| Background and purposePostoperative cognitive dysfunction (POCD) defined a commom complication ofelderly patients suffer surgical,with the clinical manifestations of mental disorder, anxiety,personality changes, and impaired memory. It can affect the long-term learning and memoryfunction in patients and may continue to deteriorate.It can cause great damage to society andpatients. With the continuous improvement of medical technology level and the number ofelderly surgical patients increased significantly, the incidence of POCD is high, take theattention of people. But the exact mechanism of POCD and related factors are still unknown.Previous studies shown us POCD merger with the disease of preoperative patients,operation, anesthesia, genetic, etc. Aging and surgical are two more important factors, andthe research showed that inflammation was related to the occurrence of AD and POCD.Microglia plays a crucial role in the central inflammatory caused by surgery. The activationof MI was currently recognized as one keypoint of the pathogenesis of POCD.The researchreported that anemia in chronic inflammation (ACD) patients often have abnormal ironmetabolism, meanwhile hepcidin is a key hormone regulated the metabolism of iron, it canadjust the transport of iron ions by changing the express of ferroportin1(FP1).Interestingly,the injury, infection and inflammation stimulation can cause high expression ofHepcidin, so we speculated that on the basis of the increase expression of hepcidin in olderrats, surgical stress could increase the expression of hepcidin easily, then block the transit ofiron, activate the microglia for the inflammatory response, lead to POCD. This is thepurpose of our study, we taked Morris water maze test, Western blot and RT-PCR to detectthe learning and memory ability of rats, the change of the express of hepecidin and FP1inthe hippocampus, explore the exact cause of POCD and the possible mechanism. Methods4months old (weighing200-350g) and18months old (weighing400-500g) male SDrats were randomly divided into4groups: group A1(surgical aged group), group A0(agedcontrol group), group B1(surgical adult group), group B0(adult control group), each groupwith50rats. One group was undergoing operation30min after anesthetized with chloralichydras. control group was anestheized with chloralic hydras.10rats randomly selected fromeach group to assessed the memory and spatial learning of rats with Morris water-maze testfrom1d to6d after treatment in24hour,10rats randomly selected from the rest rats werekilled on day1, day3, day5, day7for PCR and Western blot test.Result1. the results of Morris water-maze testThe escape latency period of the group A1were longer than group A0at day3, day4,day5(P <0.05), there were no significant differences between group B1and group B0（P>0.05, and nosignificantdifferences betweengroup A0, group B1and group B0（P>0.05）.Compared with group A0, the frequency of crossing the original platform and the timeconsumption of staying the original platform quadrant were lower in group A1(P<0.05),Compared with group B0, the frequency of crossing the original platform and the timeconsumption of staying the original platform quadrant were no differences in group B1（P>0.05）.2. the results of Western blotThe results of Western blot showed that the express of hepcidin of aged rats wereup-regulated in group A1which were sufferred operation30min（P<0.05）, especially day1after surgery the change were more obvious, and this change did not happened in the adultgroup（P>0.05）, the express of FP1of aged rats were down-regulated in group A1whichwere sufferred operation30min（P<0.05）, the change at day1were most evident.Nosignificant differences were found between group B1and group B0(P>0.05).3. the results of RT-PCRCompared with group A0, the expression levels of hepcidin in hippocampus in agedrats were significantly higher in group A1(P<0.05), increased most obviously at Day1, andgradually reduced at day3, day5, tends to be stable at day7. The expression levels of FP1in hippocampus in aged rats were significantly lower in group A1(P<0.05), no significant differences were found between group B1and group B0(P>0.05).Conclusion1. the results of Morris water-maze test confirmed that surgical stress can lead todecreased cognitive function in aged rats, it did not happened in adult rats.2. Surgical stress can affect the expression of Hepcidin/FP1in hippocampal of aged rats,no significant differences were found in adult rats.3. the abnormal expression of Hepcidin/FP1which caused by surgical stress maybeone of the reasons for the decline of cognitive function in aged rats. |
