specific DFP binding sites in cytosol, rather than on membrane, are the most important with regard to the initiation of OPIDN. Inhibitors of cholinesterase (ChE) and neuropathy target esterase (NTE) other than DFP did not affect specific [3H]DFP binding to either membranes or cytosol in vivo. Additionally, inhibition of the activities of these esterases by these compounds was not consistent with either the degree of inhibition of the [3H]DFP binding or a time-dependent manner of OPIDN. These results suggest that DFP binding site(s) involved in the initiation of OPIDN may be different from the active sites of ChE and NTE.
为了寻找有机磷诱导的迟发性神经毒性（OPIDN）的新潜在靶点，我们研究了[3H]二异丙基氟磷酸酯（DFP）与母鸡脑和脊髓的膜及胞浆制剂结合的生化和药理学特性。通过从总结合中减去非特异性结合来确定特异性[3H]DFP结合。发现诱导OPIDN的有机磷酸酯[3H]DFP的结合位点不仅存在于膜上，也存在于胞浆中。在胞浆而非膜中发现，用未标记的DFP进行体内预处理可降低随后的离体特异性[3H]DFP结合。结合减少持续到OPIDN发作，尤其是在脊髓中。这些结果表明，胞浆中而非膜上的特异性DFP结合位点对于OPIDN的起始最为重要。除DFP外，胆碱酯酶（ChE）和神经病靶酯酶（NTE）的抑制剂在体内不影响特异性[3H]DFP与膜或胞浆的结合。此外，这些化合物对这些酯酶活性的抑制与[3H]DFP结合的抑制程度或OPIDN的时间依赖性方式均不一致。这些结果表明，参与OPIDN起始的DFP结合位点可能不同于ChE和NTE的活性位点。
