Plasma catecholamines associated with hypothalamically-elicited flight behavior.

Hypothalamic sites were selected which elicited flight (escape) behavior in the freely moving cat. Sympatho-adrenal (SA) activation was determined by measuring the levels of norepinephrine (NE) and epinephrine (E) in bilateral adrenolumbar and peripheral venous plasma following stimulation of these 29 hypothalamic sites in 18 anesthetized cats. Heart rate (HR) and mean arterial pressure (MAP) were continuously monitored to permit comparisons between SA and cardiovascular (CV) activation. The most frequent SA response was a bilateral increase in the output of NE and E from the adrenal medulla greater than or equal to 10 ng/min. Increases in MAP during hypothalamic stimulation were significantly correlated with bilateral increases in both adrenal CAs, while increases in HR were significantly correlated with increases in peripheral venous NE. The data suggest that hypothalamic regions which elicit flight behavior overlap with regions that activate the adrenal medullary and CV systems. The SA activation that accompanied hypothalamically-elicited escape is compared to SA activation associated with hypothalamically-elicited affective defense.