Fig. 6: Hyper-IL-6 transneuronally stimulates neurons of raphe and red nuclei.

a Schematic of cortical AAV2-hIL-6 application and isolated brain stem tissue (dashed box) containing the raphe nuclei (RN) for western blot analysis. b Western blots: GFP, total (STAT3) and phosphorylated STAT3 (pSTAT3), phospho-AKT (pAKT), and phospho-S6 (pS6) were analyzed in lysates of the brain stem with raphe nuclei isolated 3 weeks after intracortical injection of either AAV2-GFP (gfp) or AAV2-hIL-6 (hIL-6). GFP signals in lysates verified similar amounts of transduced collateral axons that projected to the brain stem. Beta-actin served as a loading control. c Densitometric quantification of western blots from 7 to 8 animals per group (gfp, n = 7; hIL-6, n = 8) as described in (a). Data represent means ± SEM. d, m Immunostaining of brain stem sections containing the nucleus raphe magnus (NRM, d), or nucleus raphe pallidus (NRPa, m) of AAV2-GFP or AAV2-hIL-6 treated mice as described in Fig. 2a. Sections were stained for pSTAT3 (red), GFP (green), and serotonin (5-HT, blue) to identify raphe neurons. The dashed yellow line indicates the midline. We observed a similar amount of pSTAT3 positive serotonergic neurons in the left and right hemisphere of the raphe nuclei from AAV2-hIL6 treated mice (n = 6). Scale bar: 200 µm. e, f, n–u Higher magnifications of the dotted box as indicated in (d) (e–l) or (m) (n–u). Significances of intergroup differences in (c) were evaluated using the two-sided student’s t-test and indicated by p-values. Dots in c represent values of samples from single animals. Source data are provided as a Source data file.