The mouse cerebral cortex contains neurons that express choline acetyltransferase (ChAT) and are a potential local source of acetylcholine. However, the neurotransmitters released by cortical ChAT+ neurons and their synaptic connectivity are unknown. We show that the nearly all cortical ChAT+ neurons in mice are specialized VIP+ interneurons that release GABA strongly onto other inhibitory interneurons and acetylcholine sparsely onto layer 1 interneurons and other VIP+/ChAT+ interneurons. This differential transmission of ACh and GABA based on the postsynaptic target neuron is reflected in VIP+/ChAT+ interneuron pre-synaptic terminals, as quantitative molecular analysis shows that only a subset of these are specialized to release acetylcholine. In addition, we identify a separate, sparse population of non-VIP ChAT+ neurons in the medial prefrontal cortex with a distinct developmental origin that robustly release acetylcholine in layer 1. These results demonstrate both cortex-region heterogeneity in cortical ChAT+ interneurons and target-specific co-release of acetylcholine and GABA.
- Bernardo L Sabatini
- Adam J Granger
- Mahmoud El-Rifai
- Adam J Granger
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: This study was performed in accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the NIH, and according to strict adherence to the protocols approved by the Institutional Animal Care and Use Committee (IACUC) of Harvard Medical School (protocol #IS00000571). Routine examination, veterinary care, disease surveillance, and animal use compliance were all carried out by certified veterinary staff of the Harvard Center for Comparative Medicine (HCCM) in addition to full daily animal husbandry provided by trained animal technicians.
- Solange P Brown, Johns Hopkins University, United States
© 2020, Granger et al.
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