Archival Report| Volume 67, ISSUE 12, P1128-1136, June 15, 2010

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Chronic Stress Causes Amygdala Hyperexcitability in Rodents


      Chronic stress is a major health concern, often leading to depression, anxiety, or when severe enough, posttraumatic stress disorder. While many studies demonstrate that the amygdala is hyperresponsive in patients with these disorders, the cellular neurophysiological effects of chronic stress on the systems that underlie psychiatric disorders, such as the amygdala, are relatively unknown.


      In this study, we examined the effects of chronic stress on the activity and excitability of amygdala neurons in vivo in rats. We used in vivo intracellular recordings from single neurons of the lateral amygdala (LAT) to measure neuronal properties and determine the cellular mechanism for the effects of chronic stress on LAT neurons.


      We found a mechanism for the effects of chronic stress on amygdala activity, specifically that chronic stress increased excitability of LAT pyramidal neurons recorded in vivo. This hyperexcitability was caused by a reduction of a regulatory influence during action potential firing, facilitating LAT neuronal activity. The effects of stress on excitability were occluded by agents that block calcium-activated potassium channels and reversed by pharmacological enhancement of calcium-activated potassium channels.


      These data demonstrate a specific channelopathy that occurs in the amygdala after chronic stress. This enhanced excitability of amygdala neurons after chronic stress may explain the observed hyperresponsiveness of the amygdala in patients with posttraumatic stress disorder and may facilitate the emergence of depression or anxiety in other patients.

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      Linked Article

      • Amygdala Activity, Fear, and Anxiety: Modulation by Stress
        Biological PsychiatryVol. 67Issue 12
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          Over the past approximately 30 years, the neuroscience community has made terrific strides in its understanding of the small region in the temporal lobe named for its peculiar almond shape, the amygdala. This area now provides among the best examples of how neural circuits control specific behaviors. In terms of our depth of understanding of its afferent and efferent connections, the role of incoming signals in modulating emotion-related behavior, and the functional and anatomic results of its projection patterns, the detailed understanding of the amygdala is unsurpassed.
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