| Some patients with acute carbon monoxide poisoning(CO-P) suffered from delayedneurological sequelae(DNS) and some nervous or psychiatric symptoms appeared after aperiod of performance of normal or near normal time named "latent phase". In clinical, it iswell known that hyperbaric oxygen(HBO) therapy is effective in patients with acute CO-P.However whether it has preventive effect on DNS of acute CO-P,and how much ifany,and whether HBO can be an effective treatment of DNS of acute CO-P, remains quitecontroversial. In order to provide basic scientific evidence that HBO is effective inpreventing and treatment CO-P DNS, and to prove that it could be used clinically, wemodified an established acute CO-P animal model(rats) based on previous studies.According to the grouping, the treatment group after the exposure to HBO, we detected theneurological behavior of rats in each group, at the same time and in the same conditions,and evaluate the morbidity of DNS after CO-P by examination of rats’ behavioral changes.The rats’ brain have be taken for morphological and immunohistochemical studies to assessthe histocyte protection effect generated by HBO. Thus, from cellular and molecular levels,we explored the influence of HBO to the incidence of acute CO-P DNS, and discussed itspossible mechanisms. The results of this research provided scientific evidences for clinicalapplication of HBO to prevent and treat CO-P DNS, and lay the fundation of futurestudies.Objective To explore and establish the acute CO-P animal models which couldeffectively increase the morbidity of DNS in rats. TO improve the assessment whetheracute CO-P DNS has occurred. To observe the morbidity of DNS, the pathological changesand the expression of myelinbasicprotein(MBP) in rats. TO reveal the influence of HBO onacute CO-P DNS, so as to explore the possible mechanisms of prevention and treatment ofHBO on acute CO-P DNS.Methods In this study,we used the method that intraperitoneal injection of pure CO gasto establish acute CO-P rats model. Male SD rats,48, weight about400g, after the basictraining of Morris Water Maze and screening, randomly divided into normal controlgroup(NC group), acute carbon monoxide poisoning group(CO-P group), acute carbonmonoxide poisoning group and hyperbaric oxygen therapy group(HBO group). The acuteCO-P model was made by intraperitoneal injection of pure CO gas by120ml/kg, and thenevery4h, an additional injection by half of the first dose for four times.We determinedcarbonyl hemoglobin(COHB) levels and observed rats’ behavioral changes. HBO therapy was given on HBO group. Rats in each group test behavioral changes with the DNSincubation period(2~21d), using the Morris water maze test, every other day. It wasidentified as a DNS that the escape latency increased again in two successive. In the21thday after modeled, we got rats’ brain tissue(hippocampus) to make paraffin tissue sections.To observe the histological changes by HE staining. Using immunohistochemical(IHC)techniques to detect MBP levels in the hippocampus. To detect the expression of MBP inrats’ brain tissue by Western Blotting(WB), and then to analyze results by image analysissoftware(Image J). These results were compared between groups for statistical analysis.Results1.Establishment of acute CO-P model in rats. After graded intraperitoneal injection of pureCO gas, rats had varying degrees of brain damage within15min. For example, restlessness,shortness of breath, hitting the cage, convulsion and limbs limp, etc. carbonyl hemoglobindetection: COHB%>50%, continuous16h.2.Morris water maze testing: The cases of CO-P group than suffer from DNS in the7th,14th and21th, respectively, is three(in the first week), five(in the second week) and one(inthe third week). The same period of time in HBO group the number of the DNS cases is:two, two and zero.21days after exposure, the morbidity of DNS in the HBO group wassignificantly lower than it in the CO-P group.The escape latency of CO-P group and HBOgroup prolonged with varying degrees. For rats which have suffered from DNS in bothgroups, compare the score between the escape latency increased again and the rat’s averagescore of21days.The results showed that rat’s abilities of learning and memory were higherthan that in CO-P group.3.Western Blotting results showed that the expression of MBP in CO-P group rats braintissue was significantly lower than it in HBO group(P<0.05). The expression of MBP inboth groups were lower than the NC group(P<0.05）4.HE staining of rat hippocampus showed: both CO-P group and HBO group had varyingdegrees of nerve cell degeneration and necrosis. Its performance as the cell arrangement ofclutter, cyton shrink and the nucleus deeply stained.5.IHC staining results showed IOD values of MBP in hippocampal tissue of CO-P groupwas significantly lower than it in HBO group(P<0.05)Conclusion HBO can effectively reduce the morbidity of the DNS after acute CO-P,mitigate the disease severity of DNS, reduce the demyelinating injury of the brain tissueand play an important role to protect the brain cells. |
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