The Journal of Neuroscience, November 26, 2008, 28(48):12682-12690; doi:10.1523/JNEUROSCI.2305-08.2008
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Behavioral/Systems/Cognitive
The Role of Neuropeptide Y in the Expression and Extinction of Fear-Potentiated Startle
Alisa R. Gutman,
Yong Yang,
Kerry J. Ressler, and
Michael Davis
Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine and Center for Behavioral Neuroscience, Atlanta, Georgia 30329
Correspondence should be addressed to Dr. Michael Davis, Robert W. Woodruff Professor, Department of Psychiatry and Behavioral Sciences, Center for Behavioral Neuroscience, Yerkes Research Center, Emory University, 954 Gatewood Drive, Atlanta, GA 30329. Email: mdavis4{at}emory.edu
Neuropeptides are a promising target for novel treatments for anxiety and other psychiatric disorders and neuropeptide Y (NPY) has emerged as a key component of anxiolytic circuits in the brain. For this reason, we have evaluated the role of NPY in the expression and extinction of conditioned fear. We found that intracerebroventricular administration of NPY inhibits both baseline acoustic startle and the expression of fear-potentiated startle. Infusion of NPY (10 pmol/side) into the basolateral, but not the medial, nucleus of the amygdala reproduced the intracerebroventricular effect. Central administration of NPY (10 µg) also enhanced within-session extinction of fear-potentiated startle. This finding, coupled with the growing body of literature correlating NPY with resilience in humans, led us to the hypothesis that NPY may enhance the extinction of conditioned fear. When NPY (10 µg) is administered intracerebroventricularly before extinction training, extinction retention for both the contextual and cued components of conditioned fear is enhanced when tested 48 h later off drug. Additionally, we found that intra-basolateral amygdala administration of the NPY Y1 receptor antagonist BIBO 3304 (200 pmol/side) before extinction training led to a profound deficit in extinction retention. This is the first evidence that NPY facilitates and an NPY antagonist blocks the extinction of conditioned fear. We believe that the role of NPY in the extinction of conditioned fear may, at least in part, explain the mechanism underlying the association between NPY and psychobiological resilience in humans.
Key words: neuropeptide; extinction; fear; startle; rat; basolateral amygdala; amygdala; behavior
Received May 21, 2008;
revised Sept. 5, 2008;
accepted Oct. 4, 2008.
Correspondence should be addressed to Dr. Michael Davis, Robert W. Woodruff Professor, Department of Psychiatry and Behavioral Sciences, Center for Behavioral Neuroscience, Yerkes Research Center, Emory University, 954 Gatewood Drive, Atlanta, GA 30329. Email: mdavis4{at}emory.edu
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