The Effects And Mechanism Of Andrographolide On Postoperative Cognitive Dysfunction

BackgroundPOCD is a kind of cognitive ability change after operation,which is mainly manifested in the decline of memory,attention and general information processing capability after operation.The pathogenesis is still unclear,and there is no reliable treatment to interfere with the occurrence and development of POCD effectively.The morbidity of POCD is the result of multiple factors,not a single factor alone.Among all of the factors,the mechanisms of the systemic inflammatory response,cerebral microthrombosis,metabolic disturbance of oxygen,cerebral ischemia hypoperfusion and ischemia-reperfusion injury were closely related to the occurrence and development of POCD.Old age,surgical trauma,anesthesia stress and environmental factors can also aggravate the symptoms of POCD,in which age is the most important risk factor for POCD.Studies have shown that inflammation plays a key role in the onset of postoperative cognitive dysfunction in elderly patients.So the team speculated that using drug intervention during the operation and reducing neuroinflammation may help lower the incidence of POCD or improve its progression.Andrographolide is a major active component extracted from andrographolide,a Chinese herbal medicine known as natural antibiotic.It has many pharmacological characteristics,such as bacteriostasis,anti-inflammation,anti-virus,anti-platelet aggregation,hypoglycemia and immunomodulation.In recent years,it has been found that andrographolide has a preventive effect on nervous system diseases.Andrographolide can effectively inhibit the expression of inflammatory cytokines such as IL-6,NO and TNF-a in macrophages and alleviate the inflammatory reaction.Andrographolide can also inhibit the function of peroxidase,such as iNOS and COX-2,and reduce the release of inflammatory factors such as NO,prostaglandin E2 and TNF-a,so as to alleviate the inflammation of nervous system.It is rarely reported whether andrographolide can improve postoperative cognitive function.Therefore,this paper intends to select andrographolide as the target drug.First of all,we established an aged rat model of POCD to observe whether andrographolide can improve POCD,explore the protective mechanism of andrographolide on nervous system,and provide theoretical support for clinical application.Then,we evaluated the clinical value of POCD in patients undergoing cardiopulmonary bypass(CPB),to provide more new drug options for the prevention and treatment of POCD.Objective1.Investigate the protective effect and mechanism of andrographolide on the nervous system and POCD during the inflammatory reaction of the nervous system and provide a theoretical basis for the clinical application of andrographolide in improving the prognosis of patients with POCD.2.Evaluate the effect of andrographolide on cognitive function of patients undergoing cardiac valve replacement under cardiopulmonary bypass(CPB),and provide more options for the prevention and treatment of postoperative cognitive dysfunction in patients undergoing cardiopulmonary bypass(CPB).MethodsPart 1Thirty old SD male rats aged 25 months were randomly divided into 3 groups(n= 10:control group,model group and andrographolide group,respectively)after one week of adaptive feeding.Rats were deprived of diet for 8 hours before operation.They were fixed after isoflurane anesthesia.Sterilize the skin,lay aseptic towel,take the left upper abdomen longitudinal incision,and cut the abdominal wall layer by layer,then enter the abdominal cavity.Control group:In operation,abdomen was closed layer by layer after free peripheral ligaments of the spleen.Model group(Model)and andrographolide group(And):after freeing peripheral ligaments of the spleen,double line ligation of all the splenic vessels with line 1 and splenectomy were performed.If there is accessory spleen,remove together,then close the abdomen gradually.After 12 hours,the rats can have 20%glucose freely,and after 24 hours,the rats can eat freely.24 hours after operation,the control group and andrographolide group were treated with distilled water(10 ml/kg)and andrographolide 10(mg/kg)respectively,once a day for 7 days.After administration,Morris water maze test was used to evaluate the learning ability and memory retention of the rats after operation.After the water maze test was finished,the rats were anesthetized by intraperitoneal injection,and cut off the heads immediately.Then took out the whole brain,collected the blood,and quickly fixed some brain tissues in 4%paraformaldehyde for HE staining.The rest of brain tissue was used for Western blot detection.The blood was centrifuged in 4000r/min for 10 minutes,then pick up the supernatant.The serum levels of NSE,S-100?,IL-1 ?,IL-6 and TNF-a were tested by using ELISA.Western Blot was used to detect the expression of protein such as NF-?B p65,p65 p-NF-KB p65,ERK1/2,p-ERK1/2,p38MAPK and p-p38MAPK in rat brain.Part 2Forty patients undergoing cardiac valve replacement with CPB in general anesthesia,in accordance with the random number table,were divided into two groups with twenty cases in each:control group and experiment group.All surgical operations,anesthetic management and CPB were implemented by the same group of cardiac surgery team with the same scheme.After entering room,patients accepted mask hydrogen,electrocardiogramc(ECG),pulse oxygen saturation monitoring(SPO2),sedative depth monitoring by bispectral index(BIS),nasopharyngeal temperature and anus temperature monitoring and urine volume,etc.Left radial artery puncture was used to monitor arterial blood pressure.The right internal jugular vein was retrogradely inserted into the jugular bulb through the central vena cava under the guidance of ultrasound,to collect blood samples.After conventional intravenous anesthesia induction,endotracheal intubation was performed and followed by mechanical ventilation in maintenance period.PETCO2 was maintained at 35?45mmHg.Target-controlled concentration infusion of propofol was used during surgery.Anesthesia was maintained with sufentanil.According to the muscle relaxation situation,rocuronium was added discontinuously as needed.According to patient's hemodynamic changes,vasoactive agents was given to maintain the stable circulation.BIS value was maintained at 45 to 60 throughout the surgery.Drug delivery method:after anesthesia induction,experiment group was given with Andrographolide(potassium sodium pehydroandrographolide succinate for injection),2mg/mg,which was diluted with saline to 50mL and was pumped via venous.Infusion was completed before the start of CPB.Andrographolide(2mg/mg)was added into CPB preflushing fluid,and the total dose was not more than 400 mg.Control group was given with equal volume of physiological saline.The speed of infusion is consistent with the experimental group.The surgery was operated with median chest incision.After heparinization,CPB was built when activated coagulation time(ACT)was more than 480s.After the operation,patients retained endotracheal tube and returned to the extracardiac intensive care unit,and recovered.3mL blood in jugular bulb of two groups was collected before anesthesia induction(T0),30 min after CPB(T1),end of CPB(T2),6 h after CPB(T3),24 h after CPB(T4),and 48 h after CPB(T5),a total of six time points.The concentration of neuron-specific enolase(NSE)and S-100 ? protein in serum of patients were detected by enzyme linked immunosorbent assay(ELISA).Three days before surgery,7 days after surgery and one month after surgery,neuropsychological tests were performed in patients by specially trained neurologic doctors,using the Montreal Cognitive Assessment scale(MOCA),to evaluate patients' perioperative cognitive function.The higher the score,the better the cognitive ability.Less than 26 points showed that the cognitive function was impaired and the post-operative cognitive dysfunction occurred.ResultsPart 1In the 6-day water maze navigation training,with the increase of training times,the average escape latency of each group was shortened in varying degrees:from 49.74 s to 12.80 s in the control group,from 51.29 s to 41.61 s in the model group,and from 50.63 s to 19.56 s in the andrographolide group.From the second day,the escape latency of model group and andrographolide group was significantly longer than that of control group(Day2:48.48s,46.35s vs 34.66s;Day4:43.18s,31.92s vs 20.08s)(p<0.05).From the second day,compared with the model group,the escape latency of the andrographolide group was significantly shorter(Day3:45.61s vs 37.57 s;Day 5:43.36s vs 22.75s,p<0.05).After the treatment with andrographolide,the times of crossing the platform,the retention time of platform quadrant were significantly increased than those of the model group(p<0.05),and the swimming distance was shortened significantly(p<0.05).The HE staining was observed under optical microscope.The neuronal cells in the CA1 area of the rat hippocampus of the control group were neatly arranged and stained well and evenly.The neuronal cells in the model group were disorganized,irregular and unevenly stained.Compared with the model group,the neuronal cells in the CA1 area of the rat hippocampus of the andrographolide group were arranged regularly,the structure was clear and the staining was a little more uniform.NSE and S-100 ? protein were detected in venous blood of POCD rats after operation.The results showed that the content of NSES-100? protein in serum of model group and andrographolide:group was significantly higher than that of control group(p<0.05).The contents of NSE and S-100? protein in POCD rats treated with andrographolide were significantly lower than those in the model group(p<0.05).The level of serum inflammatory factor IL-1?,IL-6,TNF-a in the model group was significantly higher than that in the control group(p<0.05).Compared with the model group,the content of inflammatory factors in the serum of andrographolide group was significantly lower than that of the model group(p<0.05).Compared with the control group,the expression of NF-kappa B/MAPK pathway related protein NF-?B p65,p-NF-KB p65,ERK1/2,p-ERK1/2,p38MAPK and p-p38MAPK in model group and andrographolide treatment group were significantly increased(p<0.05).After treatment with andrographolide,the expression of each protein was significantly decreased(p<0.05),but still significantly higher than that of control group(p<0.05).Part 2There was no significant difference between the two groups in preoperative general conditions such as age,sex,body mass index,education level and cardiac function grading.There was no statistical significant difference(P>0.05)between the two groups in the type of operation,the time of aortic occlusion and CPB,the time of operation,the time of extubation and the serious complications after operation.Comparison of serum NSE and S100 ? protein levels between two groups:When preoperative(basic value)T0-,there was no significant difference in serum NSE and S100 ? protein levels between the two groups(P>0.05).The levels of serum NSE and S100 ? protein increased rapidly after the start of CPB(T1),reached the peak at the end of CPB(T2),then began to decrease gradually,and returned to the normal level at 48h after operation(T5).Compared with T0,the levels of NSE and S100? protein in serum of the two groups were increased in different degrees at the time point of T1?4,suggesting that cardiac surgery under CPB may cause brain injury to patients to a certain extent.Compared with the control group,the levels of serum NSE and S100 ?protein in the experimental group after andrographolide treatment were significantly lower than those in the control group(P<0.05),indicating that andrographolide could reduce the degree of brain injury in the patients.The first evaluation of MoCA scale was successfully completed in the two groups 3 days before operation,and there was no cognitive impairment before operation(all ? 26 points).The MoCA scores of the two groups decreased in different degrees on the 7th day after operation.The difference was statistically significant(P<0.05).Comparison between two groups showed that the MoCA score of experimental group(26.75 ±1.92)was significantly higher than that of control group(25.55 ? 1.79),and the difference was statistically significant(P<0.05),indicating that andrographolide could improve the cognitive ability of CPB patients.One month after operation,the MoCA scores of the two groups mainly recovered to the pre-operative level,indicating that the decline of cognitive ability of most patients was transient and reversible,and could be recovered.However,the MoCA scores of 5 patients in the control group and 4 patients in the experimental group were lower than 26 points,which could be considered as having occurred POCD and need to be followed up.There was no significant difference in the incidence of POCD between the two groups on the 7th day after operation and 1 month after operation(P>0.05).Conclusion1.Andrographolide can attenuate the inflammatory response of nervous system in POCD rats and alleviate the symptoms of POCD in aged rats.2.Andrographolide may reduce the degree of nervous system inflammation in POCD rats by regulating NF-?B signaling pathway and MAPK/ERK signaling pathway.3.Andrographolide can reduce perioperative brain injury in patients undergoing cardiopulmonary bypass(CPB),through anti-inflammatory action.4.Andrographolide can improve the score of neuropsychological test,and improve the cognitive ability of patients after cardiopulmonary bypass(CPB).