PMC

(A) The area postrema (arrows) in NMO patient 1 (patient 1 in and table e-1) who presented a clinically documented episode of nausea and intractable vomiting shows a characteristic selective loss of AQP4 (AQP4, scale bar = 1 mm). (B) In comparison, AQP4 is preserved in the area postrema (arrows) from a control patient with acute multiple sclerosis (Ctrl-MS) (AQP4, scale bar = 1 mm). (C) Higher magnification of the NMO area postrema (right arrow in A) shows a selective loss of AQP4, while subependymal immunoreactivity of AQP4 is preserved (AQP4, scale bar = 100 μm). (D) Higher magnification of the NMO area postrema (right arrow in A) shows the loss of the characteristic rim/rosette AQP4 distribution around blood vessels (AQP4, scale bar = 50 μm). (E) Higher magnification of area postrema (left arrow in B) shows preservation of AQP4 in Ctrl-MS (AQP4, scale bar = 200 μm). (F) Higher magnification of Ctrl-MS area postrema (left arrow in B) shows the preservation of AQP4 rim distribution around blood vessels (AQP4, scale bar = 50 μm).

(A) AAV-Flex-tdTomato was injected into the area postrema of Slc17a6-ires-Cre (top) and Gad2-ires-Cre (bottom) mice, and tdTomato-positive fibers were visualized by immunohistochemistry. (B) AAV-Flex-tdTomato was injected into the area postrema of Glp1r-ires-Cre; Chat-gfp mice. GFP was visualized by native fluorescence and tdTomato-positive fibers were visualized by immunohistochemistry. (C) AAV-Flex-tdTomato was injected into the area postrema of Glp1r-ires-Cre; Calca-gfp and Calcr-ires-Cre; Calca-gfp mice. GFP was visualized by native fluorescence (CGRP neurons) and tdTomato-positive fibers were visualized by immunohistochemistry, AP: area postrema; DMV: dorsal motor nucleus of the vagus; Amb: nucleus ambiguus; RVLM: rostral ventrolateral medulla; PBN: parabrachial nucleus; dl: dorsolateral; el: external lateral; scp: superior cerebellar peduncle; scale bars: 100 μm. See also , .

Sagittal sections through the area postrema from a WT control mouse (left panels) and from a mouse with EC-specific deletion of Ctnnb1 exon 3 (right panels), immunostained as indicated. Vimentin is enriched in area postrema glia and together with the higher cell density (marked by DAPI staining) serves to distinguish the area postrema from surrounding neural tissue. In the control area postrema (left panels), ECs are MDR1-/PLVAP+. With EC-specific deletion of Ctnnb1 exon 3 (right panels), ECs in the area postrema become MDR1+/PLVAP-. In both genotypes, ECs in the surrounding brain parenchyma are MDR1+/PLVAP-. The efficiency of CreER-mediated recombination in ECs is ~90%, as judged by the conversion of EC markers. A, anterior. P, posterior. AP, area postrema. Scale bar, 200 μm.

(A) Cartoon indicating area postrema (AP) location in the brainstem; 4V: fourth ventricle; AP: area postrema; DMV: dorsal motor nucleus of the vagus. (B) Normalized expression levels of 34 cluster-defining signature genes (see for gene names) across all cells from clusters 1-7. (C) Uniform manifold approximation and projection (UMAP) plots based on single-cell transcriptome data showing seven area postrema neuron types (color coded) including excitatory (clusters 1-4) and inhibitory neurons (clusters 5-7). (D) Receptor and neurotransmitter-related genes expressed in area postrema neuron types. (E) UMAP plots indicating expression of Cre-targeted genes in area postrema neurons (left). Cre lines indicated were crossed to a Rosa26-LSL-tdTomato reporter, and native fluorescence visualized in coronal area postrema cryosections (right), scale bars: 100 μm. See also , and .