Pope C, diLorenzo K, Ehrich M
Division of Pharmacology and Toxicology, College of Pharmacy and Health Sciences, Northeast Louisiana University, Monroe 71209-0470.
Toxicol Lett. 1995 Jan;75(1-3):111-7. doi: 10.1016/0378-4274(94)03167-6.
Little is known regarding early biochemical events in organophosphate-induced delayed neurotoxicity (OPIDN) except for the essential inhibition of neurotoxic esterase (NTE). We hypothesized that a trophic factor may be produced in situ shortly after exposure to the OP which participates in the progression of OPIDN. To bioassay for such a growth-modulating factor(s), we treated chickens with the neuropathic agents diisopropylfluorophosphate (DFP) or cyclic phenyl saligenin phosphate (PSP), with or without phenylmethylsulfonyl fluoride (PMSF, a chemical which markedly modifies OPIDN). Soluble extracts of cervical spinal cord (a region of the nervous system which degenerates with OPIDN) were collected 24 h later and these were incubated with human neuroblastoma SY5Y cells in culture. The cells were allowed to grow for another 6 days and observed for changes in morphology and growth. After 3 days in culture, tissue extracts from OP-treated chickens caused SY5Y cells to begin to elongate and extend processes (neurites), similar to cells treated with nerve growth factor (1 microgram/ml). Extracts from chickens not receiving OP had no or minimal effects on cell morphology. In addition, extracts from chickens in which OPIDN was prevented by pretreatment with PMSF did not cause the marked extension of cell processes exhibited after exposure of SY5Y cells to extracts from chickens given regimens known to cause OPIDN. In parallel-treated animals. DFP and PSP caused clinical dysfunction characteristic of OPIDN, PMSF posttreatment markedly amplified the clinical deficits and PMSF pretreatment prevented OPIDN. In vivo DFP treatment also caused a marked reduction in the activity of the growth-related enzyme ornithine decarboxylase (ODC) in spinal cord but DFP was without effect on ODC activity in vitro (up to 1 mM final concentration). Characterization of this growth-modulating factor(s) may aid in the elucidation of pathological mechanisms of OPIDN.
除了神经毒性酯酶（NTE）受到必要抑制外，关于有机磷酸酯诱导的迟发性神经毒性（OPIDN）早期生化事件的了解甚少。我们推测，接触有机磷酸酯后不久可能会原位产生一种营养因子，它参与OPIDN的进展。为了对这种生长调节因子进行生物测定，我们用神经性药物二异丙基氟磷酸酯（DFP）或环苯基磷酰二苯酯（PSP）处理鸡，同时或不使用苯甲基磺酰氟（PMSF，一种能显著改变OPIDN的化学物质）。24小时后收集颈脊髓（神经系统中一个会因OPIDN而退化的区域）的可溶性提取物，并将其与培养中的人神经母细胞瘤SY⁵Y细胞一起孵育。让细胞再生长6天，并观察其形态和生长的变化。培养3天后，经有机磷酸酯处理的鸡的组织提取物使SY⁵Y细胞开始伸长并伸出突起（神经突），类似于用神经生长因子（1微克/毫升）处理的细胞。未接受有机磷酸酯处理的鸡的提取物对细胞形态没有影响或影响极小。此外，用PMSF预处理预防了OPIDN的鸡的提取物，不会导致SY⁵Y细胞暴露于已知会导致OPIDN的鸡的提取物后所出现的细胞突起明显延长。在平行处理的动物中，DFP和PSP导致了OPIDN的临床功能障碍特征，PMSF后处理显著加重了临床缺陷，而PMSF预处理预防了OPIDN。体内DFP处理还导致脊髓中与生长相关的酶鸟氨酸脱羧酶（ODC）的活性显著降低，但DFP在体外（终浓度高达1毫摩尔）对ODC活性没有影响。对这种生长调节因子的特性进行表征可能有助于阐明OPIDN的病理机制。
