Synaptic activation of AMPA receptors inhibits GABA release from cerebellar interneurons.

A single neurotransmitter elicits diverse physiological responses through activation of multiple receptor subtypes and/or heterosynaptic interactions involving distinct synaptic targets. We found that a typical excitatory transmitter released from the climbing fiber (CF) in the cerebellar cortex not only excited Purkinje cells directly but also presynaptically inhibited GABAergic transmission from interneurons converging on the same Purkinje cells. Both homosynaptic and heterosynaptic actions of the CF transmitter (possibly glutamate) were mediated by activation of AMPA receptors.

GABA(B) receptor-mediated presynaptic inhibition of glutamatergic and GABAergic transmission in the basolateral amygdala.

The information processing at central synapses is mediated not only by homosynaptic transmission with direct synaptic connections but also by heterosynaptic interactions between distinct synaptic inputs. Using rat brain slices and whole-cell recordings this study aimed to examine the roles of GABA(B) receptors in synaptic interactions in the basolateral amygdala (BLA), a critical brain structure related to fear and anxiety. Stimulation in the BLA produced non-NMDA type glutamate receptor antagonist-sensitive excitatory postsynaptic currents (EPSCs) and bicuculline-sensitive inhibitory postsynaptic currents (IPSCs) in the BLA neurons.