The relation of emotional behavior to plasma catecholamines, cortisol and ventricular arrhythmia

Hypothalamic stimulation applied through chronically implanted electrodes elicits several kinds of emotional behavior in conscious cats. We chose 3 kinds of emotional behavior, i.e., restlessness, threat and searching-biting. Under lightly anesthetized condition, we examined the changes of E, NE, DA and cortisol levels in arterial plasma and the cardiovascular responses (changes of systolic and diastolic blood pressure, heart rate and the occurrence of poststimulus ventricular arrhythmia) associated with electrical stimulation of specific sites within the hypothalamus. Both in restlessness and threat groups, elevation in systolic blood pressure was significantly greater and also the occurrence of ventricular arrhythmia and elevation in diastolic blood pressure tended to be greater than in the searching-biting group. Plasma E, NE, DA and cortisol increased significantly in restlessness and threat groups but remained unchanged in searching-biting and control groups. The ratios of changed values in catecholamines: delta E/delta NE, delta E/delta DA or delta NE/delta DA were not significantly different between any groups of emotional behavior. Furthermore, in the restlessness group, delta E, delta NE and delta DA all showed significant correlation with both the number of ventricular arrhythmia and changes of diastolic blood pressure; and the number of ventricular arrhythmia showed significant correlation with both the changes of diastolic blood pressure and heart rate. None of these correlations was observed in the threat or searching-biting group. These results suggested that restlessness and threat behaviors were more closely related to stress response than searching-biting behavior in cats. The differences in the endocrine and cardiovascular responses between restlessness and threat behavior were also discussed in the paper.