| Postoperative cognitive dysfunction(POCD)is a clinical problem usually seen in patients after surgical procedures which is characterized by confusion of consciousness,memory loss,lack of concentration and learning difficulties,leading to a series of social problems such as reduced quality of life and higher postoperative mortality.Nowadays,due to no specific drug treatments to solve this problem,it is quite significant to figure out the preoperative risk factors of POCD and endeavour to avoid them in perioperation.However,patients’ evident preoperative pain state has not been included in the risk factors of POCD,and further study is needed to determine whether it plays a role in POCD.In this experiment,through the establishment of inflammatory model by plantar injection of Complete Freund’s adjuvant(CFA)to male SD rats of different age groups,we assessed the changes of rats’ spatial learning ability,cognitive function and memory flexibility after anesthesia by Morris Water Maze(MWM)test.Finally,we confirmed the facilitated effects of preoperative pain state on POCD and complemented the understanding of preoperative risk factors of POCD.In addition,due to the reason that serotonin(5-HT)neurons in dorsal raphe nucleus(DR)are the main source of 5-HT for most nucleus related to cognitive function,we did further research on the activated state of serotonin neurons in DR region.We expect our research to raise awareness among the clinicians on the importance of preoperative pain state.Thus,clinicians would put more efforts to solve the relative problems,reduce the impact of POCD on patients’ quality of life and likewise decrease their postoperative mortality.The followings are the main findings of this project:1.Effects of chronic inflammatory pain on cognitive function declination in the rats.Behavioral study showed that plantar injections of CFA on the rats could cause a decline in cognitive function after 7 days.This is shown in the Morris Water Maze(MWM)results that the rats spent relatively less time in the target quadrant and took a longer time to find the platform.2.Facilitated effects of chronic inflammatory pain on postoperative cognitive function declination in the rats.(1).Behavioral study showed that anesthesia after plantar injections of CFA 7 days on the rats could cause a decline in cognitive function after an additional of 7 days.This is shown in the MWM results that the rats spent relatively less time in the target quadrant and took a longer time to find the platform.(2).Immunofluorescence results showed that the quantity of activated serotonergic neurons in DR of chronic inflammatory pain rats was reduced after anesthesia procedure.(3).Western blot results showed that the content of tryptophan hydroxylase(TPH)in DR of chronic inflammatory pain rats was declined after anesthesia procedure.3.Acute inflammatory pain has no effect on postoperative cognitive function in the rats.(1).Behavioral study showed that anesthesia after plantar injections of CFA 1 day on the rats have no effect on postoperative cognitive function.This is shown in the MWM results that the rats spent relatively more time in the target quadrant and took a shorter time to find the platform than before.(2).Immunofluorescence results showed that the quantity of activated serotonergic neurons in DR of acute inflammatory pain rats had no changes after anesthesia procedure.In conclusion,the changes before and after anesthesia procedure of chronic inflammatory pain rats by the MWM showed that chronic inflammatory pain could cause a decline in cognitive function;and could contribute to a facilitated effect on postoperative cognitive function declination,while acute inflammatory pain had no impairment in rats’ postoperative cognitive function.In addition,the reduced quantity of activated serotonergic neurons in DR suggested that changes in DR might have declined the 5-HT level in the forebrain nucleus associated with cognitive function,leading to cognitive impairment.Therefore,preoperative pain state is a significant factor affecting the occurrence of POCD,which should draw attentions from clinicians.Only in this way,could we reduce the incidence of POCD for patients,improve their postoperative quality of life,decrease their postoperative mortality,and so reduce the burden of family and society. |
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