Hyperexcitability: exaggerated fear-potentiated startle produced by partial amygdala kindling.
The present study asked whether partial amygdala kindling would affect the expression of conditioned fear-potentiated startle. Rats were conditioned to be fearful of a light. They were then stimulated bilaterally in the amygdala or hippocampus on 2 consecutive days (partial kindling). Rats were tested 24 hr later for fear-potentiated startle. Amygdala-kindled rats had exaggerated fear-potentiated startle compared to sham-kindled rats. Hippocampus-kindled rats also displayed fear-potentiated startle, but no greater than that of sham-kindled rats. Partial amygdala kindling induced c-fos messenger RNA (mRNA) expression, a marker for neuronal activation, throughout the limbic and neocortices. In contrast, partial hippocampus kindling induced c-fos mRNA in the hippocampus only. The data suggest that kindled-induced hyperexcitability of the amygdala and limbic cortices produced exaggerated conditioned fear-potentiated startle.
Rosen
J B
JB
Biological Psychiatry Branch, National Institute of Mental Health, Bethesda, Maryland, USA. jrosen@udel.edu
Hamerman
E
E
Sitcoske
M
M
Glowa
J R
JR
Schulkin
J
J
D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000502:physiology*; D001245:Association Learning / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology; D005239:Fear / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D006624:Hippocampus / Q000502:physiology; D007696:Kindling, Neurologic / Q000502:physiology*; D008032:Limbic System / Q000502:physiology; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger