Nucleus of the solitary tract chemical stimulation induces extracellular norepinephrine release in the lateral and basolateral amygdala

The NTS catecholaminergic neurons, activated by a variety of afferent stimuli, are ideally situated to coordinate afferent signaling to multiple brain regions. In particular, there is evidence that systemic epinephrine injections induce a significant increase of norepinephrine (NE) in the amygdala during enhanced memory, which can be disrupted by NTS chemical blockade or interruption of vagal afferents. The present experiment was conducted to obtain information about the levels of NE release induced by activation of the whole NTS, which projects to the lateral and basolateral amygdala. Therefore, we compared NE levels before and after general stimulation of the NTS and the amygdala in anesthetized rats, without any behavioral or vagal stimulation, to find out the degree of noradrenergic activation modulated by the NTS through all its projections to the lateral and basolateral amygdala, as well as the degree of noradrenergic activation which may occur locally in the amygdala through rapid and general activation of this structure.