Cell Press, Neuron, 5(21), p. 1163-1175, 1998
DOI: 10.1016/s0896-6273(00)80633-9
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Hippocampal N-methyl-D-aspartate (NMDA) receptor-dependent long-term synaptic depression (LTD) is associated with a persistent dephosphorylation of the GluR1 subunit of AMPA receptors at a site (Ser-845) phosphorylated by cAMP-dependent protein kinase (PKA). In the present study, we show that dephosphorylation of a postsynaptic PKA substrate may be crucial for LTD expression. PKA activators inhibited both AMPA receptor dephosphorylation and LTD. Injection of a cAMP analog into postsynaptic neurons prevented LTD induction and reversed previously established homosynaptic LTD without affecting baseline synaptic transmission. Moreover, infusing a PKA inhibitor into postsynaptic cells produced synaptic depression that occluded homosynaptic LTD. These findings suggest that dephosphorylation of a PKA site on AMPA receptors may be one mechanism for NMDA receptor-dependent homosynaptic LTD expression.