| Objective:Burn injuries cause various types of long-term psychiatric problems which needs to be diagnosed and interfered.At present,there is a lack of research on post-burn mental illnesses,especially on the mechanism.Peripheral intense inflammatory stress after burn can affect the brain through a variety of mechanisms.Neuroinflammation can be seen in a variety of disorders related to mental disorders and impaired cognitive function.We used a mouse burn model to study the long-term behavioral changes in burned mice.By observing the effects of burns on the brain during the acute and recovery phases,the mechanism of neurobehavioral changes in mice was analyzed from the perspective of neu-roimmunology.Method:(1)Home-cage locomotor activity,new object recognition experiments,and social preference experiments were selected to evaluate short-term memory,social competence,and social memory of mice 1 and 3 months after burn.(2)The mononuclear cells in the brain of burned mice were extracted.Flow cytometry and immunofluorescence staining were used to observe the infiltration of peripheral im-mune cells into brain in the acute phase after burn.TUNEL was used to detect cell apopto-sis.(3)The immunofluorescence staining of mouse brain tissue at 3 months after burn was performed to observe the expression of IB A-1 and GFAP in order to determine whether there was a neuroinflammation reaction.In addition,we examined the expression of SGK-1,a protein associated with learning and memory.Results(1)At 3 months after burn.the spontaneous movement distance was significantly increased in the burn group(P<0.01),and the distance of movement in the sham injury group was lower than the normal group(P<0.05).At 1 month after injury,compared with the normal group and the sham-injured group,the burn group had a lower DI value for sniffing time(P<0.01)and sniffing number(P<0.05)to new objects.This situation can last up to 3 months after injury.In the social preference experiment,the mice's sociability and the social preference to the newly unfamiliar stimuli were lower comparing with the other two groups at the first month after burn,and they returned to normal level at 3 months after the burn.(2)At 24 hours after burn,the proportion of CD45+CD3+ T cells in the brain of burned mice was significantly higher than that in the sham group([1.103±0.674)%vs.(0.385±0.109)%,P<0.05].The proportion of CD45intCD11b+ in the burn group was higher than that in the sham injury group[(1.017±0.35)%vs.(0.502±0.358)%,P<0.05],suggesting that the degree of activation of microglial cells in the burn group was higher.Immunofluorescence staining showed that there were immunoreactive T cells and CD45high cells in the perivascular and choroidal plexus of the burn group,but no positive in the sham group.In addition,significantly more apoptotic cells were found in the brain parenchyma and surrounding periventricular in burned mice.(3)At three months after burn,the microglial cells in the brain increased and the cell body was larger,suggesting that the activation of microglial cells was increased compared with the sham-injured group,and the expression of GFAP was significantly increased in the burned mice.The expression of SGK1 in burned mice was lower than that in the sham injury group.Conclusion:1.Impaired short-term memory,social memory and decreased sociabil-ity were observed 1 month after burn.At three months after injury,short-term memory im-pairment in burned mice did not recover,and social ability and social memory had returned to normal levels.2.Peripheral immune cell infiltration,increased activation of microglia,and increased apoptosis of neurons were observed in the mouse brain 24 hours after burn.3.Signs of inflammation were still seen in the mouse brain three months after burn,and SGK-1 expression was reduced compared with the sham injury group. |
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