Behavioral changes following chronic myocardial infarction in rats

Abstract

Myocardial infarction evokes major physiological changes because of the acute loss of functional cardiac tissue, resulting in more or less severe symptoms of congestive heart failure. In addition, general well-being of patients, their quality of life, is reduced. This includes anxiety/depression, loss of interest in environment and social interactions, sexual problems, and sleep disturbances. Postinfarction treatment is aimed mainly at improving life expectancy, whereas less attention is paid to the quality of that life. The aim of the present study was to determine behavioral changes after myocardial infarction in a (otherwise proven as clinically relevant) rat model for heart failure after myocardial infarction. We have chosen four behavioral tests based upon certain aspects of quality of life in patients. Anxiety/depression, interest in environment, and mobility, tested in an open field, revealed that infarcted rats are more anxious (as inferred from a higher preference for the safe corner area and less visits to the middle area), have less interest in a new environment [as indicated by less exploratory behavior and a longer time before they go into the new area (free exploration)], and showed less mobility (as indicated by reduced distance walked and less time spent on walking). In a test on social interaction, infarcted rats spent less time on social behavior and displayed even somewhat more walking away, suggesting active avoidance of social interaction. The observed behavioral changes in infarcted rats match very well with the aspects of reduced quality of life in postinfarct patients. Therefore, we conclude that the presented behavioral tests, in combination with our previously described functional hemodynamic measurements, could provide a new basis to study treatment that improves hemodynamic state as well as the quality of life.