Postsynaptic GABABRs inhibit L-type calcium channels and abolish long-term potentiation in hippocampal somatostatin interneurons
Booker SA, Loreth D, Gee AL, Watanabe M, Kind PC, Wyllie DJA, Kulik Á, Vida I.
Inhibition provided by local GABAergic interneurons (INs) activates ionotropic GABAA and metabotropic GABAB receptors GABABRs). Despite GABABRs representing a major source of inhibition, little is known of their function in distinct IN subtypes. Here, we show that, while the archetypal dendritic- inhibitory somatostatin-expressing INs (SOM-INs) possess high levels of GABABR on their somato-dendritic surface, they fail to produce significant postsynaptic inhibitory currents. Instead, GABABRs selectively inhibit dendritic Cav1.2 (L-type) Ca2+ channels on SOM-IN dendrites, leading to reduced calcium influx and loss of long-term-potentiation at excitatory input synapses onto these INs. These data provide a mechanism by which GABABRs can contribute to disinhibition and control the efficacy of extrinsic inputs to hippocampal networks.
