Influence of BR on microglial morphologies in the CIA late phase. (A) Representative images of Iba-1 immunostaining in the area postrema (AP) on PID 84 in the Veh (left panels) and BR groups (right panels). Yellow dashed lines reflect the contours of the area postrema. Boxed areas are shown at higher magnification on the lower. (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 = 435 cells from four mice; BR, n = 519 cells from six 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 = 4 mice; BR, n = 6 mice). Although the number of total (C) and cluster-B′ (F) cells are significantly lower in the BR group, there are no differences in the number and proportion of cluster-A′ cell (D and E). 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