| ELECTROLYTIC LESIONS OF THE CENTRAL NUCLEUS OF THE
AMYGDALA (CE) BUT NOT THE BED NUCLEUS OF THE STRIA TERMINALIS (BNST)
ATTENUATE CORTICOSTERONE (CORT) RESPONSE TO A CONDITIONED TONE CUE
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| J. Apergis1; G.M. Sullivan2*;
J.E. LeDoux1 |
| 1. Center for Neural Science, New York University, New
York, NY, USA |
| 2. Department of Psychiatry, Columbia University College
of Physicians & Surgeons, New York, NY, USA |
|
Lesions of either CE or BNST attenuate the
hypothalamic-pituitary-adrenal (HPA) axis release of CORT to a contextual
fear stimulus. We investigated post-training electrolytic lesions
of CE and BNST on CORT response to a tone conditioned stimulus (CS).
Male Sprague-Dawley rats received either 5 tone-shock pairings or
5 tones. After 2 days, all animals had temporary bilateral electrode
placements at one of four sites: CE, sham CE, BNST, sham BNST. The
sham groups received no current and electrodes were 1 mm higher on
the DV axis. After 5 days, the animals were placed in a novel chamber
and received 5 tones. After 20 min, the animals were sacrificed for
serum CORT and histology. CE lesions in the conditioned animals resulted
in almost complete abolishment of freezing to tones (p<.001) and
attenuation of CORT response (p<.002) to a level no different from
non-conditioned CE lesion and sham groups. In contrast, there was
no difference in level of freezing or CORT response between the BNST
lesion, sham BNST and sham CE conditioned groups. Differing from previous
work on contextual conditioning, CORT response to a tone CS was not
affected by electrolytic BNST lesions. This may indicate that a contextual
but not a tone CS activates the HPA axis by a pathway involving BNST,
possibly via hippocampus. In ongoing studies, we are re-examining
the effects of post-training electrolytic lesions of CE and BNST on
CORT response to contextual fear stimuli.
Supported by: MH 58911-02 and the Anxiety Disorders Association
of America
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