The Therapeutic Effect Of Different Doses Of Atropine And Pralidoxime-cl (PAM-CL) On The Damage Of Nerve Of Acute Organic Phosphorus Poisoning (AOPP)

Objective: In this study, we established acute organophosphorus pesticide poisoning (AOPP) rat model, and used different doses of atropine and pyradoxime methyl chloride (PAM-Cl) to give its treatment. By observing the clinical manifestations of rats, the morphological changes of nerve cells and the determination of AChE area ratio of positive cells in rat brain to understand the mechanism of the organophosphate poisoning, the impact of different doses of atropine and PAM-Cl on the injury of the nervous system to further guide clinical treatment.Methods: An experimental model of AOPP was made by giving 2LD50 omethoate to rats intragastrically. According to the therapy, 70 rats were randomly divided into 7 groups, every group was 10 rats. Group A (the blank control group): the same volume of intragastric normal saline infusion to the experimental group; While the remaining 6 groups were infused into the stomach of 2LD50 (100mg/kg) omethoate. Group B (the untreated group): without any treatment of the posioned rats; Group C (the low-dose PAM-Cl and appropriate atropine treated group); Group D (the middle-dose PAM-Cl and appropriate atropine treated group); Group E (the concentrated-dose PAM-Cl and appropriate atropine treated group); Group F (the low-dose atropine and middle-dose PAM-Cl treated group); Group G (the large-dose atropine and middle-dose PAM-Cl treated group). After 24 hours the animals were injected intraperitoneally with chloral hydrate, and then we took the brain tissue after anesthesia, cut the brain tissue of the cerebral cortex and hippocampus simultaneously, put 4% of the specimen into the solution of paraformaldehyde and fixed it, did the observe of hematoxylin-eosin (HE) staining morphology, electron microscope and acetylcholinesterase (AChE) immunohistochemistry staining. By observing the clinical manifestations of rats, the morphological changes of nerve cells and the determination of AChE area ratio of positive cells in rat brain, we can understand the extent of nerve injury indirectly, and compare the difference between groups by Statistical Methods.Results:1 The clinical manifestations of poisoning ratsThe blank-control group didn't show any toxic manifestations. The obvious toxic manifestations can appear in the group B after 20 minutes, including the muscarinic symptoms (nausea, vomiting, sweating, tearing, salivation, miosis and polypnea, among which there were three having obvious dyspnea), the nicotinic symptoms (the myokymia of the four limbs happened), the symptoms of central nervous system (ataxia, and coma, even convulsions). The rats of group C appeared the myokymia of the four limbs,thirst and ataxia. The rats of group D showed mild ataxia. The rats of group E had no toxic manifestations, only thirst. The rats of group F showed nausea, vomiting, salivation, miosis and dispiritedness. The rats of group G showed the clinical manifestation of atropinism, such as more corectsis than before, thirst, dry skin and mucous membranes, dysthesia and irritability extremely.2 The results of rats'HE stainingNo neurologic disease happened in the blank-control group. The performance of the nerve cells of the group B were obvious swelling, degeneration, and even necrosis, the nerve cells of group C were also obvious swelling, but had no necrosis. The rats of group D,F and G were mild swelling. The rats of group E had swelling occasionally.3 The SEM performances of ratsThe cortical neuron: The neurons cells of the blank-control group were almost normal. The neurons cells of the group E were almost normal. The neurons cells of the groups of D,F and G had no swelling, but had vascular space widened and mitochondrial swelling. The neurons cells of the group C had mild swelling, accompaning by vascular space widened and mitochondrial swelling, while the neurons cells of the group B were obvious.The hippocampus: The neurons cells of the blank-control group were almost normal. The neurons cells of the group E were almost normal and glial cells were edema. The neurons cells of the groups of D,F and G had no swelling, but had neuronal shrinkage, increased electron density, neuropil and glial cells edema. The neurons cells of the group B were obvious swelled, but the organelle was almost normal.4 The results of immunohistochemical staining in ratsThe AChE of normal rats'brain tissues had significant expression, but had little expression of the untreated groups'brain tissues, after image analysis, compared the group B with the group A, which had statistical significance (P<0.05), it was reputed that the AChE-positive cells of poisoned group which compared with the normal-control group decreased, organic phosphorus can inhibit the AChE. The AChE in rat brain tissues of different treated groups had different expressions, after image analysis, compared these different treated groups with the group A and the group B, which had statistical significance (P<0.05), Arguably, organophosphorus compounds can inhibit AChE and the treated groups had reactivation of the AChE; Group E which was compared with the group C and the group D had statistical significance (P<0.05), it was reputed that the concentrated-dose PAM-Cl had better reactivation of the AChE than the low-dose and the middle-dose PAM-Cl. Compared the group F with the group G and the group D, the group F had no statistical significance, thus it was considered that Atropine had no influence on the AChE.Conclusion:Acute organophosphate poisoning can cause the damage of the rat's cerebral cortex and hippocampus. All of the groups of PAM-Cl had reactivation of the AChE of the rat's cerebral cortex and hippocampus, and the concentrated-dose PAM-Cl had the best reactivation of the AChE than the low-dose and the middle-dose PAM-Cl, the low-dose PAM-Cl was the worst, so we infer that the different groups of PAM-Cl may reduce the injury of rat's cerebral cortex and hippocampus, and the therapy by the concentrated-dose PAM-Cl is the best. The differents groups of atropine had no effect on the AChE of the rat's cerebral cortex and hippocampus, so we infer that the atropine had no effect on the cerebral cortex and hippocampus of the rat, but whether it can reduce central nervous system injury by easing the muscarinic symptoms and other mechanisms still need further study.