| ROLE OF THE NR2B SUBUNIT OF THE NMDA RECEPTOR IN LTP IN THE LATERAL AMYGDALA IN VIVO. | |
| T.Sigurdsson*; G.E.Schafe; R.Lamprecht; J.E.LeDoux | |
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| During auditory fear conditioning, an auditory conditioned
stimulus (CS) comes to elicit fear responses after being paired with
an aversive unconditioned stimulus (US). Several lines of evidence
suggest that this form of learning is mediated by long-term potentiation
(LTP) of synapses that transmit CS information to the lateral amygdala
(LA). We have previously shown that the NR2B subunit of the NMDA receptor
is critical for LTP in the LA in vitro, as well as for the
formation of auditory fear memories. In the present study we examined
the role of NR2B in LTP in the amygdala in vivo. In urethane-anesthetized
rats, LTP was induced in the LA by applying high-frequency stimulation
(HFS) to the auditory thalamus (MGm/PIN). This yielded an increase
in the amplitude of field potentials evoked in the LA by MGm/PIN stimulation,
which lasted for at least 1hr. To test whether the NR2B subunit was
required for LTP, HFS was applied in the presence of ifenprodil, an
NR2B antagonist, administered intraperitoneally. Under these conditions,
no LTP was observed, confirming in vivo what had previously
been demonstrated in vitro. The NR2B subunit can undergo phosphorylation
at tyrosine residues and such regulation has been implicated in synaptic
plasticity and learning. We therefore asked whether the NR2B subunit
undergoes tyrosine phosphorylation during LTP induction in the LA.
To answer this question, rats were given HFS as before and sacrificed
immediately, 15 min or 60 min later. Brain samples extracted from
the LA were then subjected to Western blot analysis and the resulting
blots were probed with anti-phosphotyrosine antibodies. Our preliminary
results suggest that immediately following HFS there is an increase
in tyrosine phosphorylation in the LA of a protein of 180 kDa, the
molecular weight of the NR2B subunit. We are currently in the process
of determining the identity of this protein. Support Contributed By: R01 MH46516 |
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| Citation: T. Sigurdsson, G.E. Schafe, R. Lamprecht, J.E. LeDoux. ROLE OF THE NR2B SUBUNIT OF THE NMDA RECEPTOR IN LTP IN THE LATERAL AMYGDALA IN VIVO. Program No. 623.3. 2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2003. Online. |
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