Direct modulation of synaptic vesicle priming by GABAB receptor activation at a glutamatergic synapse

Publisher Website
Google Scholar
Abstract
Second messenger cascades involving G proteins1,2 and calcium3 are known to modulate neurotransmitter release4,5. A prominent effect of such a cascade is the downmodulation of presynaptic calcium influx6,7, which markedly reduces evoked neurotransmitter release5,7,8. Here we show that G-protein-mediated signalling, such as through GABA (γ-amino butyric acid) subtype B (GABAB) receptors, retards the recruitment of synaptic vesicles during sustained activity and after short-term depression. This retardation occurs through a lowering of cyclic AMP, which blocks the stimulatory effect of increased calcium concentration on vesicle recruitment. In this signalling pathway, cAMP (functioning through the cAMP-dependent guanine nucleotide exchange factor) and calcium/calmodulin cooperate to enhance vesicle priming. The differential modulation of the two forms of synaptic plasticity, presynaptic inhibition and calcium-dependent recovery from synaptic depression, is expected to have interesting consequences for the dynamic behaviour of neural networks.