Effects of myocardial infarction and captopril therapy on anxiety-related behaviors in the rat.

The angiotensin-converting enzyme inhibitor, captopril, is used in the treatment of heart failure after myocardial infarction. This study evaluated whether different behavioral parameters of anxiety are affected by captopril therapy after myocardial infarction in rats. Myocardial infarction was induced by ligation of the left coronary artery and captopril therapy was started after 3 weeks. After 2 weeks of captopril therapy, anxiety-related behaviors were successively measured in four different tests: open field, elevated plus maze, home cage emergence, and open field escape. Myocardial infarction and captopril therapy affected behavior in the home cage emergence test and open field escape test. On the basis of the data from the open field escape test, captopril therapy appeared to decrease anxiety in infarcted rats and increase anxiety in sham rats. Because myocardial infarction and captopril therapy did not affect anxiety-related behaviors in the open field and elevated plus maze tests, it is assumed that these interventions affect anxiety-related behaviors depending on the type of test. This was partially supported by correlation analysis, which suggested that the behavior of the rats in the different tests of anxiety may reflect different anxiety-related traits.