| Objective:To investigate the effect of cardiopulmonary bypass(CPB)on postoperative cognitive function(POCD)rats and the protective effect of κ-opioid Receptor agonist against postoperative cognitive function(POCD)induced by cardiopulmonary bypass(CPB),and explore the mechanism of the protective roll mediated by CAP signaling pathways.This experiment is divided into two parts.The first part:To investigate the effects and the mechanism of cardiopulmonary bypass on postoperative cognitive dysfunction in ratsMethods:48 adult male SPF grade SD rats,aged 5-6 months,weighing 400-500g,were randomly divided into 4 groups according to before CPB(T0),the end of 1D(T1),3D(T2),7d(T3)4 time points,each group of 12.Rats were trained in water maze for five days,once a day four times before operation.Each group use the water maze experiment to test the POCD from each time point Then the animals were sacrificed for brain sample after serum samples were collected.Extent of brain damage such as the morphological changes was observed by HE staining.The serum S-100β、Interleukin-1β and tumor necrosis factor-α(TNF-α)was detected by ELISA.The distribution and expression of nuclear factor-κB(NF-κB)protein expression was detected by Western blot.Results:The water maze experiment’s results show that:compared with T0,The average incubation period was increased first and then decreased in group C at T1-3 The tendency that the number of times rats came across the original table,the distance and time rats swam in the target was reduced firstly and then increased.the longest incubation period of time appeared at T1(p<0.05).All above index has no obvious change in group S at each time point.In the hidden platform training experiment,compared with S group,the Incubation period of time to find the platform were extended in group C rats at T1-3(p<0.05).In space exploration experiments,compared with S group,the number of times rats came across the original table,the distance and time rats swam in the target were reduced in group C at T1-3(p<0.05).Compared with T0,the tendency that the levels of plasma TNF-α、S-100β、IL-1β and the expression of NF-κB protein in hippocampus was increased firstly and then reduced in group C at T1-3,and the peak appeared at T1(p<0.05).Compared with group S,the levels of plasma TNF-α、S-100β、IL-1 β and the expression of NF-κB protein in hippocampus were increased in group C at T1-2,and all above index has no obvious change at T3.Then HE staining showed that hippocampa was normal in group S,the hippocampus was damaged seriously in group C at Ti.The second part:To investigate the effect and mechanism of the kappa opioid agonist on postoperative cognitive function(POCD)induced by cardiopulmonary bypass(CPB).Methods:60 adult male SPF grade SD rats,aged 5-6 months,weighing 400-500g,were randomly divided into 5 groups(n = 12 each):sham operation group(group S),CPB operation group(group C),CPB+U50488H group(group K),CPB+U50488H intracerebral injection group(group B)and CPB+UU50488H+Nor-BNI group(group N).Rats were trained in water maze for five days,once a day four times before operation.The cauda and jugular arteries and jugular vein were cannulated at each group.CPB was performed for 60 min,except for group S.U50488H group(1.5mg/kg)or U50488(1.5mg/kg)+ Nor-BNI(2mg/kg)were administered intraperitoneally 30min prior to CPB in groups K and N respectively.U50488H(50 ug)were intracerebral injected in B group by brain stereotaxic instrument 30 min before extracorporeal circulation,while the equal volume of normal saline was added in groups S and C.One day after CPB,each group use the water maze experiment to test the POCD.Then the animals from each time point were sacrificed for brain sample after serum samples were collected.Extent of brain damage such as the morphological changes was observed by HE staining.The serumm α7nAChR、ChAT、AchE、S-100β、Interleukin-1 β and tumor necrosis factor-a(TNF-a)was detected by ELISA.The distribution and expression of nicotinic acetylcholine receptora7 subunit protein level and nuclear factor-κB(NF-κB)protein expression was detected by Western blot.Results:The water maze experiment’s results show that:compared with S group,the Incubation period of time to find the platform were extended,the number of times rats came across the original table,the distance and time rats swam in the target were reduced in all other groups at T1-3(p<0.05).Compared with C group,the incubation period of time to find the platform were reduced,the number of times rats came across the original table,the distance and time rats swam in the target were extended in group K、B(p<0.05).There was no obvious change in group N compared with C group(p>0.05).Compared with K group,the incubation period of time to find the platform were extended,the number of times rats came across the original table,the distance and time rats swam in the target were reduced in group N(p<0.05).There was no obvious change in group B(p>0.05)compared with K group.Compared with group S,the levels of plasma TNF-α、S-100β、IL-1β and the expression of NF-kB protein in hippocampus was increased in all other groups(p<0.05).Compared with group C,all above index were reduced in group K and B(p<0.05),there was no obvious change in group N(p>0.05).Compared with group K,all above index were increased in group N(p<0.05),there was no obvious change in group B(p>0.05).Compared with group S,the expression of nicotinic acetylcholine receptora7 subunit protein in hippocampus was increased in all other groups(p<0.05).Compared with group C,all above index were increased in group K and B(p<0.05),there was no obvious change in group N(p>0.05).Compared with group K,all above index were reduced in group N(p<0.05),there was no obvious change in group B(p>0.05).Compared with group S,the levels of a7nAChR.ChAT、AchE in hippocampus was reduced in group C and N(p<0.05).while the levels of above index in group K and B were no statistically difference(p>0.05).Compared with group C,all above index were increased in group K and B(p<0.05),there was no obvious change in group N(p>0.05).Compared with group K,all above index were reduced in group N(p<0.05),while the levels of above index in group N were no statistically difference(p>0.05).The histomorphology damage of hippocampus in group N was the most seriously,while that in group S was lightest.Compared with group C,the histomorphology damage of hippocampus in group K and B was less seriously.Conclusins:1.Cardiopulmonary bypass(CPB)can cause hippocampal damage and lead to the occurrence of POCD in rat,and it was the most significant in the first day after operation,CPB may activate the nf-kappa B protein expression and arouse inflammation reaction.2.κ-opioid Receptor agonist can protects POCD induced by CPB.3.κ-opioid Receptor agonist agonist can activate a7nAChR in peripheral and intracerebral,inhibit the expression of NF-kB signaling pathways downstream the cholinergic anti-inflammatory pathway,reduce inflammation,and play a protective role of on POCD induced by CPB. |
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