Search

The depolarization is also important for the short-term synaptic plasticity, known as depolarization-induced suppression of excitation (DSE). The two major types of neurons and their synapses in the lateral nucleus of amygdala (LA) are prone to plasticity. However, DSE in interneurons has not been reported in amygdala in general and in LA in particular. Therefore, we conducted the patch-clamp experiments with LA interneurons. These neurons were identified by lack of adaptation in firing rate of action potentials. In this study, we show for the first time a transient suppression of neurotransmission at synapses both within the local network and between cortical inputs and interneurons of the LA. The retrograde neurotransmission from GABAergic interneurons were comparable with that of glutamatergic pyramidal cells. That is the axonal terminals of cortical inputs do not posses selectivity toward two neuronal subtypes. However, the DSE of both types of neurons involve an increase in intracellular Ca 2+ and the release of endogenous cannabinoids (eCB) and activation of presynaptic CB1 receptors. The magnitude of DSE was significantly higher in interneurons compared with pyramidal cells, though developed with some latency., (© 2021 Kodirov et al.; Published by Cold Spring Harbor Laboratory Press.)

The amygdala is a key area of the brain where the emotional memories are stored throughout the lifespan. It is well established that synapses in the lateral nucleus of amygdala (LA) can undergo long-term potentiation, a putative cellular correlate of learning and memory. However, a type of short-term synaptic plasticity, known as depolarization-induced suppression of excitation (DSE), has not been studied previously in the amygdala in general and in the LA in particular. In this study we aimed to prove either the absence or the presence of this phenomenon in the LA. Our data demonstrate for the first time that DSE is present in the LA and that it modulates the cortical excitatory synaptic input into this region. The existence of this type of retrograde neurotransmission in glutamatergic pyramidal neurons of the LA suggests that the axonal terminals of cortical inputs do possess functional type 1 cannabinoid receptors, and provides a novel insight regarding inputs into the LA. Further experiments indeed revealed endocannabinoids as the messenger for this retrograde signaling in the LA. In conclusion, the DSE may play a functional role in synaptic plasticity and related emotional memory processing in the LA.