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Synaptic Location Is a Determinant of the Detrimental Effects of α-Synuclein Pathology to Glutamatergic Transmission in the Basolateral Amygdala
Published July 1, 2022
Output Details
Preprint June 17, 2022
Published July 1, 2022
Description
The presynaptic protein α-synuclein (αSyn) is closely linked with numerous neurological disorders, e.g., Parkinson’s disease (PD). In PD, the amygdala shows selective vulnerability to the formation of insoluble αSyn aggregates, and its circuit dysfunction can contribute to prevalent psychiatric deficits. Yet, how αSyn aggregates affect amygdala function remains elusive. In this study, we examined αSyn in glutamatergic axon terminals and the impact of its aggregation on glutamatergic transmission in the basolateral amygdala (BLA). We found that αSyn is primarily present in the vesicular glutamate transporter 1-expressing (vGluT1+) terminals in mouse BLA. This synapse- selective presence is consistent with its brain region-specific expression among glutamatergic neurons in the vGluT1+ cerebral cortex and the vGluT2+ thalamus. Moreover, αSyn aggregation was found to selectively decreases cortico-BLA transmission, but not the thalamo-BLA transmission. Additionally, αSyn aggregation decreased the level of soluble αSyn in vGluT1+ axon terminals, indicating that lower levels of αSyn might underlie an enhanced short-term depression of cortico-BLA synapses responding to repetitive stimuli. Consistently, the enhanced synaptic depression can be recapitulated in αSyn knockout mice. Thus, both basal and dynamic cortico-BLA transmission were disrupted by abnormal aggregation of αSyn. In conclusion, αSyn expression is restricted in a subset of glutamatergic synapses in BLA and its aggregation decreases cortico-BLA transmission through both gained toxicity and loss of normal function. These results might be relevant to the reduced cortical control of amygdala function that has been associated with psychiatric deficits in PD.
Identifier (DOI)
10.7554/eLife.78055