Frequency-dependent impairment of hippocampal LTP from NMDA receptors with reduced calcium permeability.

Changes in postsynaptic Ca2+ levels are essential for alterations in synaptic strength. At hippocampal CA3-to-CA1 synapses, the Ca2+ elevations required for LTP induction are typically mediated by NMDA receptor (NMDAR) channels but a contribution of NMDAR-independent Ca2+ sources has been implicated. Here, we tested the sensitivity of different protocols modifying synaptic strength to reduced NMDAR-mediated Ca2+ influx by employing mice genetically programmed to express in forebrain principal neurons an NR1 form that curtails Ca2+ permeability.

Impaired synaptic scaling in mouse hippocampal neurones expressing NMDA receptors with reduced calcium permeability.

NMDA receptors (NMDARs) play a crucial role for the acquisition of functional AMPARs during Hebbian synaptic plasticity at cortical and hippocampal synapses over a short timescale of seconds to minutes. In contrast, homeostatic synaptic plasticity can occur over longer timescales of hours to days. The induction mechanisms of this activity-dependent synaptic scaling are poorly understood but are assumed to be independent of NMDAR signalling in the cortex.

Glutamatergic plasticity by synaptic delivery of GluR-B(long)-containing AMPA receptors.

Activity-driven delivery of AMPA receptors is proposed to mediate glutamatergic synaptic plasticity, both during development and learning. In hippocampal CA1 principal neurons, such trafficking is primarily mediated by the abundant GluR-A subunit. We now report a study of GluR-B(long), a C-terminal splice variant of the GluR-B subunit.

Importance of the gamma-aminobutyric acid(B) receptor C-termini for G-protein coupling.

Functional gamma-aminobutyric acid(B) (GABA(B)) receptors assemble from two subunits, GABA(B(1)) and GABA(B(2).) This heteromerization, which involves a C-terminal coiled-coil interaction, ensures efficient surface trafficking and agonist-dependent G-protein activation. In the present study, we took a closer look at the implications of the intracellular C termini of GABA(B(1)) and GABA(B(2)) for G-protein coupling.