Role of hippocampal mast cells in early postoperative cognitive impairment in rats / 中华麻醉学杂志

ABSTRACT

Objective@#To evaluate the role of hippocampal mast cells in the early postoperative cognitive impairment in rats.@*Methods@#Eighty male Sprague-Dawley rats, aged 6-8 weeks, weighing 200-250 g, were divided into 4 groups (n=20 each) using a random number table method: normal saline control group (group C), cromolyn injected into lateral cerebral ventricle group (group L), operation group (group O), and cromolyn injected into lateral cerebral ventricle plus operation group (group LO). Cromolyn 2 μl (100 μg/ul) was intracerebroventricularly injected in L and LO groups.The equal volume of normal saline was given instead in C and O groups.Open reduction and internal fixation was performed after tibial fracture was induced 30 min later in O and LO groups.Contextual fear conditioning and Y-maze tests were performed at 1 and 3 days after operation, and the freezing time and the number of learning trails were recorded.The animals were then sacrificed, and hippocampal tissues were obtained for determination of activated mast cell count (by toluidine blue staining) and expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) mRNA (by polymerase chain reaction).@*Results@#Compared with group C, the number of learning trails was significantly increased, and the freezing time was shortened, the number of activated mast cells in hippocampi was increased, and the expression of IL-1β mRNA was up-regulated at 1 and 3 days after operation, and the expression of TNF-α mRNA was up-regulated at 1 day after operation in group O(P<0.05), and no significant change was found in the parameters mentioned above in group L (P>0.05). Compared with group O, the number of learning trails was significantly decreased, and the freezing time was prolonged, the number of activated mast cells in hippocampi was decreased, and the expression of IL-1β mRNA in hippocampi was down-regulated at 1 and 3 days after operation, and the expression of TNF-α mRNA in hippocampi was down-regulated at 1 day after operation in group LO (P<0.05).@*Conclusion@#Activation of hippocampal mast cells can induce central inflammatory responses and is involved in the mechanism of early postoperative cognitive impairment in rats.