Presentation Details
| Central Nucleus of the Amygdala Neurons that Project to the Nucleus of the Solitary Tract are Influenced by Input from the Parabrachial Nucleus Sean Masterson, Abigail Muccilli, Robert Lundy. University of Louisville School of Medicine, Louisville, KY, USA |
Abstract
The central nucleus of the amygdala (CeA) is a major source of descending input to the gustatory regions of the parabrachial nucleus (PBN) and rostral nucleus of the solitary tract (rNST) and can modulate neural processing of taste information. Moreover, CeA-to-PBN and CeA-to-rNST neurons are intermingled but largely distinct populations. However, the origin of inputs to these subpopulations of CeA neurons remains unknown. We do know that PBN projects heavily to the CeA and could be one source of input that engages CeA-to-brainstem projection neurons. To test this premise, we injected an AAV virus into the PBN to anterogradely infect axon terminals in the CeA with the excitatory opsin ChR2(H134R) and the green fluorescent protein EYFP. In the same animal, cholera toxin b subunit conjugated to a red fluorescent protein (CTb-568) was injected into the ipsilateral rNST to retrogradely label CeA-to-rNST neurons. Following two-weeks for transport and gene expression, brain slices containing the CeA were prepared for whole-cell patch clamp recording from CTB-568 positive neurons combined with blue light activation of ChR2 axon terminals. Our results show that photoactivation of ChR2 produced excitatory postsynaptic potentials (EPSPs) in most CeA-to-rNST neurons (30 out of 34). In 4 of these responsive neurons, the EPSPs were followed by inhibitory postsynaptic potentials that were blocked by bath application of the GABA receptor antagonist bicuculline. Together with a recent study from my lab showing that the PBN is a major target of rNST neurons receiving CeA input, this organization could represent a brainstem-amygdala circuit whereby ascending gustatory signals can activate inhibitory CeA feedback to rNST that in turn adjusts excitatory input from PBN to CeA.
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