| Objective:On the basis of animal model,the molecular and pathological changes of POCD were observed by imaging and pathological detection,and the possibility of PET/CT imaging in the diagnosis and mechanism of POCD was discussed,so as to lay a foundation for the transformation of further research results and clinical application,and provide new ideas for the diagnosis of POCD.Methods:SD rats aged 18-20 months were anesthetized with sevoflurane.The behavioral ability of rats was tested by Morris water maze system,and the animal model of POCD was established.The rats were divided into two groups: control group C and sevoflurane group S group.Five rats were randomly selected immediately,1 day,2 days,3 days and 7 days after modeling.According to their body weight,the rats were injected with contrast medium through tail vein and PET/CT imaging was performed after injection of 30 min.After PET/CT observation,the brains of the rats were taken immediately,and the bilateral hippocampi were separated on the ice.The specimens were weighed and stored in a cryopreservation tube in liquid nitrogen.The routine paraffin sections of hippocampal tissue were observed by electron microscope.Result:The results of animal behavior experiment showed that after the swimming latency,total swimming distance,times of crossing the original platform and staying time in the second quadrant of the aged SD rats in group S and group C,it was found that the swimming latency of the aged SD rats in group S was prolonged,the total swimming distance increased,the times of crossing the original platform decreased,and the residence time in the second quadrant shortened.The imaging results showed that the 5HT1 A receptors in the brain of aged SD rats were mainly distributed in the hippocampus and raphe nuclei,followed by other regions,such as frontal cortex,cingulate cortex,thalamus,marginal forebrain,striatum and so on.Immediately and on the 1st day after anesthesia,the SUVAve value of 5HT1 A receptor in group S was significantly lower than that in group C,and the SUVmax value in hippocampus and raphe nucleus in group S was also lower than that in group C.At the same time,the distribution of 5HT1 A in the hippocampus and raphe nucleus changed greatly,and its degree was negatively correlated with the value of 5HT1 A receptor SUVmax before anesthesia.On the 2nd,3rd and 7th day after anesthesia,the SUVmax and SUVAve values of aged rats in group S increased gradually,and gradually returned to the level close to or even higher than that in group C.Conclusion:Inhalation of 2% sevoflurane for 4 hours can cause cognitive impairment in aged rats.Compared with the control group(group C),the distribution of 5-HT1 A receptors in hippocampus,raphe nucleus,cingulate cortex,temporal lobe cortex,thalamus,striatum,limbic forebrain,cerebellum and brainstem in sevoflurane group(group S)was different,and the standard uptake value(SUV)changed.The results of 18F-MPPF PET/CT may be related to the development of POCD,which has a certain reference significance for the early diagnosis of POCD. |
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