Chronic cold stress alters prefrontal cortical modulation of amygdala neuronal activity in rats.
BACKGROUND
Recent studies suggest that long-term exposure to stress can sensitize animals to subsequent novel or acute stressors. Stressors affect amygdala activity, and the prefrontal cortex has been implicated in the regulation of responses to stress. Little is known, however, about how the physiology of amygdala neurons is altered by chronic stressors or the role of the prefrontal cortex in these changes.


METHODS
We used in vivo extracellular recordings from neurons in the rat central and basolateral amygdala nuclei to examine the effects of chronic stress on the basal firing and responses of amygdala neurons to a novel stressor. Additionally, prefrontal cortical afferents were severed to examine its role in the modulation of the response to stressors.


RESULTS
Chronic exposure to cold enhanced the sensitivity of central amygdala neurons to footshock. A portion of this may be due to enhanced basolateral amygdala output. Furthermore, prefrontal cortical regulation of this response is weakened by chronic stress.


CONCLUSIONS
The physiology of the amygdala is altered by chronic stress. Furthermore, the prefrontal cortical regulation of these responses may be weakened after chronic stress. This is a potential biological substrate for abnormal affect upon chronic stress and its effect on affective disorders.
Correll
Cynthia M
CM
Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Rosenkranz
J Amiel
JA
Grace
Anthony A
AA
D000200:Action Potentials / Q000502:physiology; D000679:Amygdala / Q000503:physiopathology*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D003080:Cold Temperature / Q000009:adverse effects*; D004597:Electroshock / Q000009:adverse effects; D008297:Male; D009474:Neurons / Q000502:physiology*; D017397:Prefrontal Cortex / Q000166:cytology* / Q000293:injuries / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000209:etiology* / Q000503:physiopathology; D013997:Time Factors