Catecholamines in rabbit nodose ganglion following exposure to an acute emotional stressor

The aim of the present investigation was to examine catecholamine content and the activities of catecholamine synthesizing and degrading enzymes in the nodose ganglia of rabbits with different patterns of arterial blood pressure during exposure to an acute emotional stressor. The stress protocol involved exposure of immobilized adult male rabbits to electrical stimulation of the ventromedial hypothalamus and the skin for 3 hours. Stress-resistant rabbits that had small fluctuations in arterial pressure during exposure to the stressor had significant reductions in levels ofnorepinephrine (NE) in the nodose ganglion during the 3 hours of stress exposure. In contrast, stress-sensitive rabbits that had progressive decreases in arterial pressure exhibited significant elevations in nodose ganglion content of NE, dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) throughout the period of stress. Tyrosine hydroxylase (TH) activity was changed during the course of the experiment while monoamine oxidase (MAO) activity was unaffected by stress exposure. The changes in nodose ganglion catecholamine content of stress-sensitive and stress-resistant rabbits suggest that the nodose ganglion plays an important role in the maintenance of cardiovascular homeostasis during exposure of animals to an acute emotional stressor.