Decrease in microglia with activated forms in the area postrema during CIA by BR on PID 35. (A) Representative images of Iba-1 immunostaining in the area postrema on PID 35 in the Veh (left panels) and BR groups (right panels). Yellow dashed lines reflect the area postrema. Boxed areas are shown at higher magnification on the lower panel. (B) Morphological plots of each microglia on the first two principal components (PC-1 and PC-2) coordinate planes with examples of their morphologies (Veh, n = 1046 cells from 11 mice; BR, n = 782 cells from 10 mice). Clustering by cell morphologies and dividing them into cluster-A (red) and -B (blue). (C–F) The density and proportion of microglia in the area postrema (Veh, n = 11 mice; BR, n = 10 mice). There are no differences in the number of total microglia (C) and cluster-B cells (F). The number and proportion of cluster-A cells (D and E) are significantly lower in the BR group. AR: aspect ratio; BR: baricitinib; cc: central canal; Circ: circularity; Feret: Feret diameter; Major: major diameter; Min Feret: minimum Feret diameter; Minor: minor diameter; NTS: nucleus of solitary tract; Peri: perimeter; PID: post-immunization day; Round: roundness; Veh: vehicle