Presentation Details
| Visualizing the central targets of peripheral gustatory and interoceptive neurons by transsynaptic labeling Gennady Dvoryanchikov1, Kathleen Depina1, Pantelis Tsoulfas2, Nirupa Chaudhari1. 1Dept of Physiology & Biophysics, University of Miami School of Medicine, Miami, FL, USA.2Miami Project to Cure Paralysis, University of Miami School of Medicine, Miami, FL, USA |
Abstract
Peripheral sensory neurons of the trigeminal, gustatory and vagal ganglia relay information from chemical and mechanical stimuli to 2nd order neurons in the brainstem and spinal cord. Yet, identifying the specific target neurons of particular peripheral axon types is challenging. We produced a construct of wheat germ agglutinin (WGA) fused to mCherry for Cre-dependent monosynaptic anterograde tracing. We delivered flex.WGA/mCherry (mWmC) packaged in AAV-PHP.S into Pirt-Cre mice (in which all peripheral sensory neurons are Cre+). We detected mWmC as discrete puncta in the somata of neurons in the Nucleus of Solitary Tract (NST), Paratrigeminal Nucleus (Pa5) and Area Postrema (AP) in 11 mice. Fluorescence intensity in these 2nd order sensory neurons was significantly higher than in neurons in adjacent areas (p <0.0001; Mann-Whitney 2-tailed unpaired t-test; 2300 neurons from 4 mice). Signal specificity was confirmed by injecting the above AAV into Phox2b-Cre (only gustatory and nodose peripheral neurons are Cre+) mice. Here, signal was lost from target areas of trigeminal and jugular axons. To enhance the transsynaptic signal, we produced AAV-PHP.S with mCherry replaced by mScarlet, a brighter protein with lower pKa (to promote stability in postsynaptic lysosomes). Fluorescent puncta in 2nd order sensory neurons were larger and more numerous in mice injected with mWmSc compared to mWmC, and intensity was significantly greater for mWmSc (p <0.0001; Mann-Whitney 2-tailed unpaired t-test; 423 neurons from 4 mice). This trans-synaptic labeling system is now optimized to mark 2nd order neurons that are the targets of molecularly defined peripheral sensory neurons for gustation and interoception.
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