Stress-induced activation of prefrontal cortex dopamine turnover: blockade by lesions of the amygdala.

Stress consistently has been found to activate peripheral and central catecholamine systems. Dopamine (DA) turnover in the prefrontal cortex is especially sensitive to stress produced by relatively mild footshock, conditioned fear, or exposure to a novel cage. Because lesions of the central nucleus of the amygdala block the effects of both stress and fear in many experimental paradigms, the present study evaluated whether such lesions would block stress-induced increases in prefrontal dopamine turnover using either mild footshock or novelty as stressors. In Experiment 1 electrolytic lesions of the central nucleus of the amygdala attenuated the increase in the dopamine metabolite homovanillic acid (HVA) in the prefrontal cortex evaluated in post-mortem tissue normally produced by footshock. In Experiment 2 similar lesions attenuated the increase in dopamine turnover in the prefrontal cortex using a different stressor, novelty, and a different measure of dopamine turnover, DOPAC/DA ratios. These data provide further evidence for the critical role of the amygdala in stress.