*D. E. BUSH, A. GEKKER, J. E. LEDOUX;
Ctr Neural Sci, New York Univ, New York, NY.

Fear conditioning is a form of Pavlovian learning that endows an initially neutral conditioned stimulus (e.g. a tone) with fear-eliciting properties by association with an aversive unconditioned stimulus (e.g. a footshock). The amygdala is essential for the acquisition and maintenance of fear conditioning, and is known to receive substantial inputs from midbrain ascending noradrenergic neurons. Amygdala beta-adrenergic receptors have been implicated in fear memory reconsolidation, but thus far little is known about the role of these receptors in fear memory acquisition and consolidation. We therefore assessed the effects of pre-training intra-amygdala propranolol, a beta-adrenergic antagonist, on short-term memory (STM) and long-term memory (LTM) for auditory fear conditioning. Male Sprague-Dawley rats were pretreated with propranolol (0, 0.1 or 1 µg; in 0.25 µl aCSF) microinjections into the lateral amygdala, approximately 45 min prior to the commencement of auditory fear conditioning. Fear conditioning consisted of three 30-sec tone (5kHz, 80dB SPL) presentations that each co-terminated with a mild footshock (1sec, 0.6mA). Testing for tone-elicited freezing in the absence of footshock took place in a distinct context, either 3 hrs (STM) or 48 hrs (LTM) after fear conditioning. Results showed that pre-training intra-amygdala propranolol significantly disrupted freezing in both STM and LTM tests. Propranolol microinjections into surrounding regions outside the lateral amygdala had no effect. These results indicate that amygdala beta-adrenergic receptors are important during the early stages of fear memory formation. Further experiments are underway to determine whether amygdala beta-adrenergic receptors contribute to fear memory acquisition, or to an early phase of memory consolidation
Support Contributed By:R01 MH046516;R37 MH38774;P50 MH058911;K05 MH067048

Program No. 370.7/KK25
Poster presentation:Monday, Oct 16, 2006, 10:00 AM -11:00 AM
Location: Georgia World Congress Center: Halls B3-B5