When citing an abstract from the 2009 Annual - Society for ...

Program#/Poster#: 582.11/GG73
Topic: F.02.f. Fear and aversive learning and memory
Support: NIMH MH073994
Title: Effects of propranolol on CREB phosphorylation in the amygdala and hippocampus of
juvenile rats exposed to predator odor
Authors: *P. A. KABITZKE 1,2 , L. K. SILVA 3 , C. P. WIEDENMAYER 1,4 ;
1 Developmental Psychobiol, NY State Psychiatric Inst., New York, NY; 2 Biopsychology &
Behavioral Neurosci., The Grad. Ctr. CUNY, New York, NY; 3 Psychology, Hunter Col. CUNY,
New York, NY; 4 Psychiatry, Columbia Univ., New York, NY
Abstract: The classic fear-conditioning paradigm employs adult animals and electric shock.
Although much has been learned from such experiments, relatively little is known about fear
learning in ecologically-relevant situations or the development of fear learning in early life.
Previously, we demonstrated that predator odors could be used to induce fear responses and
contextual fear learning in 26-day-old juvenile rats. The aim of the present study was to
investigate the role of the noradrenergic system in fear conditioning. Indeed, manipulation of the
norepinephrine (NE) system has been promising in treating fear- and anxiety-related disorders.
In particular, we hypothesized that NE is involved in the formation of long-term fear memories.
We found that systemic injections of the beta-adrenergic blocker propranolol after exposure to
cat odor inhibited the formation of contextual fear memories in juvenile rats. Next, we examined
the effects of NE manipulation on the expression of CREB, a transcription factor involved in the
formation of long-term fear memories. It was expected that fear learning increases levels of
phosphorylated CREB (pCREB) in the amygdala and hippocampus and that a NE antagonist
would inhibit this phosphorylation. We performed western blot analysis to measure levels of
pCREB in the hippocampus and amygdala after exposure to cat odor and found differences in
pCREB expression in the dorsal hippocampus, the ventral hippocampus, and amygdala in
animals that had been exposed to cat odor compared to animals that had been exposed to control
odor. Differences in pCREB expression were also seen when animals were injected systemically
with either saline or propranolol after cat odor exposure. These results support our central
hypothesis that NE mediates the formation of contextual fear memories by activation of the
transcription factor CREB. The same mechanisms that operate in the adult animal are thus
functional in juveniles but likely not in infants, who are not able to acquire contextual fear
memories.
Disclosures: P.A. Kabitzke, None; L.K. Silva, None; C.P. Wiedenmayer, None.
Poster
582. Stress and Behavior