Changes of spatial learning and memory ability in rats with heart failure after myocardial infarction / 中国组织工程研究

ABSTRACT

BACKGROUND: Chronic congestive heart failure occurs at the late stage of many heart diseases. Cognitive disability exists in chronic congestive heart failure which has been reported in most clinical studies, and measures that can successfully improve heart function can improve cognitive function.OBJECTIVE: To probe into the effect of chronic congestive heart failure after myocardial infarction on spatial learning and memory ability,and to observe the correlation between heart failure and cognitive function.DESIGN: A randomized controlled observation based on the experimental animals.SETTING: Key Laboratory of Traditional Chinese Medicine (Beijing University of Chinese Medicine), Ministry of Education.MATERIALS This experiment was performed at the Key Laboratory of Traditional Chinese Medicine (Beijing University of Chinese Medicine),Ministry of Education. in November 2001. Totally 100 healthy male rats aged 10 to 12 weeks, weighing 200 g to 220 g purchased from Beijing Weitong Lihua Experimental animal Technical Co. Ltd were enrolled and randomly divided into the operation group (n=60) and sham-operation group (n=40).METHODS: Model rats in the operation group were infarcted by ligation of the left anterior descending coronary arteries to produce acute myocardial infarction models. Those in the sham-operation group left a loose tie without ligation. The rats that showed myocardial infarction-like changes through electrocardiogram were taken as the rats for operation (n=38), and those survived rats without abnormal changes and without ligation were taken as the sham-operation group (n=25). The two groups were subdivided into 10-day gro up, 30-day group and 60-day group. Morris water maze test was performed 10, 30 and 60 days after the operation followed by hemodynamic monitoring. Among the 10-day group, 30-day group and 60-day group, rats that did not complete the whole Morris swimming test due to heart failure with poor power and died 2 days after the operation or after hemodynamic monitoring were set as heart failure end period group.Rats in the same group as those died with similar body mass were set as the control group.MAIN OUTCOME MEASURES: ① Escape logarithm latency and the good rate if cognitive ability; ② stroke volume, cardiac output per minute,heart rate and cardiac index of hemodynamics, in which cardiac index was the main index for responding heart functionRESULTS: Totally 33 rats met the criteria in the operation group and 25rats in the sham-operation group. All the animals entered the stage of result analysis. ①Results of hymodynamic index Stroke volume, cardiac output per minute and cardiac index of the rats in the 10-day group, 30-day group and 60-day group were significantly lower than those of the homochronous sham-operation group (P ＜ 0.01), and those indexes were significantly lower in the heart failure end period group than in the end period control group and each period of the operation (P ＜ 0.01-0.05). As compared with homochronous control group, the cardiac index in 10-day group, 30-day group, 60-day group and end period group was 51.21%,50.58%,55.84% and 33.91% respectively, and all were 60% lower than the normal value. ② Results of Morris water maze Logarithm latency of 10-day operation group after training of 8 times was obviously longer than that of the 10-day sham-operation group [F(1,28) =5.997,P=0.021]. As for cognitive function, it was obviously worse in the 10-day operation group than that of the 10-day sham-operation group (x2=8.142 ,P ＜ 0.005). There was no significant difference between the 30-day operation group and the 30-day sham-operation group, and there was no significant difference in the logarithm latency as well between the 60-day operation group and the 60-day sham-operation group. As for searching strategies, the good rate of general cognitive ability in the 60-day operation group was worse than that in the 60-day sham-operation group (x2=4.988 ,P ＜ 0.05). Logarithm latency prolonged significantly in the heart failure end period group than in the end period control group [F( 1,6)=19.567 ,P=0.004], and the good rate of general cognitive ability was worse in the heart failure end period than that in the end period control group(x=1 1.82,P ＜ 0.01).CONCLUSION: Spatial learning and memory ability after heart failure in rats with myocardial infarction was injured obviously 10 days after the operation, and it recovered to the normal level 30 days after the operation.Cognitive injury occurred to some extent 60 days after the operation, and the cognitive function was obviously worse at the end period of congestive heart failure.