We investigated dexamethasone therapy for preventing delayed encephalopathy after carbon monoxide (CO) poisoning. Eighty healthy male rats were exposed to CO and randomly divided into four groups: hyperbaric oxygen treatment (H), treatment (D), combined hyperbaric and dexamethasone treatment (C), and a control (M) group in which the rats inhaled CO to coma in the hyperbaric oxygen chamber, then were removed without further treatment. Twelve rats were put into the hyperbaric oxygen chamber and treated with air for 60 min (N) group. An eight arm maze was used to evaluate cognitive and memory abilities of these mice. Serum myelin basic protein (MBP) levels were evaluated using ELISA, and magnetic resonance imaging was used to observe brain demyelination and morbidity associated with delayed encephalopathy. A sample of the hippocampus from each group was examined by light microscopy. Cognitive and memory functions decreased in the control group M. Three days after CO poisoning, the serum MBP level of each group increased significantly. On Day 10 after CO poisoning, the MBP levels in groups C and D decreased significantly, but returned to normal on Day 18. MBP levels in the M and H groups were elevated at all time points. Brain MRIs showed significant differences among C, D, H and control M groups. Hematoxylin & eosin staining of the hippocampus showed greater damage in the control M and H groups. Early dexamethasone treatment may be useful for preventing delayed encephalopathy after CO poisoning and may reduce serum MBP levels.

ABSTRACT. There is structural damage to myelin and secondary immune injury in the development of delayed encephalopathy after acute carbon monoxide (CO) poisoning (DEACMP). In order to assess the role of genetic factors in this mechanism, we studied the association between tumor necrosis factor-α308 (TNF-α308) and myelin basic protein (MBP) 5ꞌ-side tetranucleotide repetitive sequence (TGGA) n gene polymorphism and DEACMP. We selected 109 DEACMP patients from the Han population in the Northern Henan Province as the case group, and 115 patients without delayed encephalopathy (called the acute CO poisoning group or the control group). There were no significant differences in TNF-α308 and MBP 5ꞌ-side TGGA n genotype distribution and allele frequency between the DEACMP group and the acute CO poisoning group (all P > 0.05). When the population was stratified by gender, only the MBP 5ꞌ-side TGGA n allele frequency was significantly different, and the frequency of allele L in the DEACMP group was significantly higher than that of the acute CO poisoning group in males (χ 2 = 4.089, P = 0.043, odds ratio = 2.103, 95% confidence interval = 1.014-4.363). The results showed that there was association between MBP 5ꞌ-side TGGA n gene polymorphism and DEACMP, and that allele L could increase the risk of occurrence in male patients with DEACMP. DEACMP may be the result of interaction of environmental and genetic factors.