[Abstract Title]. - Society for Neuroscience

52619, B. Research Grant (principal investigator, collaborator or consultant and pending grants
as well as grants already received).
Poster
283. Stress-Regulated Pathways II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 283.12/PP8
Topic: E.06.f. Stress modulated pathways
Support: NIMH Grant 067651
Title: Changes in intracellular mechanisms in the basolateral amygdala (BLA) involved in
repeated stress
Authors: *N. GRISSOM 1,2 , S. LUZ 2 , J. SINGARAVELU 2 , H. CHUNG 2 , S. BHATNAGAR 3,2 ;
1 Dept Psychol, Univ. Michigan, Ann Arbor, MI; 2 Anesthesiol., Children's Hosp. of Philadelphia,
Philadelphia, PA; 3 Anesthesiol., Univ. of Pennsylvania Med. Sch., Philadelphia, PA
Abstract: Repeated exposure to a stressor leads to adaptive changes in responses to the familiar
stressor. For example, while a first exposure to restraint elicits a high degree of hypothalamicpituitary-adrenal
(HPA) activity, by the 5th restraint, the HPA response is significantly reduced,
a phenomenon known as habituation. Habituation of HPA activity is associated with activity in a
distributed network of limbic brain regions. One such region is the basolateral amygdala (BLA).
We have previously shown that administration of the beta-receptor antagonist propranolol into
the BLA immediately following each of 4 daily exposures to 30 minute restraint prevents normal
habituation to the 5th restraint. Recently we have begun investigating intracellular changes,
including epigenetic alterations, occurring in the BLA and other limbic brain regions which
might underlie the effects of beta-adrenergic receptor blockade in the BLA on habituation to
stress. Our preliminary results indicate that repeatedly restrained animals show decreased
acetylation of the histone H3 in the BLA compared to acutely stressed rats. Histone acetylation
changes are one form of epigenetic alteration; decreases in acetylation of H3 are associated with
decreased gene expression. In contrast to the changes seen in the BLA, no change in acetylation
of H3 was seen in the dorsal hippocampus of repeatedly stressed animals as compared to acutely
stressed rats. We are currently investigating the effect of propranolol administration on repeatedstress-related
changes in histone acetylation in the BLA, as well as other intracellular changes in
the BLA and other regions. The current data indicate that a long-term changes occur in the BLA
as a result of repeated stress, and may be important for normal adaptation to stress.